FR2961642A1 - Electrical installation i.e. electrical energy production installation, protecting equipment, has control system controlling opening and closing of power supply circuits to establish insulation space in each power supply circuit - Google Patents

Abstract

The equipment (1) has a downstream protective device (13) comprising a downstream power supply circuit (33) with input terminals (34) for connection to an output of an electrical converter (4). A control system (16) is connected to an automatic monitoring device (14) and opening and closing controlling systems (25, 26) of the downstream power supply circuit and an upstream power supply circuit (21). The control system controls opening and closing of the power supply circuits when thunderstorm activity exceeds alert level to establish an insulation space in each power supply circuit.

Description

The present invention relates to the technical field of protection against lightning, electrical installations comprising photovoltaic panels connected to an electrical network. An impact or a lightning strike on an electrical installation leads to a significant risk of deterioration of the installation and in particular of the various electrical equipment forming part of such an installation. In the case of an installation comprising photovoltaic panels, the installation has a high risk of damage by an impact or a stroke at lightning given their location.

In a conventional manner, an installation for producing electrical energy of solar origin comprises a set of photovoltaic panels mounted in series to constitute different lines paralleled by a junction box. The number of series-connected photovoltaic panels provides the continuous service voltage of the installation, while the number of lines in parallel provides the maximum intensity of the installation. Photovoltaic panels are usually protected by lightning rods. The junction box is connected to a DC-AC converter connected to an electrical transport network via a step-up transformer. Conventionally, the junction box is equipped with protection fuses for each line and the input of the DC-AC converter is equipped with a surge arrester while the output of this converter is connected to protective circuit breakers. The use of lightning rods and surge arresters do not, in practice, effectively protect such an installation. Thus, the use of lightning rods installed in the middle of a field of photovoltaic panels is misguided. Indeed, if the lightning falls on the lightning rod, the discharge current is injected directly into the ground causing a sudden rise in local potential. If the equipotentiality of the site is not perfect, which is almost impossible to achieve over a large area, due in part to the resistance presented by the earth cables, it appears a flow current that is able to destroy the electrical equipment placed in its path. Moreover, it appears in addition to the abrupt rise in potential electromagnetic radiation generated by the passage of lightning current which represents a risk of destruction of sensitive electrical equipment. Indeed, this electromagnetic radiation is able to generate very high overvoltages in the loops formed by the electrical connection conductors. In the same sense, it appears that the surge arresters, in particular for continuous voltages are not entirely satisfactory. Indeed, the surge arrester has a limited life dependent on the number of strokes at the nominal value of flow of an overvoltage current. To be exploitable, the surge arrester must transmit its aging information or even end of life to a supervisory controller, which presents a risk of transmission of an overvoltage to these different equipment. Additionally, photovoltaic panels have limited resistance to overvoltages and overcurrents. However, some photovoltaic installations may have several lines connected on the same junction box so that when there is a lightning impact on or near the implantation site, a very significant risk of propagation of this surge appears on all lines. Surge arresters do not appear to be suitable for preventing this propagation of overvoltage causing a risk of damage to the photovoltaic panels.

The present invention aims to overcome the disadvantages of the state of the art by providing equipment to effectively protect an installation of photovoltaic panels against overvoltages that may appear as a result of an impact or a lightning strike affecting directly or indirectly the photovoltaic panels and / or the electrical network to which the photovoltaic panels are connected.

To achieve such an objective, the equipment comprises a set of photovoltaic panels connected to each other and connected via a DC-AC converter to an electrical network. According to the invention, the equipment comprises: an upstream protection device comprising: an upstream supply circuit comprising arrival terminals for a connection to the output of the set of photovoltaic panels and output terminals for a connection to the input of the electric converter, - a servo system for opening and closing the upstream supply circuit, comprising a disconnector connected in series with a contactor, the disconnector establishing in the open position, in the circuit of an upstream supply, an isolation space adapted to obtain a protection voltage value, - a downstream protection device comprising: - a downstream supply circuit comprising supply terminals for a connection to the output of the electrical converter and output terminals for a connection to the input of the electrical network, - a servo system for opening and closing the downstream supply circuit, comprising a dry initiator, in the open position, an isolation space adapted to obtain a protection voltage value, - an automatic monitoring device for thunderstorm activity, - and a connected control system. the monitoring device and the enslaved systems for opening and closing the downstream and upstream supply circuits, this control system being programmed to, when the thunderstorm activity exceeds an alert level, control the opening of the control circuits; upstream and downstream power supply, by the slave systems, to establish the isolation space in each upstream and downstream supply circuit.

In addition, the equipment according to the invention may additionally comprise in combination at least one and / or the following additional characteristics: for each line of photovoltaic panels, an on-line protection device comprises: an in-line supply circuit comprising an input terminal for a connection to the photovoltaic panel line output and an output terminal for connection to the input of a junction box for the photovoltaic panel lines; an enslaved system for opening and closing the in-line supply circuit, comprising a disconnector which, in the open position, establishes an isolation space in the in-line supply circuit which makes it possible to obtain a voltage value of protection, the enslaved system of opening and closing being connected to the control system which controls, when the storm activity exceeds an alert level, the opening of the supply circuit in li in order to establish the isolation space, in each of said circuits, the control system is equipped with an emergency control device adapted to control the opening of one and / or the other of the circuits. upstream, downstream or on-line power supply, - an electrical transmission circuit intended to be connected to a transmission network, and a slave system for opening and closing the electric transmission circuit, controlled by the control system to open. the electrical transmission circuit when the thunderstorm activity exceeds the alert level, - the control system is programmed to, when the atmospheric thunderstorm activity is below the alert level, control the closing of the downstream supply circuits, upstream and in line and the electrical transmission circuit, - the control system is programmed to, after a given opening time and regardless of the level of thunderstorm activity, control the closing of the circuits downstream, upstream and in-line power supply and the electrical transmission circuit, each disconnector comprises a fixed contact pad and a mobile contact pad displaced by translation between an open position and a closed position, via a jack actuated by the control system, - for each disconnector, means for connection to the earth, comprising at least one electrode placed at the mobile contact pad so that when the movable contact pad is in its position d In the opening, the connection means can discharge the lightning current between the electrode and the fixed contact pad to earth. Various other characteristics appear from the description given below with reference to the accompanying drawings which show, by way of non-limiting examples, embodiments of the subject of the invention.

Figure 1 is a diagram illustrating a first variant of a protective device according to the invention for an installation for producing electrical energy from photovoltaic panels connected to an electrical network. Figure 2 is a block diagram illustrating a protection device. Figure 3 is a detailed view of an embodiment for a disconnector implemented in a protection device according to the invention. Figure 4 illustrates another embodiment of a protective equipment 25 according to the invention. As is more particularly apparent from FIG. 1, the object of the invention relates to equipment 1 for protecting an electrical installation 2 in the general sense comprising a set of photovoltaic panels 3 connected to each other and connected via a DC-DC converter 4 to an electrical distribution network 5. In the exemplary embodiment illustrated, the photovoltaic panels 3 are connected in series in order to form lines 1 of panels placed in parallel using a junction box 7. The output of the junction box 7 is connected to the input of the DC-AC converter 4 whose output is connected via a step-up transformer 8, to the electrical network 5. According to the invention, the equipment 1 is adapted to protect the electrical installation 2 against impacts or lightning strikes likely to occur near or on the electrical installation 2. The equipment 1 according to the invention allows advantageously to protect the photovoltaic panels 3 against impacts or lightning strikes likely to occur on a line I of photovoltaic panels 3 or near or on the electrical network 5. The protective equipment 1 according to the invention comprises - a upstream protection device 11 disposed between the output of the junction box 7 and the input of the DC-AC converter 4, - a downstream protection device 13 disposed between the output of the DC-AC converter 4 and the electrical network 5 and in particular of the input of the step-up transformer 8, - a device 14 for automatic monitoring of thunderstorm activity, - a control system 16 connected to the monitoring device 14 and to the upstream and downstream protection devices 11. that this is more clearly apparent from FIG. 2, the upstream protection device 11 comprises an upstream electrical supply circuit 21 comprising, on the one hand, input terminals 22 for connection to the output of the set of photovoltaic panels 3 and in particular to the output of the junction box 7 and secondly, output terminals 23 for connection to the input of the electrical converter 4. The input terminals 22 and the output terminals 23 are for example each constituted by a terminal block having as much In the case of a single-phase power supply and four in the case of a three-phase power supply, for example, two terminals are required. The upstream protection device 11 also comprises an enslaved opening and closing system 25 of the upstream electrical supply circuit 21. This enslaved opening and closing system 25 comprises a disconnector 26 connected in series in the supply circuit upstream electric motor 21, with a contactor 27. The controlled opening and closing system 25 also comprises an electronic management circuit 28 for controlling the opening and closing of the disconnector 26 and the contactor 27. According to a preferred embodiment variant illustrated more particularly in FIG. 3, the disconnector 26 comprises a fixed contact pad 261 and a movable contact pad 262 moved by a controlled displacement member 29 so that the movable contact pad 262 occupies a closed position for which the contact pads 261i and 262 are connected (position A - Fig. 3) and an open position (position B - Fig. 3) in which the movable contact pad 262 is spaced from the fixed contact pad 261 by an isolation space 30. L slave displacement member 10 is made by any appropriate means such as a worm or as illustrated by a jack having a rod 291 whose end carries the movable contact pad 262. Such a disconnector 26 provides a insulation voltage value or protection corresponding to the value of the isolation space 30 being established between the contact pads 261 and 262 when the movable contact pad 262 is placed in the open position. For example, the insulation space between the fixed and mobile pads is between 80 and 180 mm and corresponds to a protection or insulation voltage of between 80 and 180 KV for a standardized lightning strike (1.2 / 50 ps ). The slave displacement member 29 is controlled by the management circuit 28 which forms part of the control system 16.

The downstream protection device 13 comprises a downstream electrical supply circuit 33 comprising input terminals 34 for connection to the output of the electrical converter 4 and output terminals 35 for connection to the input of the electrical network 5 and more precisely at the input of the step-up transformer 8. The downstream protection system 13 also comprises a servo-opening and closing system 36 of the downstream electrical supply circuit 33. This slave system 36 comprises on the one hand a disconnector 37 mounted in the downstream electrical supply circuit 33 and secondly, an electronic management circuit 38 for controlling the opening and closing of the disconnector 37. The disconnector 37 allows to establish in the open position, in the downstream supply circuit 33, an isolation space adapted to obtain a protection voltage value. According to a preferred embodiment, the disconnector 37 has a constitution similar to the disconnector 26 as described in FIG. 3. For example, the isolation space between the fixed and movable pads of the disconnector 37 is between 80 and 100 mm and corresponds to an insulation or protection voltage of between 80 and 100 KV for a standardized lightning strike (1.2 / 50 ps). The servo moving member of the movable contact pad of the disconnector 37 is controlled by the electronic management circuit 38 which is part of the control system 16. The monitoring device 14 makes it possible to monitor the thunderstorm activity occurring near the installation 2. The monitoring device 14 makes it possible to evaluate the risks of lightning impact on or near the electrical installation 2 and in particular on or near the photovoltaic panels 3 and the electrical network 5. This monitoring device 14 can be of any type known per se by manual action for example and monitor for example the electromagnetic activity and atmospheric and / or electrostatic and / or light and / or sound. The control system 16 is connected to the monitoring device 14 and to the slave systems 25 and 36 of the downstream 21 and upstream power supply circuits 33. This control system 16 is programmed so that when the thunderstorm activity exceeds a level of warning, control the opening of the upstream supply circuits 21 and downstream 33 by the slave systems 25 and 36 to establish the isolation space in each upstream and downstream supply circuit. The opening of the upstream supply and downstream supply circuits 33 makes it possible to physically isolate the photovoltaic panels 3 by establishing a so-called safety space sufficient to prevent any arcing between the photovoltaic panels 3 and the electrical network 5, by lightning impact case. Advantageously, the opening of the upstream supply circuit 21 is controlled by the control system 16 by first involving a disconnection by an opening of the contactor 27 followed by the opening of the disconnector 26 by the control of the displacement member 29 to obtain separation between the contact pads 261 and 262 to obtain the safety space. The disconnection of the photovoltaic panels with respect to the electricity network 5 by the contactor 27 has the advantage of avoiding any appearance of an electric arc when opening the disconnector 26.

When the thunderstorm activity falls below the alert level, the control system 16 controls the slave systems 25 and 36, closing the upstream supply circuits 21 and downstream 33. This closure of the upstream supply circuit 21 makes firstly, closing the disconnector 26 and then closing the contactor 27 to connect the photovoltaic panels 3 to the electrical network 5. This closure can be performed as soon as the thunderstorm activity falls below the alert level or after a predefined delay time. The control system 16 naturally includes a power supply circuit preferably comprising an autonomous power supply source taking over when the control system 16 controls the opening of one and / or the other of the control circuits. 'food. This control system 16 may be performed independently or otherwise with respect to the downstream protection device 13 and / or the upstream protection device 11.

According to a preferred embodiment, each disconnector 26 and 37 comprises earth connection means comprising at least one electrode placed at the mobile contact pad so that when the movable contact pad is in its open position, the connecting means can flow to the earth the lightning current established between the electrode and the fixed contact pad. Thus, in the case of a lightning strike exceeding the level of electrical isolation corresponding to the safety space between the mobile and fixed studs, the electrode is able to recover the lightning current to bring it to Earth. Fig. 4 illustrates another variant embodiment in which each line I of photovoltaic panels 3 comprises an on-line protection device 50 comprising: an on-line power supply circuit 51 comprising an input terminal 52 for connection to the output a line of photovoltaic panels 3 and an output terminal 53 for a connection to the input of the junction box 7, 10 - an enslaved opening and closing system 56 of the in-line power supply circuit 51, comprising a disconnector 57 and an electronic management circuit 58 making it possible to control the opening and closing of the disconnector 57. The disconnector 57 makes it possible to establish in the open position in the on-line supply circuit 51 a gap of insulation 15 to obtain a protection voltage value. According to a preferred embodiment, the disconnector 57 has a constitution similar to the disconnector 26 as described in FIG. 3. The slave opening and closing system 56 is connected to the control system 16 which controls when the thunderstorm activity exceeds an alert level, the opening of the in-line power supply circuit 51 to establish a gap space. in each line I of photovoltaic panels 3. According to a preferred embodiment, the control system 16 is equipped with an emergency control member 60 adapted to control the opening of the one and / or the other upstream supply circuits 21, downstream 33 25 or online 51. This emergency control member 60 can control the opening of one and / or the other of these circuits for example to allow intervention on such an installation or interrupt the production of electrical energy photovoltaic panels 3. This control member 60 can be controlled manually or remotely. According to a preferred embodiment variant, the emergency control member 60 makes it possible to cancel the output voltage of the photovoltaic panels 3 making possible an emergency external intervention such as that of the firefighters for example. According to this variant, the electronic management circuit 58 of each on-line protection device 50 drives a contactor for short-circuiting and grounding the input terminal 52 of each in-line power supply circuit 51.

According to another preferred embodiment, it should be noted that the equipment 1 may also comprise as illustrated in FIG. 2, an electrical transmission circuit 71 intended to be connected to a transmission network 72 and an enslaved opening and closing system 73 of the electrical transmission circuit 71, controlled by the control system 16 to open the electrical transmission circuit. 71 when the storm activity exceeds the alert level. Such a transmission system 72 allows transmission, for example, of weak current for connection to a telecommunication network. Such equipment thus also protects the telecommunication installation.

The invention is not limited to the examples described and shown since various modifications can be made without departing from its scope.

Claims (8)

CLAIMS1 - Equipment for protecting an electrical installation (2) comprising a set of photovoltaic panels (3) connected to each other and connected via a DC-AC converter (4) to an electrical network (5), characterized in that it comprises: an upstream protection device (11) comprising: an upstream supply circuit (21) comprising arrival terminals (22) for connection to the output of the photovoltaic panel assembly (3) and output terminals (23) for connection to the input of the electric converter; - a slave opening and closing system (25) of the upstream supply circuit (21), comprising a disconnector (26) mounted series with a contactor (27), the disconnector establishing in the open position, in the upstream supply circuit, an isolation space adapted to obtain a protection voltage value, - a downstream protection device (13) comprising : - a circuit of downstream supply (33) comprising input terminals (34) for connection to the output of the electrical converter (4) and output terminals (35) for connection to the input of the electrical network (5), - a system (36) servo opening and closing the downstream supply circuit, having a disconnector (37) establishing in the open position, in the downstream supply circuit, an insulation space adapted to obtain a value protection voltage, - an automatic storm activity monitoring device (14), - and a control system (16) connected to the monitoring device (14) and to the opening and closing systems (25, 26) of the downstream (33) and upstream (21) power supply circuits, this control system being programmed for, when the thunderstorm activity exceeds an alert level, controlling the opening of the upstream supply circuits (21) and downstream (33), by the slave systems, to establish the isolate gap ion in each upstream and downstream supply circuit. 2 - Protective equipment according to claim 1, characterized in that it comprises for each line (I) of photovoltaic panels (3), an in-line protection device (50), comprising: - an in-line supply circuit (51) comprising an input terminal (52) for connection to the line output (I) of photovoltaic panels (3) and an output terminal (53) for connection to the input of a junction box (7) for the lines (I) of photovoltaic panels (3), - a controlled opening and closing system (56) of the in-line supply circuit (51), comprising a disconnector (57) setting in position d opening, in the on-line supply circuit, an isolation space for obtaining a protection voltage value, the enslaved opening and closing system being connected to the control system (16) which controls, when the thunderstorm activity exceeds a warning level, the opening of the supply circuit in lig ne (51), for establishing the isolation space, in each of said circuits. 3 - Protective equipment according to claim 1 or 2, characterized in that the control system (16) is equipped with an emergency control member (60) adapted to control the opening of the one and / or the other upstream (21), downstream (33) or in-line (51) feed circuits. 4 - Protective equipment according to one of claims 1 to 3, characterized in that it comprises: - an electrical transmission circuit (71) intended to be connected to a transmission network (72), - and a slave system opening and closing (73) of the transmission electrical circuit (71), controlled by the control system (16) to open the transmission electrical circuit when the storm activity exceeds the alert level. 5 - Protective equipment according to one of claims 1 to 4, characterized in that the control system (16) is programmed to, when the thunderstorm activity is below the alert level, control the closing of the circuits of downstream (33), upstream (21) and in-line (51) power supply and the transmission electric circuit (71). 6 - Protective equipment according to one of claims 1 to 4, characterized in that the control system (16) is programmed to, after a given opening time and regardless of the level of thunderstorm activity, control the closure downstream (33), upstream (21) and in-line (51) power supply circuits and the transmission electric circuit (71). 7 - Protective equipment according to one of claims 1 to 6, characterized in that each disconnector (26, 37, 57) comprises a fixed contact pad and a movable contact pad moved by translation between an open position and a closed position, via a cylinder controlled by the control system. 8 - Protective equipment according to claim 7, characterized in that it comprises for each disconnector (26, 37, 57), connection means to earth, comprising at least one electrode placed at the mobile contact pad of so that when the mobile contact pad is in its open position, the connection means can flow to earth the lightning current established between the electrode and the fixed contact pad.