CN113315102B - Direct current circuit breaker of multi-terminal direct current transmission system - Google Patents
Direct current circuit breaker of multi-terminal direct current transmission system Download PDFInfo
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- CN113315102B CN113315102B CN202110595134.2A CN202110595134A CN113315102B CN 113315102 B CN113315102 B CN 113315102B CN 202110595134 A CN202110595134 A CN 202110595134A CN 113315102 B CN113315102 B CN 113315102B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
- H02H7/268—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured for dc systems
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J5/00—Circuit arrangements for transfer of electric power between ac networks and dc networks
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]
Abstract
The application relates to a direct current breaker, include: the transformer, the first switch, the second switch and the signal acquisition module are arranged on a power transmission line, a secondary winding and the first switch of the transformer are connected with an alternating current power grid through the second switch, and the signal acquisition module is connected with and acquires a first voltage of the primary winding, a second voltage of the alternating current power grid and a current of the secondary winding; when the power transmission line is in a normal operation state, the first switch is closed, and the second switch is opened; when the power transmission line is in a fault state and the difference value between the second voltage and the first voltage meets the turn-off threshold value, the second switch is closed, when the current is reduced and reaches the current threshold value, the first switch and the second switch are both switched off, the energy of the fault current can be transferred to the alternating current power grid, the fault current is automatically inhibited at the initial stage of the fault, the principle of switching off the fault point is simple and reliable, the adoption of a multi-branch parallel structure, equipment such as an arrester and the like is avoided, and the equipment complexity and the maintenance difficulty are reduced.
Description
Technical Field
The application relates to the technical field of multi-terminal direct current transmission, in particular to a direct current circuit breaker of a multi-terminal direct current transmission system.
Background
The high-voltage direct-current circuit breaker is important equipment of a multi-terminal direct-current transmission system and a direct-current power grid, can break direct-current fault current according to requirements, isolates a direct-current line with a fault and a converter station, and provides necessary guarantee for safe, reliable and stable operation of the direct-current power grid.
The existing high-voltage direct-current circuit breaker is formed by connecting a steady-state through-current branch, a current transfer branch and an energy absorption branch in parallel in the realization principle, the current transfer branch and the steady-state through-current branch realize the breaking of direct current under different working conditions, the energy absorption branch adopts a large number of lightning arrester devices to solve the overvoltage tolerance problem and the high-energy absorption problem generated in the breaking process, and the parallel connection form of the three branches is complex in structure and very inconvenient to maintain.
Disclosure of Invention
In view of the above, it is necessary to provide a dc circuit breaker for a multi-terminal dc power transmission system without a complicated multi-branch structure.
A direct current circuit breaker comprising: the transformer comprises a transformer, a first switch, a second switch and a signal acquisition module, wherein a secondary winding of the transformer and the first switch are arranged on a power transmission line, a primary winding of the transformer is connected with an alternating current power grid through the second switch, and the signal acquisition module is connected with and acquires a first voltage of the primary winding, a second voltage of the alternating current power grid and a current of the secondary winding;
when the power transmission line is in a normal operation state, the first switch is closed, and the second switch is opened; when the power transmission line is in a fault state and the difference value between the second voltage and the first voltage meets a turn-off threshold value, the second switch is closed, and when the current is reduced and reaches a current threshold value, the first switch and the second switch are both opened.
In one embodiment, the signal acquisition module comprises a voltage acquisition module and a current acquisition module, the voltage acquisition module is respectively connected with two ends of the second switch, and the current acquisition module is connected with the secondary winding.
In one embodiment, the current threshold is a safe current that allows the power transmission line to be disconnected to eliminate a fault.
In one embodiment, the transformer includes an iron core, a primary winding and a secondary winding, the primary winding and the secondary winding are wound around the iron core, an input end of the primary winding is connected to the ac power grid, an output end of the primary winding is connected to the ac power grid through the second switch, and the secondary winding is connected to the power transmission line after being connected in series with the first switch.
In one embodiment, the first switch is a first ac contactor, a coil of the first ac contactor is connected to a control module, and a contact of the first ac contactor is disposed on the power transmission line.
In one embodiment, the second switch is a second ac contactor, a coil of the second ac contactor is connected to the control module, one end of a contact of the second ac contactor is connected to the primary winding of the transformer, and the other end of the contact of the second ac contactor is connected to the ac power grid.
A multi-terminal dc transmission system comprising a dc circuit breaker as claimed in any one of the preceding claims.
In one embodiment, the multi-terminal dc power transmission system further includes a control module and a power transmission line, wherein the control module is connected to the dc circuit breaker, and the dc circuit breaker is disposed on the power transmission line.
In one embodiment, the multi-terminal dc transmission system further includes a converter station, an input terminal of the converter station is connected to an ac power grid, and an output terminal of the converter station is connected to a dc power grid through the power transmission line.
In one embodiment, the number of the power transmission lines is more than three, the number of the direct current circuit breakers and the number of the converter stations are the same as the number of the power transmission lines, the input end of each converter station is connected with the alternating current power grid, the input end of each power transmission line is correspondingly connected with one converter station, the output end of each power transmission line is connected with the direct current power grid, the output end of each power transmission line is further correspondingly provided with one direct current circuit breaker, and each direct current circuit breaker is further connected with the control module.
According to the direct current circuit breaker of the multi-terminal direct current transmission system, the energy of the fault current is transferred to the alternating current power grid by controlling the switching of the switching states of the two switching elements according to the electromagnetic induction principle of the transformer and when appropriate, the fault current can be automatically restrained at the initial stage of the fault, the principle is simple and reliable, the adoption of a multi-branch parallel structure and equipment such as a lightning arrester is avoided, and the equipment complexity and the maintenance difficulty are reduced.
Drawings
FIG. 1 is a topology diagram of a DC circuit breaker in one embodiment;
fig. 2 is a topology diagram of a prior art dc circuit breaker;
FIG. 3 is a schematic diagram of an embodiment of a DC circuit breaker in a normal circulation phase;
FIG. 4 is a schematic diagram of an embodiment of a DC circuit breaker in a self-induced current suppression phase;
FIG. 5 is a schematic diagram of an embodiment of a DC chopper during a forced current suppression phase;
fig. 6 is a schematic diagram of a dc circuit breaker in an embodiment during a fault opening phase;
fig. 7 is a topology diagram of a multi-terminal dc transmission system in an embodiment.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
It will be understood that, as used herein, the terms "first," "second," and the like may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, a first resistance may be referred to as a second resistance, and similarly, a second resistance may be referred to as a first resistance, without departing from the scope of the present application. The first resistance and the second resistance are both resistances, but they are not the same resistance.
It is to be understood that "connection" in the following embodiments is to be understood as "electrical connection", "communication connection", and the like if the connected circuits, modules, units, and the like have communication of electrical signals or data with each other.
As used herein, the singular forms "a", "an" and "the" may include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises/comprising," "includes" or "including," etc., specify the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof.
The basic principle of breaking direct current of traditional mechanical or all-solid-state direct current circuit breakers is similar, and the current is cut off by connecting a steady-state current branch circuit, a current transfer branch circuit, an energy absorption branch circuit in parallel and mutually matching. For example, in a passive self-oscillating high-voltage dc circuit breaker as shown in fig. 2, during normal operation of the system, dc current flows through the ac circuit breaker B (steady-state current branch). When a system has a fault, the alternating current breaker B is switched off, unstable arc voltage can be generated after switching off, the inductor L, the capacitor C and the resistor R branch circuit are triggered to generate oscillation (a current transfer branch circuit), the inductor L, the capacitor C and the resistor R branch circuit are matched with the negative resistance characteristic of an arc by selecting proper parameters of the inductor L and the capacitor C, the amplitude of oscillation current of the current transfer branch circuit can be rapidly increased, when the amplitude of the oscillation current is equal to that of the current flowing through the switching off part and opposite in direction, the current superposed to the switching off part is zero, and arc extinguishing is realized. And then, the short-circuit current is transferred to the current transfer branch circuit to charge the capacitor C, when the forward voltage of the capacitor C reaches the action value of the arrester MOA, the arrester MOA acts, the fault current is transferred to the arrester MOA (energy absorption branch circuit), the current becomes zero after the energy absorption is finished, and the breaking process of the high-voltage direct-current circuit breaker is finished.
Therefore, the existing high-voltage direct-current circuit breakers all need to comprise a plurality of branch structures, current transfer branches are needed to create current zero crossing points to extinguish electric arcs in principle, and when the direct-current capacity is large, a large amount of lightning arrester equipment is needed to absorb energy, so that the equipment structure is complex.
In one embodiment, the present application proposes a dc circuit breaker 10, as shown in fig. 1, comprising: the transformer 110, the first switch 120, the second switch 130 and the signal acquisition module 140, wherein the secondary winding of the transformer 110 and the first switch 120 are both arranged on the power transmission line, the primary winding of the transformer 110 is connected with the alternating current power grid through the second switch 120, and the signal acquisition module 140 is connected with and acquires a first voltage of the primary winding, a second voltage of the alternating current power grid and a current of the secondary winding; when the power transmission line is in a normal operation state, the first switch 120 is closed, and the second switch 130 is opened; when the transmission line is in a fault state and the difference between the second voltage and the first voltage meets the turn-off threshold, the second switch 130 is closed, and when the current decreases and reaches the current threshold, the first switch 120 and the second switch 130 are both opened.
Specifically, the transformer 110 is a device for changing an alternating voltage using the principle of electromagnetic induction, includes two sets of coils wound with wires, and mutually affects each other in an inductive manner. When an alternating current flows through one of the coils, an alternating voltage having the same frequency is induced in the other coil, and the magnitude of the induced voltage depends on the strength of the magnetic induction of the two coils. According to the principle of electromagnetic induction, when the alternating current flowing through the coil is larger, the magnetic induction intensity induced by the other side is larger, and the induced alternating voltage is also larger. In one embodiment, as shown in fig. 1, the transformer 110 may be a single-phase transformer, and includes an iron core, a primary winding and a secondary winding, the primary winding and the secondary winding are wound around the iron core, an input end of the primary winding is connected to an ac power grid, an output end of the primary winding is connected to the ac power grid through a second switch 130, and the secondary winding is connected to the power transmission line after being connected in series with the first switch 120.
Further, the signal collecting module 140 is connected to the primary winding of the transformer 110 and collects the first voltage thereof, which is used as a basis for judging whether the power transmission line has a fault. Specifically, in a normal operation state of the power transmission line, a direct current flows through the power transmission line, a direct voltage also flows through the secondary winding of the transformer 110, and no induced voltage is generated in the primary winding, so that in the normal operation state of the power transmission line, the first voltage of the primary winding acquired by the signal acquisition module 140 is zero; when the power transmission line has a ground fault, the direction of the fault current flowing through the secondary winding is opposite to that of the normal current, and due to the lenz law, self-induced electromotive force is generated in the secondary winding and induces voltage to the primary winding, and when the first voltage of the primary winding acquired by the signal acquisition module 140 is greater than a fault threshold, it can be determined that the power transmission line has the ground fault and the operation of restraining and isolating the fault current is required. The fault threshold is a voltage greater than zero and can be set according to actual conditions.
Further, the signal acquisition module 140 acquires the second voltage of the ac power grid as a basis for determining when to perform the fault current suppression. When the difference between the second voltage and the first voltage satisfies the turn-off threshold, the second switch 130 is closed to connect the primary winding of the transformer 110 to the ac power grid, and a reverse electromotive force is induced to the secondary winding of the transformer 110 to cancel the fault current flowing through the secondary winding. Specifically, the turn-off threshold may be set according to actual conditions, and may be a value close to zero, or may be set to zero, which is not limited to this, as long as it is ensured that the pressure difference is small when the two ends of the second switch 130 are closed, and the second switch 130 is not damaged.
Further, when a reverse electromotive force is induced in the secondary winding of the transformer 110, the fault current flowing through the secondary winding is gradually cancelled, and the current of the secondary winding is gradually reduced. Therefore, the current collected by the signal collection module 140 connected to the secondary winding of the transformer 110 can be used as a basis for determining whether to disconnect the first switch 120 and the second switch 130 to cut off the power transmission line from the ac power grid to isolate a fault point.
The first switch 120 is disposed on the power transmission line and used for connecting and disconnecting the power transmission line, and the first switch 120 further determines whether to disconnect the power transmission line according to the current of the secondary winding collected by the signal collection module 140. When the power transmission line is in a normal operation state, the first switch 120 is always in a closed state, and the direct current is transmitted through the power transmission line. And when the power transmission line has a ground fault and is reduced to the current threshold, the first switch 120 is turned off, and the fault point on the power transmission line is disconnected. Meanwhile, since the fault current does not need to be continuously offset and suppressed, the second switch 130 is also turned off, the primary winding of the transformer 110 is disconnected from the ac power grid, and the faulty power transmission line is completely isolated. In one embodiment, the current threshold is a safe current that allows the power transmission line to be disconnected to eliminate a fault, and may be determined according to parameters of the first switch 120, and the first switch 120 is disconnected when the current threshold is determined, so that it is ensured that the first switch 120 is not damaged and the impact is minimal, and may be set to zero, or may be set to a small current value close to zero.
In addition, the manner of closing and opening the first switch 120 and the second switch 130 is not exclusive and can be determined according to the application scenario of the dc circuit breaker of the present application. For example, in one embodiment, the first switch 120 and the second switch 130 may be switching elements that are manually switched on and off, the signal acquisition module 140 is connected to a display device and an alarm device of the control center through a digital-to-analog conversion circuit, and when the voltage of the primary winding or the current of the secondary winding of the transformer 110 reaches a current threshold, a technician at the control center finds and correspondingly operates the first switch 120 and the second switch 130 to complete the operation of isolating the transmission line fault. In another embodiment, if the application scenario includes a control module capable of performing automatic control, the first switch 120 and the second switch 130 may also be automatic control type switch elements, the first switch 120, the second switch 130 and the signal acquisition module 140 are all connected to the control module in the system, and the control module automatically controls the switch elements to perform corresponding actions according to the feedback data, thereby completing the power transmission line fault isolation.
According to the direct current circuit breaker, the energy of fault current is transferred to an alternating current power grid by controlling the on-off state switching of the two switching elements according to the electromagnetic induction principle of the transformer and when appropriate, self-induced electromotive force can be generated at the initial stage of a fault to automatically restrain the fault current, the principle is simple and reliable, the adoption of a multi-branch parallel structure and equipment such as a lightning arrester is avoided, and the equipment complexity and the maintenance difficulty are reduced.
In one embodiment, as shown in fig. 1, the signal collection module 140 includes a voltage collection module and a current collection module, the voltage collection module is connected to two ends of the second switch 130, and the current collection module is connected to the secondary winding.
Specifically, the voltage collection module is connected to two ends of the second switch 130, and collects a first voltage of the primary winding and a second voltage of the ac power grid as a basis for determining whether the power transmission line has a fault and when to perform fault current suppression. The current collection module is connected to the secondary winding of the transformer 110 and collects the current thereof, which is used as a basis for judging whether the first switch 120 and the second switch 130 need to be turned off to cut off the power transmission line and the ac power grid to isolate a fault point.
The voltage acquisition module and the current acquisition module can be analog acquisition modules with communication functions, the two ends of the second switch 130 and the secondary winding can be respectively connected through three channels on the analog acquisition modules to acquire voltage and current, and then the acquired data can be transmitted out through communication interfaces on the analog acquisition modules to perform related operations. In addition, the voltage acquisition module and the current acquisition module may also be formed by combining a voltage or current sensor and a digital-to-analog conversion circuit, and the voltage or current is acquired by the voltage or current sensor and then the acquired data is transmitted by the digital-to-analog conversion circuit for related operations, which is not limited in this embodiment.
In this embodiment, the signal acquisition module 140 respectively acquires the voltage and the current of the transformer 110 as the judgment basis, so as to provide a data basis for the dc circuit breaker to break the fault on the power transmission line.
When the on-off states of the first switch 120 and the second switch 130 are adjusted by an automatic control method, the first switch 120 and the second switch 130 are control switches with control terminals, and the control terminals are connected to a control module in the system.
In one embodiment, as shown in fig. 1, the first switch 120 is a first ac contactor, a coil of the first ac contactor is connected to the control module, and a contact of the first ac contactor is disposed on the power transmission line.
The alternating current contactor is a device which realizes the connection and disconnection of contacts by utilizing the cooperation of electromagnetic force and spring elasticity, when a coil of the alternating current contactor is electrified, a static iron core generates electromagnetic attraction, an armature is attracted, a connecting rod connected with the armature drives the contacts to act, the normally closed contacts are disconnected, and the contactor is in an electrified state; when the coil is powered off, the electromagnetic attraction disappears, the armature reopens, the normally open contact is closed, the position spring releases the normally open contact, all the contacts reset, and the contactor is in a power-off state.
Specifically, the coil of the first ac contactor is used as a control module in the control end connection system, and when the current fed back by the signal acquisition module 140 is reduced to a current threshold, the control module cuts off the power of the coil of the first ac contactor, so that the contact of the first ac contactor connected in series to the power transmission line is disconnected, and a fault point on the power transmission line is disconnected.
In one embodiment, as shown in fig. 1, the second switch 130 is a second ac contactor, a coil of the second ac contactor is connected to the control module, one end of a contact of the second ac contactor is connected to the primary winding of the transformer, and the other end of the contact of the second ac contactor is connected to the ac power grid.
Specifically, the coil of the second ac contactor is used as a control module in the control end connection system, and when a difference between the second voltage fed back by the signal acquisition module 140 and the first voltage satisfies a turn-off threshold, the control module energizes the coil of the second ac contactor to turn on a loop of the transformer, which is connected to the ac power grid through a contact of the second ac contactor, so as to suppress the fault current. Then, when the current fed back by the signal acquisition module 140 decreases to the current threshold, the control module cuts off the power of the coil of the second ac contactor, so that the primary winding of the transformer is connected to the loop of the ac power grid through the contact of the second ac contactor, and the fault point on the power transmission line is disconnected.
In this embodiment, by connecting the switching element in the dc circuit breaker of the present application with the control module, the purpose of quickly and automatically breaking a fault point on the power transmission line can be achieved.
In the following, the application of the dc circuit breaker to a multi-terminal dc transmission system is taken as an example for explanation, in which a converter station transmits dc current to a dc power grid through a transmission line. As shown in fig. 3-6, the dc circuit breaker includes a transformer, an ac circuit breaker a and an ac circuit breaker B, a secondary winding of the transformer and the ac circuit breaker a are disposed on the power transmission line, a primary winding of the transformer is connected to the ac power grid through the ac circuit breaker B, a terminal of the ac power grid connected to the ac circuit breaker B is a terminal K1, a terminal of the primary winding of the transformer connected to the ac circuit breaker B is a terminal K2, a first voltage is a voltage at a terminal K2, a second voltage is a voltage at a terminal K1, and the working process thereof may include the following four stages:
stage one: a normal circulation phase.
Specifically, as shown in fig. 3, when the power transmission line is in a normal operation state, the ac circuit breaker a is closed, the ac circuit breaker B is opened, at this time, a normal direct current flows through the dc circuit breaker through the transformer secondary winding and the ac circuit breaker a, the transformer secondary winding has no induced electromotive force, and the voltage at the K2 terminal is zero.
And a second stage: and a self-induction current suppression stage.
Specifically, as shown in fig. 4, when the power transmission line has an earth fault, a fault current 1 from the converter station and a fault current 2 from the dc power grid at two ends of the earth fault rapidly increase, and both currents flow to the earth fault. At this time, the fault current 2 is opposite to the normal direct current direction, the self-induced electromotive force E1 is generated in the secondary winding of the transformer according to lenz's law, the direction of the self-induced electromotive force E1 is opposite to the direction of the fault current 2, namely, the function of restraining the fault current 2 can be automatically performed at the initial stage of the fault, and meanwhile, a certain voltage is induced in the primary winding of the transformer due to the electromagnetic induction principle, so that the voltage at the K2 end is increased.
And a third stage: a forced flow-down stage.
Specifically, when the voltage at the end K2 is greater than the fault threshold value, it is determined that the power transmission line has a ground fault, and when the ac voltage at the end K1 is close to the voltage at the end K2, the ac circuit breaker B is closed, and an ac power grid is introduced into the secondary winding of the transformer, so that a forced electromotive force E2 in a direction opposite to that of the fault current 2 is generated in the secondary winding of the transformer through electromagnetic induction, and the current flowing through the secondary winding of the transformer is actively suppressed and gradually reduced, and meanwhile, the voltage generated by the forced electromotive force E2 is in the same direction as the normal dc current, which is also beneficial for the power transmission line to continue to operate during the fault, and the influence of the pull-down voltage at the ground fault point is counteracted, and in this process, the energy of the fault current 2 is gradually released to the ac power grid through the transformer.
And a fourth stage: a fault disconnect phase.
Specifically, when the current in the secondary winding of the transformer continues to decrease and reaches the current threshold, the energy release of the fault current 2 is substantially completed, and the ac circuit breaker a and the ac circuit breaker B are opened to isolate the ground fault point.
In the embodiment, the energy of the fault current is transferred to the alternating current power grid by controlling the switching of the opening and closing states of the two alternating current contactors according to the electromagnetic induction principle of the transformer, and the fault current can be automatically restrained at the initial stage of the fault, so that the principle is simple and reliable, the adoption of a multi-branch parallel structure, a lightning arrester and other equipment is avoided, and the complexity and the maintenance difficulty of the direct current breaker are reduced.
In one embodiment, as shown in fig. 7, a multi-terminal dc power transmission system is provided, comprising a dc breaker 10 according to any of the above.
Specifically, for a multi-terminal dc power transmission system, when an earth fault occurs, the whole multi-terminal dc system needs to be shut down for a short time to clear the fault, and then the dc system is restarted, which may cause the ac system connected thereto to be subjected to a large impact, and the influence on the weak ac system is more significant, and may even bring a risk of system instability. Therefore, the dc circuit breaker 10 is provided in the multi-terminal dc system to cut off the fault current and to make the fault portion quit the operation, so that the recovery time after the fault can be greatly shortened without stopping the entire multi-terminal dc system.
In an embodiment, as shown in fig. 7, the multi-terminal dc power transmission system further includes a control module 20 and a power transmission line, where the control module 20 is connected to the dc circuit breaker 10, and the dc circuit breaker 10 is disposed on the power transmission line.
Specifically, the control module 20 connects the control end of the ac circuit breaker a of the dc circuit breaker 10 and the control end of the ac circuit breaker B of the dc circuit breaker 10, and the secondary winding of the transformer of the dc circuit breaker 10 and the contact of the ac circuit breaker a are disposed on the power transmission line. When the power transmission line has a ground fault, the control module 20 controls the open and close states of the ac circuit breaker a and the ac circuit breaker B according to the first voltage, the second voltage and the current fed back by the signal acquisition module of the dc circuit breaker 10, so as to break the connection between the ground fault and the dc power grid on the power transmission line.
In the present embodiment, the dc breaker 10 interrupts the fault current and prevents the fault portion from continuing to transmit power to the dc power grid, thereby significantly shortening the recovery time after the fault.
In one embodiment, as shown in fig. 7, the multi-terminal dc transmission system further includes a converter station 30, an input terminal of the converter station 30 is connected to an ac power grid, and an output terminal of the converter station 30 is connected to a dc power grid through a transmission line.
In particular, the converter station 30 is a station that performs conversion of ac power to dc power or dc power to ac power. In this embodiment, the converter station 30 converts the ac power in the ac power grid into dc power and transmits the dc power to the dc power grid through the transmission line. In addition, when an earth fault occurs on the transmission line, the fault current 1 from the converter station end is eliminated by the control and protection system of the converter station 30 in response in time, and does not belong to the operating region of the dc breaker 10.
In one embodiment, the number of the transmission lines is more than three, the number of the direct current circuit breakers 10 and the number of the converter stations 30 are the same as the number of the transmission lines, the input end of each transmission line is correspondingly connected with one converter station 30, the output end of each transmission line is connected with a direct current power grid, the output end of each transmission line is also correspondingly provided with one direct current circuit breaker 10, and each direct current circuit breaker 10 is also connected with the control module 20.
Specifically, the multi-terminal dc transmission system is composed of three or more converter stations 30 and a transmission line connecting the converter stations 30. Each transmission line is connected to the tail end of the direct-current power grid, and the direct-current circuit breaker 10 is arranged at the tail end of each transmission line, so that a plurality of alternating-current power supplies can stably and safely supply power to a plurality of load centers.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. A direct current circuit breaker, comprising: the transformer comprises a transformer, a first switch, a second switch and a signal acquisition module, wherein a secondary winding of the transformer is connected with a power transmission line after being connected with the first switch in series, a primary winding of the transformer is connected with an alternating current power grid through the second switch, and the signal acquisition module is connected with and acquires a first voltage of the primary winding, a second voltage of the alternating current power grid and a current of the secondary winding;
when the power transmission line is in a normal operation state, the first switch is closed, and the second switch is opened; when the power transmission line is in a fault state and the difference value between the second voltage and the first voltage meets a turn-off threshold value, the second switch is closed, and when the current is reduced and reaches a current threshold value, the first switch and the second switch are both opened; wherein the current threshold is a safe current that allows the power transmission line to be disconnected to eliminate a fault.
2. The direct current circuit breaker according to claim 1, wherein the signal acquisition module comprises a voltage acquisition module and a current acquisition module, the voltage acquisition module is respectively connected to two ends of the second switch, and the current acquisition module is connected to the secondary winding.
3. The dc circuit breaker of claim 1, wherein the transmission line is in the normal operating state when the first voltage is zero; and when the first voltage is greater than a fault threshold value, the power transmission line is in a ground fault state.
4. The direct current circuit breaker according to claim 1, wherein the transformer includes an iron core, a primary winding and a secondary winding, the primary winding and the secondary winding are wound around the iron core, an input end of the primary winding is connected to the alternating current grid, an output end of the primary winding is connected to the alternating current grid through the second switch, and the secondary winding is connected to the power transmission line after being connected in series with the first switch.
5. The direct current circuit breaker of claim 1, wherein the first switch is a first alternating current contactor, a coil of the first alternating current contactor is connected with a control module, and a contact of the first alternating current contactor is arranged on the power transmission line.
6. The dc circuit breaker of claim 5, wherein the second switch is a second ac contactor, a coil of the second ac contactor is connected to the control module, one end of a contact of the second ac contactor is connected to the primary winding of the transformer, and the other end of the contact of the second ac contactor is connected to the ac power grid.
7. A multi-terminal dc transmission system comprising a dc breaker according to any of claims 1-6.
8. The multi-terminal direct current transmission system according to claim 7, further comprising a control module and a transmission line, wherein the control module is connected to the direct current circuit breaker, and the direct current circuit breaker is disposed on the transmission line.
9. The multi-terminal direct current transmission system according to claim 8, further comprising a converter station, wherein an input terminal of the converter station is connected to an alternating current power grid, and an output terminal of the converter station is connected to a direct current power grid through the transmission line.
10. The multi-terminal direct-current transmission system according to claim 9, wherein the number of the transmission lines is three or more, the number of the direct-current circuit breakers and the number of the converter stations are equal to the number of the transmission lines, an input end of each converter station is connected to the alternating-current power grid, an input end of each transmission line is correspondingly connected to an output end of one converter station, an output end of each transmission line is connected to the direct-current power grid, an output end of each transmission line is further provided with one direct-current circuit breaker, and each direct-current circuit breaker is further connected to the control module.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110595134.2A CN113315102B (en) | 2021-05-28 | 2021-05-28 | Direct current circuit breaker of multi-terminal direct current transmission system |
| PCT/CN2021/105376 WO2022246976A1 (en) | 2021-05-28 | 2021-07-09 | Direct-current circuit breaker of multi-terminal direct-current power transmission system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110595134.2A CN113315102B (en) | 2021-05-28 | 2021-05-28 | Direct current circuit breaker of multi-terminal direct current transmission system |
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| Publication Number | Publication Date |
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| CN113315102A CN113315102A (en) | 2021-08-27 |
| CN113315102B true CN113315102B (en) | 2022-05-06 |
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| CN202110595134.2A Active CN113315102B (en) | 2021-05-28 | 2021-05-28 | Direct current circuit breaker of multi-terminal direct current transmission system |
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| WO (1) | WO2022246976A1 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101174771A (en) * | 2007-11-09 | 2008-05-07 | 华中科技大学 | Fault current limiting device |
| CN101566672B (en) * | 2009-06-01 | 2011-11-30 | 浙江海得新能源有限公司 | Fall-down experimental method of simulating power grid |
| CN202663104U (en) * | 2012-05-18 | 2013-01-09 | 广东电网公司电力科学研究院 | Short-circuit current limit device |
| CN103117196B (en) * | 2013-01-17 | 2015-11-04 | 国网智能电网研究院 | One seals in coupling inductance high voltage DC breaker and control method thereof |
| CN103532088A (en) * | 2013-10-25 | 2014-01-22 | 田景洵 | Short-circuit resistance self-reset electronic circuit breaker |
| CN105024369B (en) * | 2015-06-29 | 2019-09-17 | 清华大学 | A kind of current diverting device and method suitable for hybrid dc circuit breaker |
| WO2017134825A1 (en) * | 2016-02-05 | 2017-08-10 | 三菱電機株式会社 | Direct current circuit breaker |
| CN109074980B (en) * | 2016-04-25 | 2020-02-14 | Abb瑞士股份有限公司 | Bidirectional reversing promoter |
| CN106300236B (en) * | 2016-09-27 | 2017-12-26 | 西安交通大学 | One kind isolates pouring-in electric current carry circuit and its application method |
| CN107872060A (en) * | 2016-09-27 | 2018-04-03 | 新能动力（北京）电气科技有限公司 | A kind of AC stabilizer |
| CN106786416A (en) * | 2016-12-02 | 2017-05-31 | 国网四川省电力公司成都供电公司 | A kind of two-way variable-pressure HVDC tripper and short trouble cutting method |
| CN107947173B (en) * | 2017-12-20 | 2024-02-02 | 南京南瑞继保电气有限公司 | Series compensator and control method |
| CN110912096B (en) * | 2019-08-16 | 2021-03-23 | 湖南大学 | Fault discharge device based on ZnO piezoresistor and control method thereof |
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| WO2022246976A1 (en) | 2022-12-01 |
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