CN100527561C - Short circuit fault current limiter - Google Patents

Abstract

A short-circuit fault current limiter, in particular to a fault current limiter for transmission and distribution networks. It is characterized in that on the basis of the existing bridge-type short-circuit fault current limiter, the bridge arm of the rectification bridge is composed of a parallel circuit of a controllable solid-state switch tube and a current-limiting resistor connected in series, and then connected in series with a diode. The invention realizes common current limiting of the inductor and the resistor, not only can limit the peak value of the fault current, but also can limit the steady state value of the fault current. The invention organically combines the controllable solid-state switch tube and the current-limiting resistor, reduces the manufacturing cost of the current limiter, improves the stability and reliability of the system, has strong current-limiting ability, has little influence on the line, and can improve the power grid Power quality and stability, safety and reliability of HV or EHV transmission grid systems.

Description

A short circuit fault current limiter

technical field

The invention relates to a short-circuit fault current limiter, in particular to a fault current limiter for transmission and distribution networks.

Background technique

With the rapid development of the national economy, the society's demand for electricity continues to increase, which drives the continuous development of the power system. The capacity of single machines and power plants, the capacity of substations, and the load of cities and industrial centers continue to increase, which makes the interconnection of power systems , the level of short-circuit current in the power grid at all levels is increasing continuously, and the destructiveness of short-circuit faults to the power system and its connected electrical equipment is also increasing. Moreover, while the demand for electric energy is increasing day by day, people also put forward higher requirements for power quality, power supply reliability and security. However, the transient stability of large power grids is more prominent, and one of the most important reasons is that conventional power technology lacks effective short-circuit fault current limiting technology. At present, circuit breakers are widely used in the world to break the short-circuit current at full capacity. Since the level of short-circuit current is directly related to the capacity of the system, when the rated breaking current level of the circuit breaker is certain, using the full-scale breaking short-circuit current will The growth of the capacity of the power system is limited, and the circuit breaker is expensive and its price rises rapidly with the increase of its rated breaking current. This problem will become more serious as the capacity and size of the grid increases.

The short-circuit fault current limiter provides a new idea for solving this problem. For example, the solid-state short-circuit fault current limiter can limit the fault current to a lower level by quickly changing the impedance and inductance parameters of the fault grid when it detects a short-circuit fault, so as to protect the power equipment and ensure that the existing open circuit Cut off the short-circuit fault under the premise of interrupting ability of the device. The Chinese patent application No. 200410003459.8 proposes a short-circuit fault current limiter, as shown in Figure 1(a): the circuit is mainly composed of a diode forming a rectifier bridge, a current-limiting reactor connected in series with the diode, and a super-current limiter for limiting the fault current. Conductive DC reactor and other components. During normal operation, the current limiter has no voltage drop on the grid and almost no power consumption; once a short-circuit fault occurs in the system, when the grid current reaches the current of the DC reactor, the superconducting DC reactor will automatically be connected in series to the line and bridge. The reactors jointly limit the rising rate of the fault current, thereby limiting the fault current to a certain level, so as to ensure that the circuit breaker cuts off the fault current in time. In this current limiter topology, the current limiting capability of the current limiter is improved by connecting the diode in series with the reactor. A higher level of fault current interruption operation can be achieved by using a short-circuit fault current limiter in conjunction with a circuit breaker with a lower tripping level. However, this current limiter is essentially a reactor current limiter, which can only limit the peak value of the fault current, but cannot limit the steady-state value of the fault current. A short-circuit fault current limiter proposed by the Chinese patent application number 200510007537.1 is shown in Fig. 1(b). Current-limiting inductance, the invention connects a parallel loop of a current-limiting resistor R in series with a current-limiting inductance L (general inductance or superconducting inductance) and a solid-state switch (GTO, IGBT, IGCT, etc.), and connects a current-limiting inductance L in parallel Diode Ds (in anti-parallel connection) and resistor Rs are connected in series with the freewheeling circuit to form a short-circuit fault current limiter, in which the bridge is composed of diodes, and the bias power supply is canceled at the same time. In the short-circuit fault current limiter of the invention, the solid-state switch (GTO, IGBT, IGCT, etc.) connected in parallel with the current-limiting resistor is composed of multiple solid-state switches in series, so as to meet the high-voltage operation requirements of the current limiter. This invention proposes the direct series connection of GTO, IGBT, etc. and the direct series connection of GTO, IGBT, etc. and IGCT switch structure to meet the needs of high voltage, and designs the freewheeling circuit of the superconducting current-limiting inductor, thus forming a short circuit of various structures Fault current limiter topology. The invention essentially realizes the common current limitation of resistance and reactance, which can not only limit the peak value of fault current, but also limit the steady state value of fault current. However, as the short-circuit fault capacity of the power grid increases, the current-limiting resistance of the current limiter is technically difficult to realize.

Contents of the invention

In order to overcome the shortcomings of the prior art, the present invention proposes a short-circuit fault current limiter for transmission and distribution networks, which can limit both the peak value of the fault current and the steady-state value of the fault current. The invention organically combines the current-limiting resistor and the solid-state switch tube, so that the short-circuit fault current limiter of the invention has simple structure, low manufacturing and operating costs, and is more suitable for engineering.

The technical scheme adopted in the present invention:

The present invention includes that the existing fault current limiter is composed of a rectifier bridge composed of a diode, a controllable solid-state switch tube and a current-limiting resistor and a current-limiting inductance. Connected to the DC side. On the bridge arm of the rectifier bridge, the current limiting resistor and the controllable solid-state switch (GTO, IGBT, SCR, etc.) stream network.

In the short-circuit fault current limiter of the present invention, the switch control and current-limiting network on the bridge arm can be connected in parallel with the controllable solid-state switch tube (GTO, IGBT, SCR, etc.) by changing the resistance value of the current-limiting resistor. The number of loops is used to meet the needs of the high-voltage operation of the current limiter.

The present invention can be a single-phase short-circuit fault current limiter structure, or a single-phase short-circuit fault current limiter structure with a coupling transformer, or three single-phase short-circuit fault current limiters applied to a three-phase system To form a three-phase short-circuit fault current limiter structure, three single-phase short-circuit fault current limiters with coupling transformers can be applied to a three-phase system to form a three-phase fault current limiter structure, or an optimized The fault current limiter structure of the three-phase system and the optimized three-phase system fault current limiter structure with a coupling transformer.

Main advantage of the present invention:

1. The present invention can not only limit the peak value of the fault current, but also limit the steady state value of the fault current. The present invention adopts the joint current limiting mode of reactance and resistance, improves the current limiting capacity of the current limiter, and thus obtains a better current limiting effect than the existing short circuit fault current limiter.

2. The series and parallel structure of the controllable solid-state switch tube, the current-limiting resistor and the diode used in the present invention not only facilitates the realization of high-voltage current limiting, but also avoids the impact of high voltage on the controllable solid-state switch tube and prolongs its use. life and improve the reliability of the current limiter.

3. In the present invention, the current-limiting resistor is designed on the bridge arm of the rectifier bridge and directly connected in parallel with the controllable solid-state switch tube, which simplifies the buffer circuit of the controllable solid-state switch tube, avoids the impact of large current due to short-circuit faults, and is beneficial to the current-limiting resistor Excellent heat dissipation design, easy to achieve large capacity.

4. The control method of the current limiter in the present invention is simple. The current limiter needs periodic control, and the algorithm is complicated. However, the present invention only needs to turn off the parallel controllable solid state switch tube of the current limiting resistor when a fault is detected.

5. The short-circuit fault current limiter of the present invention can cooperate with reclosing action. After the fault disappears, the freewheeling circuit provided by the current-limiting resistor can quickly reduce the current of the current-limiting inductor to the normal current value, so as to achieve the purpose of quickly cooperating with reclosing. If the current-limiting inductor of the present invention adopts superconducting inductors, it does not need superconducting inductor quenching to limit the fault current, and the current limiting resistors are used to limit the current. Similarly, it is also very suitable for the needs of reclosing.

6. The present invention eliminates the bias power supply, forms a passive short-circuit fault current limiter, and ensures that the current limiter does not cause line current waveform distortion in a steady state. If the inductance in the circuit of the present invention adopts superconducting inductance, heat loss can be reduced, and the influence of the current limiter on the circuit can be further reduced. At the same time, the cancellation of the bias power supply reduces the cost of the current limiter and improves the reliability of the current limiter.

Description of drawings

Fig. 1 (a), Fig. 1 (b) are the circuit schematic diagrams of existing short-circuit fault current limiter;

Fig. 2 is the circuit schematic diagram of embodiment 1 of the present invention;

Fig. 3 is the circuit schematic diagram of embodiment 2 of the present invention;

Fig. 4 is the circuit schematic diagram of embodiment 3 of the present invention;

Fig. 5 is the circuit schematic diagram of embodiment 4 of the present invention;

6 is a schematic diagram of the circuit principle of Embodiment 5 of the present invention;

7 is a schematic diagram of the circuit principle of Embodiment 6 of the present invention;

Fig. 8 is a schematic diagram of the circuit principle of Embodiment 7 of the present invention.

Detailed ways

The present invention will be further described below in conjunction with accompanying drawing and specific embodiment:

As shown in FIG. 2 , Embodiment 1 of the present invention is a single-phase short-circuit fault current limiter. The 1st-1st controllable solid-state switch tube K11, the 1st-2nd controllable solid-state switch tube K12, ..., the 1-Nth controllable solid-state switch tube K1n are respectively connected with the 1-1st current limiting resistor R11, the 1st-2nd controllable solid-state switch tube K1n Current limiting resistors R12, ..., 1-N current limiting resistors R1n are connected in parallel, and then connected in series with 1-1 diode D11, 1-2 diode D12, ..., 1-M diode D1m in series, 2- 1 Controllable solid-state switch tube K21, 2-2nd controllable solid-state switch tube K22, ..., 2-N controllable solid-state switch tube K2n respectively connected with 2-1st current-limiting resistor R21, 2-2nd current-limiting resistor R22, ..., the 2-N current limiting resistor R2n are connected in parallel, and then connected in series with the 2-1 diode D21, the 2-2 diode D22, ..., the 2-M diode D2m in series, the 3-1 is controllable The solid-state switch tube K31, the 3-2nd controllable solid-state switch tube K32, ..., the 3-N controllable solid-state switch tube K3n are respectively connected with the 3-1st current-limiting resistor R31, the 3-2nd current-limiting resistor R32, ... ..., the 3-N current-limiting resistor R3n is connected in parallel, and then connected in series with the 3-1 diode D31, the 3-2 diode D32, ..., the 3-M diode D3m in series, the 4-1 controllable solid-state switch tube K41, the 4-2th controllable solid-state switch tube K42, ..., the 4-N controllable solid-state switch tube K4n are respectively connected with the 4-1st current-limiting resistor R41, the 4-2nd current-limiting resistor R42, ..., the 4th-Nth controllable solid-state switch tube K4n, respectively. The 4-N current-limiting resistor R4n is connected in parallel, and then connected in series with the 4-1 diode D41, the 4-2 diode D42, ..., and the 4-M diode D4m to form four bridge arms of the rectifier bridge. The parameters of the controllable solid-state switching tubes of the bridge arms are the same, the parameters of the current limiting resistors are the same, and the parameters of the diodes are the same. On this basis, the current-limiting inductance L (ordinary inductance or superconducting inductance) is connected to the DC terminal of the rectifier bridge to form a single-phase short-circuit fault current limiter. SW is the circuit breaker, Vac is the line AC power, and R is the load.

When the line is in normal state, the controllable solid state switches K11, K12, ..., K1n, K21, K22, ..., K2n, K31, K32, ..., K3n, K41, K42, ..., K4n are triggered by high level , and diodes D11, D12, ..., D1m, D21, D22, ..., D2m, D31, D32, ..., D3m, D41, D42, ..., D4m are alternately in forward bias conduction or freewheeling state, the power grid Constantly charge the current-limiting inductor L to make it equivalent to a constant current source. Current limiting resistors R11, R12, ..., R1n, R21, R22, ..., R2n, R31, R32, ..., R3n, R41, R42, ..., R4n are turned on due to the conduction of the corresponding controllable solid-state switches Short circuit, so that the voltage drop across the current limiter is approximately zero, and has no effect on the line.

When a short-circuit fault occurs in the power grid, if the fault current is a positive half-cycle current, when the instantaneous value of the fault current is equal to the current value of the current-limiting inductance L, the fault current will pass through D1m—…——D12—D11—K1n—…——K12— K11—L—D4m—……—D42—D41—K4n——…—K42—K41 is turned on, the current limiting inductor L is automatically connected in series to the circuit to limit the current, K21, K22,..., K2n, D21, D22,... , D2m, K31, K32, ..., K3n, D31, D32, ..., D3m are in cut-off state due to reverse bias. If the fault current is a negative half-cycle current, when the instantaneous value of the fault current is equal to the current value of the current-limiting inductance L, the fault current will pass through D3m—…——D32—D31—K3n—…——K32—K31—L—D2m—… …—D22—D21—K2n—……—K22—K21 is turned on, the current-limiting inductor L is automatically connected in series to the circuit to limit the current, K11, K12,..., K1n, D11, D12,..., D1m, K41, K42, ..., K4n, D41, D42, ..., D4m are in cut-off state due to reverse bias. —Once the system detects a short-circuit fault, all switches on the bridge arm will be triggered by a low level and forced to turn off. At this time, if the fault current is a positive half-cycle current, the fault current will pass through D1m—…——D12—D11—R1n—…——R12—R11—L—D4m—…——D42—D41—R4n—…——R42 —R41 is turned on, which realizes the common current limiting of the resistor and the inductor, and the diodes D21, D22, ..., D2n, D31, D32, ..., D3n are in the cut-off state due to reverse bias. If the fault current is a negative half-cycle current, the fault current will pass through D3m—…——D32—D31—R3n——…—R32—R31—L—D2m—…——D22—D21—R2n—…——R22—R21 Through, the common current limiting of the resistance and the inductance is realized, and the diodes D11, D12, ..., D1n, D41, D42, ..., D4n are in the cut-off state due to reverse bias. During this current limiting process, each current limiting resistor only passes a half-wave current, which greatly reduces the design capacity of the heat dissipation system of the current limiting resistor. Once the short-circuit fault disappears and the system detects the fault recovery signal, the trigger levels of all the controllable solid-state switch tubes on the bridge arm become high at the same time. The current limiter returns to the normal state, and cooperates with the system to realize the reclosing operation. From the above analysis, it can be seen that the joint current limiting of the resistor and the inductor can not only limit the peak value of the fault current, but also limit the steady-state value of the fault current, thus more effectively limiting the impact of the fault current on the current limiter and the line.

As shown in FIG. 3 , Embodiment 3 of the present invention is a single-phase short-circuit fault current limiter with a coupling transformer. The structure of the single-phase short-circuit fault current limiter is the same as that of the specific embodiment 1. TR is the coupling transformer of the current limiter, SW is the circuit breaker, Vac is the AC power supply, and R is the load. The single-phase short-circuit fault current limiter is connected in parallel on the secondary side of the coupling transformer TR to form a single-phase short-circuit fault current limiter with a coupling transformer; for high-voltage or ultra-high-voltage transformers, the power of the current limiter can be reduced through transformer coupling. The rated voltage and insulation level of the device, thereby reducing the cost of the current limiter. The working principle of the single-phase short-circuit fault current limiter with coupling transformer is the same as that of the single-phase short-circuit fault current limiter of the present invention.

As shown in Figure 4, the specific embodiment 4 of the present invention is that three single-phase short-circuit fault current limiters are respectively connected in series with a, b, c three-phase AC power supply Va, Vb, Vc, a, b, c three-phase circuit breaker A three-phase fault current limiter composed between the switch SW and the a, b, c three-phase load R1oad. The structures of the three single-phase short-circuit fault current limiters are the same as those in Embodiment 1. The working principle of each phase of the three-phase short-circuit fault current limiter is the same as that of the single-phase short-circuit fault current limiter of the present invention. The three single-phase short-circuit fault current limiters work independently in the three-phase circuit, which is beneficial to realize the flexible control of the current limiters and improve the reliability of the system.

As shown in Figure 5, the specific embodiment 4 of the present invention is that three single-phase short-circuit fault current limiters are respectively connected in parallel on the secondary side of a, b, c three-phase coupling transformer Tr, and a, b, c three-phase coupling transformer Tr The primary sides of the a, b, c three-phase AC power supply Va, Vb, Vc and a, b, c three-phase load R1oad are respectively connected in series to form a three-phase short-circuit fault current limiter with coupled transformer. The structure of the single-phase short-circuit fault current limiter with coupling is the same as that of the specific embodiment 3. The working principle of each phase of the three-phase short-circuit fault current limiter with coupling transformer is the same as that of the single-phase short-circuit fault current limiter with coupling of the present invention. The short-circuit fault current limiter has the advantages of a single-phase short-circuit fault current limiter and a short-circuit fault current limiter with a coupling transformer.

As shown in FIG. 6 , Embodiment 5 of the present invention is an optimized three-phase short-circuit fault current limiter. The optimized three-phase short-circuit fault current limiter consists of a three-phase rectifier bridge and a current-limiting inductor L (ordinary inductor or superconducting inductor). The 1st-1st controllable solid-state switch tube K11, the 1st-2nd controllable solid-state switch tube K12, ..., the 1-Nth controllable solid-state switch tube K1n are respectively connected with the 1-1st current limiting resistor R11, the 1st-2nd controllable solid-state switch tube K1n Current limiting resistors R12, ..., 1-N current limiting resistors R1n are connected in parallel, and then connected in series with 1-1 diode D11, 1-2 diode D12, ..., 1-M diode D1m in series, 2- 1 Controllable solid-state switch tube K21, 2-2nd controllable solid-state switch tube K22, ..., 2-N controllable solid-state switch tube K2n respectively connected with 2-1st current-limiting resistor R21, 2-2nd current-limiting resistor R22, ..., the 2-N current limiting resistor R2n are connected in parallel, and then connected in series with the 2-1 diode D21, the 2-2 diode D22, ..., the 2-M diode D2m in series, the 3-1 is controllable The solid-state switch tube K31, the 3-2nd controllable solid-state switch tube K32, ..., the 3-N controllable solid-state switch tube K3n are respectively connected with the 3-1st current-limiting resistor R31, the 3-2nd current-limiting resistor R32, ... ..., the 3-N current-limiting resistor R3n is connected in parallel, and then connected in series with the 3-1 diode D11, the 3-2 diode D32, ..., the 3-M diode D3m in series, the 4-1 controllable solid-state switch tube K41, the 4-2th controllable solid-state switch tube K42, ..., the 4-N controllable solid-state switch tube K4n are respectively connected with the 4-1st current-limiting resistor R41, the 4-2nd current-limiting resistor R42, ..., the 4th-Nth controllable solid-state switch tube K4n, respectively. The 4-N current-limiting resistor R4n is connected in parallel, and then connected in series with the 4-1 diode D41, the 4-2 diode D42, ..., the 4-M diode D4m, the 5-1 controllable solid-state switch tube K51, the 5-1 diode 5-2 controllable solid-state switch tubes K52, ..., 5-N controllable solid-state switch tubes K5n and 5-1st current-limiting resistor R51, 5-2nd current-limiting resistor R52, ..., 5-Nth The current-limiting resistor R5n is connected in parallel, and then connected in series with the 5-1 diode D11, the 5-2 diode D52, ..., the 5-M diode D5m, the 6-1 controllable solid-state switch tube K61, the 6-2 The controllable solid-state switch tubes K62, ..., the 6-N controllable solid-state switch tube K6n are respectively connected with the 6-1st current-limiting resistor R61, the 6-2nd current-limiting resistor R62, ..., the 6-N-th current-limiting resistor R6n is connected in parallel, and then connected in series with the 6-1 diode D61, the 6-2 diode D62, ..., the 6-M diode D6m in series, the 7-1 controllable solid-state switch tube K71, the 7-2 controllable solid-state The switch tubes K72, ..., the 7-N controllable solid-state switch tube K7n are respectively connected in parallel with the 7-1st current-limiting resistor R71, the 7-2nd current-limiting resistor R72, ..., the 7-N-th current-limiting resistor R7n, The circuit connected in series with the 7-1st diode D71, the 7th-2nd diode D72, ..., the 7th-M diode D7m, the 8th-1st controllable solid-state switch tube K81, the 8th-2nd controllable solid-state switch tube K82 , ..., the 8-N controllable solid-state switch tube K8n is respectively connected with the 8-1 current limiting resistor R81, The 8-2nd current-limiting resistor R82, ..., the 8-Nth current-limiting resistor R8n are connected in parallel, and then connected in series with the 8-1st diode D81, the 8-2nd diode D82, ..., the 8th-M diode D8m in series , forming each bridge arm of the rectifier bridge respectively. The common connection point of the 1-M diode D1m, the 4-1 controllable solid-state switch K41 and the 4-1 current limiting resistor R41, the 3-M diode D3m, the 6-1 controllable solid-state switch K61 and the 4-1st current limiting resistor R41 6-1 The common connection point of the current limiting resistor R61, the common connection point of the 5-M diode D5m, the 6-1st controllable solid-state switch K61 and the 6-1st current limiting resistor R61, respectively connected to a, b, c One end of the three-phase power supply Va, Vb, and Vc is connected, and the other end of the three-phase power supply Va, Vb, and Vc of a, b, and c are respectively connected to the three-phase circuit breaker SW of a, b, and c, and the three-phase load Rload of a, b, and c is phased. in series. The common connection point of the three-phase load Rload of a, b, c connected in series is connected with the common connection point of the 7-M diode D7m, the 8-1 controllable solid-state switch K81 and the 8-1 current limiting resistor R81. The parameters of the controllable solid-state switching tubes constituting each bridge arm are the same, the parameters of the current limiting resistors are the same, and the parameters of the diodes are the same.

When the line is in a normal state, each controllable solid-state switch is triggered by a high level, so they are alternately in the forward-bias conduction or freewheeling state, and the grid continuously charges the current-limiting inductor L to make it equivalent to a constant current source. The current-limiting resistors are all short-circuited due to the conduction of the corresponding controllable solid-state switches, so that the voltage drop at both ends of the current limiter is approximately zero and has no effect on the circuit.

When a short-circuit fault occurs in the power grid (take A-phase circuit as an example), if the fault current is a positive half-cycle current, when the instantaneous value of the fault current is equal to the current value of the current-limiting inductance L, the fault current will pass through D1m—…——D12—D11 —K1n—……—K12—K11—L—D8m—……—D82—D81—K8n——…—K82—K81 conduction, the current limiting inductor L is automatically connected in series to the circuit to limit the current, K21, K22,……, K2n, D21, D22, ..., D2m, K71, K72, ..., K7n, D71, D72, ..., D7m are in cut-off state due to reverse bias. If the fault current is a negative half-cycle current, when the instantaneous value of the fault current is equal to the current value of the current-limiting inductance L, the fault current will pass through D7m—…——D72—D71—K7n—…——K72—K71—L—D2m—… …—D22—D21—K2n—……—K22—K21 is turned on, the current-limiting inductor L is automatically connected in series to the circuit to limit the current, K11, K12,..., K1n, D11, D12,..., D1m, K81, K82, ..., K8n, D81, D82, ..., D8m are in cut-off state due to reverse bias. —Once the system detects a short-circuit fault, all switches on the bridge arm will be triggered by a low level and forced to turn off. At this time, if the fault current is a positive half-cycle current, the fault current will pass through D1m—…——D12—D11—R1n—…——R12—R11—L—D8m—…——D82—D81—R8n—…——R82 —R81 is turned on, which realizes the common current limiting of the resistor and the inductor, and the diodes D21, D22, ..., D2n, D71, D72, ..., D7n are in the cut-off state due to reverse bias. If the fault current is a negative half-cycle current, the fault current will pass through D7m—…——D72—D71—R7n——…—R72—R71—L—D2m—…——D22—D21—R2n—…——R22—R21 Through, the common current limiting of the resistance and the inductance is realized, and the diodes D11, D12, ..., D1n, D81, D82, ..., D8n are in the cut-off state due to reverse bias. During this current limiting process, each current limiting resistor only passes a half-wave current, which greatly reduces the design capacity of the heat dissipation system of the current limiting resistor. Once the short-circuit fault disappears and the system detects the fault recovery signal, the trigger levels of all the controllable solid-state switch tubes on the bridge arm become high at the same time. The current limiter returns to the normal state, and cooperates with the system to realize the reclosing operation. From the above analysis, it can be seen that the joint current limiting of the resistor and the inductor can not only limit the peak value of the fault current, but also limit the steady-state value of the fault current, thus more effectively limiting the impact of the fault current on the current limiter and the line. By adopting optimization measures, the structure of the fault current limiter of the present invention is simpler, thereby reducing the manufacturing cost of the system.

As shown in FIG. 7 , Embodiment 6 of the present invention is an optimized short-circuit fault current limiter for a three-phase system with a coupling transformer. The structure of the optimized three-phase short-circuit fault current limiter is the same as that of Embodiment 5. TR is the coupling transformer of the current limiter, SW is the circuit breaker, Va, Vb, Vc are the three-phase AC power supply, and R is the equivalent resistance of the three-phase load. The optimized three-phase short-circuit fault current limiter is connected in parallel to the secondary side of the a, b, c three-phase coupling transformer TR, and the primary side of the a, b, c three-phase coupling transformer Tr is connected in series with the a, b, c three-phase AC Between the power supply Va, Vb, Vc and the a, b, c three-phase load Rload, an optimized three-phase system short-circuit fault current limiter with a coupling transformer is formed. For high-voltage or ultra-high-voltage transformers, through transformer coupling, the rated voltage and insulation level of power devices in the current limiter can be reduced, thereby reducing the cost of the current limiter. The optimized three-phase system short-circuit fault current limiter with coupling transformer works on the same principle as the optimized three-phase short-circuit fault current limiter.

As shown in FIG. 8 , Embodiment 7 of the present invention is an asymmetrical single-phase short-circuit fault current limiter. The 1st-1st controllable solid-state switch tube K11, the 1st-2nd controllable solid-state switch tube K12, ..., the 1-Nth controllable solid-state switch tube K1n are respectively connected with the 1-1st current limiting resistor R11, the 1st-2nd controllable solid-state switch tube K1n Current limiting resistors R12, ..., 1-N current limiting resistors R1n are connected in parallel, and then connected in series with 1-1 diode D11, 1-2 diode D12, ..., 1-M diode D1m in series, 2- 1 Diode D21, the 2nd-2nd diode D22, ..., the 2nd-S diode D2s series circuit, the 3-1st controllable solid-state switch K31, the 3-2nd controllable solid-state switch K32, ..., the 3rd The 3-N controllable solid-state switch tube K3n is respectively connected in parallel with the 3-1st current-limiting resistor R31, the 3-2nd current-limiting resistor R32, ..., the 3-Nth current-limiting resistor R3n, and then connected with the 3-1st diode D31 , 3-2 diodes D32, ..., 3-M diodes D3m connected in series, 4-1 diodes D41, 4-2 diodes D42, ..., 4-S diodes D4s connected in series to form a rectifier For the four bridge arms of the bridge, the parameters of the controllable solid-state switching tubes constituting each bridge arm are the same, the parameters of the current limiting resistors are the same, and the parameters of the diodes are the same. On this basis, the current-limiting inductance L (ordinary inductance or superconducting inductance) is connected to the DC terminal of the rectifier bridge to form a single-phase short-circuit fault current limiter.

When the line is in normal state, the controllable solid-state switch tubes K11, K12, ..., K1n, K31, K32, ..., K3n are triggered by high level, and diodes D11, D12, ..., D1m, D21, D22, ... , D2s, D31, D32,..., D3m, D41, D42,..., D4s are alternately in the positive bias conduction or freewheeling state, and the grid continuously charges the current-limiting inductor L to make it equivalent to a constant current source. The current-limiting resistors R11, R12, ..., R1n, R31, R32, ..., R3n are short-circuited due to the conduction of the corresponding controllable solid-state switch, so that the voltage drop at both ends of the current limiter is approximately zero, and there is no damage to the line Influence.

When a short-circuit fault occurs in the power grid, if the fault current is a positive half-cycle current, when the instantaneous value of the fault current is equal to the current value of the current-limiting inductance L, the fault current will pass through D1m—…——D12—D11—K1n—…——K12— K11—L—D4s—……—D42—D41 is turned on, the current limiting inductor L is automatically connected in series to the circuit to limit the current, D21, D22,..., D2s, K31, K32,..., K3n, D31, D32,... , D3m is in cut-off state due to reverse bias. If the fault current is a negative half-cycle current, when the instantaneous value of the fault current is equal to the current value of the current-limiting inductance L, the fault current will pass through D3m—…——D32—D31—K3n—…——K32—K31—L—D2m—… …—D22—D21 is turned on, the current-limiting inductance L is automatically connected in series to the circuit to limit the current, and K11, K12, ..., K1n, D11, D12, ..., D1m, D41, D42, ..., D4s are in the state due to reverse bias Deadline. Once the system detects a short-circuit fault, all switches on the bridge arm will be triggered by a low level and forced to turn off. At this time, if the fault current is a positive half-cycle current, the fault current will be conducted through D1m—…——D12—D11—R1n——…—R12—R11—L—D4m—…——D42—D41, realizing the resistance and The inductors jointly limit the current, and the diodes D21, D22, ..., D2s, D31, D32, ..., D3m are in a cut-off state due to reverse bias. If the fault current is a negative half-cycle current, the fault current will be conducted through D3m—…——D32—D31—R3n—…—R32—R31—L—D2s—…——D22—D21, realizing the common limitation of resistance and inductance flow, diodes D11, D12, ..., D1m, D41, D42, ..., D4s are in a cut-off state due to reverse bias. During this current limiting process, each current limiting resistor only passes a half-wave current, which greatly reduces the design capacity of the heat dissipation system of the current limiting resistor. Once the short-circuit fault disappears and the system detects the fault recovery signal, the trigger levels of all the controllable solid-state switch tubes on the bridge arm become high at the same time. The current limiter returns to the normal state, and cooperates with the system to realize the reclosing operation. From the above analysis, it can be seen that the joint current limiting of the resistor and the inductor can not only limit the peak value of the fault current, but also limit the steady-state value of the fault current, thus more effectively limiting the impact of the fault current on the current limiter and the line.

The test was completed in a three-phase 380V AC system. The current limiting inductor L is a high temperature superconducting inductor, L=10mH. Parameters m=n=3, s=6, the resistance value of each current limiting resistor R1=1Ω, the power diode is MDF150A, the controllable solid-state switch is DGT304, the steady-state fault current can be limited when there is no short-circuit fault current limiter About 40% of the fault current. If the resistance value R1 of the current-limiting resistor is 2Ω, the steady-state fault current can be limited to about 15% of the fault current when there is no short-circuit fault current limiter.

Claims (9)

1. A short-circuit fault current limiter, comprising a single-phase rectifier bridge and a current-limiting inductance (L) made up of a diode, a controllable solid-state switch tube and a current-limiting resistor, characterized in that on the bridge arm of the single-phase rectifier bridge, The current-limiting resistor and the controllable solid-state switch tube are connected in parallel, multiple parallel circuits are connected in series, and then connected in series with the diode; the four bridge arms of the single-phase rectifier bridge are respectively composed of the first-1 controllable solid-state switch tube (K11), the first -2 controllable solid-state switch tubes (K12), ..., the 1-N controllable solid-state switch tubes (K1n) are respectively connected with the 1-1st current limiting resistor (R11), the 1st-2nd current limiting resistor (R12), ..., the 1-N current-limiting resistor (R1n) is connected in parallel, and then connected in series with the 1-1 diode (D11), the 1-2 diode (D12), ..., the 1-M diode (D1m) in series, The 2-1st controllable solid-state switch tube (K21), the 2-2nd controllable solid-state switch tube (K22), ..., the 2-N controllable solid-state switch tube (K2n) and the 2-1st current-limiting resistor respectively (R21), the 2-2 current limiting resistor (R22), ..., the 2-N current limiting resistor (R2n) in parallel, and then with the 2-1 diode (D21), the 2-2 diode (D22), ..., the 2nd-M diode (D2m) series circuit, the 3-1st controllable solid-state switch (K31), the 3-2nd controllable solid-state switch (K32), ..., the 3-N controllable The solid-state switching tube (K3n) is respectively connected in parallel with the 3-1 current limiting resistor (R31), the 3-2 current limiting resistor (R32), ..., the 3-N current limiting resistor (R3n), and then connected with the 3- 1 diode (D31), the 3-2 diode (D32), ..., the 3-M diode (D3m) series circuit, the 4-1 controllable solid-state switch tube (K41), the 4-2 controllable solid-state The switch tube (K42), ..., the 4-N controllable solid-state switch tube (K4n) are respectively connected with the 4-1 current limiting resistor (R41), the 4-2 current limiting resistor (R42), ..., the 4th -N current-limiting resistor (R4n) is connected in parallel, and then forms a loop in series with the 4-1 diode (D41), the 4-2 diode (D42),..., the 4-M diode (D4m); the current-limiting inductance ( L) is connected to the DC end of the single-phase rectifier bridge. 2. According to the short-circuit fault current limiter according to claim 1, it is characterized in that the controllable solid-state switching tubes forming the current limiter are GTO, IGBT or IGCT, and the parameters of each controllable solid-state switching tube are the same, and the parameters of each diode are the same , the parameters of each current limiting resistor are the same. 3. The short-circuit fault current limiter according to claim 1, characterized in that the 1-M diode (D1m), the 2-1 controllable solid-state switch (K21) and the 2-1 The common connection point of the current limiting resistor (R21) is connected to the AC power supply (Vac), the 3-M diode (D3m), the 4-1 controllable solid-state switch tube (K41) and the 4-1 current limiting resistor (R41) The common connection point of the circuit breaker (SW) is connected to one end of the circuit breaker (SW), and the other end of the circuit breaker (SW) is connected to the load (Rload) to form a single-phase short-circuit fault current limiter. 4. The short-circuit fault current limiter according to claim 3, characterized in that the single-phase short-circuit fault current limiter is connected in parallel to the secondary side of the coupling transformer (Tr), and the primary side of the coupling transformer (Tr) is connected in series Between the AC power supply (Vac) and the load (Rload), a single-phase short-circuit fault current limiter with coupled transformer is formed. 5. According to the short-circuit fault current limiter as claimed in claim 3, it is characterized in that the three single-phase short-circuit fault current limiters are respectively connected in series with a, b, and c three-phase AC power supplies (Va, Vb, Vc) , between the three-phase circuit breaker (SW) and the three-phase load (Rload), a three-phase short-circuit fault current limiter is formed. 6, according to the described short-circuit fault current limiter of claim 3, it is characterized in that three described single-phase short-circuit fault current limiters are connected in parallel respectively on the secondary side of a, b, c three-phase coupling transformer (Tr), a The primary side of the three-phase coupling transformer (Tr) of , b, c is respectively connected in series between the three-phase AC power supply (Va, Vb, Vc) of a, b, c and the three-phase load (Rload) of a, b, c to form a three-phase Phase short-circuit fault current limiter with coupled transformer. 7. The short-circuit fault current limiter according to any one of claims 1 to 3, characterized in that the four bridge arms of the rectifier bridge are respectively composed of the 1-1st controllable solid-state switch tube (K11), the 1-2nd The controllable solid-state switch tube (K12), ..., the 1-N controllable solid-state switch tube (K1n) are respectively connected with the 1-1st current limiting resistor (R11), the 1st-2nd current limiting resistor (R12), ... , the 1-N current limiting resistor (R1n) connected in parallel, and then connected in series with the 1-1 diode (D11), the 1-2 diode (D12), ..., the 1-M diode (D1m) in series, the 2nd -1 diode (D21), the 2-2 diode (D22), ..., the 2-S diode (D2s) series circuit, the 3-1 controllable solid-state switch tube (K31), the 3-2 controllable The solid-state switching tube (K32), ..., the 3-N controllable solid-state switching tube (K3n) are respectively connected with the 3-1st current limiting resistor (R31), the 3-2nd current limiting resistor (R32), ..., the 3rd The 3-N current limiting resistor (R3n) is connected in parallel, and then connected in series with the 3-1 diode (D31), the 3-2 diode (D32), ..., the 3-M diode (D3m), and the 4-1 The diode (D41), the 4th-2nd diode (D42), ..., the 4th-S diode (D4s) are connected in series to form an asymmetrical single-phase short-circuit fault current limiter. 8. A short-circuit fault current limiter, which is characterized by a three-phase short-circuit fault current limiter composed of a three-phase rectifier bridge and a current-limiting inductor (L), wherein each bridge arm of the three-phase rectifier bridge is composed of a 1-1 The controllable solid-state switch tube (K11), the 1st-2nd controllable solid-state switch tube (K12), ..., the 1st-N controllable solid-state switch tube (K1n) are respectively connected with the 1st-1st current-limiting resistor (R11), The 1-2 current limiting resistor (R12), ..., the 1-N current limiting resistor (R1n) are connected in parallel, and then connected with the 1-1 diode (D11), the 1-2 diode (D12), ..., the first 1-M diode (D1m) series circuit, the 2-1st controllable solid-state switch tube (K21), the 2-2nd controllable solid-state switch tube (K22), ..., the 2-N controllable solid-state switch tube ( K2n) are respectively connected in parallel with the 2-1 current limiting resistor (R21), the 2-2 current limiting resistor (R22), ..., the 2-N current limiting resistor (R2n), and then connected with the 2-1 diode (D21 ), the 2-2 diode (D22), ..., the 2-M diode (D2m) series circuit, the 3-1 controllable solid-state switch tube (K31), the 3-2 controllable solid-state switch tube (K32 ), ..., the 3-N controllable solid-state switch tube (K3n) and the 3-1 current limiting resistor (R31), the 3-2 current limiting resistor (R32), ..., the 3-N current limiting resistor The resistor (R3n) is connected in parallel, and then connected in series with the 3-1 diode (D11), the 3-2 diode (D32), ..., the 3-M diode (D3m), and the 4-1 controllable solid-state switch tube (K41), the 4-2 controllable solid-state switch tube (K42), ..., the 4-N controllable solid-state switch tube (K4n) are respectively connected with the 4-1 current-limiting resistor (R41), the 4-2 limit The flow resistance (R42), ..., the 4-N current limiting resistance (R4n) are connected in parallel, and then connected with the 4-1 diode (D41), the 4-2 diode (D42), ..., the 4-M diode ( D4m) in a series circuit, the 5-1st controllable solid-state switch tube (K51), the 5-2nd controllable solid-state switch tube (K52), ..., the 5-N controllable solid-state switch tube (K5n) and the 5th-N controllable solid-state switch tube (K5n) respectively 5-1 current-limiting resistor (R51), 5-2 current-limiting resistor (R52), ..., 5-N current-limiting resistor (R5n) in parallel, and then with 5-1 diode (D11), 5- 2 diodes (D52), ..., the 5th-M diode (D5m) in series loop, the 6-1st controllable solid-state switch tube (K61), the 6-2nd controllable solid-state switch tube (K62), ..., The 6-N controllable solid-state switch tube (K6n) is respectively connected in parallel with the 6-1 current limiting resistor (R61), the 6-2 current limiting resistor (R62), ..., the 6-N current limiting resistor (R6n) , and then the circuit connected in series with the 6-1 diode (D61), the 6-2 diode (D62), ..., the 6-M diode (D6m), the 7-1 controllable solid-state switch tube (K71), the 7-1 7-2 Controllable solid-state switch tube (K 72), ..., the 7-N controllable solid-state switch tube (K7n) and the 7-1 current limiting resistor (R71), the 7-2 current limiting resistor (R72), ..., the 7-N limiting resistor The current circuit resistor (R7n) is connected in parallel, and then connected in series with the 7-1 diode (D71), the 7-2 diode (D72), ..., the 7-M diode (D7m), the 8-1 controllable solid-state switch tube (K81), the 8-2 controllable solid-state switch tube (K82), ..., the 8-N controllable solid-state switch tube (K8n) and the 8-1 current limiting resistor (R81), the 8-2 The current limiting resistor (R82), ..., the 8-N current limiting resistor (R8n) are connected in parallel, and then connected with the 8-1 diode (D81), the 8-2 diode (D82), ..., the 8-M diode (D8m) is composed of a series circuit; the common connection point of the 1-M diode (D1m), the 4-1 controllable solid-state switch (K41) and the 4-1 current limiting resistor (R41), the 3-M diode (D3m), the common connection point of the 6-1st controllable solid-state switch tube (K61) and the 6-1st current limiting resistor (R61), the 5th-M diode (D5m), the 6th-1st controllable solid-state switch tube (K61) and the common connection point of the 6-1 current-limiting resistor (R61) are respectively connected to one end of a, b, c three-phase power supply (Va, Vb, Vc), and a, b, c three-phase power supply (Va, The other ends of Vb, Vc) are respectively connected in series with a, b, c three-phase circuit breaker (SW) and a, b, c three-phase load (Rload), and a, b, c three-phase load (Rload) is connected in series The common connection point is connected to the common connection point of the 7-M diode (D7m), the 8-1 controllable solid-state switch (K81) and the 8-1 current limiting resistor (R81). 9. The short-circuit fault current limiter according to claim 8, characterized in that it consists of three coupling transformers (Tr) and a three-phase short-circuit fault current limiter to form a three-phase fault current limiter with coupling transformers.

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