Fault current limiter and control method thereof

Abstract

The invention discloses a fault current limiter and a control method thereof, and belongs to the technical field of fault current limiting, the fault current limiter comprises a plurality of current limiting modules, a first measurement CT, a control and protection device and an energy supply system, each current limiting module comprises a high-speed switch and a current limiting reactor, and the second measurement CT, the high-speed switch and the current limiting reactor are connected in parallel. The second measurement CT collects the current flowing through the current limiting reactor; the quick switch comprises a switch body and a trigger loop, and the trigger loop outputs energy to open and close the switch body. The first measurement CT measures the current flowing through the current limiting module; the control and protection device collects current values of the first measurement CT and the second measurement CT, collects signals of the quick switch and controls the quick switch to be turned on and off. The first measurement CT and the second measurement CT are directly connected with the control and protection device to supply a current value, or the current value is transferred and supplied through a trigger loop; the energy supply system provides operation energy for the trigger loop. The purpose of the invention is to solve the problem that the CT cannot obtain energy when the bus current is small.

Description

Technical Field

[0001] This application relates to the field of fault current limiting technology, specifically to a fault current limiter and its control method. Background Technology

[0002] Existing fault current limiters are equipped with only one total current-limiting reactor. When the fast switch connected in parallel with the current-limiting reactor fails, the current limiter function is lost. For high-potential energy extraction, existing technology generally uses a current transformer (CT) to extract energy from the bus. However, when the bus current is low, energy cannot be extracted. Summary of the Invention

[0003] Purpose of the invention: This application develops a fault current limiter and its control method, aiming to solve the technical problems in the prior art where a single current limiting reactor is prone to functional failure and the CT cannot obtain energy when the bus current is small.

[0004] Technical solution: Embodiments of this application provide a fault current limiter, including:

[0005] Multiple current limiting modules are provided, each current limiting module including a fast switch, a current limiting reactor, and a second measuring current transformer (CT). The fast switch and the current limiting reactor are connected in parallel, and the second measuring CT is used to collect the current flowing through the current limiting reactor. The fast switch includes a switch body and a trigger circuit, and the trigger circuit is used to output energy to realize the opening and closing of the switch body.

[0006] The first measuring CT is used to measure the current flowing through the current limiting module;

[0007] The control and protection device is used to collect the current values ​​of the first measuring CT and the second measuring CT, and to collect the fast switch signal and control the fast switch to open and close; the first measuring CT and the second measuring CT are directly connected to the control and protection device to send current values, or they can transfer the current values ​​through the trigger circuit.

[0008] A power supply system is provided to supply operating energy to the trigger circuit.

[0009] In some embodiments, the trigger circuit includes a control board and a charging / discharging system, and the power supply system includes a power supply, a first power module, a second power module, a third power module, and a fourth power module, wherein:

[0010] The power supply is used to output two voltages. The first voltage is used to supply the first power module and the second power module, and the second voltage is used to supply the third power module and the fourth power module.

[0011] The trigger circuit is used to acquire the two voltage outputs of the power supply.

[0012] The first power module and the third power module are connected in parallel to provide operating energy to the control board, and the second power module and the fourth power module are connected in parallel to provide operating energy to the charging and discharging system.

[0013] In some embodiments, the power source includes a third power-harvesting CT and a fourth power-harvesting CT, wherein:

[0014] The third energy-harvesting CT is used to output the first voltage, and the fourth energy-harvesting CT is used to output the second voltage. Both the third and fourth energy-harvesting CTs are used to harvest current energy from the bus.

[0015] In some embodiments, the power supply includes a CVT, a first contactor, a second contactor, a first step-down transformer, and a second step-down transformer. The CVT includes a first type of capacitor and a second type of capacitor, wherein:

[0016] The first type of capacitor and the second type of capacitor are connected in series. The high-voltage terminal of the first type of capacitor is connected to the bus, and the low-voltage terminal of the second type of capacitor is grounded. The voltage output between the terminals of the first type of capacitor is used to supply voltage to the first contactor and the second contactor respectively. The first contactor is used to supply voltage to the first step-down transformer. The output of the first step-down transformer is used as the first voltage of the power supply. The second contactor is used to supply voltage to the second step-down transformer. The output of the second step-down transformer is used as the second voltage of the power supply.

[0017] In some embodiments, the power supply further includes a fifth power module and a sixth power module, wherein:

[0018] The fifth power module is used to take voltage from the first output of the power supply and then send it to the first contactor;

[0019] The sixth power module is used to take voltage from the second output of the power supply and then send it to the second contactor;

[0020] The control and protection device is used to send opening and closing commands to the first contactor and the second contactor through the trigger circuit.

[0021] In some embodiments, the second type of capacitor includes a first capacitor and a second capacitor, wherein:

[0022] The first capacitor and the second capacitor are connected in series. The first capacitor is connected to the first type of capacitor. The output voltage of the second capacitor serves as the bus voltage signal, which is sent to the control and protection device.

[0023] In some embodiments, the power supply further includes a leakage current acquisition CT, which is used to acquire the leakage current flowing through the CVT and output a voltage as a bus voltage signal, which is sent to the control and protection device.

[0024] In some embodiments, a high-potential platform is also included, wherein the current limiting module, the first measuring CT, and the power supply system are arranged on the high-potential platform, and the control and protection device is at ground potential.

[0025] In some embodiments, a control method for a fault current limiter is also provided. The fault current limiter includes a protection device and a power supply. The power supply includes a first contactor and a second contactor, and the power supply includes a first output and a second output. The control method includes:

[0026] The voltage of the first output, the second output, and the bus is detected by the control and protection device.

[0027] If the control and protection device determines that the first output has no voltage and the second output has voltage, it opens the first contactor and issues a warning that the first output is short-circuited.

[0028] If the control and protection device determines that there is no voltage in the second output and there is voltage in the first output, it opens the second contactor and issues a warning that the second output is short-circuited.

[0029] If the control and protection device determines that there is no voltage in the first output, the second output, and the bus, neither the first contactor nor the second contactor will operate.

[0030] In some embodiments, when the fault current limiter monitors the bus voltage, the control method further includes:

[0031] The control and protection device determines that there is no voltage in the first output and the second output, but there is voltage in the bus.

[0032] The first contactor is opened, and the protection device determines that there is no voltage at the second output.

[0033] The second contactor is opened, the first contactor is closed, and the protection device determines that there is no voltage at the first output.

[0034] Control the second contactor to close, and warn of a simultaneous short circuit on the input side of the first contactor and the second contactor or a simultaneous short circuit on the output side.

[0035] In some embodiments, when the fault current limiter does not monitor the bus voltage, the control method further includes:

[0036] The control and protection device determines that there is no voltage in both the first output and the second output;

[0037] The first contactor is opened, and the protection device determines that there is no voltage at the second output.

[0038] The second contactor is opened, the first contactor is closed, and the protection device determines that there is no voltage at the first output.

[0039] Control the second contactor to close, and warn of a simultaneous short circuit on the input side of the first contactor and the second contactor or a simultaneous short circuit on the output side.

[0040] In some embodiments, the control method further includes:

[0041] When the first contactor opens, the control and protection device determines that there is voltage in the second output and warns of a short circuit on the output side of the first contactor.

[0042] In some embodiments, the control method further includes:

[0043] When the second contactor opens and the first contactor closes, the control and protection device determines that there is voltage at the first output and warns of a short circuit on the output side of the second contactor.

[0044] Beneficial effects:

[0045] Compared with existing technologies, the fault current limiter provided in this application embodiment has at least dual power supply, so that when one power supply fails, the other power supply can continue to supply power, thereby improving power supply reliability. When this application draws power from the bus current transformer (CT), the cost of the CT is reduced because drawing power from the bus is simple and convenient. When this application draws power from the CVT, as long as there is voltage on the bus, energy can be drawn to power the components on the high-potential platform, and power can also be drawn when the bus is under low load.

[0046] This application also provides a control method for a fault current limiter. When a short circuit occurs on the primary side of the step-down transformer, fault clearance is achieved simply by sequentially opening and closing the first and second contactors, resulting in simple logic. By monitoring the bus voltage, the first and second contactors do not operate when the bus is de-energized, reducing the number of contactor operations. When using logic that does not monitor the bus voltage, there is no need to detect the bus voltage, reducing equipment usage. At the moment of bus de-energization, the first and second contactors operate according to the no-voltage logic, ultimately both being in the closed position. When the bus is energized again, equipment on the high-potential platform can operate with power. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0048] Figure 1 This is a schematic diagram of the electrical principle of a fault current limiter provided in an embodiment of this application;

[0049] Figure 2 A schematic diagram showing the fault current limiter provided in this application embodiment being powered by a bus current transformer (CT).

[0050] Figure 3 A schematic diagram showing the fault current limiter provided in this application embodiment being powered by a CVT;

[0051] Figure 4 A schematic diagram of a fault current limiter monitoring bus voltage via a CVT capacitor, provided in an embodiment of this application;

[0052] Figure 5 A schematic diagram of a fault current limiter monitoring bus voltage via CVT leakage current, provided in an embodiment of this application;

[0053] Figure 6 The fault protection operation logic diagram of the power supply circuit of the temporary fault current limiter provided in the embodiments of this application;

[0054] Figure 7 The fault protection operation logic diagram of the power supply circuit of the fault current limiter under two operating conditions provided in the embodiments of this application;

[0055] Figure 8 The fault protection operation logic diagram of the power supply circuit of the fault current limiter under three operating conditions provided in the embodiments of this application;

[0056] Figure 9 The fault protection operation logic diagram of the power supply circuit of the fault current limiter under four-time fault conditions provided in the embodiments of this application;

[0057] Figure 10 This is an overall structural diagram of the trigger circuit provided in an embodiment of this application.

[0058] Figure label:

[0059] 1-Current limiting module, 11-Fast switch, 111-Switch body, 112-Trigger circuit, 1121-Control board, 1122-Charging and discharging system, 12-Current limiting reactor, 13-Second measuring CT;

[0060] 2-First measurement CT;

[0061] 3-Control and protection devices;

[0062] 4-Power supply system, 41-Power supply, 411-Third power CT, 412-Fourth power CT, 413-CVT, 4131-First type capacitor, 4132-Second type capacitor, 41321-First capacitor, 41322-Second capacitor, 414-First contactor, 415-Second contactor, 416-First step-down transformer, 417-Second step-down transformer, 418-Leakage current acquisition CT, 42-First power module, 43-Second power module, 44-Third power module, 45-Fourth power module, 46-Fifth power module, 47-Sixth power module;

[0063] 5-High-potential platform. Detailed Implementation

[0064] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0065] It should be understood that although the terms first, second, etc., may be used herein to describe various components, these components should not be limited by these terms. These terms are used to distinguish one component from another. Therefore, the first component discussed below may be referred to as the second component without departing from the teachings of this application. As used herein, the term "and / or" includes all combinations of any and more of the associated listed items.

[0066] Those skilled in the art will understand that the accompanying drawings are merely schematic diagrams of exemplary embodiments and may not be to scale. The modules or processes shown in the drawings are not necessarily essential for implementing this application and therefore should not be used to limit the scope of protection of this application.

[0067] With increasing demands for power grid reliability, the grid structure is becoming increasingly complex. Furthermore, the growing electricity load is exacerbating the problem of excessive short-circuit current. Excessive short-circuit current means the current exceeds the breaking capacity of the circuit breaker, rendering it unable to interrupt the fault and severely impacting grid operational safety. Fault current limiters are one effective measure to address excessive short-circuit current. When a short-circuit fault occurs, a current-limiting reactor is connected in series with the line before the circuit breaker opens, reducing the current amplitude to below the circuit breaker's interruptible current, thus ensuring reliable fault interruption.

[0068] The existing technology has the following problems: ① In the existing technology, the fault current limiter is only equipped with a single total current-limiting reactor. When the fast switch connected in parallel with the current-limiting reactor fails, the current limiter function is lost. ② For high-potential energy extraction, the existing technology generally uses a current transformer (CT) to extract energy from the bus. When the bus current is small, energy cannot be extracted. ③ In the existing technology, fast switches are generally in switchgear form for 10kV-35kV, and in tank type for 110kV to 500kV. However, fast switch products are not found for 750kV and above. The 750kV level power grid also has the problem of excessive short-circuit current, which urgently needs to be addressed.

[0069] Please see Figure 1 This application provides a fault current limiter, which includes multiple current limiting modules 1, a first measuring current transformer (CT) 2, a control and protection device 3, a power supply system 4, and a high-potential platform 5. Each current limiting module 1 includes a fast switch 11, a current limiting reactor 12, and a second measuring CT 13. The fast switch 11 and the current limiting reactor 12 are connected in parallel. The fast switch 11 includes a switch body 111 and a trigger circuit 112, which outputs energy to open and close the switch body 111. All current limiting modules 1 are connected in series. The first measuring CT2 measures the current flowing through the current limiting module 1, and the second measuring CT 13 collects the current flowing through the current limiting reactor 12. The control and protection device 3 collects the current values ​​of the first measuring CT2 and the second measuring CT 13, and collects the signal from the fast switch 11 to control its opening and closing. The first measuring CT2 and the second measuring CT 13 can be directly connected to the control and protection device 3 to send current values, or they can be transferred to send current values ​​through the trigger circuit 112. The power supply system 4 is used to provide operating energy to the trigger circuit 112. The current limiting module 1, the first measuring CT 2, and the power supply system 4 are arranged on the high-potential platform 5, and the control and protection device 3 is at ground potential.

[0070] Through the above scheme, this embodiment adopts a high-potential platform structure. For example, the 750kV bus voltage is borne by the platform insulators, and the current-limiting unit terminals only bear the recovery voltage after the fast switch 11 is interrupted. If the fast switch 11 is 72.5kV, the voltage level between the current-limiting unit terminals is only 72.5kV. Other components on the high-potential platform 5 are at the same potential as the high-potential platform 5 with no voltage difference, making the technical solution simple to implement. Assuming that the number of current-limiting modules 1 is N, where N is an integer greater than or equal to 2, N current-limiting modules 1 are connected in series to achieve current limiting. If a single current-limiting module 1 fails, the current limiting effect only becomes N-1, without losing the current-limiting function. Each current-limiting module 1 is equipped with a reactor, and the fast switch 11 operating in series does not require an equalizing capacitor. By collecting the current of the current-limiting reactor 12, it can be prevented from being damaged due to long-term current flow. When a closing command is sent to the fast switch 11 connected in parallel with the current-limiting reactor 12, if there is still current in the current-limiting reactor 12, a closing command is sent to the fast switch 11 again to ensure that the current-limiting reactor 12 does not carry current for a long time.

[0071] In some embodiments, the trigger circuit 112 includes a control board 1121 and a charging / discharging system 1122, with the control board 1121 connected to the charging / discharging system 1122. Please refer to [link to relevant documentation]. Figure 10 , Figure 10 The overall structure of the trigger circuit is illustrated. The trigger circuit 112 also includes a tripping coil and a closing coil. The charging and discharging system 1122 includes a tripping charging diode, a tripping capacitor, a tripping IGBT, a tripping discharge diode, a closing charging diode, a closing capacitor, a closing IGBT, and a closing discharge diode. The tripping discharge diode and the tripping coil are connected in parallel and then in series with the tripping IGBT, then in parallel with the tripping capacitor, and finally in series with the tripping charging diode. The closing discharge diode and the closing coil are connected in parallel and then in series with the closing IGBT, then in parallel with the closing capacitor, and finally in series with the closing charging diode. When the voltages of the tripping capacitor and the closing capacitor are less than the DC voltages output by the second power module 43 and the fourth power module 45, the charging current charges the tripping capacitor and the closing capacitor respectively through the tripping charging diode and the closing charging diode. Charging automatically stops when the voltages of the power modules and the capacitors are the same. When the fast switch 11 needs to open, the control board 1121 triggers the opening IGBT to turn on. The opening capacitor discharges to the opening coil, generating an electromotive force that causes the switch to open. The voltage on the opening coil changes from positive at the top and negative at the bottom during discharge to positive at the bottom and negative at the top at the end of discharge. At this time, the opening discharge diode conducts, releasing the energy of the opening coil. When the fast switch 11 needs to close, the control board triggers the closing IGBT to turn on. The closing capacitor discharges to the closing coil, generating an electromotive force that causes the switch to close. The voltage on the closing coil changes from positive at the top and negative at the bottom during discharge to positive at the bottom and negative at the top at the end of discharge. At this time, the closing discharge diode conducts, releasing the energy of the closing coil.

[0072] In some embodiments, please refer to Figure 2 This embodiment is a bus current transformer (CT) power supply scheme. The power supply system 4 includes a power supply 41, a first power module 42, a second power module 43, a third power module 44, and a fourth power module 45. The power supply 41 includes a third current transformer (CT) 411 and a fourth current transformer (CT) 412. The third current transformer (CT) 411 outputs a first voltage, and the fourth current transformer (CT) 412 outputs a second voltage. Both the third current transformer (CT) 411 and the fourth current transformer (CT) 412 harvest current energy from the bus. The first voltage output by the power supply 41 is supplied to the first power module 42 and the second power module 43. The second voltage is supplied to the third power module 44 and the fourth power module 45. The first power module 42 and the third power module 44 are connected in parallel to provide operating energy to the control board 1121. The second power module 43 and the fourth power module 45 are connected in parallel to provide operating energy to the charging and discharging system 1122.

[0073] Through the above solution, this embodiment provides at least dual power supply. If one supply fails, the others continue to supply power, improving power supply reliability. Furthermore, drawing power from the busbar is simple and convenient, and the cost of the power supply current transformer (CT) is low.

[0074] In some embodiments, please refer to Figure 3 This embodiment uses a CVT (capacitor voltage transformer) power supply scheme. The power supply system 4 includes a power supply 41, a first power module 42, a second power module 43, a third power module 44, a fourth power module 45, a fifth power module 46, and a sixth power module 47. The power supply 41 outputs two voltages: the first voltage is supplied to the first power module 42 and the second power module 43, and the second voltage is supplied to the third power module 44 and the fourth power module 45. The first power module 42 and the third power module 44 are connected in parallel to provide operating energy to the control board 1121, and the second power module 43 and the fourth power module 45 are connected in parallel to provide operating energy to the charging and discharging system 1122. The trigger circuit 112 is used to collect the two voltages output by the power supply 41. The power supply 41 includes a CVT 413, a first contactor 414, a second contactor 415, a first step-down transformer 416, and a second step-down transformer 417. CVT413 includes a first type of capacitor 4131 and a second type of capacitor 4132, which are connected in series. The high-voltage end of the first type of capacitor 4131 is connected to the bus, and the low-voltage end of the second type of capacitor 4132 is grounded. The voltage output between the terminals of the first type of capacitor 4131 is respectively supplied to the first contactor 414 and the second contactor 415. The voltage of the first contactor 414 is then supplied to the first step-down transformer 416. The output of the first step-down transformer 416 is used as the first voltage of the power supply 41. The voltage of the second contactor 415 is then supplied to the second step-down transformer 417. The output of the second step-down transformer 417 is used as the second voltage of the power supply 41. The fifth power module 46 takes voltage from the first output of the power supply 41 and sends it to the first contactor 414. The sixth power module 47 takes voltage from the second output of the power supply 41 and sends it to the second contactor 415. The opening and closing commands of the control and protection device 3 to the first contactor 414 and the second contactor 415 are forwarded through the trigger circuit 112.

[0075] Through the above scheme, in this embodiment, as long as there is voltage on the busbar, energy can be drawn to power the components on the high-potential platform 5. Power can also be drawn when the busbar is operating under low load and the line current is low. Faults are cleared by contactors, improving power supply reliability.

[0076] In some embodiments, please refer to Figure 4In this embodiment, the second type of capacitor 4132, which monitors the bus voltage via CVT capacitors, includes a first capacitor 41321 and a second capacitor 41322 connected in series. The first capacitor 41321 is connected to the first type of capacitor 4131, and the output voltage of the second capacitor 41322 serves as the bus voltage signal, which is then sent to the control and protection device 3. Specifically, during normal operation, the voltage between the terminals of the first type of capacitor 4131 is 8.5kV, and the voltage between the terminals of the second type of capacitor 4132 is 433kV. The second capacitor 41322 is used to measure the bus voltage, and its voltage is approximately 10kV. The voltage input to the control and protection device is at most several hundred volts. This embodiment uses the first capacitor 41321 to divide the voltage, making the step-down transformer (i.e., the first step-down transformer 416 and the second step-down transformer 417 in this embodiment) smaller and more economical.

[0077] In some embodiments, please refer to Figure 5 The bus voltage monitoring scheme using CVT413 leakage current also includes a leakage current acquisition CT418. The leakage current acquisition CT418 acquires the leakage current flowing through CVT413 and outputs a voltage as a bus voltage signal, which is then sent to the control and protection device 3.

[0078] With the above solution, this embodiment does not require complex design of CVT413. The bus voltage signal can be acquired by simply adding a CT to the bottom line of CVT413.

[0079] Accordingly, this application also provides a control method for a fault current limiter, as detailed below:

[0080] In some embodiments, please refer to Figure 6 , Figure 6 The control method steps under one operating condition according to the embodiment of this application are illustrated. The control and protection device 3 detects that the first output of the power supply 41 has no voltage and the second output has voltage; it opens the first contactor 414 and issues an alarm for a short circuit in the first output of the power supply 41.

[0081] In some embodiments, please refer to Figure 7 , Figure 7 The control method steps in the second operating condition of the embodiment of this application are illustrated. The control and protection device 3 detects that there is voltage on the first output of the power supply 41 and no voltage on the second output; it opens the second contactor 415 and issues an alarm for a short circuit in the second output of the power supply 41.

[0082] In some embodiments, please refer to Figure 8 , Figure 8The control method steps under operating condition three of the embodiments of this application are illustrated. The control and protection device 3 detects that there is no voltage on the first output of the power supply 41, no voltage on the second output, and no voltage on the bus; the first contactor 414 and the second contactor do not operate.

[0083] In some embodiments, please refer to Figure 9 , Figure 9 The illustration shows the control method steps under four operating conditions according to the embodiments of this application.

[0084] The control and protection device 3 determines that there is no voltage in both the first and second outputs of the power supply 41, and the bus voltage signal shows that there is voltage on the bus; or if the bus voltage is not monitored, the control and protection device 3 determines that there is no voltage in both the first and second outputs of the power supply 41.

[0085] When the first contactor 414 is opened, the control and protection device 3 confirms that there is no voltage at the second output of the power supply 41.

[0086] The second contactor 415 opens, the first contactor 414 closes, and the control and protection device 3 confirms that there is no voltage in the first output of the power supply 41.

[0087] When the second contactor 415 closes, it will warn that the input side of the first contactor 414 and the output side of the second contactor 415 are both short-circuited or both are short-circuited.

[0088] In some embodiments, please refer to Figure 9 When the first contactor 414 is opened, the control and protection device 3 confirms that there is voltage on the second output of the power supply 41 and issues a warning that the output side of the first contactor 414 is short-circuited.

[0089] In some embodiments, please refer to Figure 9 When the second contactor 415 opens and the first contactor 414 closes, the control and protection device 3 confirms that there is voltage on the first output of the power supply 41 and warns of a short circuit on the output side of the second contactor 415.

[0090] With the above solution, when a short circuit occurs on the primary side of the step-down transformer in this embodiment, the fault is cleared simply by sequentially opening and closing the first contactor 414 and the second contactor 415, resulting in a simple logic. By monitoring the bus voltage, the contactors do not operate when the bus is de-energized, reducing the number of times the first contactor 414 and the second contactor 415 operate. When using logic that does not monitor the bus voltage, there is no need to detect the bus voltage, reducing equipment requirements. At the moment of bus de-energization, the first contactor 414 and the second contactor 415 operate according to the no-voltage logic, and ultimately both the first contactor 414 and the second contactor 415 are in the closed position. When the bus is energized, the equipment on the high-potential platform 5 can be powered and operated.

[0091] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0092] The above provides a detailed description of a fault current limiter and its control method provided in the embodiments of this application, and uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the technical solutions and core ideas of this application. Those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A fault current limiter, characterized in that, include: Multiple current limiting modules (1) are provided. Each current limiting module (1) includes a fast switch (11), a current limiting reactor (12), and a second measuring current transformer (13). The fast switch (11) and the current limiting reactor (12) are connected in parallel. The second measuring current transformer (13) is used to collect the current flowing through the current limiting reactor (12). The fast switch (11) includes a switch body (111) and a trigger circuit (112). The trigger circuit (112) is used to output energy to open and close the switch body (111). The first measuring CT (2) is used to measure the current flowing through the current limiting module (1); The control and protection device (3) is used to collect the current values ​​of the first measuring CT (2) and the second measuring CT (13), and to collect the signal of the fast switch (11) and control the fast switch (11) to open and close; the first measuring CT (2) and the second measuring CT (13) are directly connected to the control and protection device (3) to send current values, or they are transferred to send current values ​​through the trigger circuit (112); The power supply system (4) is used to provide operating energy to the trigger circuit (112).

2. A fault current limiter as described in claim 1, characterized in that, The trigger circuit (112) includes a control board (1121) and a charging / discharging system (1122), and the power supply system (4) includes a power supply (41), a first power module (42), a second power module (43), a third power module (44), and a fourth power module (45), wherein: The power supply (41) is used to output two voltages. The first voltage is used to supply the first power module (42) and the second power module (43), and the second voltage is used to supply the third power module (44) and the fourth power module (45). The trigger circuit (112) is used to collect the two voltages output by the power supply (41); The first power module (42) and the third power module (44) are connected in parallel to provide operating energy to the control board (1121), and the second power module (43) and the fourth power module (45) are connected in parallel to provide operating energy to the charging and discharging system (1122).

3. A fault current limiter as described in claim 2, characterized in that, The power supply (41) includes a third energy-harvesting CT (411) and a fourth energy-harvesting CT (412), wherein: The third energy-harvesting CT (411) is used to output the first voltage, and the fourth energy-harvesting CT (412) is used to output the second voltage. Both the third energy-harvesting CT (411) and the fourth energy-harvesting CT (412) are used to harvest current energy from the bus.

4. A fault current limiter as described in claim 2, characterized in that, The power supply (41) includes a CVT (413), a first contactor (414), a second contactor (415), a first step-down transformer (416), and a second step-down transformer (417). The CVT (413) includes a first type of capacitor (4131) and a second type of capacitor (4132), wherein: The first type of capacitor (4131) and the second type of capacitor (4132) are connected in series. The high voltage end of the first type of capacitor (4131) is connected to the bus, and the low voltage end of the second type of capacitor (4132) is grounded. The voltage output between the terminals of the first type of capacitor (4131) is used to supply voltage to the first contactor (414) and the second contactor (415) respectively. The first contactor (414) is used to supply voltage to the first step-down transformer (416). The output of the first step-down transformer (416) is used as the first voltage of the power supply (41). The second contactor (415) is used to supply voltage to the second step-down transformer (417). The output of the second step-down transformer (417) is used as the second voltage of the power supply (41).

5. A fault current limiter as described in claim 4, characterized in that, The power supply (41) also includes a fifth power supply module (46) and a sixth power supply module (47), wherein: The fifth power module (46) is used to take voltage from the first output of the power supply (41) and then send it to the first contactor (414); The sixth power module (47) is used to take voltage from the second output of the power supply (41) and then send it to the second contactor (415); The control and protection device (3) is used to send opening and closing commands to the first contactor (414) and the second contactor (415) through the trigger circuit (112).

6. A fault current limiter as described in claim 4, characterized in that, The second type of capacitor (4132) includes a first capacitor (41321) and a second capacitor (41322), wherein: The first capacitor (41321) and the second capacitor (41322) are connected in series. The first capacitor (41321) is connected to the first type of capacitor (4131). The output voltage of the second capacitor (41322) is used as the bus voltage signal, and the bus voltage signal is sent to the control and protection device (3).

7. A fault current limiter as described in claim 4, characterized in that, The power supply (41) also includes a leakage current acquisition CT (418), which is used to acquire the leakage current flowing through the CVT (413) and output voltage as a bus voltage signal, which is sent to the control and protection device (3).

8. A fault current limiter as described in claim 4, characterized in that, It also includes a high-potential platform (5), the current limiting module (1), the first measuring CT (2), and the power supply system (4) are arranged on the high-potential platform (5), and the control and protection device (3) is at ground potential.

9. A control method for a fault current limiter, characterized in that, The fault current limiter includes a control and protection device (3) and a power supply (41). The power supply (41) includes a first contactor (414) and a second contactor (415), and the power supply (41) includes a first output and a second output. The control method includes: The voltage of the first output, the second output, and the bus is detected by the control and protection device (3); If the control and protection device (3) determines that the first output has no voltage and the second output has voltage, it opens the first contactor (414) and warns that the first output is short-circuited; If the control and protection device (3) determines that there is no voltage in the second output and there is voltage in the first output, it opens the second contactor (415) and warns that the second output is short-circuited; If the control and protection device (3) determines that there is no voltage in the first output, the second output, and the bus, the first contactor (414) and the second contactor (415) will not operate.

10. The control method for a fault current limiter as described in claim 9, characterized in that, When the fault current limiter monitors the bus voltage, the control method further includes: The control and protection device (3) determines that there is no voltage in the first output and the second output, but there is voltage in the bus. The first contactor (414) is opened, and the control and protection device (3) determines that there is no voltage in the second output; The second contactor (415) is opened and the first contactor (414) is closed, and the control and protection device (3) determines that there is no voltage in the first output; Control the second contactor (415) to close, and warn that the input side of the first contactor (414) and the second contactor (415) are short-circuited simultaneously or the output side is short-circuited simultaneously.

11. The control method for a fault current limiter as described in claim 9, characterized in that, When the fault current limiter does not monitor the bus voltage, the control method further includes: The control and protection device (3) determines that there is no voltage in both the first output and the second output; The first contactor (414) is opened, and the control and protection device (3) determines that there is no voltage in the second output; The second contactor (415) is opened and the first contactor (414) is closed, and the control and protection device (3) determines that there is no voltage in the first output; Control the second contactor (415) to close, and warn that the input side of the first contactor (414) and the second contactor (415) are short-circuited simultaneously or the output side is short-circuited simultaneously.

12. The control method for a fault current limiter as described in claim 10 or 11, characterized in that, The control method further includes: When the first contactor (414) is opened, the control and protection device (3) determines that there is voltage in the second output and warns that the output side of the first contactor (414) is short-circuited.

13. The control method for a fault current limiter as described in claim 12, characterized in that, The control method further includes: When the second contactor (415) opens and the first contactor (414) closes, the control and protection device (3) determines that there is voltage in the first output and warns that the output side of the second contactor (415) is short-circuited.

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