A short circuit protection device and method for power grid series compensation equipment

Abstract

The application discloses a short-circuit protection device and method for power grid series compensation equipment, and relates to the field of power distribution networks, which comprises the following steps: collecting a power grid side current value through a current sampling unit arranged on a primary side of a transformer, and transmitting the current value to a main controller; comparing the current value with a preset current threshold and an overcurrent protection threshold respectively; when the current value is less than the current threshold, controlling a high-speed switch in a current limiting unit CLU to be in an off state, and controlling a series switch KM1 to be in a closed state, so that the series compensation equipment is connected to a secondary side of the transformer and participates in power grid operation; when the current value is greater than or equal to the overcurrent protection threshold, issuing a linkage trigger instruction within a preset time, controlling the high-speed switch in the current limiting unit CLU to be turned on, and controlling a bypass switch BS to be closed within a preset time after the high-speed switch is turned on, and controlling the series switch KM1 to be disconnected. The application improves the response speed in view of the long protection response time of the series side compensation equipment in the prior art.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power distribution network, in particular to a short-circuit protection device and method for power grid series compensation equipment. BACKGROUND

[0002] With the development of power electronics technology, more and more new energy power generation equipment and power quality management equipment are connected to the power grid, such as photovoltaic power generation system, energy storage equipment, active power filter, etc. These devices improve power quality and increase the flexibility of the power grid, but also bring new challenges to the power grid protection.

[0003] In the prior art, in order to realize short-circuit current limiting protection, a circuit breaker is usually connected in parallel to the primary side of the series transformer. When the circuit is disconnected, the secondary side induction voltage of the transformer is 0 by closing the circuit breaker KM, so that the series compensation equipment is exited. However, the above existing scheme has the problem of long response time. When the power quality management equipment connected to the power grid, such as series side equipment, has a short circuit, if it cannot be disconnected at the fastest speed, it may cause serious consequences such as power outage of the transformer area, which will cause great loss to the power grid and users.

[0004] The existing patent application No. 201410500288.9 discloses a series capacitor compensation device for power distribution network, which comprises a series capacitor group connected by a series disconnecting switch and a bypass circuit breaker at both ends, a grounding switch connected between the series disconnecting switch and the series capacitor group, and a series capacitor group connected in parallel with a thyristor and a damping device. However, in this scheme, if a short circuit fault occurs in the series capacitor group, the thyristor may be damaged, so that the series capacitor compensation device cannot quickly reach the exit state. SUMMARY

[0005] In view of the problem of long protection response time of series side compensation equipment short circuit in the prior art, the present application provides a short-circuit protection device and method for power grid series compensation equipment, which improves the short-circuit protection response speed by setting bypass switch, series switch and main controller, etc.

[0006] The purpose of the present application is achieved by the following technical solutions.

[0007] One aspect of the present application provides a short-circuit protection device for a power grid series compensation device, comprising: a bypass switch BS connected in parallel to a transformer secondary side and short-circuited in three phases; the bypass switch BS is an AC contactor KM2; a current limiting unit CLU connected in parallel to the transformer secondary side circuit; a main controller setting a current threshold and an overcurrent protection threshold, receiving a circuit operating current detected by a current sampling unit, controlling the conduction and turn-off of a high-speed switch in the current limiting unit CLU, and controlling the closing and opening of a series switch KM1 and the bypass switch BS; when the series switch KM1 is closed, the series compensation device is connected to the transformer secondary side, so that the series compensation device participates in the operation of the power grid; when the series switch KM1 is opened, the series compensation device is disconnected from the transformer secondary side, so that the series compensation device exits the operation of the power grid.

[0008] Another aspect of the present application also provides a short-circuit protection method for a power grid series compensation device, comprising: collecting a power grid side current value by a current sampling unit arranged on a transformer primary side, and transmitting the current value to a main controller; comparing the current value with a preset current threshold and an overcurrent protection threshold respectively; when the current value is less than the current threshold, controlling the high-speed switch in the current limiting unit CLU to be in a turn-off state, and controlling the series switch KM1 to be in a closed state, so that the series compensation device is connected to the transformer secondary side and participates in the operation of the power grid; when the current value is greater than or equal to the overcurrent protection threshold, issuing a linkage trigger instruction within a preset time, controlling the high-speed switch in the current limiting unit CLU to be conductive, and controlling the bypass switch BS to be closed within a preset time after the high-speed switch is conductive, and controlling the series switch KM1 to be opened, so that the series compensation device exits the operation of the power grid.

[0009] Further, the current limiting unit CLU includes a reactor connected in series with the high-speed switch, when the current value is detected to be greater than the overcurrent protection threshold, the high-speed switch is conductive, and the reactor limits the rising rate of the circuit current, so as to reduce the impact of current mutation on the series compensation device.

[0010] Further, the current sampling unit adopts a current transformer connected in series to the transformer primary side to collect the power grid side current.

[0011] Further, a switch K1 is also connected in series in the circuit of the bypass switch BS; the switch K1 is a disconnecting switch with a break, and an insulation gap is formed at the break when the switch K1 is opened; the main controller is connected with a control end of the switch K1, and is used for controlling the closing and opening of the switch K1; when the main controller detects that the current sampling value exceeds the overcurrent protection threshold or the voltage of the series compensation device exceeds an overvoltage protection threshold, the main controller issues a linkage trigger instruction, controls the high-speed switch in the current limiting unit CLU to be conductive, controls the bypass switch BS to be closed, controls the series switch KM1 to be opened, and controls the switch K1 to be closed.

[0012] Further, the switch K1 comprises an electrically operated mechanism and an isolating switch; the electrically operated mechanism comprises a motor, a speed reducer and an output shaft, the motor drives the output shaft to rotate through the speed reducer; the isolating switch comprises an operating shaft, a movable contact and a stationary contact, the operating shaft drives the movable contact to open and close relative to the stationary contact; the output shaft of the electrically operated mechanism is connected with the operating shaft of the isolating switch through a shaft coupling, so that the electrically operated mechanism drives the isolating switch to close and open; the isolating switch is provided with a feedback signal output end, the feedback signal output end is connected with the movable contact, when the isolating switch is closed and the movable contact is in contact with the stationary contact, the feedback signal output end outputs a closing state signal which is at the same potential as the stationary contact; when the isolating switch and the movable contact are separated from the stationary contact, the feedback signal output end outputs an opening state signal which is at a different potential from the stationary contact; the electrically operated mechanism is provided with a position signal output end, the position signal output end is connected with an angular displacement sensor on the output shaft, the angular displacement sensor detects the angular position of the output shaft and transmits the angular position signal to the position signal output end; the feedback signal output end of the isolating switch and the position signal output end of the electrically operated mechanism are connected with the signal input end of the main controller, and the position signals of the feedback signals are transmitted to the main controller.

[0013] Further, the main controller also pre-stores corresponding standard feedback signal values and standard position signal values when the isolating switch is closed and opened; the main controller compares the feedback signals of the isolating switch and the position signals of the electrically operated mechanism with the pre-stored standard values, and judges the actual state of the switch K1: when the feedback signal is consistent with the standard value of the closing state and the position signal is consistent with the standard value of the closing position, the main controller determines that the switch K1 is in the closed state; when the feedback signal is consistent with the standard value of the opening state and the position signal is consistent with the standard value of the opening position, the main controller determines that the switch K1 is in the open state; if the feedback signal and the position signal are inconsistent with the corresponding standard values or any signal is missing, the main controller issues a fault warning.

[0014] Further, the switch K1 is connected in parallel with the bypass switch BS in series in the secondary side of the transformer, when the switch K1 and the bypass switch BS are closed at the same time, the secondary side of the transformer is short-circuited.

[0015] Further, after the main controller issues the linkage trigger instruction: the main controller controls the switch K1 to be closed within the preset time after the current limiting unit CLU is turned on.

[0016] Further, the main controller also comprises transformer secondary side voltage acquisition, when a short circuit occurs, the main controller detects that the short circuit current or the transformer secondary side voltage exceeds the safety protection threshold of the series compensation device, the main controller issues a trigger instruction, the high-speed switch is triggered to be turned on, the reactor limits the instantaneous current rise rate and the maximum amplitude, at the same time, the bypass switch BS is closed, the transformer secondary side voltage is 0, the series switch KM1 is opened, and the series compensation device exits the power grid operation.

[0017] Compared with the prior art, the application has the advantages of:

[0018] The main controller samples the circuit working current in real time, controls the working of the current limiting unit CLU, samples the secondary side voltage of the series injection transformer, controls the closing or opening of the bypass switch and the series switch KM1, and the high-precision sampling of the current and voltage greatly shortens the short-circuit protection response time and avoids damage to the equipment caused by the short-circuit current.

[0019] The current limiting unit CLU is connected in parallel with the secondary side of the series injection transformer, is connected in series with the current limiting impedance through a high-speed switch, and protects the series compensation equipment when a short circuit occurs.

[0020] The protection circuit is connected in parallel with the main equipment circuit, is in an open state during normal operation, has small loss, and does not affect the operation of the main circuit. When the series side equipment is short-circuited, the protection circuit quickly acts to cut off the fault circuit, and ensures that the normal operation of the power grid main circuit is not affected. BRIEF DESCRIPTION OF DRAWINGS

[0021] The application will be further described in the form of exemplary embodiments, which will be described in detail with reference to the accompanying drawings. These embodiments are not limiting, and in these embodiments, the same numbers represent the same structures, wherein:

[0022] Figure 1 is a circuit block diagram and a main control logic flowchart according to some embodiments of the application;

[0023] Figure 2 is a current limiting unit CLU circuit diagram according to some embodiments of the application;

[0024] Figure 3 is a circuit diagram according to some embodiments of the application;

[0025] Figure 4 is another circuit diagram according to some embodiments of the application. DETAILED DESCRIPTION

[0026] The method and system provided by the embodiments of the application will be described in detail below with reference to the accompanying drawings.

[0027] Embodiment 1:

[0028] Figure 1is a circuit block diagram and main control logic flow chart according to some embodiments of the present application, including: collecting grid side current value through current sampling unit arranged on transformer primary side, transmitting current value to main controller; comparing current value with preset current threshold and overcurrent protection threshold respectively: when current value is less than current threshold, control high-speed switch in current limiting unit CLU to be in off state, and control series switch KM1 to be in closed state, so that series compensation device accesses transformer secondary side and participates in grid operation; when current value is greater than or equal to overcurrent protection threshold, issue linkage trigger instruction within preset time, control high-speed switch in current limiting unit CLU to be on, and control bypass switch BS to be closed within preset time after high-speed switch is on, and control series switch KM1 to be disconnected, so that series compensation device exits grid operation. High-speed switch can select bidirectional thyristor.

[0029] Figure 2 is a current limiting unit CLU circuit diagram according to some embodiments of the present application, the embodiment provides a short circuit protection device for grid series compensation device and a method thereof, the circuit diagram is as shown in Figure 1 , containing bypass switch BS, current limiting unit CLU, series switch KM1, series compensation device and main controller, bypass switch BS, bypass switch upper port is parallel in transformer secondary side, and lower port is three-phase short circuit.

[0030] Figure 3 is a circuit diagram according to some embodiments of the present application, current limiting unit CLU current limiting unit CLU selects the structure of three high-speed switches and reactor in series; a group of "high-speed switch + reactor" series branches are parallel connected on each phase line; three-phase current limiting unit CLU is parallel connected on transformer secondary side line as a whole; the on and off of high-speed switch are controlled by main controller according to detection current and instruction; when detecting that short circuit current exceeds overcurrent protection threshold, main controller triggers high-speed switch to be on; after high-speed switch is on, reactor plays a role of limiting short circuit current rising rate, reduces impact; reactor can select air-core reactor or core reactor, and parameters are designed according to rated current and current limiting demand.

[0031] Series switch KM1 selects AC contactor as switch element; AC contactor KM1 is connected in series between transformer secondary side and compensation device; when KM1 is closed, series compensation device is connected with transformer secondary side through KM1, and accesses grid operation; when KM1 is disconnected, series compensation device is disconnected with transformer secondary side, and exits grid operation; the switch state of KM1 is controlled by main controller according to comparison result of sampling current and threshold; under normal working condition, main controller controls KM1 to keep closed state, and compensation device continuously inputs operation; when short circuit occurs, main controller first triggers current limiting unit CLU to be on, and then controls KM1 to be disconnected.

[0032] The series compensation device can be selected from a plurality of compensation devices such as TCSC, TCSR and TCPST; the compensation device is selected and parameter designed according to the compensation requirement of the power transmission line; the transformer secondary side is connected with an AC contactor KM1, and the compensation device is switched by the switching state of the KM1.

[0033] The main controller is internally provided with a current threshold value and an overcurrent protection threshold value for judging whether a short circuit fault occurs; the main controller receives the circuit working current detected by the current sampling unit in real time; the main controller controls the state of the parallel circuit and the series switch KM1 according to the comparison result of the sampling current value and the threshold value; when it is judged that a short circuit occurs, the main controller timely turns on the current limiting unit CLU and starts the current limiting protection; the main controller sends a control instruction to coordinate the actions of the bypass switch BS, the series switch KM1 and the current limiting unit CLU.

[0034] The bypass switch BS is selected from an AC contactor as a switching element, and the model is KM2; the AC contactor KM2 is connected in parallel with the transformer secondary side line; under normal working conditions, the main controller controls the KM2 to keep the open state; when a short circuit occurs, the main controller controls the KM2 to close after the current limiting unit CLU is turned on; the closing of the KM2 makes the transformer secondary side line short-circuit, provides a bypass for the current limiting unit and reduces the influence on the transformer.

[0035] The current sampling unit is selected from a high-precision current transformer for current sampling; the high-precision current transformer is connected in series with the line on the grid side; the current transformer can be selected from a zero-drift magneto-electric current sensor or a Hall effect current sensor; the ratio and accuracy level of the current transformer are selected according to the rated current and sampling accuracy requirement; the secondary side of the current transformer is connected with the main controller to transmit the sampling value to the main controller in real time.

[0036] The main controller samples the current value of the grid side in real time through the current transformer; when the sampling current value is less than the set current threshold value, the main controller performs the following control: controls the bypass switch BS to keep the open state; controls the high-speed switch in the current limiting unit CLU to keep the open state; controls the series switch KM1 to keep the closed state, so that the series compensation device is normally put into operation; when the sampling current value is greater than the current threshold value but less than the overcurrent protection threshold value, the main controller can adjust the compensation device switching according to the requirement; when the sampling current value is greater than the overcurrent protection threshold value, the main controller judges that a serious short circuit fault occurs and performs protection control.

[0037] Short-circuit current protection: the main controller monitors the circuit working current in real time through the current sampling unit; when the sampling current value is greater than or equal to the preset overcurrent protection threshold, the main controller determines that the series compensation device has a short circuit; the main controller immediately sends a trigger command to the high-speed switch, the contactor KM1 and the contactor KM2 at the same time; due to the characteristics of the device, the high-speed switch can respond to the trigger command and turn on in a very short time (usually in microseconds); after the high-speed switch is turned on, the reactor in the current limiting unit CLU begins to play a current limiting role; the reactor suppresses the rapid rise of the short-circuit current, preventing the current from suddenly changing and causing impact on the series compensation device; at the same time, the main controller trigger command makes the contactor KM1 open, quickly isolating the series compensation device from the fault point; the main controller trigger command also makes the bypass switch BS close, forming a short circuit on the transformer secondary side to provide a bypass for the current limiting unit; through the rapid conduction of the high-speed switch and the current limiting effect of the reactor, the short-circuit current is effectively suppressed, and the series compensation device is protected.

[0038] Overvoltage protection: the main controller also monitors the voltage across the series compensation device in real time through the voltage sampling unit; when the sampling voltage value is greater than or equal to the preset overvoltage protection threshold, the main controller determines that the series compensation device has an overvoltage; the main controller immediately sends a trigger command to the contactor KM1 and the contactor KM2; the trigger command makes the bypass switch BS close, forming a short circuit on the transformer secondary side, and the secondary side voltage becomes zero, while the trigger command makes the contactor KM1 open, quickly isolating the series compensation device from the transformer secondary side; through the coordinated action of KM1 and KM2, the series compensation device is quickly removed from operation in the power grid; after the series compensation device stops running, its voltage across returns to a safe level, avoiding the harm of overvoltage.

[0039] Example 2

[0040] Figure 4 Another circuit diagram according to some embodiments of the application is shown, which is based on example 1, and a switch K1 with a clear breakpoint is added to the bypass switch circuit. Short-circuit current protection: the implementation of short-circuit current protection is the same as in example 1; the main controller monitors the circuit working current in real time through the current sampling unit; when the sampling current value is greater than or equal to the preset overcurrent protection threshold, the main controller determines that the series compensation device has a short circuit; the main controller immediately sends a trigger command to the high-speed switch, the contactor KM1 and the contactor KM2 at the same time; the high-speed switch quickly turns on, and the reactor suppresses the rapid rise of the short-circuit current, protecting the series compensation device; the contactor KM1 opens, isolating the series compensation device from the fault point; the contactor KM2 closes, providing a bypass for the current limiting unit.

[0041] Overvoltage protection: on the basis of embodiment 1, a switch K1 with an obvious breaking point is added in the bypass switch circuit; the main controller monitors the voltage across the series compensation device in real time through the voltage sampling unit; when the sampled voltage value is greater than or equal to the preset overvoltage protection threshold, the main controller determines that overvoltage occurs in the series compensation device; the main controller immediately sends a trigger instruction to the contactor KM1, the contactor KM2 and the switch K1; the trigger instruction makes the contactor KM1 open, isolating the series compensation device from the transformer secondary side; the trigger instruction makes the bypass switch BS close, and at the same time makes the switch K1 close; after the switch K1 is closed, an obvious short-circuit breaking point is formed in the bypass branch; the transformer secondary side voltage drops to zero, and the series compensation device reliably exits the power grid operation; the switch K1 can be closed by an electric operating mechanism, and is provided with a disconnecting switch feedback signal. After the switch K1 is closed, an obvious short-circuit breaking point is formed in the bypass branch, which more reliably isolates the series compensation device from the power grid. The switch K1 can be an electrically operated disconnecting switch with an obvious breaking point, which is convenient for maintenance personnel to identify and operate. The switch K1 is provided with a disconnecting switch feedback signal, which can feed back the switch state to the main controller, facilitating monitoring and recording.

[0042] Embodiment 3

[0043] Voltage and current sampling: the main controller sets a high-precision voltage transformer and a high-precision current transformer on the transformer secondary side; the voltage transformer and the current transformer can be selected from high-precision electronic transformers or optical transformers; the voltage transformer is used to sample the voltage value of the transformer secondary side winding in real time; the current transformer is used to sample the current value of the transformer secondary side in real time; the sampled voltage value and current value are transmitted to the main controller in real time for processing and judgment.

[0044] Control under normal operating conditions: the main controller monitors the current value sampled by the current transformer in real time; when the sampled current value is less than the preset overcurrent protection threshold, the main controller performs the following control: controls the contactor KM2 to remain in an open state, ensuring that the bypass branch is in an open state; controls the high-speed switch in the current limiting unit CLU to remain in an open state, without affecting the circuit operation under normal operating conditions; controls the contactor KM1 to remain in a closed state, so that the series compensation device is normally put into operation in the power grid.

[0045] Short-circuit current protection: when the transformer secondary side current sampling value is greater than or equal to the overcurrent protection threshold, the main controller determines that a short-circuit fault occurs; the main controller immediately sends a trigger instruction to the high-speed switch, the contactor KM1 and the contactor KM2 at the same time; the high-speed switch is quickly turned on, and the reactor in the current limiting unit CLU starts to play a current limiting role; the reactor suppresses the rapid rise of the short-circuit current, preventing the current from suddenly changing and causing damage to the high-speed switch, thereby playing a protection role; at the same time, the contactor KM1 is opened, isolating the series compensation device from the fault point; the contactor KM2 is closed, providing a bypass for the current limiting unit.

[0046] Overvoltage protection: the main controller monitors the voltage transformer sampling transformer secondary winding voltage value in real time; when the sampling voltage value is greater than the preset overvoltage protection threshold, the main controller determines that an overvoltage fault occurs; the main controller immediately sends a trigger instruction to the contactor KM2 and the contactor KM1; the contactor KM2 is closed, making the transformer secondary side form a short circuit, and the secondary side voltage quickly drops to 0V; the contactor KM1 is subsequently opened, reliably removing the series compensation device from the power grid operation; at this point, the entire device completely exits the power grid operation state, and the power grid main circuit resumes normal operation.

[0047] The above has described the application creation and its implementation modes schematically, which is not limited, and the application can be realized in other specific forms without departing from the spirit or essential characteristics of the application. The embodiments shown in the drawings are only one of the embodiments of the application creation, and the actual structure is not limited thereto, and any reference signs in the claims should not limit the claims involved. Therefore, if a person skilled in the art is inspired by it, without departing from the spirit of the creation, similar structure modes and embodiments can be designed without creativity, which should belong to the protection scope of the patent. In addition, the word "comprising" does not exclude other elements or steps, and the word "one" before the element does not exclude "multiple" elements. The multiple elements stated in the product claim can also be realized by one element through software or hardware. The words "first", "second" and the like are used to represent names, and do not represent any specific order.

Claims

1. A short circuit protection device for a series compensation device of a power grid, characterized in that The application relates to a series compensation device for power grid, which comprises the following components: a bypass switch BS, one end of which is connected in parallel with a transformer secondary side, and the other end of which is three-phase short-circuited; the bypass switch BS is an AC contactor; a current-limiting unit CLU, which is connected in parallel with the transformer secondary side circuit; a main controller, which sets current threshold value and overcurrent protection threshold value, receives circuit working current detected by a current sampling unit, controls the conduction and turn-off of high-speed switches in the current-limiting unit CLU, and controls the closing and opening of the series switch KM1 and the bypass switch BS; the series switch KM1, when closed, connects the series compensation device to the transformer secondary side, so that the series compensation device participates in power grid operation; when opened, the series compensation device is disconnected from the transformer secondary side, so that the series compensation device exits power grid operation; a current sampling unit arranged on the transformer primary side, which collects power grid side current value and transmits the current value to the main controller; the current value is compared with the preset current threshold value and overcurrent protection threshold value respectively: when the current value is less than the current threshold value, the high-speed switches in the current-limiting unit CLU are in the turn-off state, and the series switch KM1 is in the closed state, so that the series compensation device is connected to the transformer secondary side and participates in power grid operation; when the current value is greater than or equal to the overcurrent protection threshold value, a linkage trigger instruction is sent within a preset time, the high-speed switches in the current-limiting unit CLU are turned on, the bypass switch BS is closed within a preset time after the high-speed switches are turned on, and the series switch KM1 is opened, so that the series compensation device exits power grid operation; the current-limiting unit CLU comprises a reactor connected in series with the high-speed switches, when the current value is detected to be greater than the overcurrent protection threshold value, the high-speed switches are turned on, and the reactor limits the rising rate of circuit current, so as to reduce the impact of current mutation on the series compensation device; the current sampling unit adopts a current transformer, which is connected in series with the transformer primary side and collects power grid side current; a switch K1 is further connected in series in the circuit of the bypass switch BS; the switch K1 is a disconnecting switch with a break, and an insulation gap is formed at the break when the switch K1 is opened; the main controller is connected with the control end of the switch K1, and is used for controlling the closing and opening of the switch K1; when the main controller detects that the current sampling value exceeds the overcurrent protection threshold value or the voltage of the series compensation device exceeds the overvoltage protection threshold value, the main controller sends a linkage trigger instruction, controls the high-speed switches in the current-limiting unit CLU to be turned on, controls the bypass switch BS to be closed, controls the series switch KM1 to be opened, and controls the switch K1 to be closed; the switch K1 comprises an electric operating mechanism and a disconnecting switch; the electric operating mechanism comprises a motor, a speed reducer and an output shaft, the motor drives the output shaft to rotate through the speed reducer; the disconnecting switch comprises an operating shaft, a moving contact and a static contact, the operating shaft drives the moving contact to move relative to the static contact; the output shaft of the electric operating mechanism is connected with the operating shaft of the disconnecting switch through a shaft coupling, so that the electric operating mechanism drives the closing and opening of the disconnecting switch. The isolating switch is provided with a feedback signal output end, the feedback signal output end is connected with the movable contact, when the isolating switch is closed and the movable contact is in contact with the static contact, the feedback signal output end outputs a closed state signal with the same potential as the static contact; when the isolating switch and the movable contact are separated from the static contact, the feedback signal output end outputs an open state signal with different potential from the static contact; The electric operating mechanism is provided with a position signal output end, the position signal output end is connected with an angular displacement sensor on the output shaft, the angular displacement sensor detects the angular position of the output shaft and transmits the angular position signal to the position signal output end; The feedback signal output end of the isolating switch and the position signal output end of the electric operating mechanism are both connected with the signal input end of the main controller, and the position signal of the feedback signal is transmitted to the main controller.

2. The short-circuit protection device for power grid series compensation equipment according to claim 1, characterized in that: The main controller also pre-stores standard feedback signal values and standard position signal values corresponding to the closing and opening of the isolating switch; The main controller judges the actual state of the switch K1 by receiving the feedback signal of the isolating switch and the position signal of the electric operating mechanism and comparing them with the pre-stored standard values: When the feedback signal is consistent with the closed state standard value and the position signal is consistent with the closed position standard value, the main controller determines that the switch K1 is in the closed state; When the feedback signal is consistent with the open state standard value and the position signal is consistent with the open position standard value, the main controller determines that the switch K1 is in the open state; If the feedback signal and the position signal are inconsistent with the corresponding standard values or any signal is missing, the main controller issues a fault warning.

3. The short-circuit protection device for power grid series compensation equipment according to claim 2, characterized in that: The switch K1 is connected in series with the bypass switch BS and is connected in parallel with the transformer secondary side, when the switch K1 and the bypass switch BS are both closed, the transformer secondary side is short-circuited.

4. The short-circuit protection device for power grid series compensation equipment according to claim 3, characterized in that: After the main controller issues the linkage trigger instruction: The switch K1 is controlled to be closed within a preset time after the current limiting unit CLU is turned on.

5. The short-circuit protection device for power grid series compensation equipment according to claim 4, characterized in that: The main controller also includes transformer secondary side voltage acquisition, when a short circuit occurs, the main controller detects that the short-circuit current or the transformer secondary side voltage exceeds the safety protection threshold of the series compensation equipment, the main controller issues a trigger instruction, the high-speed switch is triggered to be turned on, the reactor limits the instantaneous current rise rate and maximum amplitude, at the same time, the bypass switch BS is closed, the transformer secondary side voltage is 0, the series switch KM1 is opened, and the series compensation equipment exits the power grid operation.

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