FR3113334A1 - Current cut-off device for electrical current under high direct voltage, installation with such a device, control method, and process for evaluating the integrity of an electrical conductor - Google Patents

Abstract

Power cutting device for electric current under high direct voltage, installation with such a device, control method, and process for evaluating the integrity of an electrical conductor The invention relates to a switching device (28) for high voltage direct current comprising, successively, an isolation switch (48), a first primary point (44.1) and a first switching module (40.1); characterized in that the cutting device (28) comprises, between the first primary point (44.1) and earth (52), a pre-charge circuit (50) having a pre-charge capacitor (54, 54.1), a pre-charge resistor (56) and a pre-charge switch (58), and in that the cutting device has at least: - a charging configuration (C_CH) to allow charging of the pre-charge capacitor; - a pre-charge configuration (C_PCH) to allow discharge of the pre-charge capacitor (54, 54.1) in a conductor (12). The invention also relates to a method for controlling such a device, and a process for evaluating the integrity of an electrical conductor. . Figure for abstract: Fig. 1.

Description

Current cut-off device for electrical current under high direct voltage, installation with such a device, control method, and process for evaluating the integrity of an electrical conductor

The invention relates to the field of high voltage direct current (HVDC) electrical current cut-off devices and their control methods. Such devices are intended to be implemented in HVDC network units in the event of the appearance of an electrical fault in an electrical conductor of this network unit.

HVDC network units are in particular envisaged as a solution for the interconnection of disparate or non-synchronous electricity production sites, in particular to increase the energy transport capacity between countries (interconnections between countries), via what we call energy highways. HVDC network units are particularly considered for the transmission and distribution of energy produced by wind farms rather than alternating current technologies, due to lower line losses and no incidence of parasitic capacitances in the network unit over long distances. Such HVDC network units typically have voltage levels on the order of 100 kV and above.

In the present text, for a device in which a high DC voltage current flows, a high voltage device is considered to be either a "high voltage A" device, in which the nominal service voltage is DC and greater than 1500 V, but less than or equal to 75,000 V ( 75 kV), i.e. a “high voltage B” device when the rated service voltage is continuous and greater than 75,000 V (75 kV). Thus, the domain of high DC voltage includes the domain of “high voltage A” and that of “high voltage B”.

Breaking the DC high voltage current in such networks or network units is a crucial issue directly conditioning the feasibility and development of such networks.

Generally, in the field of high voltages, direct or alternating, at each of the two ends of an electrical conductor, there is an electrical cut-off device capable of cutting the flow of electrical current in the conductor, whether the current is the nominal current , which is the maximum current that the conductor is likely to conduct in steady state, or a fault current, which may exceed this rated current. In the event of a fault, the electrical network is designed to implement a network fault elimination strategy, aimed at interrupting the current in the faulty electrical conductor. Breaking electrical currents under high direct voltage (HVDC) is more complex to achieve than breaking currents under alternating voltage (AC). Indeed, when breaking an alternating current, we take advantage of a passage through zero of the current to carry out the electrical break, which we cannot benefit from with a current under direct voltage, in particular HVDC. In the event of a fault, the electrical network is designed to implement a network fault elimination strategy, aimed at interrupting the current in the faulty electrical conductor.

Most currently planned HVDC network units will use buried or submarine cables as electrical conductors, as right of way for overhead conductors is difficult to obtain. However, the overhead conductors of the existing overhead lines, intended for the circulation of alternating currents, could be upgraded and subsequently used in the HVDC network units as electrical conductors, which would be an attractive solution due to the both its simplicity and its cost-effectiveness.

Each of these two types of electrical conductors may, in service, experience electrical faults.

The probability of a fault occurring is higher for overhead conductors, in particular due to their exposure to harsh meteorological conditions, such as lightning strikes. Indeed, a lightning strike on an overhead conductor produces overvoltages which can temporarily affect the dielectric properties of the insulators and lead to a breakdown of the insulation. This therefore necessarily leads to having to isolate the conductor in which the fault has appeared by opening an electrical cut-off device with respect to the rest of the network. Generally, a given conductor is provided, at each of its two ends, with a breaking device, and in the event of the appearance of a fault, the two breaking devices are open to isolate the conductor, and therefore isolate the fault. compared to the rest of the HVDC network unit. After the insulation of the conductor thus impacted and after the deionization of the air, the conductor could be reconnected to the HVDC network unit since the fault generated by a lightning strike is very often non-persistent. This process is called automatic re-closing, by closing the breaking device(s) which have been opened to isolate the conductor. However, other fault scenarios could cause permanent insulation failure. In this case, automatic re-closing would lead to a second fault on the conductor in question and would require the reopening of the breaking device(s) which makes it possible to isolate this conductor. In general, the electrical network operator sets a maximum number of successive re-closure attempts that can be attempted following the isolation of a faulty conductor. These successive re-closing attempts are conducted in a short period of time to minimize the time during which the driver is unavailable. Of course, successive attempts at re-closure relating to a conductor which has a permanent fault are doomed to failure, and this succession of attempts leads to a certain number of problems concerning the stability of the network and increases the stresses on the component. breaks, such as:
- disturbances in the HVDC network unit;
- an interruption or disturbance of power flow which may lead to instability of any network units under alternating voltage connected to this network unit;
- high requirements for high energy absorption in a short time, for example in lightning arresters;
- A significant thermal impact on the components of any adjacent electrical power converters, in particular on the freewheel diodes of such converters.

The above-mentioned problems are the consequence of the fact that before the automatic re-closure, the driver's health status is unknown. Therefore, the main problem to be solved is the evaluation of the persistence of the fault on the conductor. Research has shown that recurrence of the fault is more likely at voltage levels close to the nominal voltage. Thus, a fault may not manifest at low voltage levels (see for example G. Ebner, W. Hartmann, M. Hergt and S. Wietzel, " Fault arc extinction and system re-start on HVDC transmission lines using LCC or VSC full-bridge converters with integrated arc recovery simulation models ," 13th IET International Conference on AC and DC Power Transmission (ACDC 2017), Manchester, 2017, pp. 1-5, doi: 10.1049/cp.2017.0018). This implies that a reliable assessment is only possible when the conductor is fully charged, i.e. when its electrical potential is brought to a potential which represents a significant proportion of its electrical potential in nominal operation.

It has already been proposed to arrange, in series with the conductor, an insertion resistor device consisting of a resistor in parallel with a short-circuit switch. There are solutions in which the insertion resistor device is integrated into the breaking device (see for example J. Shu, S. Wang, T. Liu, , “ A Soft Reclosing Model for Hybrid DC Circuit Breaker in VSC -MTDC System ,” 2018 IEEE 4th South. Power Electron. Conf . , pp. 1–5, 2018). In normal operation, the resistor is bypassed keeping the shorting switch in its closed state. After the faulty line is isolated by the breaking device, the short-circuit switch in parallel with the resistor goes into the open state. When re-closing the breaking device, an initial inrush current is observed due to the potential difference between the HVDC network unit and the conductor which was previously insulated and discharged through the default. In the event of a non-permanent fault, the presence of the insertion resistor in series with the conductor makes it possible to limit the inrush current and therefore to limit disturbances in the HVDC network unit. Also, the insertion resistor limits the surge in the conductor, when the incoming voltage wave is reflected at twice its rated value, considering an open circuit at the other end of the conductor. In the case of automatic re-closing on a persistent fault, the insertion resistor can also limit the fault current and therefore the voltage on the breaking device. However, even if the impact of automatic re-closing on a persistent fault is lower with an insertion resistor, there is still a disturbance on the DC network side, and component wear. Also, no prediction is made before the start of the automatic re-closing process.

In Vinothkumar, K., Segerqvist, I., Johannesson, N., & Hassanpoor, A., (2016), “ Sequential auto- reclosing method for hybrid HVDC breaker in VSC HVDC links ”, “ 2016 IEEE 2nd Annual Southern Power Electronics Conference (SPEC) ”, 1-6, the proposed solution is based on a hybrid type DCCB with several sub-modules connected in series. The hybrid type DCCB is composed of a main branch, a main breaking branch and an energy absorbing branch. The main branch contains a high-speed disconnector (UFD) and a load switching switch (LCS) in series. The main cutoff branch contains a stack of IGBT modules. Parallel to each stack, a surge suppressor (SA) absorbs energy during the opening sequence. Once the faulty overhead conductor has been isolated and the de-ionization time (200ms-500ms) has elapsed, the proposed automatic re-closing sequence proceeds as follows:
- 1. Sequential closing of the breaking modules to gradually increase the voltage on the overhead conductor side;
- 2. Verification of the persistence of the fault using a fault detection algorithm;
- 3. If the fault persists, all the breaking modules open again.

This process is repeated until the maximum number of attempts, defined by the network operator, is reached. To avoid unacceptable thermal heating of the surge limiters (SA), the document proposes to alternate the choice of breaking modules to be closed. However, this solution requires an ultra-fast circuit breaker, therefore of the hybrid type, due to the fast operating time in the event of a persistent fault. In addition, surge arresters (SA) must be designed for such energy absorption. The proposed solution still risks causing complete re-closure on a fault that is still present because no assessment of the health of the overhead conductor is made before complete re-closure, which here also leads to wear of the components.

The document WO2018162421 describes a method for closing a circuit breaker (10) having a main branch (M), which comprises a main module comprising a sub-branch comprising a mechanical switch-disconnector (UFS) connected to two circuit breaker cells consisting of a power semiconductor element with controlled duty cycle, the main branch (M) being connected to a pre-insertion module. The circuit breaker (10) and the pre-insertion module form an assembly having a first (111) and a second (112) terminal, respectively connected to a source (S) and to the power transmission link (C). In parallel with the main branch, there is a parallel arm (Arm) comprising two thyristors in opposite directions and a capacitor in parallel with both a resistor and a switch. Finally, also in parallel with the main branch, there is an energy absorption branch (Ex) which is here made in the form of a surge protector (SA3).

The method includes the steps of:
a) first closing the mechanical switch-disconnector (UFS) when the voltage difference between the voltages at the first and second terminals is less than a predefined voltage;
b) closing the bypass switch (S2); And
c) closing the power semiconductor element.

During the opening sequence, the fault current is redirected from the main branch to the parallel arm by turning on the thyristor in the parallel arm and then opening the mechanical switch-disconnector (UFS). This is possible, since the capacity was initially discharged. Once charged to the protective voltage level of the mechanical switch-disconnector (UFS), the magnetic energy is absorbed, forcing a zero crossing of the fault current. Before starting the re-closing sequence, the capacitor must be discharged by the resistor in parallel. The re-closure sequence begins with the thyristor in the parallel arm branch closing, resulting in a current that charges both the capacitor and the transmission line. In the event of a persistent fault, the capacitor continues to charge up to the protection voltage level of the surge protector and the rest of the energy is absorbed by the SA3 surge protector. The advantage of this solution is that the mechanical switch-disconnector (UFS) does not need to be opened again since the current passes directly through the parallel arm. However, in the event of a persistent fault, the initial current remains high since the reopening takes place on a discharged capacitor without any resistance. Also, the condition of the transmission line is not evaluated before re-opening.

The document S. Zhang, G. Zou, B. Li, B. Xu, and J. Li, “ Electrical Power and Energy Systems Fault property identification method and application for MTDC grids with hybrid DC circuit breaker ”, “ Electr . Power Energy System .”, vol. 110, no. January, pp. 136–143, 2019, further describes a solution implementing a hybrid breaking device. The proposed device comprises an auxiliary circuit for a hybrid breaking device. The main circuit consists of several sub-modules in series. Each sub-module is composed of an IGBT module in parallel with a snubber circuit, which basically consists of a small capacitance and a small resistor in parallel with a diode. The idea is to interconnect the sub-modules in such a way that the capacitance is used to send trigger signals (10 to 20% of the nominal voltage) in the line. In a later step, the persistence of the fault is identified using a “wavelet transform” algorithm which analyzes the reflected traveling waves created either by the fault or by the open circuit at the far end of the line. The auxiliary circuit includes at least one thyristor between each sub-module, a grounding resistor Rg and a fast grounding switch (FMS). The proposed solution aims to assess the fault condition of the transmission line before re-closure. However, several problems remain. The solution sends low amplitude tripping signals which do not provide reliable information because the fault may reappear after complete re-closure, once the line again reaches a voltage close to the nominal voltage. The intent is clearly to analyze the trigger signal and not to energize the line, so there will still be a large current when fully re-closing on the unloaded transmission line. Furthermore, the proposed solution is strongly limited to the specific architecture of the hybrid breaking device which is described.

The object of the invention is therefore to propose a device and a method which make it possible to secure the re-closing sequence of a breaking device which has been previously opened to isolate a conductor from an electrical line arranged downstream of this switching device. breaking, in particular in the case of an overhead conductor of an overhead electric power transmission line.

For this purpose, the invention proposes a cut-off device for electric current under high direct voltage comprising:
- a main circuit, in which a nominal direct current flows in a conduction configuration of the cut-off device, the main circuit extending between an upstream point intended to be electrically connected to a direct high voltage source and a downstream point intended to be electrically connected to a conductor of a downstream power line;
- at least one first cut-off module comprising at least one cut-off switch interposed in the main circuit between a first primary point and a first secondary point of the main circuit, the first primary point and the first secondary point being located in this order in the main circuit between the upstream point and the downstream point, and the cut-off switch being capable of being controlled between an open state and a closed state to respectively determine an open state and a closed state of the first cut-off module;
- an isolation switch, interposed in the main circuit between the upstream point and the first primary point, the isolation switch being capable of being controlled between an open state and a closed state.

The switching device comprises a pre-charge circuit which extends between the first primary point and ground (52) and which comprises at least one pre-charge capacitor, at least one pre-charge resistor and a pre-charge.

The breaking device has at least:
- a charging configuration in which the pre-charge switch is in a closed state such that the pre-charge capacitor, the pre-charge resistor and the pre-charge switch are all electrically in series in the pre-charge circuit between the first primary point and earth, while the first primary point is electrically isolated from the downstream point of the cut-off device but electrically connected to the upstream point to allow charging of the pre-charge capacitor;
- a pre-charge configuration in which the pre-charge switch is in its closed state such that the pre-charge capacitor, the pre-charge resistor and the pre-charge switch are all electrically in series in the pre-charge circuit between the first primary point and earth, while the first primary point is electrically isolated from the upstream point of the breaking device but electrically connected to the downstream point to allow discharge of the pre-charge capacitor in the conductor of the downstream power line;
- an isolation configuration in which the first primary point is isolated from the upstream point, with the isolation switch in its open state, and is isolated from the downstream point, with the cut-off switch in its open state.

In the conduction configuration, the pre-charge switch is open to isolate the first primary point from ground, and the upstream point is electrically connected to the downstream point by the main circuit comprising the cut-off switch and the isolation switch both in their closed state.

The invention also proposes such a device with the following optional characteristics, taken individually or in combination.

The first cut-off module may comprise a cut-off assistance circuit which extends electrically by-passing the cut-off switch and the main circuit between the first primary point and the first secondary point of the main circuit, and, in a cut-off configuration, the cut-off device can then be configured such that at least one pre-charge capacitor of the pre-charge circuit forms part of the cut-off assistance circuit of the first cut-off module.

The cut-off device may comprise, downstream of the first cut-off module in the main circuit of the cut-off device, at least one last cut-off module comprising at least one cut-off switch interposed in the main circuit between a last primary point, downstream of the first secondary point, and a last secondary point of the main circuit, and the cut-off switch of the last cut-off module being able to be controlled between an open state and a closed state to respectively determine an open state and a closed state of the last cutoff module.

The last cut-off module may comprise a cut-off assistance circuit which extends electrically by-passing the cut-off switch of the last cut-off module and of the main circuit, between the last primary point and the last secondary point of the circuit main, and, in a cut-off configuration, the cut-off device can be configured such that at least one pre-charge capacitor of the pre-charge circuit forms part of the cut-off assistance circuit of the last cut-off module .

The pre-charge circuit may comprise at least a first pre-charge capacitor and at least a second pre-charge capacitor, and, in the cut-off configuration, the cut-off device may be configured such that the first capacitor of pre-charge forms part of the cut-off assistance circuit of the first cut-off module while the second pre-charge capacitor forms part of the cut-off assistance circuit of the last cut-off module.

The cut-off device may comprise, in the main circuit of the cut-off device, between the first cut-off module and the last cut-off module, at least one additional cut-off module comprising at least one cut-off switch interposed in the main circuit between a additional primary point, downstream of the first secondary point, and an additional secondary point of the main circuit, upstream of the last primary point, and the cut-off switch of the additional cut-off module being capable of being controlled between an open state and a closed state to respectively determine an open state and a closed state of the additional breaking module.

An additional cut-off module may include a cut-off assistance circuit which extends electrically by-passing the cut-off switch of the additional cut-off module considered and of the main circuit between the additional primary and secondary points of the main circuit which correspond to the additional cut-off module considered, and, in a cut-off configuration, the cut-off device can be configured such that at least one pre-charge capacitor of the pre-charge circuit forms part of the cut-off assistance circuit of the additional breaking module.

The cut-off device may comprise a single cut-off module whose cut-off assistance circuit comprises, successively and in this order from the first primary point, the at least one pre-charge capacitor and an activation switch, with a tapping point between the two in the cut-off assistance circuit, and the pre-charge circuit may comprise a first section, which is common with the cut-off assistance circuit, which extends between the first primary point and the tapping point and which comprises the at least one pre-charge capacitor, and the pre-charge circuit comprises a second section, distinct from the cut-off assistance circuit, which extends between the tapping point and earth and in which the pre-charge switch is interposed.

The cut-off device may comprise at least one upstream cut-off module and a downstream cut-off module whose cut-off assistance circuits are, in the cut-off configuration of the cut-off device, arranged electrically in series; the cut-off assistance circuit of the downstream cut-off module may comprise, successively and in this order from the downstream primary point, the at least one pre-charge capacitor and an activation switch, with a tapping point between both in the cut-off assistance circuit, and the pre-charge circuit may comprise a first section which extends between the upstream primary point and the tapping point, which is common with the cut-off assistance circuits series cut-off, and which comprises the at least one pre-charge capacitor of each of the series cut-off assistance circuits, and the pre-charge circuit may comprise a second section, separate from the the break, which extends between the tapping point and the earth and in which the pre-charge switch is interposed.

The current breaking device may comprise a bypass circuit which extends, electrically in parallel with the main circuit, between the first primary point and a bypass point arranged between the last secondary point and the downstream point, and in which is interposed a bypass switch which is in a closed state in the pre-charge configuration and in an open state in the charging, isolation and cut-off configurations.

The breaking device may comprise a configuration switch which is arranged in the main circuit between the last secondary point and the bypass point, and which is in an open state in the pre-charging and charging configurations, and in a closed state in conduction and cut-off configurations.

The switching device may comprise at least one shunt switch which, in the charging configuration and in the pre-charging configuration, is in a closed state to connect in series, in the pre-charging circuit, the pre-charging capacitors - load belonging to the different breaking modules.

The cut-off switch of a cut-off module may comprise a primary, mechanical switch, and a secondary, mechanical switch, interposed successively in the main circuit between the primary point and the secondary point which correspond to the cut-off module considered, but of on either side of an intermediate point of the main circuit which corresponds to the cut-off module considered, the two mechanical switches each being controlled between an open state and a closed state, and this cut-off module may comprise a primary surge protector arranged in parallel the primary switch between the primary point and the intermediate point which correspond to the cut-off module considered, and a secondary surge protector arranged electrically in parallel with the secondary switch between the intermediate point and the secondary point which correspond to the cut-off module considered, and the cut-off assistance circuit of this cut-off module considered can be shut down electrically in parallel with the assembly formed by the primary switch and the secondary switch of this switching module considered, and electrically in parallel with the assembly formed by the primary surge protector and the secondary surge suppressor of this switching module considered.

The downstream electrical line may comprise an overhead line, the conductor of the downstream electrical line being an overhead conductor.

The invention also relates to an electrical installation comprising a DC high voltage source electrically connected to at least one overhead conductor of a downstream electrical line comprising an overhead line, characterized in that it comprises, interposed between the DC high voltage source and the overhead conductor of the downstream power line comprising an overhead line, a current breaking device having any of the preceding characteristics, the DC high voltage source being connected to the upstream point of the breaking device, and the overhead conductor being electrically connected by an upstream end to the downstream point of the cut-off device.

Such an electrical installation may comprise, at a downstream end of the conductor of the downstream electrical line, another current cut-off device.

The invention also relates to a method for controlling the closing of such a current breaking device, the breaking device being initially in the isolation configuration, characterized in that the controlling method comprises at least one step of pre- charging of the conductor during which the switching device is brought into its pre-charging configuration to energize a conductor of a downstream electric line downstream of the downstream point (38), and in that the method of driving in closure comprises, during or after the conductor pre-charging step, at least one parameter determination step) comprising the determination of at least one current or voltage parameter in the main circuit or in the downstream electrical line, and a decision step, during which it is decided, depending on the at least one parameter determined during the parameter determination step, whether or not to continue the complete closure of the neck device pure current by switching from the current interrupting device to the conduction configuration.

The invention also proposes such a control method with the following optional characteristics, taken individually or in combination.

Thus, in such a process it can be provided that, to reach the conduction configuration, the pre-charge switch is open before the closing of the cut-off switch and the isolation switch.

In such a method, if the decision step is not positive, provision can be made for the method to continue, without passing through the conduction configuration of the cut-off device, with a step of recharging the pre-charge capacitor at the during which the breaking device is brought into the charging configuration, then successively by a new conductor pre-charging step, a new parameter determination step, and a new decision step, according to a pre-charging cycle .

The pre-charge capacitor recharge step may include:
- closing the isolation switch and closing the pre-charge switch to charge the pre-charge capacitor, maintaining the cut-off switch in its open state;
- After said closing of the pre-charge switch, the reopening of the isolation switch.

The number of pre-charge cycles for a given attempt to re-close the breaking device can be limited.

After at least one conductor pre-charging step, complete closing of the current breaking device by passing the breaking device to its conduction configuration can be continued if a voltage value in the main circuit, or in the electrical line downstream, exceeds a threshold value.

The invention also proposes a process for evaluating the integrity of an electrical conductor in an electrical power transmission line in an electrical installation comprising a main DC high voltage source electrically connected to an upstream end of the electrical conductor, with an upstream current cut-off device interposed between the main voltage source and with a downstream end of the electric conductor connected to a downstream electric cut-off device, the evaluation process being of the type in which, in an initial state, the upstream cut-off device and the downstream cut-off device are respectively each in an isolation configuration so that, in the initial state, the electrical conductor is, except for an electrical fault affecting the electrical conductor, electrically isolated from the installation and from the environment, characterized in that the evaluation process comprises at least one step of pre-loading the driver in which an auxiliary auxiliary voltage source, separate from the main voltage source, is connected to the conductor to energize the electrical conductor while maintaining the conductor insulated from the main voltage source and from the rest of electrical installation. Such an evaluation process comprises, during or after the driver pre-charging step, at least one parameter determination step comprising the determination of at least one current or voltage parameter in the downstream electric line, and an evaluation step during which the integrity of the electrical conductor is evaluated according to the at least one parameter determined during the parameter determination step.

Such an evaluation process may comprise or be followed by a decision step, during which it is decided, depending on the at least one parameter determined during the parameter determination step, whether or not to continue complete closure of the current interrupting device by switching the current interrupting device to a conduction configuration.

FIG. 1 is a general schematic view of an electrical current transmission and distribution installation comprising a multi-terminal HVDC current network unit in which a device and a method according to the invention can be implemented.

Figure 2 shows a point-to-point HVDC current network unit in which a device and a method according to the invention can be implemented.

FIG. 3 represents a slightly more detailed view, while remaining schematic and simplified, of part of the installation 10, illustrating the environment of a cut-off device of an HVDC network unit in accordance with the teachings of the 'invention.

FIGS. 4A and 4B are simplified diagrams of the part of the installation 10 which is illustrated in FIG. 3, illustrating the isolation configuration of the switching device and a preparation configuration.

FIGS. 5A and 5B are simplified diagrams of the part of the installation 10 which is illustrated in FIG. 3, illustrating a control sequence of the breaking device including its transition from a preparation configuration to its pre-charge configuration.

FIGS. 6A to 6D are simplified diagrams of the part of the installation 10 which is illustrated in FIG. 3, illustrating a control sequence of the breaking device comprising its passage through a charging configuration of the pre-charging capacitor.

FIGS. 7A to 7C are simplified diagrams of the part of the installation 10 which is illustrated in FIG. 3, illustrating a control sequence of the switching device including its transition to a conduction configuration.

FIG. 8 is a schematic flowchart of an electrical protection method comprising a method for controlling the closing of a cut-off device 28 according to the invention.

FIG. 9A illustrates another embodiment of a switching device according to the invention.

FIG. 9B is a table indicating the switching states of the various switches of the breaking device of FIG. 9A, in different configurations of this cut-off device.

FIG. 10A illustrates another embodiment of a switching device according to the invention.

Figure 10B is a table similar to that of FIG. 9B for the cut-off device of FIG. 10A.

FIG. 11A illustrates another embodiment of a switching device according to the invention.

FIG. 11B illustrates a variant of the switching device of FIG. 11A according to the invention.

Figure 11C is a table similar to that of FIG. 9B for the breaking devices of Figs. 11A and 11B.

FIG. 12A illustrates another embodiment of a switching device according to the invention.

Figure 12B is a table similar to that of FIG. 9B for the cut-off device of FIG. 12A

FIG. 13A illustrates another embodiment of a switching device according to the invention.

Figure 13B is a table similar to that of FIG. 9B for the cut-off device of FIG. 13A.

FIG. 14A illustrates another embodiment of a switching device according to the invention.

Figure 14B is a table similar to that of FIG. 9B for the cut-off device of FIG. 14A.

FIG. 15A illustrates another embodiment of a switching device according to the invention.

Figure 15B is a table similar to that of FIG. 9B for the cut-off device of FIG. 15A.

FIG. 16A illustrates another embodiment of a switching device according to the invention.

Figure 16B is a table similar to that of FIG. 9B for the cut-off device of FIG. 16A.

FIG. 17A illustrates another embodiment of a switching device according to the invention.

Figure 17B is a table similar to that of FIG. 9B for the cut-off device of FIG. 17A.

Fig. 1 shows an example of an electrical current transmission and distribution installation 10 comprising a high voltage direct current electrical current network unit, hereinafter referred to as HVDC network unit 12 . The HVDC network unit 12 operates under a single nominal operating voltage which is a high DC voltage, for example with a continuous nominal operating voltage greater than 75,000 V (75 kV).

In an electrical network, the transmission of electrical power between two given points of the network is done by a power transmission line which generally comprises several conductors, each of which corresponds to an electrical pole of the power transmission line. In all cases, within the meaning of this text, an electrical conductor may be in the form of a single electrical conductor which extends between two distinct points of a network unit considered, or in the form of a set of electrical conductors which extend in electrical parallel between two distinct points of a network unit under consideration, all the conductors of the assembly being, at all times, at the same electrical potential for the same position between the two distinct points along each of these conductors (this in order to take into account a possible voltage drop along each given conductor due to the resistivity of the conductor).

Thus, in an HVDC network unit, the transmission of electric power between two given points of the network is done by a power transmission line which, in many cases, comprises two electric poles, each pole comprising an electric conductor which extends between the two given points of the network. In this case, the power transmission line therefore comprises two electrical conductors of different polarities, with, under load, for example an electrical conductor which is at a positive potential and an electrical conductor which is at a negative or neutral potential. Still in an HVDC network unit, the transmission of electrical power between two given points of the network can also be done by a power transmission path with three electrical poles comprising three electrical conductors, with, under load, an electrical conductor which is at a positive potential, an electrical conductor that is at a negative potential, and an electrical conductor that is at a neutral potential. In some cases, the transmission of electrical power between two given points of the network can be done by a power transmission line with a single electrical pole, with an electrical conductor at line potential and with an electrical return through earth.

In Figs. 1 and 2 , a single line represents a power transmission line between two distinct points of a network unit, in particular in the HVDC network unit 12 , in order to clearly show the topology of the network without having to go into technical details. Similarly, where an electrical bus has been represented at a given point of the network unit, there will in reality be as many electrical buses as the number of poles, therefore as many electrical buses as the number of electrical conductors in the transmission lines that depart from the point under consideration. For example, it can be assumed that only the electrical conductors and the electrical buses corresponding to a positive pole have been represented in the HVDC network unit 12 .

In the example of theFig. 1, the HVDC grid unit12has 4 terminals, in this case a first terminal14.1, a second terminal14.2, a third terminal14.3and a fourth terminal14.4. The HVDC Grid Unit12comprises, to electrically connect these 4 terminals, electrical conductors21,22,23,24, electric buses26.1,26.2,26.3,26.4, switching devices, etc., all of which operate at the nominal service voltage of the HVDC network unit12.

Fig. 2 shows another example of an electrical current transmission and distribution installation 10 comprising an HVDC network unit 12 . In this second example, the HVDC network unit 12 has 2 terminals, in this case a first terminal 14.1 and a second pair of terminals 14.2 . The HVDC network unit 12 comprises, to electrically connect these 2 terminals, a single electrical line comprising an electrical conductor 21 which extends electrically between two electrical power converters 18 .1 , 18 .2 , with interposition, at each end of the electrical conductor 21 , of cut-off devices 28.1 , 28.2 which operate under the nominal service voltage of the HVDC network unit 12 .

In each of its 4 terminals, the HVDC network unit12of theFig. 1, is connected to another network unit16.1,16.2,16.3,16.4. In the example, each of these other network units16.1,16.2,16.3,16.4is an alternating voltage network unit, so that each of the 4 terminals14.1,14.2,14.3And14.4is actually connected to the DC side of an AC-DC power converter18.1,18.2,18.3,18.4. However, one or other or more of these other network units16.1,16.2,16.3,16.4, could be of another nature, and could for example be another HVDC network unit. Each of these other network units16.1,16.2,16.3,16.4 can be an electricity generation network unit (e.g. a wind farm), and/or an electricity transmission and distribution network unit.

In the example shown inFig. 1, the HVDC grid unit12includes several connection nodes, in this case 3 connection nodes, here made in the form of electrical buses26.1,26.3And26.4, each of which comprises at least three separate links which are electrically connected to each other in a continuous manner, that is to say without the possibility of electrical interruption between the links.

The link node 26.1 illustrated in FIG. 1 is made in the form of an electrical bus and comprises a first connection 26.11 which is electrically connected to a proximal end of a first electrical conductor 21 of a first power transmission line of the electrical network unit considered, with the interposition of a first electrical cut-off device 28.11 , associated with the first connection 26.11 , which has an open state and a closed state. In its closed state, the first electrical cut-off device 28.11 allows the circulation of a first power flow between the connection node considered and the first conductor 21 , in the first connection 26.11 . This first power flow corresponds, in normal operation and in the absence of a fault, to that which circulates in the first conductor 21 . In its open state, the first electrical cut-off device 28.11 interrupts the flow of all electrical power between the connection node in question and the first conductor 21 , in the first connection 26.11 .

In general, an electrical cut-off device may comprise one or more current cut-off devices, in particular of the switch type, arranged in parallel and/or in series between an input point of the device and an output point of the device. In the open state, an electrical cut-off device prevents the flow of current through the device. In a closed state, an electrical cut-off device allows an electrical current to flow through the device. An electrical cut-off device may comprise one or more circuit breaker type devices, optimized to interrupt an established current, and/or one or more disconnector type devices, optimized to maintain electrical insulation between its two terminals when it is in a state open. Such devices can be mechanical, electronic or hybrid devices. However, in the example, the first electrical cutoff device 28.11 is preferably of the mechanical type, in which the electrical cutoff corresponds to a mechanical separation of two electrodes.

On theFig. 1, we see that the first electrical conductor21is connected, by its distal end, to the fourth terminal14.4of the HVDC network unit12, here via a fourth electric bus26.4of the HVDC network unit12. In this example, an electrical disconnect device28.41is interposed between the distal end of the first electrical conductor21and a link26.41of the fourth electric bus26.4. Preferably, in particular for reasons of reduced cost, the electrical cut-off device28.41is a mechanical type electrical cut-off device. Thus, the first electrical conductor21is capable of being fully insulated, at each of its two ends, by means of an electrical cut-off device of the mechanical type which ensures the interruption of the flow of power between the first electrical conductor21and the rest of the infrastructure. In the particular example ofFig. 1, the fourth terminal14.4is electrically connected to a fourth further electrical network unit16.4.

Although not shown on theFig. 1, it is possible to provide, at the ends of this first conductor21, for example at each end of this first conductor, a protection inductance which can be made in the form of a dedicated inductive component, such as a coil. Such protective inductors play the role of inductive-type current limiter, and may be provided in particular if the first conductor21itself has a low equivalent inductance. In a manner known per se, other parameters can be taken into account to determine the need for the presence of such a protective inductance, such as for example the type and/or the number of adjacent conductors connected to other connections of the node considered, and/or the number and/or the power of the electrical power converter(s) connected to other links of the node considered.

The link node 26.1 illustrated in FIG. 1 comprises a second link 26.12 which, in this example, is electrically connected to a second electrical conductor 22 , belonging to a second power transmission line of the HVDC network unit 12 , via a second power cut 28.12 . In the example of FIG. 1 , it can be seen that this second electrical conductor 22 is connected, via its distal end, to the third terminal 14.3 of the HVDC network unit 12 , here via a third electrical bus 26.3 of the HVDC network unit 12 . In this example, an electrical cut-off device 28.31 is interposed between the distal end of the second electrical conductor 22 and a connection of the third electrical bus 26.3 .

The connecting node26.1illustrated theFig. 1also has a third link26.13. In this example, the third bond26.13is electrically connected to another electrical network unit. The passage of a third flow of electrical power is permitted through the third link26.13. This third power flow is controlled by at least one third electrical cut-off device28.13, associated with the third link, which has an open state and a closed state. In the example of theFig. 1, we note that a current cut-off device29.1, which will be referred to as an external cut-off device with respect to the HVDC network unit12 considered, is arranged electrically between the electrical power converter18.1to the first other electrical network unit16.1and this same other electrical network unit16.1strictly speaking. If the other external unit is an alternating voltage network, the external cut-off device 29.1is an alternating voltage cut-off device.

The link node 26.1 illustrated in FIG. 1 comprises a fourth connection 26.4 which is electrically connected to a third electrical conductor 23 of a third power transmission line of the HVDC network unit 12 , with the interposition of a fourth electrical cut-off device 28.14 . In the example, it can be seen that this third electrical conductor 23 is connected, via its distal end, to the second terminal 14.2 of the HVDC network unit 12 , with the interposition of an electrical cut-off device 28.22 .

In the example illustrated in FIG. 1 , it can be seen that the second terminal 14.2 is connected, within the HVDC network unit 12 , only to the first terminal 14.1 the HVDC network unit 12 , here by the third electrical conductor 23 . Conversely, in the example illustrated in FIG. 1 , the HVDC network unit 12 comprises another electrical conductor 24 which is connected, via a first end, to the third terminal 14.3 of the HVDC network unit 12 , here via an electrical cut-off device 28.32 . This other electrical conductor 24 is connected, via its second end, to the fourth terminal 14.4 of the HVDC network unit 12 , here via an electrical cut-off device 28.4 2 .

We therefore notice that the HVDC network unit12of theFig. 1is a network unit which is meshed, in the sense that it has at least two points, here two terminals, which are electrically connected by two electrical paths which are at least partly distinct. In this way, we understand that, in the example of theFig. 1, in normal operation of the HVDC network unit12, electrical power can be transmitted between two terminals, here the first terminal14.1and the fourth terminal14.4according to two electrical paths which are at least partly distinct. However, the HVDC network unit can take other configurations, for example a star network unit, or, as in the example of theFig. 2, take the form of a point-to-point network unit.

In the following, it will be considered that an electrical fault has appeared in the first electrical conductor21, leading to the opening of the first electrical cut-off device28.11. We note here that, with respect to theFig. 1, it is by arbitrary choice that we choose to describe the situation of a defect in the first electrical conductor21, and that one could similarly describe the situation of a fault in one of the other electrical conductors of the HVDC network unit12, for example in the second electrical conductor22.

We represented on theFig. 3a first embodiment of a cut-off device28in accordance with the teachings of the invention.

In this Fig. 3 , it has been illustrated that such a cut-off device 28 is intended to be implemented in an electrical installation comprising a DC high voltage source 17 electrically connected to at least one conductor 21 of a downstream electrical line, which may comprise an airline. In the example of FIG. 3 , the DC high voltage source 17 comprises for example, as seen above in relation to FIG. 1 , an electric power converter 18 which is moreover supplied by another network unit 16 , for example an alternating current network unit. The cut-off device 28 is intended to be interposed between the DC high voltage source 17 and the conductor 21 of the downstream electric line. In the context of an installation according to FIG. 1 , the cut-off device 28 of FIG. 3 can correspond for example to one or the other of the cut-off devices 28.11 , 28.12 , 28.14 , 28.22 , 28.31 , 28.32 , 28.41 , 28.42 of FIG. 1 which are linked to an electrical conductor of a power transmission line without the interposition of another switching device. In the context of an installation according to FIG. 2 , The cut-off device 28 of FIG. 3 can correspond for example to one or the other of the switching devices 28.1 , 28.2 which are respectively linked to the electrical conductor of the power transmission line.

The cut-off device 28 , provided for cutting off an electric current at high DC voltage, comprises a main circuit 34 , in which circulates, in a conduction configuration C_COND of the cut-off device, a nominal current which is for example greater than 500 Amps, or even greater than 1000 amperes, under a nominal continuous service voltage which is for example greater than 75,000 volts. The main circuit 34 of the cut-off device 28 extends between an upstream point 36 of the main circuit, which is intended to be electrically connected to the DC high voltage source 17 , and a downstream point 38 of the main circuit, which is intended to be electrically connected to the conductor 21 of a downstream power line. In some cases, there will be no interposition of another cut-off device between the downstream point 38 and the conductor 21 , or for example at the very least no interposition of another cut-off device playing a role within the framework of a process for evaluating the integrity of an electrical conductor during the closing control of the cut-off device 28 .

The cut-off device 28 comprises at least a first cut-off module 40.1 comprising at least one cut-off switch 42.1 which is interposed in the main circuit 34 between a first primary point 44.1 and a first secondary point 46.1 of the main circuit 34 . The first breaking module is represented here in a simplified way by a simple switch. In reality, those skilled in the art are well aware that, in the field of direct high voltage, such a cut-off switch can be associated with other elements allowing it to effectively fulfill its primary function of power cut-off. For example, a cut-off switch may have primary contacts and secondary contacts electrically in parallel. A cut-off switch may include arc blowout means. It will be illustrated in FIGS. 9A et seq. that, within a cut-off module, a cut-off switch can be associated with a cut-off assistance circuit. The following description of the embodiment of FIG. 3 encompasses all these possibilities, which will however not be detailed insofar as the principle of operation which is described is not affected by the possible presence of such additional equipment in the breaking module.

The first primary point 44.1 and the first secondary point 46.1 are located in this order in the main circuit 34 between the upstream point 36 and the downstream point 38 . In the example of FIG. 3 , the cut-off device is represented with a single cut-off module 40.1 , but it will be seen later that the cut-off device 28 may comprise several cut-off modules interposed successively in the main circuit 34 between the upstream point 36 and the downstream point 38 . Usually, the cut-off switch 42.1 is capable of being controlled between an open state and a closed state to respectively determine an open state and a closed state of the first cut-off module. Typically, cut-off switch 42.1 acts as a circuit breaker. As will be seen later, the cut-off switch 42.1 of a cut-off module can be formed of several switches arranged in series and/or in parallel to ensure the current cut-off function.

The cut-off device 28 also comprises an isolation switch 48 which is interposed in the main circuit 34 of the cut-off device 28 between the upstream point 36 and the first primary point 44.1 , the isolation switch 48 being capable of being controlled between an open state and a closed state. Typically, the isolation switch 48 acts as a disconnector. Of course, nothing prevents the provision of other switches interposed in the main circuit 34 of the switching device 28 between the upstream point 36 and the first primary point 44.1 , whether they are switches playing the role of a disconnector or playing another role.

As can be seen in Fig. 3 , the cut-off device 28 comprises a pre-charge circuit 50 which extends between the first primary point 44.1 and the earth 52 and which comprises at least one pre-charge capacitor 54 , at least one pre-charge resistor 56 and a pre-charge switch 58 . It will be seen that different arrangements are possible for the pre-charge capacitor 54 , the pre-charge resistor 56 and the pre-charge switch 58 in the pre-charge circuit 50 . In the example of FIG. 3 , there are successively in the pre-charge circuit 50 , going from the first primary point 44.1 to the ground 52 , first the pre-charge switch 58 , then the pre-charge resistor 56 , then the capacitor pre-charge 54 . We will see in other examples that we can also have, successively in the pre-charge circuit 50 , going from the first primary point 44.1 towards the ground 52 , first the pre-charge capacitor 54 , then the pre-charge resistor 56 , then the pre-charge switch 58 . According to other variants, one could have the pre-charge resistor 56 between the pre-charge capacitor 54 and the ground 52 . Other variants are still possible, for example by reversing the position of the pre-charge capacitor 54 and of the pre-charge resistor 56 . The pre-charge capacitor 54 can for example comprise a single physical component, or be formed from several distinct physical components which are then arranged in series and in parallel in the form of a capacitive system electrically equivalent to the capacitor 54 illustrated.

Depending on the open or closed state of the different switches, the breaking device 28 has different configurations, which allow the breaking device 28 to perform different functions vis-à-vis the HVDC network unit 12 . In Figures 4A - 4B ; 5A - 5B ; 6A - 6D ; 7A - 7D there are illustrated different switching sequences of the different switches, thus implementing different configurations of the switching device 28 .

First of all, the breaking device 28 has an isolation configuration C_ISOL in which the first primary point 44.1 is isolated from the upstream point 36 , with the isolation switch 48 in its open state, and is isolated from the downstream point 38 , with cut-off switch 42.1 in its open state. In this configuration, which is that illustrated in FIG. 3 , the downstream point 38 is therefore electrically isolated from the upstream point 36 . In this way, the electrical conductor 21 of the power transmission line, which is connected to the downstream point 38 , is electrically isolated from the voltage source 17 which is connected to the upstream point 36 . In the embodiments comprising several cut-off modules, it will preferably be provided that, in the isolation configuration C_ISOL , all the cut-off modules are in their open state. Similarly, when a cut-off module comprises a switch formed by several successive cut-off switches in the main circuit 34 (see the examples described later with reference to Figs. 9A , 9B , 13 and 14A ), all the cut-off switches of the module are preferably in their open state when the switching device is in its isolation configuration C_ISOL .

Preferably, when the cut-off device 28 is in its C_ISOL isolation configuration, the pre-charge switch 58 is in its open state. However, it is understood that, at least in the embodiment of FIG. 4B , the pre-charge switch 58 could be in its closed state, without this calling into question the fact that the first primary point 44.1 is electrically isolated from the upstream point 36 and from the downstream point 38 , nor consequently the fact that the electrical conductor 21 of the power transmission line, which is connected to the downstream point 38 , is electrically insulated from the voltage source which is connected to the upstream point 36 .

In a C_COND conduction configuration, the cut-off device 28 allows the nominal electric current to flow through the cut-off device 28 , from the upstream point 36 to the downstream point 38 , therefore from the voltage source 1 7 , 18 towards the electrical conductor 21 of the power transmission line. The principle of this conduction configuration C_COND is, for the switching device of FIG. 3 , illustrated in FIG. 7C . For this, the isolation switch 48 and the cut-off switch 42.1 are both in their closed state. Of course, in the embodiments comprising several cut-off modules, in the C_COND conduction configuration, all the cut-off modules 40.1 , 40.2 , …, 40.n are in their closed state. Similarly, when a cut-off module comprises a switch formed by several successive cut-off switches in the main circuit 34 , all the cut-off switches of the module are in their closed state when the cut-off device 28 is in its conduction configuration C_COND . In contrast, in the C_COND conduction configuration, the pre-charge switch 58 is open to isolate the first primary point from ground.

The breaking device 28 can moreover be configured in a charging configuration C_CH which aims to electrically charge the pre-charge capacitor 54 of the pre-charge circuit 50 . The principle of this loading configuration C_CH is, for the breaking device of FIG. 3 , shown in Figure 6C . In the C_CH charging configuration, the pre-charge switch 58 is in a closed state such that the pre-charge capacitor 54 , the pre-charge resistor 56 and the pre-charge switch 58 are all electrically in series in the pre-charge circuit 50 between the first primary point 44.1 and the ground 52 , while the first primary point 44.1 is electrically isolated from the downstream point 38 of the cut-off device 28 but electrically connected to the upstream point 36 to allow charging the pre-charge capacitor. Indeed, in this configuration, the electrical energy coming from the voltage source 17 to which the upstream point 36 is connected is capable of charging the pre-charge capacitor 54 . For this, the isolation switch 48 is in its closed state and the cut-off switch 42.1 is in its open state. Of course, in the embodiments comprising several cut-off modules interposed successively in the main circuit 34 of the cut-off device 28 , it will be provided that, in the loading configuration C_CH , at least one cut-off module is in an open state. Provision may be made for several cut-off modules, or even all of the cut-off modules 40.1 , 40.2 , …, 40.n , to be in their open state. Similarly, when a cutoff module comprises 40.1 , 40.2 , ..., 40.n , a switch formed of several successive cutoff switches in the main circuit 34 , at least one cutoff switch, or even all the cutoff switches of the module are in their open state when the cut-off device 28 is in its C_CH loading configuration. Similarly, in the event of the presence of another switch between the first primary point 44.1 and the voltage source 17 , these will be in their closed state.

The cut-off device 28 can moreover be configured in a C_PCH pre-charge configuration to allow discharge of the pre-charge capacitor in the conductor 21 of the downstream electric line. In the C_PCH pre-charge configuration of interrupter 28 , pre-charge switch 58 is in its closed state so that pre-charge capacitor 54 , pre-charge resistor 56 and switch pre-charge 58 are all electrically in series in the pre-charge circuit 50 between the first primary point 44.1 and the ground 52 , while the first primary point 44.1 is electrically isolated from the upstream point 36 of the cut-off device 28 but connected electrically at the downstream point 3 8 . For this, the isolation switch 48 is in its open state and the cut-off switch 42.1 is in its closed state. Of course, in the embodiments comprising several cut-off modules, in the pre-charge configuration, all the cut-off modules 40.1 , 40.2 , …, 40.n are in their closed state. Similarly, when a cut-off module comprises a switch formed by several successive cut-off switches in the main circuit 34 , all the cut-off switches of the module are in their closed state when the cut-off device 28 is in its pre-configuration. load C_PCH . The pre-charge configuration C_PCH is, for the breaking device of FIG. 3 , shown in FIG. 5B .

This is in fact the case where the electrical conductor, arbitrarily the first electrical conductor 21 of FIG. 1 or Fig.2 , has previously been the site of an electrical fault which resulted in its electrical isolation, by opening of the cut-off devices at its two ends.

In the following, the upstream cut-off device is referred to as the one of these two cut-off devices which is located at the upstream end of the electrical conductor 21 , therefore between the conductor 21 which was the subject of the electrical fault and the voltage source 1 7 . Consequently, the one of these two switching devices which is located at the downstream end of the electrical conductor 21 is called the downstream switching device. In the example of FIG. 1 , it can be assumed that the upstream cut-off device is, for the first electrical conductor 21 , the cut-off device 28.11 , the state downstream cut-off device then, for this first electrical conductor 21 , the cut-off device 28.41 . For a given electrical conductor, the notion of two upstream and downstream therefore depends on which end of this conductor is connected to what can be considered as a high voltage direct current voltage source. In some installations, for a given electrical conductor of a power transmission line, it will always be the same end of the conductor which can be considered as the upstream end. For example, in an installation of the type of that of FIG. 2 , a first end of the electrical conductor 21 can be connected, for example, to a wind turbine field, while the other end can, for example, be connected to a distribution network and/or to an electricity consumer. In this case, the end connected to the wind farm will be the upstream end. In other cases, which of the ends of the electrical conductor will be the upstream end may depend on the instantaneous state of the installation. For example, in an installation of the type illustrated in FIG. 1 , which of the two ends of the first electrical conductor 21 is the upstream end may depend on the state, for example, of the other network units 16.1 , 16.4 which are respectively connected respectively to each of the two ends of this first electrical conductor 21 .

In Fig. 3 , the upstream end of the electrical conductor 21 of the power transmission line has been illustrated as being connected to what, at least at the instant of re-closure of the line, is considered to be a voltage source DC high voltage 17 . The cut-off device 28 illustrated in FIG. 3 is therefore considered, vis-à-vis the method which will be described below, as an upstream cut-off device.

Such a cut-off device can be used to implement a process for evaluating the integrity of an electrical conductor 21 in an electrical power transmission line in an electrical installation 10 comprising a main DC high voltage source 17 connected electrically to the electrical conductor 21 with an upstream current cutoff device 28 interposed between the main voltage source 17 and the electrical conductor 21 .

In an initial state, when the electrical conductor 21 is electrically insulated from the installation, the upstream cut-off device 28 is in an insulation configuration C_ISOL . Furthermore, the electrical conductor 21 is, at a distal end, connected to a downstream electrical cut-off device which, in the initial state, is in an insulation configuration C_ISOL so that, in the initial state, the conductor electrical is, except for a possible electrical fault affecting the electrical conductor 21 , electrically isolated from the installation 10 and the environment.

The evaluation process envisaged comprises at least one step of pre-charging the electrical conductor 21 during which an auxiliary auxiliary voltage source, separate from the main voltage source 17 , is connected to the electrical conductor of the power transmission line. electrical, to energize the electrical conductor 21 while maintaining the electrical conductor isolated from the main voltage source 17 and from the rest of the electrical installation 10 .

It will be seen that, with a cut-off device 28 according to the invention, for example that illustrated schematically in F ig. 3 , the auxiliary voltage source is formed by at least one pre-charging capacitor 54 of the pre-charging circuit 50 such that the step of pre-charging the electrical conductor 21 is carried out by bringing the charging device upstream cut in its C_PCH pre-charge configuration. Of course, care is then taken to maintain the downstream cut-off device in its isolation configuration C_ISOL . However, in other embodiments of an evaluation process, the auxiliary source could comprise another electrical network, or a generator, possibly with a power converter, but in any case separate from the voltage source. main 17 which delivers the nominal service voltage to the HVDC network unit 12 .

The evaluation process envisaged comprises, during or after the driver pre-charging step, at least one parameter determination step comprising the determination of at least one current or voltage parameter in the downstream electrical line, and an evaluation step during which the integrity of the electrical conductor 21 is evaluated as a function of the at least one parameter determined during the parameter determination step.

It is in fact understood that, in the event of an electrical fault affecting the electrical conductor 21 , the current or voltage parameter in the line will be notably different from that which could be found in the line in the absence of this fault. Typically, the electrical potential of the electrical conductor 21 will be different depending on whether or not, during the implementation of the evaluation process, an electrical fault affecting the electrical conductor 21 is present. For example, with an upstream breaking device 28 in accordance with the teachings of the invention, and provided that, before the pre-charging step, the pre-charging capacitor 54 belonging to the upstream breaking device has been charged beforehand, the conductor pre-charging step results in a discharge of the electrical energy contained in the pre-charging capacitor 54 towards the electrical conductor 21 . In the hypothesis, except the presence of an electrical fault affecting the electrical conductor 21 , the electrical conductor 21 is, on the side of its downstream end, electrically insulated from the installation 10 and from the environment. Therefore, the electrical potential of the electrical conductor 21 , which results from this discharging of the pre-charge capacitor in the electrical conductor whose state of health, and therefore the integrity, is to be assessed, will be different depending on the presence or no electrical fault affecting this electrical conductor. Also, by evaluating the electrical potential of the electrical conductor 21 , an indication of the integrity of this electrical conductor 21 can be deduced therefrom.

Preferably, the evaluation process is carried out by bringing the electrical conductor 21 whose integrity is to be evaluated to a test potential level whose value is for example greater than or equal to at least 50%, preferably greater than or equal to at 70% of the value of its nominal electrical potential in service, when the power line is subjected to the nominal service voltage of the HVDC network unit 12 . Indeed, it appeared that for lower potential levels, an electrical fault is not necessarily detectable. For example, in the event of only partial rupture of an electrical insulator surrounding the electrical conductor, it is possible that the electrical fault only appears for a potential in the electrical conductor 21 which reaches at least the level of test potential described above. -above.

For this, it will be seen that, in the context of the use of a cut-off device 28 according to the invention, for example one of those illustrated in the figures, comprising at least one pre-charge capacitor 54 , it It is possible, depending in particular on the capacitance value of the pre-charging capacitor 54 with respect to the characteristic impedance, in particular the equivalent capacitance, of the electrical conductor 21 , that a single pre-charging step of the conductor does not allow to reach the desired level of potential. In this case, the evaluation process can then comprise several successive pre-charging steps, separated by steps of recharging the pre-charging capacitor 54 , preferably by maintaining the electrical conductor 21 electrically isolated from the main voltage source 17 , as will be described below, in order not to disturb the latter in the event of a persistent electrical fault in the electrical conductor 21 . In this way, in the event that a pre-charge step does not make it possible to reach the desired test potential level, the evaluation process continues, without going through the conduction configuration C_COND of the circuit breaker device. current, that is to say without connecting the electrical conductor 21 whose integrity is to be assessed with the main voltage source 17 , by a step of recharging the pre-charging capacitor during which the device is brought into the charging configuration C_CH , then successively, still without connecting the electrical conductor 21 whose integrity is to be assessed with the main voltage source 17 , by a new electrical conductor pre-charging step and a new parameter determination step , according to a pre-charge cycle. It is noted that the step of determining the current and/or voltage parameter in the line, implemented to make it possible to evaluate the integrity of the line, can be carried out after each pre-charging step, or possibly after a predetermined number of successive pre-charge steps.

Of course, it will be sought not to multiply the number of pre-charge cycles necessary to achieve the possibility of evaluating the integrity of the conductor. To do this, it is understood that it is necessary to dimension the pre-charge capacitor 54 so that the energy which it is capable of accumulating allows, in a reasonable number of pre-charge cycles, to reach , in the electrical conductor 21 , the desired test potential level, which will for example be greater than or equal to at least 50%, preferably greater than or equal to 70% of the value of the nominal electrical potential in service in the electrical conductor 21 , when the power line is subjected to the rated service voltage of the HVDC network unit 12 .

For example, it is possible to choose to size the pre-charge capacitor 54 so that the energy that it is capable of accumulating makes it possible to reach, in the electrical conductor 21, and on the assumption that the electrical conductor is not affected by an electrical fault, the desired test potential level in a single pre-charge, or in a number of pre-charge cycles in the range from 1 to 10, preferably from 1 at 4.

Of course, this dimensioning will depend on the equivalent capacitance of the electrical conductor 21 . For example, the equivalent capacitance of the pre-charge capacitor 54 could be at least 10% of the equivalent capacitance of the electrical conductor 21 (the equivalent capacitance of a conductor being the linear capacitance of the conductor multiplied by the length of this conductor) . In practice, the equivalent capacitance of the pre-charge capacitor 54 may thus be greater than 1 microfarad (μF), or even greater than 5 microfarads (μF).

By providing the possibility of having several pre-charge cycles to reach the desired test potential level, it is possible to reduce the equivalent capacitance of the pre-charge capacitor54, hence its size and cost. Thus, we can generally be satisfied with a pre-charge capacitor54 having an equivalent capacitance of less than 20 microfarads (µF), or even in some cases an equivalent capacitance of less than 10 microfarads (µF).

The equivalent capacitance of the pre-charge capacitor 54 may thus be comprised in the range going from 1 microfarad (µF) to 20 microfarads (µF), or even in the range going from 5 microfarads (µF) to 20 microfarads (µF).

For example, in a single conductor line, the following relationship can be used to determine the dimensioning of the equivalent capacitance C₅₄pre-charge capacitor54 :

With :
VS₂₁: the equivalent capacity of the conductor21
V_{21 test}: the desired level of test potential in the conductor21
V₁₂: the rated service voltage in the HVDC network unit12
n: a maximum number of pre-charge cycles that we authorize to reach, in the electrical conductor21, the desired test potential level.

In all cases, the equivalent capacitance of the pre-charge capacitor 54 can be determined and/or refined empirically, for example by digital simulation or by a few experimental tests.

In some embodiments, the pre-charge capacitor 54 must be able to hold a voltage across it that is at least equal to the nominal operating voltage in the HVDC array unit 12 , for example be able to hold a voltage across it which is in the range from 1 to 2 times the rated service voltage in the HVDC network unit 12 . In certain illustrated examples, the pre-charge capacitor 54 is integrated into a cut-off assistance circuit in parallel with a surge suppressor. In such cases the pre-charge capacitor 54 must be able to withstand a voltage across its terminals which is equal to the protection voltage of the surge protector, which is for example included in a range going from 1.5 and 1.7 times the nominal service voltage in the HVDC network unit 12 .

A description will now be given of a method for controlling the closing of an electric current cut-off device in accordance with the teachings of the invention. This closing control method includes a process for evaluating the integrity of the electrical conductor. This closing control method of a cut-off device 28 falls within the general framework of an electrical protection method 100 , a schematic flowchart of which is illustrated in FIG. 8 .

Different steps of the closing control method will be described with reference to FIGS. 4A , 4B , 5A , 5B , 6A - 6D and 7A - 7D which schematically describe the different successive states of the cut-off device during such a control method.

As indicated previously, Fig. 4A describes the configuration of the switching device of FIG. 3 , just after a preliminary step 120 of electrical insulation of the electrical conductor 21 considered, for example following the detection 110 of an electrical fault in this electrical conductor 21 . It is noted that, in FIG. 4A , the pre-charge switch 58 is in its open state. However, as shown in Fig. 4B , it could be expected to be in its closed state.

In this example, the case will be described in which, just after the preliminary step 120 of electrical insulation of the electrical conductor considered, the capacitor 54 of the pre-charging circuit is in a charged state. It is then considered that the voltage across the terminals of the pre-charge capacitor 54 is equal to or of the same order of magnitude as the voltage between the electrical conductor 21 in question and the ground when the power transmission line is under its nominal service voltage. If such is not the case, the first step of the closing control method can be a step similar to the step of recharging the pre-charge capacitor 54 which will be described below. Furthermore, before initiating step 141 of pre-charging the driver, it is possible, depending on the embodiments, to provide a preparation process 130 , an example of which will be described below.

In all cases, starting from the principle that the capacitor 54 of the pre-charge circuit is in its charged state, at least one step of pre-charging the conductor 14 1 is carried out, comprising switching the cut-off device 28 to its pre-charge configuration C_PCH , described above and illustrated in FIG. 5B , to energize the electric conductor of the electric power transmission line which is arranged downstream of the downstream point 38 of the cut-off device 28 . Preferably, as illustrated by the succession of Figs. 5A and 5B , the step of pre-charging the conductor 141 comprises firstly the closing of the pre-charging switch 58 , and then the closing of the cut-off module(s) 40.1 , 42.1 .

During or after the conductor 141 pre-charge step, in any case once the pre-charge capacitor 54 has been placed in electrical communication with the power line, the evaluation process 140 comprises at least one step 143 parameter determination comprising the determination of at least one current or voltage parameter in the main circuit 34 or in the downstream electric line. The at least parameter to be determined can for example comprise or be selected from:
- the intensity of the current in the main circuit 34 or in the downstream electric line, in particular in the first conductor 21 ,
- the derivative with respect to time of the intensity of the current in the main circuit 34 or in the downstream electric line, in particular in the first conductor 21 ,
- the electrical potential of the first conductor 21 , and/or
- the derivative with respect to time of the electric potential of the first conductor 21 ,
or among their logical and/or arithmetic combinations.

The electric potential of the first conductor21can typically be determined through the voltage between this first conductor21and ground, or through the voltage between this first conductor 21and another conductor, in particular another conductor of the same electrical power transmission line.

Typically, the parameter to be determined is measured, or determined from a measurement. Thus, as shown in FIG. 2 , the first electrical conductor 21 and/or the main circuit 34 of the switching device 28 is preferably equipped with a measuring device 32.1 , 32.2 delivering a measurement result used for determining the parameter. The measuring device can notably comprise a voltmeter and/or an ammeter. It will be noted that, in certain cases, the parameter can be measured or be determined from a measurement in the link of a link node to which the electrical conductor 21 is connected via the switching device 28 .

As shown in the example shown in FIG. 8 , it is possible to provide within the evaluation process 140 , a delay step 142 between the transition 141 of the switching device 28 to its pre-charge configuration and the step 143 of parameter determination. This delay step 142 can be provided for example to wait for the stabilization of the electrical conditions in the electrical conductor 21 . This can for example be advantageous when the parameter to be determined is a parameter linked to the final electrical potential in the electrical conductor, resulting from the pre-charging of the conductor by passage of the switching device 28 to its pre-charging configuration C_PCH . Such a delay step 142 can for example have a duration of between 1 ms and 20 ms milliseconds. However, in other embodiments, for example embodiments in which the parameter to be determined relates to a variation of current or electrical potential in the electrical conductor 21 , it may be advantageous to avoid such a delay and to carry out the step 143 of determining parameters immediately after switching of the switching device 28 to its pre-charge configuration C_PCH , for example to monitor the derivative of the current or of the electrical potential in the electrical conductor 21 at the moment of the establishment of the current, including by analyzing transient or oscillatory phenomena during step 141 of pre-charging the driver.

As indicated above, on the basis of this parameter, the evaluation process 140 can include a step 144 of evaluating the integrity of the electrical conductor 21 . Typically, this evaluation step 144 can include a comparison between the parameter that has been determined and a threshold value, which can be predetermined, or can be calculated according to the conditions under which the evaluation step takes place. This threshold value may be the desired test potential level described above, or may be another value. Indeed, if the threshold value of the parameter is reached or exceeded, it can be deduced that the electrical conductor is not, or is no longer, affected by an electrical fault, thus resulting in a positive evaluation of the integrity of the electrical conductor 21 . In some cases, the value determined for the parameter will make it possible to deduce that the electrical conductor remains affected by an electrical fault, thus leading to a negative evaluation of the integrity of the electrical conductor 21 . In some cases, the value determined for the parameter will make it possible to deduce that the electrical conductor remains affected by an electrical fault, thus resulting in a negative evaluation of the integrity of the electrical conductor 21 , even after a single pre-charging step of the conductor electric. However, in certain cases, the value determined for the parameter does not make it possible to conclude as to the integrity of the electrical conductor. For example, this situation may be one in which the determined parameter does not allow the conclusion of the presence of a fault to be concluded, but the electrical potential reached in the electrical conductor 21 following the pre-charging step has not reaches the test electric potential value.

Thus, typically, after at least one step 141 of pre-charging the conductor, complete closing of the current breaking device by passing the current breaking device to its conduction configuration C_COND is continued if a voltage value in the circuit main 34 of the cut-off device 28 , or in the downstream electric line, exceeds a threshold value.

In general, the method for controlling the switching device may comprise a decision step, during which it is decided, as a function of at least one parameter determined during the parameter determination step, of the continuation or not of the complete closing of the current breaking device by passage of the current breaking device to the conduction configuration C_COND . Typically, this step of decision to proceed with complete closure therefore results in a positive continuation decision, if the evaluation of the integrity of the electrical conductor could be carried out and is positive. On the other hand, this step of deciding to continue with full closure therefore results in a negative continuation decision, if the evaluation of the integrity of the electrical conductor could not be carried out or is negative.

In the example illustrated, the evaluation step and the decision step are one and the same step 144 . For example, this step can include a comparison between an electrical potential value of the first conductor 21 , determined in the determination step 143 , and a threshold value, for example the desired test potential level described above.

Of course, one and/or the other of the evaluation step and the decision step can be based on the determination of several parameters. Furthermore, provision can be made for the evaluation step and the decision step to be based on the determination of different parameters, or on the basis of partly different sets of parameters.

If the continuation decision is positive, then the method triggers a continuation 160 of the complete closing of the cut-off device 28 .

An example of a process 160 for continuing the complete closing of the breaking device 28 is illustrated by the succession of Figs. 7A to 7C . According to this example, the cut-off device 28 passes for example from the state of FIG. 7A , corresponding to the breaking device 28 in its C_PCH pre-charge configuration, in the state of FIG. 7C corresponding to switching device 28 in its C_COND conduction configuration. Preferably, as illustrated in FIG. 7B , this can be done in particular by first providing the opening 161 of the pre-charge switch 58 before proceeding to the closing 163 of the isolation switch 48 of the cut-off device 28 which makes it possible to bring the device in its C_COND conduction configuration. It is noted that, in the example illustrated, the isolation switch 48 is the one which is closed last to reach the conduction configuration C_COND .

In Fig. 8 , the process 160 of continuing the complete closing of the breaking device 28 ends with the step 163 of passing the breaking device 28 to its conduction configuration C_COND . As described above, the process 160 of continuing the complete closing of the breaking device 28 may comprise additional steps, in particular steps prior to step 163 of switching the breaking device 28 to its conduction configuration C_COND . These additional steps 162 can for example allow a reconfiguration of the cut-off device 28 , in particular with a view to enabling it to be ready for a new power cut in the event of detection of an electrical fault affecting the electrical conductor 21 .

As indicated above, provision can be made for the decision to continue complete closing of the cut-off device 28 to be conditional on the step 144 of evaluating the integrity of the electrical conductor 21 having been carried out under satisfactory conditions, in particular vis-à-vis the electrical potential reached in the electrical conductor 21 following the pre-charging step. If this electrical potential is insufficient to be able to decide positively as to the integrity of the electrical conductor, provision can be made for the decision step to remain negative, without this necessarily leading to the conclusion that the electrical conductor 21 would necessarily be affected by a electrical fault.

If the decision step 144 is negative, the method can continue, without passing through the conduction configuration C_COND of the current breaking device, with a step 180 of recharging the pre-charge capacitor during which the device is brought into the charging configuration C_CH , then successively by a new driver pre-charging step 141 , a new parameter determination step 143 , and a new evaluation and/or decision step 144 , according to a new cycle of pre-charge. Provision can be made for this new pre-charge cycle to be implemented only if the evaluation step has not previously resulted in a negative evaluation of the integrity of the electrical conductor.

It is understood that this pre-charging cycle may be repeated several times in succession as long as the evaluation and/or decision step is not positive, therefore as long as the method does not continue with a process 160 complete closing of the cut-off device 28 .

Preferably, the number of pre-charge cycles for a given attempt to re-close the cut-off device 28 will be limited.

This has been shown in Fig. 8 by a verification step 170 of the number of pre-charges performed. For example, each time the evaluation and/or decision step 144 is not positive, it is possible to increment a counter by one unit, and verify, during the verification step 170 , that the value of this counter does not exceed a maximum value.

If the verification step 170 of the number of pre-charges performed reveals that a maximum number has been exceeded, the control process can be terminated 190 , without having resulted in complete re-closing of the cut-off device. Thus, if, after several pre-charge cycles, the decision step is negative, the closing control method is interrupted. In this case, it is preferable to bring the cut-off device 28 into its isolation configuration C_ISOL . Generally, this hypothesis materializes in the event of the presence of a persistent fault affecting the electrical conductor 21 , requiring intervention.

If the verification step 170 of the number of pre-charges carried out reveals that a maximum number has not been exceeded, the control method can restart a new pre-charge step 141 of the driver 21 , but after having carried out a recharging step 180 of the pre-charging capacitor 54 .

Typically, the recharging step 180 of the pre-charge capacitor 54 includes:
- the closing of the isolation switch 48 and the closing of
the pre-charge switch 58 , maintaining the cut-off switch 40.1 , 42.1 in its open state, to charge the pre-charge capacitor 54 , which is illustrated in FIG. 6C ;
- after said closure of the pre-charge switch, the reopening of the isolation switch 48 , which is illustrated in FIG. 6D .

As a preliminary, starting from the pre-charge configuration C_PCH as illustrated in FIG. 6A , the at least one breaking module 40.1 will have been opened, which is illustrated in FIG. 6B , therefore before switching the cut-off device into its recharging configuration illustrated in FIG. 6C .

Above, we placed ourselves in the case in which, just after the preliminary step 120 of electrical insulation of the electrical conductor considered, the capacitor 54 of the pre-charging circuit 50 is in a charged state. However, in certain embodiments, the implementation of the cut-off device 28 will cause that, just after the preliminary step 120 of electrical insulation of the electrical conductor considered, the capacitor 54 of the pre-charging circuit is in a discharged state. , or insufficiently charged. In this case, provision will advantageously be made for the control method to include, after the preliminary step 120 of electrical insulation of the electrical conductor considered but before a first step of pre-charging the conductor 141 , a preliminary step 13 2 of recharging the capacitor pre-loading, for example within the preparation process 130 . The preparation process 130 may also include other preparation steps 131 .

Fig. 3 illustrates a particularly simple embodiment of a switching device according to the invention.

A description will now be given of embodiments of a switching device according to the invention which are more complex, while presenting the same general architecture as that of FIG. 3 .

As will be seen below, some of these embodiments of a breaking device 28 will include a single breaking module 40.1 between the first primary point 44.1 and the downstream point 38 . Other embodiments will comprise, downstream of the first cut-off module 40.1 in the main circuit 34 of the cut-off device 28 , at least one last cut-off module 40.n comprising at least one cut-off switch 42.n interposed in the main circuit 34 between a last primary point 44.n , downstream of the first secondary point 46.1 , and a last secondary point 46.n of the main circuit 34 . The cut-off switch 42.n of the last cut-off module 40.n is capable of being controlled between an open state and a closed state to respectively determine an open state and a closed state of the last cut-off module 40.n. Among these embodiments comprising at least two successive cutoff modules in the main circuit 34 between the first primary point 44.1 and the downstream point 38 , certain cutoff devices 28 will have only two cutoff modules, between the first primary point 44.1 and the downstream point 38 , namely therefore a first cut-off module 40.1 and a last cut-off module 40.n , the last cut-off module then also being the second cut-off module. On the contrary, certain cut-off devices 28 will include, in the main circuit 34 of the cut-off device 28 , between the first cut-off module 40.1 and the last cut-off module 40.n , at least one additional cut-off module 40.2 , ..., comprising at least one cut-off switch 42.2 ,..., interposed in the main circuit 34 between an additional primary point 44.2 ,..., downstream of the first secondary point 46.1 , and an additional secondary point 46.2 ,..., of the main circuit 34 , upstream of the last primary point 44 .n , and the cut-off switch 42.2 , ..., of the additional module 40.2 , ..., being able to be controlled between an open state and a closed state to respectively determine an open state and a closed state of the module additional cut-off 40.2 , …,. Thus, such a cut-off device 28 may comprise a single additional cut-off module interposed in the main circuit between the first cut-off module and the last cut-off module, or several additional cut-off modules successively interposed, in the main circuit, between the first break module and the last break module.

It will be seen that, for two successive cut-off modules 40.i , 40.i + 1 in the upstream-downstream direction in the main circuit 34 , the primary point 44.i + 1 of that which is downstream may be electrically confused with the secondary point 46.i of that which is upstream, in the sense that the two points are always at the same electrical potential.

Embodiments will also be described in which the cut-off device 28 comprises at least one cut-off module 40. i (i=1, 2, ..,) comprising a cut-off assistance circuit 70. i (i = 1 , 2 , ..,) which extends electrically in derivation from cut-off switch 42.i (i=1, 2, ..,) and from main circuit 34 between point first primary point 44 . i (i=1, 2, ..,) and a secondary point 46 . i (i=1, 2, ..,) of the main circuit 34 .

Such a cut-off assistance circuit 70.i is a device which, when the cut-off module passes from its closed state to its open state , will favor the cut-off of the electric current through the cut-off switch 42. i of the breaking module 40. i considered. Typically, such a cut-off assistance circuit 70. i will make it possible to transiently reduce the intensity of the electric current in the cut-off switch 42. i with which it is electrically associated in parallel, or even will allow, in a transient way , to tend to the cancellation, or the inversion of the direction of circulation, of the electric current in the cut-off switch 42.i with which it is electrically associated in parallel. In such embodiments, it will be particularly advantageous if, in a C_C cutoff configuration, the cutoff device 28 is configured such that at least one pre-charge capacitor 54 . i (i=1, 2, ..,) of the pre-charge circuit is also part of the cut-off assistance circuit 70.i. Indeed, in this cutoff configuration C_C , the pre-charge capacitor 54.i will advantageously also be used to provide the function of facilitating the cutoff. In this way, the same electrical component, the pre-charge capacitor 54.i will be used for two different functions, which will be a source of cost and bulk reduction for a cut-off device 28 having both a circuit of cut-off assistance and a pre-charge circuit as described above.

In general, this can be implemented as follows. In each of the embodiments, for at least one cut-off module 40.i , a cut-off assistance circuit 70.i comprises , successively and in this order from the primary point 44.i associated with the module considered, the at least one pre-charge capacitor 54. i and an activation switch 72. i , with a tapping point 76 between the two in the cut-off assistance circuit 70. i . Thus, it can be defined that the pre-charge circuit comprises a first section, which is common with the cut-off assistance circuit 70.i , which extends between the first primary point 44.1 and the tapping point 76 and which comprises the at least one pre-charge capacitor 54. i , and a second section, distinct from the cut-off assistance circuit 70. i , which extends between the tapping point 76 and the earth 52 and in which is interposed the pre-charge switch 58 .

In the embodiments that will be described, the preparation process 130 within the control method may include a preparation step during which all current flow is cut in the cut-off assistance circuit between the point of tapping and the secondary point, for example using a switch placed between these two points.

Illustrated in FIG. 9A a first embodiment of a cut-off device 28 whose cut-off module 40.1 comprises both a cut-off assistance circuit 70.1 and a pre-charge circuit 50 as described above. This embodiment comprises a single cut-off module 40.1 between the first primary point 44.1 and the downstream point 38 . This embodiment of a cut-off device 28 extends between an upstream point 36 and a downstream point 38 and can therefore be used instead of the embodiment illustrated in FIG. 3 . Such a breaking module is described in more detail in document WO 2020/136340 to which reference may be made for a detailed description.

This single cut-off module 40.1 comprises a cut-off switch 42.1 having a primary switch 60 .1 , mechanical, and a secondary switch 6 2.1 , mechanical, interposed successively in the main circuit 34 between the first primary point 44.1 and the first secondary point 46.1 associated with this single cut-off module 40.1 , but on either side of a first intermediate point 64.1 of the main circuit 34 which corresponds to the cut-off module 40.1 . The two primary 60 .1 and secondary 62 .1 mechanical switches can each be controlled between an open state and a closed state. As the breaking module 40.1 is here unique in the breaking device 28 , the first secondary point 46.1 of the breaking module 40.1 can be considered as electrically coincident with the downstream point 38 of the breaking device 28 , in the sense that the two points are always at the same electrical potential.

In this embodiment, the cut-off switch 42.1 comprises:
- a primary surge protector 66.1 arranged in parallel with the primary switch 60.1 between the first primary point 44.1 and the first intermediate point 64.1 ,
- A secondary surge protector 6 8 . 1 arranged electrically in parallel with the secondary switch 6 2 .1 between the first intermediate point 64.1 and the first secondary point 46.1 .

Such surge protectors make it possible to limit the amplitude of the potential difference across the terminals of the switch in parallel with which they are arranged. Among surge arresters, surge arresters are known in particular, which may in particular include varistors (or varistors) and “TVS” (Transient Voltage Suppressor) diodes, such as “Transil™” diodes. In particular, the primary surge arrester 66.1 and/or the secondary surge protector 68.1 can each comprise a metal oxide varistor (or MOV, meaning “metal oxide varistor”).

In this embodiment, the cut-off assistance circuit 70.1 of the cut-off switch 42.1 extends between the first primary point 44.1 and the first secondary point 46.1 in the form of a capacitive buffer circuit which extends electrically in parallel with the assembly formed by the primary switch 60.1 and the secondary switch 6 2 . 1 , and electrically in parallel with the assembly formed by the primary surge protector 66.1 and the secondary surge protector 68.1 , and which comprises an activation switch 72.1 and a buffer capacitor which is here formed by the pre-charge capacitor 54.1 . Preferably, in this embodiment, the capacitive buffer circuit forming a cut-off assistance circuit 70.1 does not include a dedicated inductive component. The capacitive buffer circuit forming a cut-off assistance circuit 70.1 may comprise a tertiary surge protector 74.1 arranged in parallel with the activation switch 72.1 , for example directly across the terminals of the activation switch 72.1 .

It can be seen that the cut-off assistance circuit 70.1 comprises, successively and in this order from the first primary point 44.1 , the at least one pre-charge capacitor 54.1 and an activation switch 72.1 , with a point of stitching 76 between the two in the cut-off assistance circuit 70.1 . The pre-charge circuit 50 comprises a first section, which is common with the cut-off assistance circuit, which extends between the first primary point 44.1 and the tapping point 76 and which comprises the at least one capacitor pre-charge 54.1 . The pre-charge circuit 50 comprises a second section, distinct from the cut-off assistance circuit 70.1 , which extends between the tapping point 76 and the earth 52 and in which the pre-charge switch 58 is interposed. . It is noted that the pre-charge resistor 56 of the pre-charge circuit 50 is arranged in the second section, separate from the cut-off assistance circuit 70.1 , which extends between the tapping point 76 and the earth 52 , therefore outside the cut-off assistance circuit 70.1 . It is understood that, in this second section which extends between the tapping point 76 and the ground 52 , the pre-charge resistor 56 of the pre-charge circuit 50 could be arranged on one side or the other of the pre-charge switch.

Note that, in this embodiment, which includes a tertiary surge protector 74.1 at the terminals of the activation switch 72.1 , a configuration switch 78.1 is provided in the section of the cut-off assistance circuit which is separate from the circuit of pre-charge 50 . The configuration switch 78.1 is arranged between the tertiary surge protector 74.1 and the downstream point 38 . This configuration switch 78.1 is closed in a cut-off configuration C_C of the cut-off device 28 , during which the cut-off assistance circuit 70.1 is active to interrupt the flow of current in the cut-off switch 42.1 in progress opening. This configuration switch 78.1 is in its open state in the C_CH charging and C_PCH pre-charging configurations of the cut-off device 28 , to prevent the electrical conductor 21 , connected to the downstream point 38 , from being able to discharge through the circuit cut-off assistance 70.1 , in particular through the tertiary surge protector 74.1 . Preferably, this configuration switch 78.1 is in its closed state in conduction configuration C_C OND to anticipate a possible need for re-opening of the cut-off device 28 .

In this embodiment, it is necessary that, to perform the cut, the pre-charge capacitor 54 is in a discharged state at the moment when it is desired that it operates in the context of the cut-off assistance. . It is therefore necessary to provide a discharge circuit for the pre-charge capacitor 54.1 . Such a discharge circuit (not shown in the figures) can be a passive discharge circuit, comprising no active component, for example comprising a discharge resistor arranged in parallel with the pre-charge capacitor 54 . Preferably, such a discharge resistor has a high electrical resistance value such that the dipole which consists of the pre-charge capacitor 54 and the discharge resistor arranged in parallel, has a large time constant with respect to an electrical cut-off delay in the secondary switch 62.1 , for example a time constant greater than 50 milliseconds, preferably greater than 100 milliseconds. Another type of discharge circuit may include at least one active component, such as a controlled switch. Thus, a discharge circuit could include a controlled switch which would be arranged electrically directly in series with the discharge resistor mentioned above, all of these two components being in parallel with the pre-charge capacitor 54 .1 . When the controlled switch would be switched to a closed state allowing the current to flow, a discharge circuit would form between the two plates of the pre-charge capacitor 54 .

In a method for controlling a cut-off device28according toFig. 9A, in order to bring the device from its closed state to its open state, a step is provided comprising the mechanical opening of the primary switch60.1and secondary switch66.1. The two switches can be opened mechanically simultaneously, or successively in any order. Such a step of opening the two switches can be triggered in the presence of an electrical fault in the electrical installation, in particular in the electrical conductor of the downstream line which is connected to the downstream point.38. It is possible that the mechanical opening of the two switches60.1,66.1cut-off switch42.1 does not, on its own, allow electrical opening in the sense of interrupting the passage of current through the cut-off device10, by the fault of the establishment of an electric arc through each of the two switches60.1,66.1. In this hypothesis, the process provides for cutting off the current in the primary switch60.1 open to cause the appearance, at the terminals of the primary switch60.1, of a voltage higher than the transition voltage of the primary arrester66.1suitable for switching it into a current conduction mode. To turn off the current in the primary switch60.1open, use may be made of an oscillation circuit as described in one or other of documents WO-2020/136340, WO-2015/103857, EP-3,091,626, CN-103,296,636 and WO-2012/100831, combining in series a capacitor and a dedicated inductive component, to create an oscillating current to impose a zero crossing of the current in the primary switch60.1open. The power failure in the primary switch60.1 open can be obtained by other means, in particular by suitable sizing of the primary switch60.1, even if this dimensioning leads to a bulkier and/or more expensive primary switch than that which can be used in the event of the presence of an oscillation circuit. Once obtained, this breaking of the current through the primary switch60.1 forces current through the interrupting device28charging the pre-charge capacitor54.1, causing a rise in voltage at its terminals, which results in the appearance of this same voltage at the terminals of the primary surge protector66.1, and therefore of the same voltage across the terminals of the primary switch60.1. In the event of a large fault current, this voltage reaches the transition voltage of the primary surge protector66.1, which then sees its resistance vary to limit the increase in voltage, which reaches a plateau. At this stage, it is considered that the primary surge protector66.1becomes conductive for the current. Thus, it can be considered that, from this instant, the current through the breaking device28passes through the primary surge protector66.1but continues to flow through the secondary switch62.1due to the presence of an electric arc between the contacts of the latter. To break the electric arc in the secondary switch62.1, the cut-off assistance circuit is activated by closing the activation switch72.1. It will be assumed that the configuration switch will have previously been brought to its closed state, otherwise it can be done at this time. This allows, in the cut-off assistance circuit70.1, the passage of a clean current to charge the pre-charge capacitor54.1and to shed the current in the secondary switch62.1. In the initial state, the pre-charge capacitor54 .1is discharged, for example by the presence of the discharge circuit. In other words, the cut-off device28is configured so that, in the initial state, i.e. on switching of the activation switch72.1to allow the passage, in the cut-off assistance circuit70.1, of a current capable of charging the pre-charge capacitor54.1, the pre-charge capacitor54.1is unloaded. Because of this, and because of the presence of a potential difference across the terminals of the primary surge protector66.1, the current through the device28switches to cut-off assistance circuit70.1to charge the pre-charge capacitor54.1. During the charging time of the pre-charge capacitor54.1, the current through the breaking device28is mainly driven by the cut-off assistance circuit70.1, which has the effect of lowering or even canceling the current flowing through the secondary switch62.1, which it should be remembered is in a state of mechanical breaking, with its contacts separated from each other. This reduction, or even cancellation, of the current through the secondary switch62.1will advantageously cause the extinction of the electric arc in the secondary switch62.1. We then consider that the secondary switch62.1is electrically open and that a voltage can appear at its terminals without risk of re-ignition of the electric arc. This voltage is reflected across the terminals of the secondary surge protector68.1, which can then play its role of limiting the voltage across the terminals of the secondary switch. We can then consider that the breaking device28is open, because only a leakage current can flow through the device28through the primary surge protector60.1and by the secondary surge protector62.1. For this, it is therefore wise to choose the primary surge protector60.1and the secondary surge protector62.1so that the sum of their transition voltage is greater than the nominal voltage of the installation.

In the example, the pre-charge capacitor 54.1 is the only capacitor in the cut-off assistance circuit 70.1 , in the sense that there is no capacitor in the section of the cut-off assistance circuit 70.1 which is separate from the pre-charge circuit 50 , here between the tapping point 76 and the secondary point 46.1 . However, depending on the capacitive needs for on the one hand the pre-charge operation and on the other hand the cut-off assistance operation, it is possible to have, in addition to the pre-charge capacitor 54.1 which is arranged in the section of the pre-charge circuit 50 which is common with the cut-off assistance circuit 70.1 , at least one other capacitor, this other capacitor being arranged in the section of the cut-off assistance circuit 70.1 which is separate from the pre-charge circuit 50 , here between the tapping point 76 and the secondary point 46.1 . In all cases, the pre-charge capacitor 54.1 can take the form of a single physical component, or be formed of several physical components which can be arranged electrically in series and/or in parallel so as to form an equivalent capacitive system. electrically to capacitor 54.1 shown.

For this embodiment of a switching device 28 illustrated in FIG. 9A , there is illustrated in FIG. 9B a table in which there is represented, for each of the configurations described above of a switching device 28 according to the invention, the state of the various switches in the configuration represented. Each row of the table corresponds to one of these configurations, and the columns of the table correspond to the switches of the breaking device 28 , designated by the corresponding references used in the figures and in the text above. The open state is represented by the number 0, and the closed state is represented by the number 1. In the absence of any indication, the switch can be in one or the other of its states, with the possibility that there is a preferential state depending on the installation considered.

Thus, for this embodiment of a switching device 28 illustrated in FIG. 9A , the conduction configuration C_COND is obtained by bringing the isolation switch 48 and the cut-off switch 42.1 , the latter being here formed by the primary switch 60.1 and the secondary switch 60.2 , in their closed state. The pre-charge switch 58 can for example be in its open state. Preferably, enable switch 72.1 is in its open state and configuration switch 78.1 is in its closed state.

In this embodiment, the cutoff configuration C_C involves bringing the pre-charge switch 58 to its open state, then the configuration switch 78.1 to its closed state. We saw above that the cut-off switch 42.1 , namely here the primary switch 60.1 and the secondary switch 60.2 , is brought into its open state, and the activation switch 72.1 is brought into its closed state by so that the cut-off assistance circuit 70.1 , which includes the pre-charge capacitor 54.1 , can play its cut-off assistance function. Preferably, for example once the break has been obtained, the isolation switch 48 is brought into its open state.

For this embodiment of a switching device 28 illustrated in FIG. 9A , the isolation configuration C_ISOL is obtained by bringing the isolation switch 48 , and the cut-off switch 42.1 , namely here the primary interior 60.1 and the secondary switch 60.2 , into their open state. At least one of enable switch 72.1 and configuration switch 78.1 is in its open state. For example, the pre-charge switch 58 is in its open state.

The charging configuration C_CH which aims to electrically charge the pre-charge capacitor 54 of the pre-charge circuit 50 is obtained by bringing the isolation switch 48 and the pre-charge switch 58 into their closed state, the cut-off switch 42.1 , namely here the primary interior 60.1 and the secondary switch 60.2 , being brought into their open state just as the configuration switch 78.1 is also in its open state. Preferably, the activation switch 72.1 is also in its open state.

The pre-charge configuration C_PCH to allow discharge of the pre-charge capacitor 54.1 into the conductor of the downstream power line is obtained by bringing the isolation switch 48 to its open state, and by bringing the pre-charge switch -load 58 and the cut-off switch 42.1 , namely here the primary interior 60.1 and the secondary switch 60.2 , in their closed state. Preferably, to anticipate a possible need for re-opening of the cut-off device 28 , it is possible to bring the configuration switch 78.1 into its closed state, but the activation switch 72.1 then being in its open state.

It will be understood that, to ensure the pre-charging of the electrical conductor 21 of the downstream line which is electrically connected to the downstream point 38 , this embodiment of the cut-off device illustrated in FIG. 9A is driven in the manner described with reference to FIG. 3 .

It is noted that it is possible to provide, before a first step of pre-charging the electrical conductor 21 , a preparation step during which all current flow is cut in the cut-off assistance circuit 70.1 between the point stitching 76 and the secondary point 46.1 . This can be done for example by opening the activation switch 7 2 .1 .

It has been illustrated in Fig. 10A a variant embodiment of the switching device 28 of FIG. 9A . The alternative embodiment of FIG. 10A is identical to that of FIG. 9A , except for the presence of a bypass circuit 80 which extends, electrically in parallel with the main circuit 34 , between the first primary point 44.1 and a bypass point 82 arranged between the last secondary point, here the first secondary point 46.1 since this embodiment comprises only a single cut-off module 40.1 , and the downstream point 38 . In this bypass circuit is interposed a bypass switch 84 which is in a closed state in the C_PCH pre-charge configuration and in an open state in the C_CH charging, C_ISOL isolation, C_C cut-off configurations. , and also in the conduction configuration C_COND . The bypass circuit 80 makes it possible to ensure, for the pre-charge configuration C_PCH , the pre-charge of the electrical conductor 21 of the downstream power transmission line, through a circuit having the most parasitic inductance possible low. The presence of the bypass circuit 80 makes it possible to move the configuration switch 78 to place it in the main line 34 between the first secondary point 46.1 and the bypass point 82 . In this position in the breaking device, the configuration switch 78 is closed in the conduction configuration C_COND , and in the breaking configuration C_C of the breaking device 28 . In this position in the breaking device, the configuration switch 78 is open in the C_CH charging and C_PCH pre-charging configurations of the breaking device 28 , to prevent the electrical conductor 21 , connected to the downstream point 38 , from can be discharged through the cut-off assistance circuit 70.1 . This embodiment, which makes it possible to move the configuration switch 78 outside the cut-off assistance circuit 70.1 , makes it possible to have a cut-off assistance circuit 70.1 having the lowest possible parasitic inductance.

As can be seen in Fig. 10B , the state of the other switches in the different configurations is the same as for the previous variant.

We have illustrated on thefig s . 11AAnd11Btwo variants of a breaking device according to the invention which are derived from a breaking device architecture which is described in particular in the documents WO-2016/003357 and WO-2017/116296, to which reference will be made in more detail for the operation of the cut-off assistance circuit70.1. In breaking devices28of theFigs. 11AAnd11B, so we find a main circuit34, in which a nominal direct current flows in a conduction configurationCC OND of the breaking device, the main circuit34extending between an upstream point36intended to be electrically connected to a direct high voltage source17and a downstream point38intended to be electrically connected to a conductor21of a downstream electric power transmission line. These two embodiment variants here comprise a single cut-off module40.1comprising at least one cut-off switch42.1interposed in the main circuit34between a first primary point44.1and a first secondary point46.1of the main circuit34. The first primary point44.1and the first subpoint46.1are located in this order in the main circuit34between the upstream point36and the downstream point38. These two embodiment variants include an isolation switch48, interposed in the main circuit34between the upstream point36and the first primary point44.1. In this architecture, it is planned, in parallel with the breaking module40.1, a cut-off assistance circuit70. 1which extends between the primary point44.1and the secondary point46.1which correspond to the breaking module considered. In a cutoff configurationCC, the cut-off assistance circuit70.1is provided to promote the extinction of an electric arc which may form between the terminals of the cut-off switch42.1when it is opened. For this, the cut-off assistance circuit70.1comprises, between the primary point44.1and the secondary point46.1which correspond to the cut-off module considered, at least one dedicated inductive component90 .1, a controlled voltage source92 .1and a capacitor54.1. In this architecture, the cut-off assistance circuit70.1therefore forms an LC circuit in which current oscillations can be forced. The controlled voltage source92 .1is controlled to create current alternations of increasing intensity in the cut-off assistance circuit70.1, until these current oscillations exceed in intensity the fault current in the cut-off switch42.1. Thanks to such oscillation, the cut-off assistance circuit70.1ends up injecting into the main circuit34, through the cut-off switch, a counter-current in the opposite direction to the fault current, and of an intensity greater than the fault current, causing the current to pass through zero in the cut-off switch42.1, which leads to the extinction of the electric arc. We also note that the cut-off module40.1of the embodiment of theFig. 11Ahas a surge protector73.1which is arranged electrically in parallel with the assembly comprising the capacitor54.1, the controlled voltage source92.1, and a configuration switch78.1which will be detailed later, to limit the voltage at the terminals of this assembly. For its part, the breaking module40.1of the embodiment of theFig. 11Bhas a surge protector75.1which is arranged electrically in parallel with the capacitor54.1to limit the voltage across the capacitor54.1.

Unlike the basic architecture described in particular in documents WO-2016/003357 and WO-2017/116296, the switching devices 28 of Figs. 11A and 11B comprise a pre-charge circuit 50 which extends between the first primary point 44.1 and ground 52 and which comprises at least one pre-charge capacitor 54.1 at least one pre-charge resistor 56 and a pre-charge 58 . As can be seen in the figures, in a C_C cut-off configuration, the cut-off device 28 is configured such that the pre-charge capacitor 54.1 of the pre-charge circuit 50 forms part of the cut-off assistance circuit 70.1 , in which it acts as the capacitor of the LC circuit intended to generate the oscillations.

The pre-charge circuit 50 comprises a first section, which is common with the cut-off assistance circuit 70.1 , which extends between the first primary point 44.1 and a tapping point 76 and which comprises the at least one pre-charge capacitor 54.1 . The pre-charge circuit 50 comprises a second section, separate from the cut-off assistance circuit 70.1 , which extends between the tapping point 76 and the earth 52 and in which the pre-charge switch 58 is interposed. . It is noted that the pre-charge resistor 56 of the pre-charge circuit 50 is, in these two variants, arranged in the second section of the pre-charge circuit 50 which extends between the tapping point 76 and the ground 52 , therefore outside of the cut-off assistance circuit 70.1 .

In the variant of FIG. 11A , the controlled voltage source 92 .1 , which comprises for example a point of controlled thyristors and capacitors, is arranged in the part of the cut-off assistance circuit 70.1 which is common with the pre-charge circuit 50 , here between the at least one pre-charge capacitor 54.1 and the tapping point 76 . In the variant of FIG. 11B , the controlled voltage source 92 .1 , is arranged in the part of the cut-off assistance circuit 70.1 which is separate from the pre-charge circuit 50 , here between the tapping point 76 and the secondary point 46.1 .

Unlike the basic architecture described in particular in documents WO-2016/003357 and WO-2017/116296, the switching devices 28 of Figs. 11A and 11B comprise a configuration switch 78.1 in the section of the cut-off assistance circuit 70.1 which is separate from the pre-charge circuit 50 . The configuration switch 78.1 is arranged between the tapping point 76 and the downstream point 38 . This configuration switch 78.1 is closed in a cut-off configuration C_C of the cut-off device 28 , during which the cut-off assistance circuit 70.1 is active to interrupt the flow of current in the cut-off switch 42.1 in progress opening. This configuration switch 78.1 is open in the C_CH charging and C_PCH pre-charging configurations of the cut-off device 28 , to prevent the electrical conductor 21 , connected to the downstream point 38 , from being able to discharge through the assistance circuit at cutoff 70.1 .

It has been illustrated in FIG. 11C a table which reads in the same way as that of FIG. 9B , in which there is shown, for each of the configurations described above, a switching device 28 according to one or other of the variants of Figs. 11A and 11B , the state of the various switches in the configuration. In addition to the C_COND conduction, C_ISOL insulation and C_C cut-off configurations, there is therefore a C_CH charging configuration in which the pre-charge switch 58 is in a closed state so that the pre-charge capacitor 54.1 , the pre-charge resistor 56 and the pre-charge switch 58 are all electrically in series in the pre-charge circuit 50 between the first primary point 44.1 and ground 5 2 , while the first primary point 44.1 is electrically isolated from the downstream point 38 of the cut-off device 28 , in particular by the opening of the cut-off switch 42.1 , but electrically connected to the upstream point 36 , by the closing of the isolation switch 48 to allow the loading of the pre-charge capacitor 54.1 . There is a pre-charge configuration C_PCH in which the pre-charge switch 58 is in its closed state so that the pre-charge capacitor 54.1 , the pre-charge resistor 56 and the interrupt pre-charge switch 58 are all electrically in series in the pre-charge circuit 50 between the first primary point 44.1 and earth 52 , while the first primary point 44.1 is electrically isolated from the upstream point 36 of the cut-off device, by the opening of the isolation switch 48 , but electrically connected to the downstream point 38 , by the closing of the cut-off switch 42.1 to allow discharge of the pre-charge capacitor 54.1 in the conductor 21 of the downstream electric line .

It has been illustrated in FIG. 12A a switching device according to the invention which is derived from a switching device architecture which is described in particular in the document K. TAKATA et. para. " HVDC Circuit Breakers for HVDC Grid Applications ", CIGRE AORC 2014, to which reference will be made in more detail for the operation of the breaking assistance device. In the cut-off device 28 of Figs. 1 2 A , there is therefore a main circuit 34 in which a nominal direct current flows in a conduction configuration of the cut-off device, the main circuit 34 extending between an upstream point 36 intended to be electrically connected to a source of DC high voltage 17 and a downstream point 38 intended to be electrically connected to a conductor 21 of a downstream electric power transmission line. This embodiment here comprises a single cut-off module 40.1 comprising at least one cut-off switch 42.1 interposed in the main circuit 34 between a first primary point 44.1 and a first secondary point 46.1 of the main circuit 34 . The first primary point 44.1 and the first secondary point 46.1 are located in this order in the main circuit 34 between the upstream point 36 and the downstream point 38 . This embodiment variant comprises an isolation switch 48 , interposed in the main circuit 34 between the upstream point 36 and the first primary point 44.1 . In this architecture, there is provided, in parallel with the cut-off module 40.1 , a cut-off assistance circuit 70.1 which extends between the primary point 44.1 and the secondary point 46.1 which correspond to the cut-off module considered. In a cut-off configuration C_C , the cut-off assistance circuit 70.1 is provided to promote the extinction of an electric arc which may form between the terminals of the cut-off switch 42.1 when it opens. For this, the cut-off assistance circuit 70.1 comprises, between the primary point 44.1 and the secondary point 46.1 which correspond to the cut-off module considered, at least one dedicated inductive component 90.1 , a capacitor 54.1 and an activation switch 72.1 . In this architecture, cut-off assistance circuit 70.1 therefore forms an LC circuit in which current oscillations can be forced, here by discharging capacitor 54.1 . Indeed, starting from a charged capacitor 54.1 , the closing of the activation switch causes the discharge of the capacitor in the cut-off assistance circuit 70.1 which forms an LC circuit. This discharge takes the form of an oscillatory current. In a known manner, this LC-type cut-off assistance circuit 70.1 is dimensioned, in particular in terms of capacitance and inductance, such that the current oscillations exceed in intensity the fault current in the cut-off switch 42.1 . Thanks to such an oscillation, the cut-off assistance circuit 70.1 injects into the main circuit 34 , through the cut-off switch 42.1 , a counter-current in the opposite direction to the fault current, and intensity greater than the fault current, causing the current to pass through zero in the cut-off switch 42.1 , which leads to the extinction of the electric arc. It is also noted that the cut-off module includes a surge protector 75.1 which is arranged electrically in parallel with capacitor 54.1 to limit the voltage across the terminals of capacitor 54.1 .

Unlike the basic architecture described in particular in the document K. TAKATA et. para. " HVDC Circuit Breakers for HVDC Grid Applications ", CIGRE AORC 2014, the breaking device 28 in Fig. 12A comprises a pre-charge circuit 50 which extends between the first primary point 44.1 and ground 52 and which comprises at least one pre-charge capacitor 54.1 , at least one pre-charge resistor 56 and a pre-charge switch -load 58 . As can be seen in the figure, in a C_C cut-off configuration, the cut-off device 28 is configured such that the pre-charge capacitor 54.1 of the pre-charge circuit 50 forms part of the cut-off assistance circuit 70.1 , in which it plays the role of the capacitor of the LC circuit intended to generate the oscillations. In the example, the pre-charge capacitor 54.1 is the only capacitor in the cut-off assistance circuit 70.1 , in the sense that there is no capacitor in the section of the cut-off assistance circuit 70.1 which is separate from the pre-charge circuit 50 , here between the tapping point 76 and the secondary point 46.1 . However, depending on the capacitive needs for on the one hand the pre-charge operation and on the other hand the cut-off assistance operation, it is possible to have, in addition to the pre-charge capacitor 54.1 which is arranged in the section of the pre-charge circuit 50 which is common with the cut-off assistance circuit 70.1 , at least one other capacitor, this other capacitor being arranged in the section of the cut-off assistance circuit 70.1 which is separate from the pre-charge circuit 50 , here between the tapping point 76 and the secondary point 46.1 .

The pre-charge circuit 50 comprises a first section, which is common with the cut-off assistance circuit 70.1 , which extends between the first primary point 44.1 and a tapping point 76 and which comprises the at least one pre-charge capacitor 54.1 . The pre-charge circuit 50 comprises a second section, separate from the cut-off assistance circuit 70.1 , which extends between the tapping point 76 and the earth 52 and in which the pre-charge switch 58 is interposed. . Note that the pre-charge resistor 56 of the pre-charge circuit 50 is, in this variant, arranged in the second section of the pre-charge circuit 50 which extends between the tapping point 76 and the earth 52 , therefore outside of the cut-off assistance circuit 70.1 .

In the embodiment of FIG. 1 2 A , the dedicated inductive component 90.1 of the cut-off assistance circuit 70.1 is arranged in the part of the cut-off assistance circuit 70.1 which is separate from the pre-charge circuit 50 , here between the tapping point 76 and sub-point 46.1 .

The activation switch 7 2 .1 is arranged in the section of the cut-off assistance circuit 70.1 which is distinct from the pre-charge circuit 50 , here between the tapping point 76 and the secondary point 46.1 . This activation switch 72 .1 is in its closed state in a cut-off configuration C_C of the cut-off device 28 , during which the cut-off assistance circuit 70.1 is active to interrupt the flow of current in the circuit. cut-off switch 42.1 being opened. This activation switch 7 2 .1 is open in the C_CH charging and C_PCH pre-charging configurations of the cut-off device 28 , to prevent the electrical conductor 21 , connected to the downstream point 38 , from being able to discharge through the cut-off assistance circuit 70.1 .

It has been illustrated in FIG. 1 2B a table which reads in the same way as that of FIG. 9B , in which there is represented, for each of the configurations described above, of a switching device 28 according to FIG. 1 2 A , the state of the various switches in the configuration. In addition to the C_COND conduction, C_ISOL insulation and C_C cut-off configurations, there is therefore a C_CH charging configuration in which the pre-charge switch 58 is in a closed state, so that the pre-charge capacitor 54.1 , the pre-charge resistor 56 and the pre-charge switch 58 are all electrically in series in the pre-charge circuit 50 between the first primary point 44.1 and the earth 5 2 , while the first primary point 44.1 is electrically isolated from the downstream point 38 of the cut-off device 28 , in particular by the opening of the cut-off switch 42.1 , but electrically connected to the upstream point 36 , by the closing of the isolation switch 48 to allow loading of the pre-charge capacitor 54.1 . In this loading configuration C_CH , the activation switch 72.1 of the cut-off assistance circuit 70.1 is also open to isolate the tapping point 76 with respect to the first secondary point 46.1 and therefore with respect to the downstream point 38 . There is also a pre-charge configuration C_PCH in which the pre-charge switch 58 is in its closed state so that the pre-charge capacitor 54.1 , the pre-charge resistor 56 and the pre-charge switch -load 58 are all electrically in series in the pre-charge circuit 50 between the first primary point 44.1 and the earth 52 , while the first primary point 44.1 is electrically isolated from the upstream point 36 of the cut-off device 28 , by the opening of the isolation switch 48 , but electrically connected to the downstream point 38 , by the closing of the cut-off switch 42.1 to allow discharge of the pre-charge capacitor 54.1 in the conductor 21 of the downstream power line. In this C_PCH pre-charge configuration, the activation switch 72.1 of the cut-off assistance circuit 70.1 is open to isolate the tapping point 76 with respect to the first secondary point 46.1 and therefore with respect to the downstream point 38 .

It is noted that, in the embodiment of FIG. 12A , when the cut-off switch 42.1 opens and the cut-off assistance is triggered, the capacitor 54.1 which is shared by the cut-off assistance circuit 70.1 and by the pre-charge circuit 50 unloads. Thus, when the current has been interrupted, capacitor 54.1 can be discharged to a voltage different from that of voltage source 17 , or even lower than that of voltage source 17 . Also, in the context of a re-closing, it will be necessary, if one wants to carry out a step of pre-charging the electrical conductor 21 , to first proceed to a step of recharging the capacitor 54.1 to recharge it , before being able to perform the first pre-charge stage.

It has been illustrated in Figs. 13A to 17A different embodiments of a cut-off device which comprises several cut-off modules 40.1 , 40.2 , 40.3 which are interposed successively in the main circuit 34 between the first primary point 44.1 and the downstream point 38 . In each of the embodiments of Figs. 13A to 17A , the switching device 28 described can be used instead of those described above, with the same possible configurations, and with the same possible control mode during re-closing as described above, to implement a process for evaluating the integrity of an electrical conductor with at least one step of pre-charging the conductor during which an auxiliary auxiliary voltage source, distinct from the main voltage source 17 , is connected to the electrical conductor 21 to turn it on while maintaining it isolated from the main voltage source 17 and from the rest of the electrical installation 10 as described above. These embodiments also make it possible to implement a step of recharging the pre-charge capacitor during which the cut-off device is brought into the charging configuration C_CH .

It will be understood that the multiplication of the breaking devices arranged successively in the main circuit 34 makes it possible to reduce, at the moment of opening, the voltage at the terminals of each of the breaking modules. This makes it possible either to increase the breaking power of the breaking device 28 , at a given performance of each module, or, to obtain a given breaking power of the breaking device, to implement breaking modules having a power of noticeably lower cutoff.

Thus, in each of these embodiments, the cut-off device 28 comprises, downstream of the first cut-off module 40.1 in the main circuit 34 of the cut-off device 28 , at least one last cut-off module. A cut-off device comprising several cut-off modules could comprise only two cut-off modules, namely a first cut-off module and a last cut-off module interposed successively in the main circuit 34 between the first primary point 44.1 and the downstream point 38 .

However, in the examples illustrated, the cut-off device 28 comprises more than two cut-off modules, namely, interposed successively in the main circuit 34 between the first primary point 44.1 and the downstream point 38 , a first cut-off module, at least an additional cut-off module and a final cut-off module. Thus, in the examples illustrated, the cut-off device 28 comprises three cut-off modules, namely, interposed successively in the main circuit 34 between the first primary point 44.1 and the downstream point 38 , a first cut-off module 40.1 , a second module cutoff 40.2 forming an additional cutoff module, and a third cutoff module forming the last cutoff module. A cut-off device 28 according to the invention may comprise several additional cut-off modules interposed successively, in the main circuit 34 , between the first cut-off module 40.1 and the last cut-off module 40.n.

The last cut-off module 40.3 , here the third, comprises at least one cut-off switch 42.3 , 60.3 , 6 2.3 interposed in the main circuit 34 between a last primary point 44.3 , downstream of the first secondary point 46.1 , and a last secondary point 46.3 of the main circuit 34 . Of course, the cut-off switch 42.3 , 60.3 , 62.3 of the last cut-off module 40.3 can be controlled between an open state and a closed state to respectively determine an open state and a closed state of the last cut-off module 40.3 .

Between the first cutoff module 40.1 and the last cutoff module 40.3 in the main circuit of the cutoff device 28 , the additional cutoff module also comprises at least one cutoff switch 42.2 , 60.2 , 62.2 , interposed in the main circuit 34 between an additional primary point, here therefore the second primary point 44.2 downstream of the first secondary point 46.1 , and an additional secondary point of the main circuit, here therefore the second secondary point 46.2 upstream of the last primary point 44.3 . Of course, the cut-off switch 42.2 , 60.2 , 62.2 of the additional module 40.2 can be controlled between an open state and a closed state to respectively determine an open state and a closed state of the additional cut-off module.

In a breaking device comprising several breaking modules, one could have a pre-charging circuit which would be a dedicated circuit, as illustrated in FIG. 3 , with a pre-charge circuit extending between the first primary point 44.1 and ground and comprising at least one pre-charge capacitor, at least one pre-charge resistor and a pre-charge switch.

However, in the case where at least one of the cut-off modules comprises a cut-off assistance circuit 70.1 implementing a capacitor, provision will preferably be made for at least one pre-charge capacitor of the pre-charge circuit load 50 is also part of the cut-off assistance circuit of at least one of the cut-off modules. If several of the cut-off modules, or even all of them, each comprise a cut-off assistance circuit implementing a capacitor, provision will preferably be made for the pre-charge circuit 50 to comprise several pre-charge capacitors, and that at the at least one pre-charge capacitor of the pre-charge circuit is also part of the cut-off assistance circuit of a cut-off module while at least one other pre-charge capacitor of the pre-charge circuit is are part of the cut-off assistance circuit of another cut-off module. For example, the pre-charge circuit 50 comprises several pre-charge capacitors, and each cut-off assistance circuit comprises at least one pre-charge capacitor of the pre-charge circuit. In other words, at least one of the cut-off assistance circuits, preferably several, more preferably all of the cut-off assistance circuits, comprising at least one capacitor which has a function in the cut-off assistance, shares this at least one capacitor with the pre-charge circuit 50 .

In the examples illustrated, the last cut-off module 40.3 comprises a cut-off assistance circuit 70.3 which extends electrically in derivation from the cut-off switch 42.3 of the last cut-off module 40.3 and from the main circuit 34 , between the last primary point 44.3 and last secondary point 46.3 of the main circuit 34 . In a C_C cut-off configuration, the cut-off device 28 is configured such that at least one pre-charge capacitor 54.3 of the pre-charge circuit forms part of the cut-off assistance circuit 70.3 of the last cut-off module 40.3 . Similarly, in the examples illustrated, the additional cut-off module, for example the second additional cut-off module 40.2 comprises a cut-off assistance circuit 70.2 which extends electrically in derivation from the cut-off switch 42.2 of the additional cutoff 40.2 and of the main circuit 34 , between the primary point 44.2 and the secondary point 46.2 of the main circuit 34 which are associated with this cutoff module, here the second 40.2 . In a C_C cut-off configuration, the cut-off device 28 is configured such that at least one pre-charge capacitor 54.2 of the pre-charge circuit forms part of the cut-off assistance circuit 70.2 of the additional cut-off module, for example the second cut-off module 40.2 .

Preferably, in the C_C cut-off configuration of the cut-off device, the cut-off assistance circuits of at least one upstream cut-off module, for example the first cut-off module 40.1 , and of a downstream cut-off module, for example the last cut-off module 40.3 , are arranged electrically in series. In certain embodiments, this series connection is obtained by correctly configuring certain configuration switches 78.1 and/or isolation switches 77.1 and/or even shunt switches 79.1 . In this context, it will be seen that, preferably, the cut-off assistance circuit of the downstream cut-off module, for example the cut-off assistance circuit 70.3 of the last cut-off module 40.3 , comprises, successively and in this order from the primary point of this downstream module, for example the last primary point 44.3 , at least one pre-charge capacitor 54.3 and an activation switch 72.3 , with a tapping point 76 between the two in this power assistance circuit cut 70.3 . Thus, the pre-charge circuit 50 comprises a first section which extends between the primary point of the upstream module, for example the first primary point 44.1 , and the tapping point 76 . This first section of the pre-charge circuit 50 is common with the cut-off assistance circuit, and comprises the at least one pre-charge capacitor of each of the cut-off assistance circuits of the modules whose circuits d assistance are in series, for example those of the first breaking module and the last breaking module. The pre-charge circuit comprises a second section, distinct from the cut-off assistance circuit, which extends between the tapping point 76 and the earth 52 , and in which the pre-charge switch 58 is interposed.

It is therefore understood that, in a cut-off device 28 comprising several cut-off modules having a cut-off assistance circuit, it is sufficient for one of them to have a tapping point from which the second section of the circuit is detached. pre-charge, distinct from the cut-off assistance circuit, which extends between the tapping point 76 and the ground 52 , and in which the pre-charge switch 58 is interposed. Indeed, in this case, it suffices that, in the C_PCH pre-charge configuration and/or in the C_CH loading configuration, the cut-off assistance circuits of these modules, or at least the parts of these circuits cut-off assistance comprising the capacitor of these circuits, are placed in series to form the first section of the pre-charge circuit. This first section of the pre-charge circuit, which therefore includes capacitors also belonging to the cut-off assistance circuits, is connected, at the tapping point 76 , with the second section of the pre-charge circuit, separate from the cut-off assistance circuit, which includes the pre-charge switch 58 .

We will now detail how the general characteristics above are declined in the various embodiments which are illustrated.

In the following description, it will be considered that, in each configuration of the cut-off device 28 , all the cut-off modules 40.1 , 40.2 and 40.3 which follow one another in the main circuit are in the same state at the same time, including for what is the state of the cut-off assistance circuits of each of the cut-off modules.

In the embodiment of FIG. 13A , all the cut-off modules 40.1 , 40.2 and 40.3 are identical and similar to what has been described in relation to the embodiment of FIG. 9A . The different configurations of the cut-off device of FIG. 13A are deduced from the different states of the switches which are indicated in the table of FIG. 13B , which reads in the same way as that of FIG. 9B .

In the embodiment of FIG. 13A , shunt switches 79.1 , 79.2 have been shown which, for the usual configurations of conduction C_COND , of cutoff C_C , are in an open state. However, with the pre-charge switch 58 in its open state, one could have the shunt switches 79.1 , 79.2 in their closed state for these configurations.

A configuration switch 78 has also been shown for each cut - off module 40.i. i (here 78.1 , 78.2 , 78.3 ) in the cut-off assistance circuit 70.i , between the activation switch 72.i of the cut-off module considered and the secondary point 46.i of the module considered. In each cut-off module 40.i , this configuration switch 78.i therefore has the same location as the counterpart in the embodiment of FIG. 9A .

It has also been shown that the last module 70.3 , and each additional cut-off module, therefore here the second cut-off module 70.2 , comprise an isolation switch 77.2 , 77.3 in the cut-off assistance circuit considered, between the primary point 44.2 , 44.3 of the cut-off module considered and respectively the capacitor 54.2 , 54.3 of the cut-off assistance circuit of the cut-off module considered. Thus, the isolation switch 77.2 , 77.3 and the configuration switch 78.2 , 78.3 of a cut-off module considered delimit between them a segment of the cut-off assistance circuit which comprises the following elements of this circuit of cut-off assistance: the capacitor 54.2 , 54.3 , the activation switch 72.2 , 72.3 and any tertiary surge protector 74.2 , 74.3 which can be arranged across the terminals of the activation switch 72.2 , 72.3 . In the cut-off configuration C_C , the isolation switch 77.2 , 77.3 and the configuration switch 78.1 of a cut-off module considered are in their closed state, so that the elements included in the segment can play their role of cutting assistance. It is further noted that, in the cut-off configuration C_C , the cut-off assistance circuits at least of the first cut-off module 40.1 and of the last cut-off module 40.3 , but preferably also those of the additional cut-off module(s) 40.2 are electrically arranged in series. For example, in the C_C cut-off configuration of the cut-off device 28 , the cut-off assistance circuit 70.2 of the additional cut-off module 40.2 is arranged electrically in series between and with the cut-off assistance circuits 70.1 , 70.3 of the first and last cut-off modules 40.1 , 40.3 .

However, in the cut-off configuration C_C , each cut-off assistance circuit, at least of the first cut-off module 40.1 and of the last cut-off module 40.3 , but preferably also that or those of the additional cut-off module(s) 40.2 remains , considered individually, arranged in parallel with the cut-off switch 42.i of the cut-off module to which it belongs.

In the C_CH charging and C_PCH pre-charging configurations, the isolation switch 77.2 , 77.3 and the configuration switch 78.1 , 78.2 , 78.3 of a cut-off module considered are in their open state, to isolate the elements included in the segment relative to the main line 34 . Moreover, in the C_CH charging and C_PCH pre-charging configurations, the activation switch 72.i is open and the shunt switches 79.1 , 79.2 are closed. By this combination, it is noted that, in the C_CH charging and C_PCH pre-charging configurations, the capacitors 54.1 , 54.2 and 54.3 which, in the C_C cut-off configuration, are in the cut-off assistance circuit, are then find themselves arranged directly in series with each other in the pre-charge circuit 50 , between the first primary point 44.1 and the ground. In this embodiment, and by this combination, only the capacitors 54.i of the cut-off assistance circuits are found in series in the pre-charge circuit. This arrangement in series makes it possible to increase the voltage withstand of the assembly formed by these capacitors in the pre-charge circuit 50 , which, in the cut-off configuration C_C , are each associated with a cut-off module. The presence of the shunt switches 79.1 , 79.2 , in their closed state, makes it possible to have, for the C_CH charging and C_PCH pre-charging configurations, the most direct possible path of the current in the pre-charging circuit 50 .

On the other hand, it is understood that in this embodiment of FIG. 13A , for the C_PCH pre-charge configuration, the current generated by the discharging of the capacitors must pass through all the cut-off switches which are in their closed state.

Also, it has been illustrated in FIG. 14A an embodiment in which all the switching modules 40.1 , 40.2 and 40.3 are identical to each other, and are similar to what has been described in relation to the embodiment of FIG. 10 A , The different configurations of the breaking device of FIG. 1 4 A are deduced from the various states of the switches which are indicated in the table of FIG. 1 4 B , which is read in the same way as that of Figure 10 B .

The cut-off device 28 comprises, interposed successively in the main circuit 34 between the first primary point 44.1 and the downstream point 38 , a first cut-off module 40.1 , an additional cut-off module 40.2 , also called here second cut-off module 40.2 , and a last cut-off module 40.3 . Each cut-off module 40.i comprises a cut-off switch 42.i , here made in the form of two successive switches 60.i , 62.i interposed in the main circuit 34 between a primary point 44.i and a secondary point 46 i of the main circuit 34 which are associated with the cut - off module 40.i. It is understood that each module is arranged in such a way that the primary point of an additional module or of the last module is directly connected, and preferably electrically merged, with the secondary point of the module which precedes it in the upstream-downstream direction in the main circuit 34 .

Each cut-off module 40.i includes a cut-off assistance circuit 70.i implementing a capacitor, and it will be seen that the cut-off device 28 includes a pre-charge circuit 50 having at least as many pre-charge capacitors. -charge 54.i than the number of modules, and that each cut-off assistance circuit 70.i comprises at least one pre-charge capacitor 54.i of the pre-charge circuit.

In the C_C cutoff configuration of the cutoff device, the cutoff assistance circuits 70.i are arranged electrically in series between the first primary point 44.1 and the last secondary point 46.3 . This stems from the fact that each module is arranged in such a way that the primary point of an additional module or of the last module is directly connected, and preferably electrically merged, with the secondary point of the module which precedes it in the upstream-downstream direction. in the main circuit 34 , and that the cut-off assistance circuit 70.i of each cut-off module extends electrically in derivation from the cut-off switch 42.i of the cut-off module 40.i and from the main circuit 34 , between the primary point 44.i and the secondary point 46.i of the main circuit 34 which are associated with this module.

Each cut-off assistance circuit 70.i comprises at least one capacitor, which can be seen to be advantageously a pre-charge capacitor 54.i in the sense that it also belongs to the pre-charge circuit 50 , and an activation switch 72.i.

The cut-off assistance circuit 70.3 of the last cut-off module 40.3 comprises, successively and in this order from the last primary point 44.3 , at least one pre-charge capacitor 54.3 and an activation switch 72.3 , with a point of tapping 76 between the two in this last cut-off assistance circuit 70.3 .

The pre-charge circuit 50 comprises a first section which extends between the first primary point 44.1 and the tapping point 76 , which is common with the succession of series cut-off assistance circuits, and which comprises the at least one pre-charge capacitor of each of the cut-off assistance circuits of each of the cut-off modules. The pre-charge circuit 50 comprises a second section, distinct from the various cut-off assistance circuits, which extends between the tapping point 76 and the earth 52 and in which is interposed the pre-charge switch 58 .

In this embodiment, the breaking modules do not need to incorporate a configuration switch in each reference breaking assistance circuit as provided in the embodiment of FIG. 10A .

It has been illustrated in Fig. 14 A the presence of a bypass circuit 80 which extends, electrically parallel to the main circuit 34 between the first primary point 44.1 and a bypass point 82 arranged between the last secondary point 46.3 and the downstream point 38 . In this bypass circuit 80 is interposed a bypass switch 84 which is in a closed state in the C_PCH pre-charge configuration and in an open state in the C_CH charging, C_ISOL isolation, cut-off configurations C_C , and also in the conduction configuration C_COND . The bypass circuit 80 makes it possible to carry out, for the pre-charging configuration C_PCH , the pre-charging of the electrical conductor 21 of the downstream power transmission line, while maintaining cut-off assistance circuits 70. i with the lowest possible parasitic inductance. The presence of the bypass circuit 80 makes it possible to move the configuration switch 78 to place it in the main line 34 between the last secondary point 46.3 and the bypass point 82 . The configuration switch 78 is closed in the conduction configuration C_COND , and in the cut-off configuration C_C of the cut-off device 28 . The configuration switch 78 is open in the C_CH charging and C_PCH pre-charging configurations of the cut-off device 28 , to prevent the electrical conductor 21 , connected to the downstream point 38 , from being able to discharge in particular through the cut-off assistance circuit 7 0.3 . Preferably, the configuration switch 78 is open in the C_ISOL isolation configuration.

In the cut-off device 28 of FIG. 14A , only one cut-off module, the last one, has a tapping point 76 from which the second section of the pre-charge circuit is detached. In the C_PCH pre-charging configuration and/or in the C_CH charging configuration, the entirety of each power-cutting module assistance circuit is placed in series to form the first section of the pre-charging circuit.

It is noted that it is possible to provide, before a first step of pre-charging the electrical conductor 21 , a preparation step during which all current flow is cut off in the cut-off assistance circuits 70. i between the stitching point 76 and the last secondary point 46.3 . This can be done for example by opening the configuration switch 78 .

It has been illustrated in FIG. 15A an embodiment in which all the switching modules 40.1 , 40.2 and 40.3 are identical to each other, and are similar to what has been described in relation to the embodiment of FIG. 11A , with the difference that the configuration switch is no longer in the breaking modules, as has just been described with reference to FIG. 14A .

The cut-off device 28 comprises, successively interposed in the main circuit 34 between the first primary point 44.1 and the downstream point 38 , a first cut-off module 40.1 , an additional cut-off module 40.2 , also called here second cut-off module 40.2 , and a last cut-off module 40.3 . Each cut-off module 40.i comprises a cut-off switch 42.i interposed in the main circuit 34 between a primary point 44.i and a secondary point 46.i of the main circuit 34 which are associated with the cut-off module 40.i. It is understood that each cutoff module 40.i is arranged in such a way that the primary point of an additional cutoff module or of the last cutoff module is directly connected, and preferably electrically merged, with the secondary point of the module which precedes in the upstream-downstream direction in the main circuit 34 .

Each breaking module 40.i comprises a breaking assistance circuit 70.i implementing a capacitor, an inductance 90.i and a controlled voltage source 92.i. The cut-off device 28 includes a pre-charge circuit 50 having at least as many pre-charge capacitors 54.i as the number of modules, and each cut-off assistance circuit 70.i includes at least one pre-charge 54.i of the pre-charge circuit.

In the embodiment of FIG. 15A , shunt switches 79.1 , 79.2 have been shown which, for the usual configurations of conduction C_COND , cutoff C_C and insulation C_ISOL , are in an open state. Thus, in the C_C breaking configuration of the breaking device, the breaking assistance circuits 70.i are arranged electrically in series, successively between the first primary point 44.1 and the last secondary point 46.3 .

The cut-off assistance circuit 70.3 of the last cut-off module 40.3 comprises, successively and in this order from the last primary point 44.3 , at least one pre-charge capacitor 54.3 and a controlled voltage source 92.3 , with a point of tapping 76 between the two in this last cut-off assistance circuit 70.3 .

The pre-charge circuit 50 comprises a first section which extends between the first primary point 44.1 and the tapping point 76 , which is common with the succession of series cut-off assistance circuits, and which comprises the at least one pre-charge capacitor of each of the cut-off assistance circuits of each of the cut-off modules. The pre-charge circuit 50 comprises a second section, distinct from the various cut-off assistance circuits, which extends between the tapping point 76 and the earth 52 and in which is interposed the pre-charge switch 58 . In the example, the pre-charge resistor 56 is also in this second section which is distinct from the various cut-off assistance circuits.

It can advantageously be provided that, in the C_CH charging and C_PCH pre-charging configurations, the shunt switches 79.1 , 79.2 are closed. Thus, the capacitors 54.1 , 54.2 and 54.3 which, in the C_C cut-off configuration, are in the cut-off assistance circuit, are found, in the C_CH charging and C_PCH pre-charging configurations, then arranged directly in series to each other in the pre-charge circuit 50 , between the first primary point 44.1 and the earth 52 . More specifically, in the C_PCH pre-charge configuration and/or in the C_CH charging configuration, only part of each power-cutting module assistance circuit, comprising at least one capacitor 54.1 of the capacity of each power-assist circuit cut-off, is put in series to form the first section of the pre-charge circuit. This arrangement in series makes it possible to increase the voltage withstand of the assembly formed by the capacitors in the pre-charge circuit 50 , which, in the cut-off configuration C_C , are each associated with a cut-off module. The presence of the shunt switches 79.1 , 79.2 , in their closed state, makes it possible to have, for the C_CH charging and C_PCH pre-charging configurations, the most direct possible path of the current in the pre-charging circuit. In particular, it can be seen that the pre-charge circuit thus formed with the shunt switches 79.1 , 79.2 , in their closed state, avoid the inductors 90.2 and 90.3 of at least some cut-off assistance circuits 70.2 , 70.3 .

In this embodiment, the breaking modules 40.i do not need to incorporate a configuration switch in each breaking assistance circuit. Indeed, it has been illustrated in FIG. 15 In the presence of a bypass circuit 80 identical to that of the embodiment of FIG . 14A . The bypass circuit 80 extends electrically in parallel with the main circuit 34 between the first primary point 44.1 and a bypass point 82 arranged between the last secondary point 46.3 and the downstream point 38 . In this bypass circuit 80 is interposed a bypass switch 84 which is in a closed state in the C_PCH pre-charge configuration and in an open state in the C_CH charging, C_ISOL isolation, cut-off configurations C_C , and also in the conduction configuration C_COND . The bypass circuit 80 makes it possible to carry out, for the pre-charge configuration C_PCH , the pre-charge of the electrical conductor 21 of the downstream power transmission line, while maintaining cut-off assistance circuits 70. i with the lowest possible inductance. The presence of the bypass circuit 80 makes it possible to move the configuration switch 78 to place it in the main line 34 between the last secondary point 46.3 and the bypass point 82 . The configuration switch 78 is closed in the conduction configuration C_COND , and in the cut-off configuration C_C of the cut-off device 28 . The configuration switch 78 is open in the C_CH charging and C_PCH pre-charging configurations of the cut-off device 28 , to prevent the electrical conductor 21 , connected to the downstream point 38 , from being able to discharge in particular through the cut-off assistance circuit 70.3 . Preferably, the configuration switch 78 is open in the C_ISOL isolation configuration.

The different configurations of the cut-off device of FIG. 15A are deduced from the various states of the switches which are indicated in the table of FIG. 1 5 B , which is read in the same way as that of FIG. 9B .

It has been illustrated in FIG. 16A an embodiment comprising several successive cut-off modules in the main circuit, all the cut-off modules 40.1 , 40.2 and 40.3 being identical to each other, and being similar to what has been described in relation to the embodiment of FIG. 11B , but the breaking modules being assembled in a manner analogous to what has been described in relation to FIG. 13A . Thus, in the C_C breaking configuration of the breaking device 28 of FIG. 16A , all of the cut-off assistance circuits 70.i are electrically arranged in series by correctly configuring certain configuration switches 78.i , isolation 77.i and shunt 79.i.

A configuration switch 78 has thus been shown for each cut - off module 40.i. i (here 78.1 , 78.2 , 78.3 ) in the cut-off assistance circuit 70.i , between the controlled voltage source 92 i of the cut-off module considered and the secondary point 46.i of the module considered. In each cut-off module 40.i , this configuration switch 78.i therefore has the same location as the counterpart in the embodiment of FIG. 11B .

There is also, for the last module 70.3 , and for each additional cut-off module, therefore here for the second cut-off module 70.2 , an isolation switch 77.2 , 77.3 in the cut-off assistance circuit considered, between the point primary 44.2 , 44.3 of the cut-off module considered and respectively the capacitor 54.2 , 54.3 of the cut-off assistance circuit of the cut-off module considered. Thus, the isolation switch 77.2 , 77.3 and the configuration switch 78.2 , 78.3 of a cut-off module considered delimit between them a segment of the cut-off assistance circuit which comprises the following elements of this circuit of cut-off assistance: the capacitor 54.2 , 54.3 , the controlled voltage run 92 i and any surge protector 7 5 .2 , 7 5 .3 which can be arranged across the terminals of the capacitor 54 .2 , 54 .3 . In the cut-off configuration C_C , the isolation switch 77.2 , 77.3 and the configuration switch 78.i of a cut-off module considered are in their closed state, so that the elements included in the segment can play their role cutting assistance.

In this embodiment of FIG. 16A , shunt switches 79.1 , 79.2 have been shown which, for the usual C_COND conduction, C_C cutoff and C_ISOL insulation configurations, are in an open state and arranged so that, in the C_C cutoff configuration of the cut-off device, the cut-off assistance circuits 70.i are, in their entirety, arranged electrically in series, successively between the first primary point 44.1 and the last secondary point 46.3 . while remaining, considered individually, arranged in parallel with the cut-off switch 42.i of the cut-off module to which they belong.

The cut-off assistance circuit 70.3 of the last cut-off module 40.3 comprises, successively and in this order from the last primary point 44.3 , at least one pre-charge capacitor 54.3 , a controlled voltage source 92.3 , and a configuration 78.3 , with a tapping point 76 between the two in this last cut-off assistance circuit 70.3 .

In the C_CH charging and C_PCH pre-charging configurations, the isolating switch n 77.2 , 77.3 and the configuration switch 78.1 , 78.2 , 78.3 of a breaking module considered are in their open state, to isolate the elements included in the segment relative to the main line 34 . Moreover, in the C_CH loading and C_PCH pre-charging configurations, the shunt switches 79.1 , 79.2 are closed. Thus, the capacitors 54.1 , 54.2 and 54.3 which, in the cut-off configuration C_C , are each located in a cut-off assistance circuit 70.i , are found, in the C_CH charging and C_PCH pre-charging configurations, arranged in series in the pre-charge circuit 50 , between the first primary point 44.1 and the ground 52 . The presence of the shunt switches, in their closed state, makes it possible to have, for the C_CH charging and C_PCH pre-charging configurations, a more direct current path in the pre-charging circuit, avoiding the inductances 90.2 and 90.3 of the second and last breaking modules.

In the C_CH charging and C_PCH pre-charging configuration, the pre-charging circuit 50 comprises a first section which extends between the first primary point 44.1 and the tapping point 76 , which comprises the at least one pre-charging capacitor -loading of each of the cut-off assistance circuits of each of the cut-off modules. In this embodiment of FIG. 16A , it can be seen that, in the C_CH charging and C_PCH pre-charging configurations, the first section of the pre-charging circuit 50 also comprises the controlled voltage source 92.1 of each of the power cut-off assistance circuits. each of the breaking modules. In doing so, the pre-charging step of the conductor 21 can be taken advantage of to also charge capacitors in the controlled voltage source, which is then operational for a following cut-off step.

The pre-charge circuit 50 comprises a second section, distinct from the various cut-off assistance circuits, which extends between the tapping point 76 and the earth 52 and in which is interposed the pre-charge switch 58 . In the example, the pre-charge resistor 56 is also in this second section which is distinct from the various cut-off assistance circuits.

The different configurations of the cut-off device of FIG. 16 A are deduced from the different states of the switches which are indicated in the table of FIG. 1 6 B , which is read in the same way as that of FIG. 9B .

It has been illustrated in FIG. 17A an embodiment comprising several successive cut-off modules in the main circuit, all the cut-off modules 40.1 , 40.2 and 40.3 being identical to each other, and being similar to what has been described in relation to the embodiment of FIG. 12A , but the breaking modules being assembled in a manner analogous to what has been described in relation to FIG. 1 4 A .

The cut-off device 28 comprises, interposed successively in the main circuit 34 between the first primary point 44.1 and the downstream point 38 , a first cut-off module 40.1 , an additional cut-off module 40.2 , also called here second cut-off module 40.2 , and a last cut-off module 40.3 . Each cut-off module 40.i comprises a cut-off switch 42.i , interposed in the main circuit 34 between a primary point 44.i and a secondary point 46.i of the main circuit 34 which are associated with the cut-off module 40.i . It is understood that each module is arranged in such a way that the primary point of an additional module or of the last module is directly connected, and preferably electrically merged, with the secondary point of the module which precedes it in the upstream-downstream direction in the main circuit 34 .

Each cut-off module 40.i comprises a cut-off assistance circuit 70.1 implementing a capacitor 54.i and an inductor 90.i , and it will be seen that the cut-off device 28 comprises a pre-charge circuit 50 having at least as many pre-charge capacitors 54.i as the number of modules, and each cut-off assistance circuit 70.i comprises at least one pre-charge capacitor 54.i of the pre-charge circuit.

As in the embodiment of FIG. 14A , the cut-off assistance circuits are, in the cut-off configuration C_C of the cut-off device, electrically arranged in series, in their entirety, between the first primary point 44.1 and the last secondary point 46.3 . Each assistance circuit comprises at least one pre-charge capacitor 54.i , which can be seen to be advantageously a pre-charge capacitor and in the sense that it also belongs to the pre-charge circuit 50 , and a activation switch 72.i . In the example illustrated, each assistance circuit comprises an inductance 90.i between the activation switch 72.i and the secondary point of the cut-off module 40.i considered.

The cut-off assistance circuit 70.3 of the last cut-off module 40.3 comprises, successively and in this order from the last primary point 44.3 , at least one pre-charge capacitor 54.3 and an activation switch 72.3 , with a point of stitching 76 between the two in this last cut-off assistance circuit 70.3 .

The pre-charge circuit 50 comprises a first section which extends between the first primary point 44.1 and the tapping point 41 , which is common with the succession of series cut-off assistance circuits, and which comprises the at least one pre-charge capacitor of each of the cut-off assistance circuits of each of the cut-off modules. The pre-charge circuit 50 comprises a second section, distinct from the various cut-off assistance circuits, which extends between the tapping point 76 and the earth 52 and in which is interposed the pre-charge switch 58 .

In this embodiment, the breaking modules do not need to incorporate a configuration switch in each reference breaking assistance circuit as was provided in the embodiment of FIG. 10A . In fact, the presence of a bypass circuit 80 and of a configuration switch 78 in the main line 34 has been illustrated, for the description of which reference will be made to the above passage with reference to FIG. 14 A.

Depending on the embodiments, it may be provided that, after the complete closing of the current cut-off device 28 by switching the current cut-off device to a conduction state, the discharge of the pre-charge capacitor or capacitors is caused. This could for example be implemented in particular within the framework of the embodiments of FIGS . 9A , 10A , 13A and 14A where the pre-charge capacitor must be discharged to ensure its role in the cut-off assistance function.

In the embodiments described above with reference to FIGS. 9A et seq., each of the cut-off modules of the embodiment considered comprises a capacitor which is implemented within the framework of the method for pre-charging the electrical conductor of the line power transmission by being inserted, at least for the charge and pre-charge configurations, in the pre-charge circuit. However, the invention also covers the case of a cut-off device which, in addition to a cut-off module comprising a capacitance which is thus exploited, may comprise one or more additional switches in the main circuit 34 between the first primary point 44.1 and the downstream point 38 , which are not associated with a capacity. Such switches may for example not include cut-off assistance circuits. Similarly, the invention also covers the case of a cut-off device which, in addition to a cut-off module comprising a capacitance which is thus exploited, may comprise one or more additional switches in the main circuit 34 between the first point primary 44.1 and the downstream point 38 , which are associated with a capacitor, for example a capacitor, but whose capacitor is not inserted in the pre-charge circuit for the charge and pre-charge configurations. In both cases, such switches will preferably be driven between their open and closed states, for each of the respective embodiments, in the same way as cut-off switches as described with reference to FIGS. 9A et seq. It is thus noted that one or more such switches can be found in the main circuit 34 between the first primary point 44.1 and the downstream point 38 , upstream of the first cut-off module 44.1 , downstream of the last cut-off module 44.3 , or between the first cut-off module 44.1 and the last cut-off module 44.3 . Thus, in the context of the invention, it is appropriate to interpret the last breaking module as being the last breaking module associated with a capacitor which is inserted in the pre-charging circuit for the charging and pre-charging configurations. charge. Likewise, in the context of the invention, the first cut-off module should be interpreted as being the first cut-off module associated with a capacitor which is inserted in the pre-charging circuit for the charging and pre-charging configurations. -charge.

In general, each of the embodiments described above makes it possible to implement a control method to ensure the re-closing of the cut-off device by which the overhead line is supplied before reconnecting it to the high voltage direct current network. by using the internal energy of the capacitor integrated in a cut-off device, in particular of the mechanical type, without placing the line directly in electrical connection with the high voltage DC source 17 , in order to limit the disturbances induced in the HVCD network unit 12 , and more generally, in order to limit the disturbances imposed on the DC high voltage source 17 . The pre-charging of the line is carried out using an auxiliary circuit, referred to above as the pre-charging circuit. The solution enables multiple retries through controlled capacitor recharging and enables pre-charging of very long transmission lines.

Claims (24)

Switching device ( 28 ) for electric current under high direct voltage comprising:
- a main circuit ( 34 ), in which a nominal direct current flows in a conduction configuration ( C_COND ) of the cut-off device, the main circuit extending between an upstream point ( 36 ) intended to be electrically connected to a source of direct high voltage ( 17 ) and a downstream point ( 38 ) intended to be electrically connected to a conductor ( 21 ) of a downstream electric line;
- at least a first cut-off module ( 40.1 ) comprising at least one cut-off switch ( 42.1 ) interposed in the main circuit between a first primary point ( 44.1 ) and a first secondary point ( 46.1 ) of the main circuit, the first primary point and the first secondary point being located in this order in the main circuit between the upstream point and the downstream point, and the cut-off switch being able to be controlled between an open state and a closed state to respectively determine an open state and a closed state of the first breaking module,
- an isolation switch ( 48 ), interposed in the main circuit between the upstream point and the first primary point, the isolation switch being capable of being controlled between an open state and a closed state;
characterized in that the cut-off device ( 28 ) comprises a pre-charge circuit ( 50 ) which extends between the first primary point ( 44.1 ) and the ground ( 52 ) and which comprises at least one pre-charge capacitor ( 54 , 54.1 ), at least one pre-charge resistor ( 56 ) and a pre-charge switch ( 58 ),
in that the cut-off device has at least:
- a charging configuration ( C_CH ) in which the pre-charging switch ( 58 ) is in a closed state so that the pre-charging capacitor ( 54 , 54.1 ), the pre-charging resistor ( 56 ) and the pre-charge switch ( 58 ) are all electrically in series in the pre-charge circuit ( 50 ) between the first primary point ( 44.1 ) and earth, while the first primary point ( 44.1 ) is electrically isolated from the downstream point ( 38 ) of the cut-off device but electrically connected to the upstream point ( 36 ) to allow charging of the pre-charge capacitor;
- a pre-charge configuration ( C_PCH ) in which the pre-charge switch ( 58 ) is in its closed state so that the pre-charge capacitor ( 54 , 54.1 ), the pre-charge resistor ( 56 ) and the pre-charge switch ( 58 ) are all electrically in series in the pre-charge circuit ( 50 ) between the first primary point ( 44.1 ) and ground ( 52 ), while the first primary point ( 44.1 ) is electrically isolated from the upstream point ( 36 ) of the cut-off device ( 28 ) but electrically connected to the downstream point ( 38 ) to allow discharge of the pre-charge capacitor ( 54 , 54.1 ) in the conductor ( 21 ) of the downstream power line;
- an isolation configuration ( C_ISOL ) in which the first primary point ( 44.1 ) is isolated from the upstream point ( 36 ), with the isolation switch ( 48 ) in its open state, and is isolated from the downstream point ( 38 ), with the cut-off switch ( 40.i ) in its open state,
and in that , in the conduction configuration ( C_COND ), the pre-charge switch ( 58 ) is open to isolate the first primary point ( 44.1 ) with respect to ground, and the upstream point ( 36 ) is connected electrically at the downstream point by the main circuit ( 34 ) comprising the cut-off switch ( 40.1 ) and the isolation switch ( 48 ) both in their closed state. Current cut-off device according to Claim 1 , characterized in that the first cut-off module ( 40.1 ) comprises a cut-off assistance circuit ( 70.1 ) which extends electrically in branch from the cut-off switch ( 42) . 1 ) and of the main circuit ( 34 ) between the first primary point ( 44.1 ) and the first secondary point ( 46.1 ) of the main circuit ( 34 ), and in that, in a cut-off configuration ( C_C ), the cut-off device ( 28 ) is configured in such a way that at least one pre-charge capacitor ( 54.1 ) of the pre-charge circuit ( 50 ) forms part of the cut-off assistance circuit ( 70.1 ) of the first cut-off module ( 40.1 ) . Current cut-off device according to any one of claims 1 or 2 , characterized in that it comprises, downstream of the first cut-off module ( 40.1 ) in the main circuit ( 34 ) of the cut-off device ( 28 ), at the at least one last cut-off module ( 40.n ) comprising at least one cut-off switch ( 42.n ) interposed in the main circuit ( 34 ) between a last primary point ( 44.n ), downstream of the first secondary point ( 46.1 ), and a last secondary point ( 46.n ) of the main circuit, and the cut-off switch ( 42.n ) of the last cut-off module ( 40.n ) being capable of being controlled between an open state and a state closed to respectively determine an open state and a closed state of the last breaking module ( 40.n ). Current cut-off device according to Claim 3 , characterized in that the last cut-off module ( 40.n ) comprises a cut-off assistance circuit ( 70.n ) which extends electrically in branch from the cut ( 42.n ) of the last cut-off module ( 40.n ) and of the main circuit, between the last primary point ( 44.n ) and the last secondary point ( 46.n ) of the main circuit, and in that, in a cut-off configuration ( C_C ), the cut-off device ( 28 ) is configured such that at least one pre-charge capacitor ( 40.n ) of the pre-charge circuit ( 50 ) is part of the circuit of cut-off assistance ( 70.n ) of the last cut-off module ( 40.n ). Current breaking device according to Claim 4 , characterized in that the pre-charge circuit ( 50 ) comprises at least a first pre-charge capacitor ( 54.1 ) and at least a second pre-charge capacitor ( 54.n ), and in that, in the cut-off configuration ( C_C ), the cut-off device is configured in such a way that the first pre-charge capacitor ( 54.1 ) forms part of the cut-off assistance circuit ( 70.1 ) of the first cutoff module while the second pre-charge capacitor ( 54.n ) forms part of the cutoff assistance circuit ( 70.n ) of the last cutoff module ( 40.n ). Current breaking device according to any one of Claims 3 to 5 , characterized in that it comprises, in the main circuit ( 34 ) of the breaking device ( 28 ), between the first breaking module ( 40.1 ) and the last cut-off module ( 40.3 ), at least one additional cut-off module ( 40.2 ) comprising at least one cut-off switch ( 42.2 ) interposed in the main circuit between an additional primary point ( 44.2 ), downstream of the first secondary point ( 46.1 ), and an additional secondary point ( 46.2 ) of the main circuit, upstream of the last primary point ( 44.3 ), and the cut-off switch ( 42.2 ) of the additional cut-off module ( 40.2 ) being capable of being controlled between a state open and a closed state to respectively determine an open state and a closed state of the additional breaking module ( 40.2 ). Current cut-off device according to Claim 6 , characterized in that an additional cut-off module ( 40.2 ) comprises a cut-off assistance circuit ( 70.2 ) which extends electrically in branch from the cut-off switch ( 42.2 ) of the additional cut-off module ( 40.2 ) considered and of the main circuit ( 34 ) between the primary ( 44.2 ) and secondary ( 46.2 ) additional points of the main circuit which correspond to the additional cut-off module ( 40.2 ) considered, and in that, in a cut-off configuration ( C_C ), the cut-off device ( 28 ) is configured such that at least one pre-charge capacitor ( 54.2 ) of the pre-charge circuit ( 50 ) forms part of the assistance circuit at breaking ( 70.2 ) of the additional breaking module ( 40.2 ). Current cut-off device according to Claim 2 , characterized in that the cut-off device comprises a single cut-off module ( 40.1 ) whose cut-off assistance circuit ( 70.1 ) comprises, successively and in this order from the first point primary ( 44.1 ), the at least one pre-charge capacitor ( 54.1 ) and an enable switch ( 72.1 ), with a tapping point ( 76 ) between the two in the cut-off assistance circuit ( 70.1 ), in that the pre-charge circuit ( 50 ) comprises a first section, which is common with the cut-off assistance circuit ( 70.1 ), which extends between the first primary point ( 44.1 ) and the point tapping ( 76 ) and which comprises the at least one pre-charge capacitor ( 54.1 ), and in that the pre-charge circuit ( 50 ) comprises a second section, distinct from the cut-off assistance circuit ( 70.1 ), which extends between the tapping point ( 76 ) and the earth ( 52 ) and in which the switch is interposed. pre-charge meter ( 58 ). Current cut-off device according to any one of Claims 1 to 7 taken in combination with Claims 2 and 4 , characterized in that the cut-off device comprises at least one upstream cut-off module ( 40.1 ) and a downstream cut-off module ( 40.3 ) whose cut-off assistance circuits ( 70.1 , 70.3 ) are, in the cut-off configuration ( C_C ) of the cut-off device ( 28 ), arranged electrically in series, in that the cut-off assistance circuit cutoff ( 70.3 ) of the downstream cutoff module ( 40.3 ) comprises, successively and in this order from the downstream primary point ( 44.3 ), the at least one pre-charge capacitor ( 54.3 ) and an activation switch ( 72.3 ) , with a tapping point between the two in the cut-off assistance circuit, in that the pre-charge circuit comprises a first section which extends between the upstream primary point ( 44.1 ) and the tapping point ( 76 ), which is common with power-cut assist circuits in series, and which comprises the at least one pre-charging capacitor ( 54.1 , 54.3 ) of each of the series cut-off assistance circuits, and in that the pre-charging circuit ( 50 ) comprises a second section, distinct from the cut-off assistance circuit, which extends between the tapping point ( 76 ) and the earth ( 52 ) and in which the pre-charge switch ( 58 ) is interposed. Current breaking device according to any one of the preceding claims, characterized in that it comprises a bypass circuit ( 80 ) which extends, electrically in parallel with the main circuit ( 34 ), between the first primary point ( 44.1 ) and a bypass point ( 82 ) arranged between the last secondary point ( 46.1 , 46.n ) and the downstream point ( 38 ), and in which is interposed a bypass switch ( 84 ) which is in a closed state in the pre-charge ( C_PCH ) configuration and in an open state in the charging ( C_CH ), isolation ( C_ISOL ) and cut-off ( C_C ) configurations. Current cut-off device according to Claim 10 , characterized in that it comprises a configuration switch ( 78 ) which is arranged in the main circuit ( 34 ) between the last secondary point ( 46.1 , 46.3 ) and the by-pass point. -pass ( 82 ), and which is in an open state in the pre-charge ( C_PCH ) and charging ( C_CH ) configurations, and in a closed state in the conduction ( C_COND ) and cut-off ( C_C ) configurations. Current-breaking device according to any one of Claims 1 to 11 taken in combination with Claims 2 and 4 , characterized in that it comprises at least one shunt switch ( 79.1 , 79.2 ) which, in the charging configuration ( C_CH ) and in the pre-charge configuration ( C_PCH ), is in a closed state to connect in series, in the pre-charge circuit ( 50 ), the pre-charge capacitors ( 50.1 ) belonging to the different modules of cut ( 40.i ). Current cut-off device according to any one of the preceding claims, characterized in that the cut-off switch ( 42.i ) of a cut-off module comprises a primary switch ( 60.i ), mechanical, and a secondary switch ( 62.i ), mechanical, interposed successively in the main circuit ( 34 ) between the primary point ( 44.i ) and the secondary point ( 46.i ) which correspond to the cut-off module ( 40.i ) considered, but of either side of an intermediate point ( 64.i ) of the main circuit ( 34 ) which corresponds to the cut-off module ( 40.i ) considered, the two mechanical switches ( 60.i , 62.i ) each being controlled between an open state and a closed state, and in that a cut-off module ( 40.i ) comprises a primary surge protector ( 66.i ) arranged in parallel with the primary switch ( 60.i ) between the primary point ( 44.i ) and the intermediate point ( 64.i ) which correspond to the cut-off module ( 40.i ) considered, and a surge protector r secondary ( 68.i ) arranged electrically in parallel with the secondary switch ( 62.i ) between the intermediate point ( 64.i ) and the secondary point ( 46.i ) which correspond to the cut-off module ( 40.i ) considered, and in that the cut-off assistance circuit ( 70.i ) of this cut-off module considered extends electrically in parallel with the assembly formed by the primary switch ( 60.i ) and the switch secondary ( 6 2 .i ) of this cut-off module considered, and electrically in parallel with the assembly formed by the primary surge protector ( 66.i ) and the secondary surge protector ( 68.i ) of this cut-off module ( 40.i ) considered. Current cut-off device according to any one of the preceding claims, characterized in that the downstream electrical line comprises an overhead line, the conductor ( 21 ) of the downstream electrical line being an overhead conductor. Electrical Installation (10) comprising a DC high voltage source (17) electrically connected to at least one overhead conductor (21) a downstream power line including an overhead line,characterized in thatit comprises, interposed between the DC high voltage source (17) and the overhead conductor of the downstream power line including an overhead line,A device power outage(28)according to any preceding claim s, the DC high voltage source (17) being connected to the upstream point (36) of the cut-off device (28), and the overhead conductor (21) being electrically connected by an upstream end to the downstream point (38) of the cut-off device (28). Electrical installation according to claim 1 5 , characterized in that it comprises, at a downstream end of the conductor ( 21 ) of the downstream electrical line, a current cut-off device. Method for controlling the closing of a current breaking device according to any one of claims 1 to 14 , the breaking device ( 28 ) being initially in the isolation configuration ( C_ISOL ), characterized in that it comprises at least one conductor pre-charging step during which the cut-off device ( 28 ) is brought into its pre-charging configuration ( C_PCH ) to energize a conductor ( 21 ) of a downstream electrical line in downstream of the downstream point ( 38 );
and in that the closing control method comprises, during or after the conductor pre-charging step, at least one parameter determination step ( 143 ) comprising the determination of at least one current or voltage parameter in the main circuit ( 34 ) or in the downstream electric line, and a decision step ( 144 ), during which it is decided, according to the at least one parameter determined during the parameter determination step, the continuation or not of the complete closing ( 160 ) of the current breaking device by passing the current breaking device to the conduction configuration ( C_COND ). Control method according to claim 17 , characterized in that, to reach the conduction configuration ( C_COND ), the pre- charge switch ( 58 ) is open before the closing of the cut-off switch ( 40.i ) and the isolation switch ( 48 ). Control method according to any one of claims 1 7 or 1 8 , characterized in that, if the decision step ( 143 ) is not positive, the method continues, without going through the conduction configuration ( C_COND ) of the cut-off device ( 28 ), by a recharging step ( 180 ) of the pre-charge capacitor ( 54.i ) during which the cut-off device ( 28 ) is brought into the charging configuration ( C_CH ), then successively by a new pre-charge step ( C_PCH ) of the conductor ( 21 ), a new parameter determination step ( 143 ), and a new decision step ( 144 ), according to a pre-charge cycle. Control method according to Claim 19 , characterized in that the step of recharging ( 180 ) the pre-charge capacitor ( 54.i ) comprises:
- closing the isolation switch ( 48 ) and closing the pre-charge switch ( 58 ) to charge the pre-charge capacitor ( 54.i ), maintaining the cut-off switch ( 40 .i ) in its open state;
- After said closure of the pre-charge switch ( 58 ), the reopening of the isolation switch ( 48 ). Control method according to any one of Claims 1 9 or 20 , characterized in that the number of pre-charge cycles for a given attempt to re-close the cut-off device is limited. Control method according to any one of Claims 1 7 to 21 , characterized in that, after at least one pre-charging step ( 141 ) of the conductor ( 21 ), the complete closing ( 160 ) of the current breaking device by passage of the cut-off device ( 28 ) to its conduction configuration ( C_COND ) is continued if a voltage value in the main circuit ( 34 ), or in the downstream electrical line, exceeds a threshold value. Process for evaluating the integrity of an electrical conductor in an electrical power transmission line in an electrical installation comprising a main DC high voltage source electrically connected to an upstream end of the electrical conductor, with an upstream current interposed between the main voltage source and with a downstream end of the electrical conductor connected to a downstream electrical cut-off device, the evaluation process being of the type in which, in an initial state, the upstream cut-off device and the downstream cutoff are respectively each in an insulation configuration C_ISOL so that, in the initial state, the electrical conductor is, except for an electrical fault affecting the electrical conductor, electrically insulated from the installation and from the environment, characterized in that that the evaluation process includes at least one driver pre-loading stage during which a the auxiliary voltage source, separate from the main voltage source, is connected to the conductor to energize the electrical conductor while maintaining the conductor insulated from the main voltage source and from the rest of the electrical installation ;
and in that the evaluation process comprises, during or after the step of pre-charging the conductor, at least one parameter determination step comprising the determination of at least one current or voltage parameter in the electric line downstream, and an evaluation step during which the integrity of the electrical conductor is evaluated as a function of the at least one parameter determined during the parameter determination step. Evaluation process according to Claim 23, characterized in that the evaluation process comprises or is followed by a decision step, during which it is decided, according to the at least one parameter determined during the step of determining the parameter, whether or not to continue the complete closing of the current breaking device by passing the current breaking device to a conduction configuration ( C_COND ).