CN110460028A - A device and method for limiting short-circuit fault current of power grid - Google Patents

Abstract

The invention relates to a device and method for limiting the short-circuit fault current of a power grid, comprising: a first isolation switch, a series reactor, a capacitor bank, a second isolation switch, a bypass circuit breaker, a lightning arrester, a damping reactor, a power electronic solid state switch and bypass isolation switch; the first isolation switch, the series reactor, the capacitor bank and the second isolation switch are connected in series in sequence; the damping reactor is connected in series with the power electronic firmware switch; the damping reactor and The series branch formed by the power electronic firmware switch, the bypass circuit breaker and the arrester are all connected in parallel at both ends of the capacitor bank; the first isolation switch, the series reactor, the capacitor bank and the second isolation switch form the series branch Both ends are connected with a bypass isolation switch; the device provided by the invention is connected to the neutral point side of the grid transformer, which can effectively limit the short-circuit current when the grid short-circuit fault occurs, and ensure the safe operation of the grid.

Description

A device and method for limiting short-circuit fault current of power grid

technical field

The invention relates to the field of power system automation, in particular to a device and method for limiting the short-circuit fault current of a power grid.

Background technique

With the rapid development of the power system, the system capacity of each voltage level of the power grid is getting older and larger, and the 500kV and 220kV grid structures are increasingly strengthened. Especially in the economically developed coastal areas, the distance between 500kV substations has been reduced to 30 ~ 60km, and the power supply capacity has increased. The reduction of line impedance causes the grid short-circuit fault current to exceed the standard more and more seriously. When the grid short-circuit current exceeds 50kA, it not only tests the breaking capacity of the transmission line circuit breaker, but also affects the stability of the transformer winding structure. At present, the maximum short-circuit current breaking capacity of the 500kV transmission line circuit breaker is only 63kA, and the maximum short-circuit current breaking capacity of the 220kV transmission line circuit breaker is only 50kA. The current has exceeded this value. The high-voltage circuit breaker forcibly breaking the short-circuit current exceeding its breaking capacity may cause the circuit breaker to explode, which will seriously affect the safety of power grid operation. The current countermeasures are mainly to adjust the operation mode through power grid dispatch, open the electromagnetic ring network to make the power grid open-loop operation or install series reactors in the transmission line, but these methods limit the flexibility, safety and reliability of the power grid operation. Reduced transmission capacity of transmission lines. Excessive short-circuit current has become one of the factors that troubles the safe operation of the power grid and limits the development of the power grid.

At present, although various technologies for limiting the short-circuit current of the power grid have been carried out, including superconducting technology, non-superconducting technology, magnetic saturable reactor, neutral point series small reactance, etc., but the effect is not satisfactory and has not been widely promoted. The Fault Current Limiter (FCL) needs to present zero impedance or tiny impedance during normal operation, and the impedance increases rapidly when a short-circuit fault occurs in the grid to limit the short-circuit current peak and reduce the short-circuit current. FCL devices must be fast (<3-5ms), large capacity, reliable and have a small footprint.

In the prior art, the technical research on limiting the short-circuit fault current of the power system, especially the ultra-high voltage transmission network, has a long history, and the technical route mainly includes the following categories:

1) Current limiting reactor

That is, a current limiting reactor is connected in series on the transmission line or a small reactor is connected in series at the neutral point of the transformer. This is a method widely adopted by the power grid to limit short-circuit current, and has the characteristics of low cost and high reliability. However, the high-voltage current-limiting reactor will reduce the stability margin of the system and reduce the transmission capacity of the system, while the small reactor in series with the neutral point of the transformer can only limit the short-circuit current of the single-phase grounding fault of the power grid, and there is no limit for the two-phase or three-phase grounding fault. flow effect.

2) Resonant type current limiter Resonant type current limiter is a technical solution for current limiting through the power frequency resonance principle of capacitance and reactance, including series resonance type current limiter and parallel resonance type current limiter.

The series resonant current limiter has the characteristic of outputting zero impedance in series resonance at the power frequency through the capacitance and reactance. When the grid is short-circuited, the capacitor is quickly bypassed, and the short-circuit current is limited by the series reactance. The parallel resonant current limiter controls the reactor through a thyristor when a short-circuit fault occurs in the power grid to form a power-frequency parallel resonance of capacitance and reactance to limit the short-circuit current. The resonant current limiter is connected in series in the high-voltage transmission line, which requires high ground insulation, occupies a large area, and has a high cost. It only restricts the transmission line where it is located, so it is rarely used.

3) Magnetic saturation type current limiter

The output reactance of the iron core reactor is small in the deep saturation state of the iron core, and the reactance value increases when it exits the saturation state. After the control system detects the grid fault state, the excitation current of the iron core is controlled to change the output reactance of the iron core reactor, which can limit the short-circuit fault. current. Due to the large loss of the iron core reactor, the time for the iron core to enter and exit the saturation state is not fast enough, and the cost of applying to the ultra-high voltage power grid is high, so it is not widely used in the power grid.

4) Superconducting current limiter

Based on the characteristics of superconducting materials, the resistance of the line is close to zero in the superconducting critical state, and the short-circuit current is greater than the supercritical current when the fault occurs. The device quickly quenches to form a high resistance to limit the short-circuit current. This scheme currently relies heavily on the properties of superconducting materials, and there are reports of engineering applications abroad, but it is not yet mature in China.

5) High voltage current limiter

It is also a method to limit or disconnect the short-circuit current when the short-circuit fault current occurs through the fuse, such as the high arc voltage current limiter, etc., but it can only interrupt the short-circuit current at one time, and cannot realize the reclosing. limitation.

No matter which of the above technical routes, there are certain defects. In terms of engineering practice, series harmonic current limiters and magnetic saturation current limiters have been applied in 500kV power grids, but due to various reasons such as cost, land occupation, loss and reliability, they have not been widely promoted in power grids .

SUMMARY OF THE INVENTION

In view of the deficiencies of the prior art, the purpose of the present invention is to provide a device and method for limiting the short-circuit fault current of the grid. The device provided by the present invention is connected to the neutral point side of the grid transformer, which can effectively limit the short-circuit current when the grid short-circuit fault occurs. , to ensure the safe operation of the power grid.

The purpose of this invention is to adopt following technical scheme to realize:

A device for limiting short-circuit fault current in a power grid, the improvement is that the device comprises: a first isolation switch, a series reactor, a capacitor bank, a second isolation switch, a bypass circuit breaker, a lightning arrester, and a damping reactor , Power electronic solid state switch and bypass isolation switch;

The first isolation switch, the series reactor, the capacitor bank and the second isolation switch are connected in series in sequence;

the damping reactor is connected in series with the power electronic firmware switch;

The series branch composed of the damping reactor and the power electronic firmware switch, the bypass circuit breaker and the arrester are all connected in parallel at both ends of the capacitor bank;

The first isolation switch, the series reactor, the capacitor bank and the second isolation switch form a series branch, and both ends of the series branch are connected with the bypass isolation switch.

Preferably, the type of the arrester is a metal oxide arrester.

Preferably, the series reactor and the damping reactor are both oil-immersed iron-core reactors, the impedance range of the series reactor is 10-20 ohms, and the impedance range of the damping reactor is 2-5 ohms ohm.

Preferably, the capacitance value of the capacitor bank ranges from 318uf to 159uf.

Preferably, the power electronic solid state switch includes: a thyristor valve with an average on-state current of 5000A and an instantaneous inrush current of 90kA, or an IGBT valve with an average on-state current of 5000A and an instantaneous inrush current of 90kA.

Further, the thyristor valve is composed of a plurality of thyristor valves connected in series;

The thyristor series valve is composed of a series branch composed of a resistor and a capacitor and two parallel anti-parallel thyristors.

Further, the IGBT valve is composed of a plurality of IGBT valves connected in series;

The IGBT series valve is composed of a first diode, a second diode, a third diode, a fourth diode and an IGBT;

The cathode of the first diode is connected to the cathode of the second diode, the anode of the second diode is connected to the anode of the fourth diode, and the cathode of the fourth diode is connected to the third diode The cathode of the diode is connected, and the anode of the third diode is connected with the anode of the first diode;

the collector of the IGBT is connected to the connection point between the first diode and the second diode;

The emitter of the IGBT is connected to the connection point between the third diode and the fourth diode.

Preferably, one of the devices is provided between the neutral point and the ground point of each phase transformer of the power system.

Preferably, one of the devices is provided between the neutral point and the ground point of each phase transformer of the power system.

Further, a connection point between the series branch composed of the first isolation switch, the series reactor, the capacitor bank and the second isolation switch in the device and the bypass isolation switch is neutral with each phase transformer of the power grid. The other connection point between the series branch composed of the first isolation switch, the series reactor, the capacitor bank and the second isolation switch in the device and the bypass isolation switch is connected to the grounding point.

A method for limiting grid short-circuit fault current of the device for limiting grid short-circuit fault current is improved in that the method comprises:

Disconnecting the bypass isolation switch, when a single-phase/three-phase-to-ground or phase-to-phase short-circuit fault occurs in the power grid, the power electronic solid-state switch is triggered to conduct through a trigger circuit, and the bypass circuit breaker is closed;

After the bypass circuit breaker is closed, stop triggering the power electronic solid state switch;

After the grid resumes normal operation, the bypass circuit breaker is opened.

Compared with the closest prior art, the present invention has the following beneficial effects:

The device provided by the invention has the characteristics of simple structure, low operating voltage, low cost and small footprint, and is convenient for the expansion and reconstruction of 500kV and 220kV substations. Its design advantages are as follows:

1) The present invention bypasses the capacitor bank in the series resonant circuit through the power electronic solid state switch, and the response time is fast, only 2-3ms, which can quickly suppress the short fault current of the power grid.

2) In the present invention, the device is connected in series with the neutral point of the primary winding of the 500kV and 220kV transformers. During normal operation of the power grid, since the impedance is zero, it has no influence on the operation of the transformer, and because the neutral point of the transformer is grounded, the voltage level of the device is low. The requirements for ground insulation are not high, the cost is low, and the floor area is small, which is convenient for the transformation of existing transformers in 500kV and 220kV substations.

3) The present invention connects the device in series with the neutral point of the primary winding of the 500kV and 220kV transformers, and has a suppressing effect on the short-circuit fault current of all 500kV and 220kV transmission lines connected to the high-voltage side of the transformer. The device can effectively suppress the short-circuit fault current of the 500kV and 220kV transmission lines of the power grid in a region, instead of installing one set on each transmission line, which greatly reduces the cost and improves the use efficiency.

4) The present invention can suppress single-phase-to-ground short-circuit fault current, three-phase-to-ground short-circuit fault current, and two-phase short-circuit fault current of the power grid.

5) Since the capacitor/reactor is connected in series in the primary winding of the transformer, the present invention has a significant effect on suppressing the DC component of the neutral point flowing into the transformer winding, and can eliminate the bias phenomenon of the DC winding of the 500kV and 220kV transformers.

Description of drawings

1 is a schematic structural diagram of a device for limiting short-circuit fault current in a power grid provided by the present invention;

2 is a schematic structural diagram of a thyristor valve composed of a plurality of thyristor series valves in series in an embodiment of the present invention;

3 is a schematic structural diagram of an IGBT valve composed of a plurality of IGBT series valves in series in an embodiment of the present invention;

4 is a schematic structural diagram of the device of the present invention respectively provided between the neutral point and the ground point of each phase transformer of the power system in an embodiment of the present invention;

5 is a schematic structural diagram of the device of the present invention provided between the neutral point and the ground point of each phase transformer of the power system in an embodiment of the present invention;

Among them, 1 is bypass circuit breaker, 2 is isolation switch (with ground knife), 3 is series reactor, 4 is capacitor bank, 5 is MOV, 6 is damping reactor, 7 is thyristor valve, and 8 is bypass Isolation knife switch, 9 is the control system, 10 is the trigger circuit, and 11 is the current transformer.

Detailed ways

The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

In order to make the purposes, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments These are some embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

The invention provides a device for limiting the short-circuit fault current of the power grid. The capacitor/reactor and the power electronic solid-state switch of series resonance are installed on the neutral point side of the grid transformer grounding, and the power electronic solid-state switch is immediately triggered when a short-circuit fault occurs in the power grid. It is turned on, and the reactor is quickly inserted into the transformer winding circuit to effectively suppress the rapid rise of the short-circuit current, and its action response time can reach 2-3ms. When the transformer is in normal operation, since the capacitor/reactor is in series resonance state at the 50Hz power frequency, the AC reactance and the AC capacitive reactance completely cancel each other, the total impedance value is basically zero, the impedance value of the transformer grounding resistance remains unchanged, and the transformer will not be raised. The voltage of the neutral point will not affect the normal operation of the transformer;

Specifically, a device for limiting the short-circuit fault current of a power grid provided by the present invention, as shown in FIG. 1 , includes:

First isolation switch, series reactor, capacitor bank, second isolation switch, bypass circuit breaker, arrester, damping reactor, power electronic solid state switch and bypass isolation switch;

The first isolation switch, the series reactor, the capacitor bank and the second isolation switch are connected in series in sequence;

the damping reactor is connected in series with the power electronic firmware switch;

The series branch composed of the damping reactor and the power electronic firmware switch, the bypass circuit breaker and the arrester are all connected in parallel at both ends of the capacitor bank;

The first isolation switch, the series reactor, the capacitor bank and the second isolation switch form a series branch, and both ends of the series branch are connected with the bypass isolation switch.

Among them, in order to prevent the power frequency overvoltage at both ends of the capacitor from breaking down the capacitor bank at the moment of the grid short-circuit fault, a metal oxide arrester (MOV) can be installed at both ends of the capacitor to limit the transient overvoltage.

The types of the series reactor and the damping reactor of the present invention are both oil-immersed iron core reactors, the impedance range of the series reactor is 10-20 ohms, and the impedance range of the damping reactor is 2-5 ohms.

Both the series reactor and the damping reactor are oil-immersed iron core reactors, the impedance range of the series reactor is 10-20 ohms, and the impedance range of the damping reactor is 2-5 ohms.

The capacitance value of the capacitor bank ranges from 318uf to 159uf, which can be composed of multiple power capacitors in series and parallel. In order to prevent capacitor failures, the capacitor bank adopts bridge wiring to detect and protect the capacitor bank through the unbalanced current of the capacitor bank.

The power electronic solid state switch adopts a thyristor valve with an average on-state current of 5000A and an instantaneous inrush current of 90kA or an IGBT valve with an average on-state current of 5000A and an instantaneous inrush current of 90kA.

As shown in Figure 2, the thyristor valve is composed of a plurality of thyristor valves connected in series;

The thyristor series valve is composed of a series branch composed of a resistor and a capacitor and two parallel anti-parallel thyristors.

Alternatively, as shown in FIG. 3 , the IGBT valve is composed of a plurality of IGBT valves connected in series;

The IGBT series valve is composed of a first diode, a second diode, a third diode, a fourth diode and an IGBT;

The cathode of the first diode is connected to the cathode of the second diode, the anode of the second diode is connected to the anode of the fourth diode, and the cathode of the fourth diode is connected to the third diode The cathode of the diode is connected, and the anode of the third diode is connected with the anode of the first diode;

the collector of the IGBT is connected to the connection point between the first diode and the second diode;

The emitter of the IGBT is connected to the connection point between the third diode and the fourth diode.

In the embodiment provided by the present invention, a device of the present invention is respectively provided between the neutral point and the ground point of each phase transformer of the power system, and the device is connected in series with the neutral point of each phase and the low voltage of the primary winding of the 500kV or 220kV transformer of the power system. Between the terminals, one set of each phase is connected in series, a total of 3 sets, and the three-phase neutral point connection and grounding are realized at the other end of the device, as shown in Figure 4, wherein the power electronic solid state switch is a thyristor as an example. When three-phase-to-ground short-circuit, single-phase-to-ground short-circuit or phase-to-phase short-circuit fault occurs in the 500kV and 220kV transmission lines of the power grid, the control system detects a sudden increase in the short-circuit current of the transmission line, and triggers the power electronic solid-state switch within 2-3ms to make the neutral point of the transformer. The impedance to ground increases instantaneously, which greatly reduces the short-circuit current. When the faulty line is cut off by the line high-voltage circuit breaker or disappears, the power electronic solid-state switch stops triggering, and the device quickly restores the state of zero external output impedance.

In the embodiment provided by the present invention, a device of the present invention is provided between the neutral point and the ground point of each phase transformer of the power system, and the device is connected in series between the three-phase neutral point and the ground point of the 500kV or 220kV transformer of the power system , only one set of three-phase series is connected in series, one end of the device is connected to the neutral point of the transformer and the other end is directly grounded, as shown in Figure 5, wherein the power electronic solid state switch is a thyristor as an example. When a single-phase-to-ground short-circuit fault occurs in the 500kV and 220kV transmission lines of the power grid, the control system detects a sudden increase in the short-circuit current of the transmission line, and triggers the power electronic solid-state switch within 2-3ms, so that the transformer neutral point-to-ground impedance increases instantaneously, which can greatly increase the Reduce the single-phase short-circuit current. When the faulty line is cut off by the circuit breaker or disappears, the power electronic solid-state switch stops triggering, and the device quickly restores the state of zero external output impedance.

In the above two connection modes, the device of the present invention is installed at the neutral point of the 500kV or 220kV transformer. Since the external impedance of the device is zero during normal operation of the power grid, the voltage drop across the device is zero. Since the neutral point of the 550kV and 220kV transformers is directly grounded, the potential of the device to the ground is also zero. Only when there is a short-circuit fault in the power grid, since the two ends of the capacitor are short-circuited by the power electronic solid-state switch, the reactor will withstand a high instantaneous power frequency overvoltage, but will not exceed the 500kV or 220kV transformer neutral point bushing. Frequency overvoltage withstand value. The device of the invention has lower requirements for ground insulation when the power grid is in normal operation, so the land occupation and cost are greatly reduced compared with those connected to high-voltage transmission lines.

Further, a connection point between the series branch composed of the first isolation switch, the series reactor, the capacitor bank and the second isolation switch in the device and the bypass isolation switch is neutral with each phase transformer of the power grid. The other connection point between the series branch composed of the first isolation switch, the series reactor, the capacitor bank and the second isolation switch in the device and the bypass isolation switch is connected to the grounding point.

The present invention also provides a method for limiting grid short-circuit fault current based on the device for limiting grid short-circuit fault current, the method comprising:

Disconnecting the bypass isolation switch, when a single-phase/three-phase-to-ground or phase-to-phase short-circuit fault occurs in the power grid, the power electronic solid-state switch is triggered to conduct through a trigger circuit, and the bypass circuit breaker is closed;

After the bypass circuit breaker is closed, stop triggering the power electronic solid state switch;

After the grid resumes normal operation, the bypass circuit breaker is opened.

Based on the above solution, in the application scenario shown in Figure 1, the specific implementation process is as follows:

(1) Device put-in process: Before the device is put in, the bypass isolation switch 8 is in a closed state, and the bypass circuit breaker 1 is in an open state. The isolation switch 2 on both sides of the device is first opened from the closed state, and the isolation switch 2 is then closed from the open state. After all the equipments are ready, the control system 9 remote-controls the bypass isolation knife gate 8 to open from the closed state, and the device is put into operation.

(2) Device operation process: After the device is put into operation, the external output impedance is zero, which does not affect the operation of the power grid. The control system 9 can monitor the working state of the thyristor valve 7 in real time. When a single-phase/three-phase-to-ground or phase-to-phase short-circuit fault occurs in the power grid, the grid current increases sharply, the voltage at both ends of the capacitor bank 4 rises, and the MOV5 connected in parallel at both ends acts immediately to suppress the rapid rise of the voltage. The control system 9 operates within 2-3ms After the grid fault is detected, the thyristor valve 7 is quickly triggered through the trigger circuit 10, so that the capacitor bank 4 is quickly bypassed through the damping reactor 6, and the command to close the bypass circuit breaker 1 is issued at the same time, and the bypass circuit is opened after 100ms. The reactor 1 is closed, the control system 9 stops triggering the thyristor valve 7, the reactor 3 is inserted into the faulted grid, and the short-circuit fault current is successfully limited. After a short-circuit fault occurs in the power grid, the relay protection device will remove the faulty line, and the power grid will resume normal operation immediately. is in a disconnected state, and the device is put into operation again.

(3) Device exit process: the device needs to be out of operation during maintenance. First, the control system 9 issues an instruction to close the bypass isolation knife gate 8, the bypass isolation knife gate 8 is turned from the open state to the closed state, and then the isolation knives at both ends of the device are disconnected. Gate 2, close the ground isolation knife gate 2, and the device is out of operation.

The technical scheme provided by the invention has the characteristics of simple device structure, low operating voltage, low cost and small footprint, and is convenient for the expansion and reconstruction of 500kV and 220kV substations. Its design advantages are as follows:

1) The present invention bypasses the capacitor bank in the series resonant circuit through the power electronic solid state switch, and the response time is fast, only 2-3ms, which can quickly suppress the short fault current of the power grid.

2) In the present invention, the device is connected in series with the neutral point of the primary winding of the 500kV and 220kV transformers. During normal operation of the power grid, since the impedance is zero, it has no influence on the operation of the transformer, and because the neutral point of the transformer is grounded, the voltage level of the device is low. The requirements for ground insulation are not high, the cost is low, and the floor area is small, which is convenient for the transformation of existing transformers in 500kV and 220kV substations.

3) The present invention connects the device in series with the neutral point of the primary winding of the 500kV and 220kV transformers, and has a suppressing effect on the short-circuit fault current of all 500kV and 220kV transmission lines connected to the high-voltage side of the transformer. The device can effectively suppress the short-circuit fault current of the 500kV and 220kV transmission lines of the power grid in a region, instead of installing one set on each transmission line, which greatly reduces the cost and improves the use efficiency.

4) The present invention can suppress single-phase-to-ground short-circuit fault current, three-phase-to-ground short-circuit fault current, and two-phase short-circuit fault current of the power grid.

5) Since the capacitor/reactor is connected in series in the primary winding of the transformer, the present invention has a significant effect on suppressing the DC component of the neutral point flowing into the transformer winding, and can eliminate the bias phenomenon of the DC winding of the 500kV and 220kV transformers.

As will be appreciated by those skilled in the art, the embodiments of the present application may be provided as a method, a system, or a computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) having computer-usable program code embodied therein.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the present application. It will be understood that each flow and/or block in the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to the processor of a general purpose computer, special purpose computer, embedded processor or other programmable data processing device to produce a machine such that the instructions executed by the processor of the computer or other programmable data processing device produce Means for implementing the functions specified in a flow or flow of a flowchart and/or a block or blocks of a block diagram.

These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory result in an article of manufacture comprising instruction means, the instructions The apparatus implements the functions specified in the flow or flow of the flowcharts and/or the block or blocks of the block diagrams.

These computer program instructions can also be loaded on a computer or other programmable data processing device to cause a series of operational steps to be performed on the computer or other programmable device to produce a computer-implemented process such that The instructions provide steps for implementing the functions specified in the flow or blocks of the flowcharts and/or the block or blocks of the block diagrams.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: the present invention can still be Modifications or equivalent replacements are made to the specific embodiments of the present invention, and any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention shall be included within the protection scope of the claims of the present invention.

Claims (11)

1. a kind of device for limiting short circuit malfunction electric current, which is characterized in that described device includes: the first isolation switch, string Join reactor, capacitor group, the second isolation switch, bypass breaker, arrester, damping reactor, power electronics solid-state switch With bypass isolation switch；

First isolation switch, current-limiting reactor, capacitor group and the second isolation switch are sequentially connected in series；

The damping reactor and power electronics firmware switch are connected in series；

The series arm of the damping reactor and power electronics firmware switch composition, bypass breaker and arrester are in parallel At capacitor group both ends；

First isolation switch, current-limiting reactor, capacitor group and the second isolation switch composition series arm two are terminated with side Road isolation switch.

2. device as described in claim 1, which is characterized in that the type of the arrester is metal oxide arrester.

3. device as described in claim 1, which is characterized in that the type of the current-limiting reactor and damping reactor is oil Immersion iron core reactor, the impedance ranges of the current-limiting reactor are 10~20 ohm, the impedance ranges of the damping reactor It is 2~5 ohm.

4. device as described in claim 1, which is characterized in that the capacitance range of the capacitor group is 318uf~159uf.

5. device as described in claim 1, which is characterized in that the power electronics solid-state switch includes: mean on state current The IGBT valve of 5000A, the thyristor valve for the 90kA that instantaneously shoves or mean on state current 5000A, the 90kA that instantaneously shoves.

6. device as claimed in claim 5, which is characterized in that the thyristor valve is by multiple Thyristors in series valve connection groups At；

The thyristor of series arm and two reverse parallel connections that the Thyristors in series valve is made of resistance and capacitor composes in parallel.

7. device as claimed in claim 5, which is characterized in that the IGBT valve is made of the connection of multiple IGBT series valves；

The IGBT series valve is made of first diode, the second diode, third diode, the 4th diode and IGBT；

The cathode of the first diode is connect with the cathode of the second diode, the anode of second diode and the four or two pole The anode of pipe connects, and the cathode of the 4th diode is connect with the cathode of third diode, the anode of the third diode It is connect with the anode of first diode；

Tie point connection between the collector and first diode and the second diode of the IGBT；

Tie point connection between the emitter and third diode and the 4th diode of the IGBT.

8. device as described in claim 1, which is characterized in that divide between each phase transformer neutral point of electric system and grounding point It She You not a described device.

9. device as described in claim 1, which is characterized in that set between each phase transformer neutral point of electric system and grounding point There is a described device.

10. device as claimed in claim 8 or 9, which is characterized in that the first isolation switch, series reactance in described device A tie point and power grid between device, the series arm of capacitor group and the second isolation switch composition and bypass isolation switch is each Phase transformer neutral point connects, the first isolation switch, current-limiting reactor, capacitor group and the second isolation switch in described device Another tie point between the series arm and bypass isolation switch of composition is connect with grounding point.

11. a kind of limitation power grid of the device based on the described in any item limitation short circuit malfunction electric currents of claim 1-9 is short The method of road fault current, which is characterized in that the described method includes:

The bypass isolation switch is disconnected, when single-phase/three-phase occurs for power grid over the ground or when phase fault, passes through triggering route The power electronics solid-state switch conducting is triggered, the bypass breaker is closed；

After the bypass breaker closure, stop triggering the power electronics solid-state switch；

After power system restoration operates normally, the bypass breaker is disconnected.