Energy storage type medium voltage switch test system and method

Abstract

The invention discloses an energy storage type medium-voltage switch test system, which comprises an energy storage power supply, a three-phase closing switch, a three-phase operating circuit breaker, an adjusting reactor, an adjusting resistor and a test object circuit breaker, and is characterized in that a three-phase alternating current output end of a generator is connected with a wiring port at one end of the three-phase closing switch; a wiring port at the other end of the three-phase closing switch is connected with a wiring port at one end of a three-phase operating circuit breaker, a wiring port at the other end of the three-phase operating circuit breaker is connected with a wiring port at one end of an adjusting reactor, and a wiring port at the other end of the adjusting reactor is connected with a wiring port at one end of an adjusting resistor. A wiring port at the other end of the adjusting resistor is connected to a wiring port at one end of the test object circuit breaker, and the wiring port at the other end of the test object circuit breaker is in short-circuit connection. According to the invention, the energy storage power supply completely replaces a short-circuit generator power supply, the 10 kV circuit breaker is turned on and off, the test device is completely disconnected from the mains supply in the test process, no impact is caused to a power grid, the operation is simple, the input scale is small, a matched voltage reduction station does not need to be built, and the operation and maintenance cost is low.

Description

Technical Field

[0001] The present invention relates to the technical field of electric power testing, and in particular to an energy storage type medium voltage switch testing system and method. Background Art

[0002] In recent years, medium-voltage switchgear has been severely damaged due to internal faults for various reasons, and some have even developed into accidents in which multiple sets of switchgear were burned at the same time. The arc short-circuit fault inside the switchgear may also affect the station DC system and develop into a system fault. These accidents that occur from time to time seriously threaten the safe and economical operation of the distribution system. Medium-voltage test short-circuit test The rated short-circuit closing current is a parameter that characterizes the closing current capacity of the circuit breaker. When the circuit breaker is connected to the circuit, there may be a short-circuit fault in the circuit. At this time, the circuit breaker will close a large short-circuit current. In this way, on the one hand, the electric force of the short-circuit current weakens the closing operation force, and on the other hand, the arc is generated due to the breakdown before the contacts are in contact, which may cause the contacts to weld, thereby causing damage to the circuit breaker.

[0003] The maximum peak current that the circuit breaker can reliably close is called the rated closing current. The rated closing current is equal to the dynamic stability current in value and is 2.55 times the rated breaking current, which means that the grid power supply or the short-circuit generator power supply must also withstand a large peak impact capacity, and a large capacity is required to complete the test. There are three main types of test power supplies for large-capacity test stations. One type of test power supply is mainly supplied directly by the substation to supply power to the short-circuit test transformer of the test station. The second type of test power supply is the test power supply of the short-circuit generator, which is mainly used to impact the short-circuit generator. The third type of test power supply is an oscillation circuit, which is mainly composed of capacitors, reactances and ignition trigger devices. The main principle is to discharge the charged capacitor to the reactance through the ignition trigger device to form an LC oscillation power supply.

[0004] However, the three existing power sources each have their own disadvantages. The network test station is actually subject to many restrictions of the power grid, and the test capacity is only the short-circuit capacity of the test station transformer, so it cannot provide a particularly large test capacity. At the same time, because the impact of the medium-voltage short-circuit test is relatively large and the fluctuations caused to the power grid are relatively large, there are also strong restrictions on the quality of power, test time, and number of tests. The disadvantage of the short-circuit generator is that the investment, operation, and maintenance are relatively complicated, there are many components, and variable frequency starting is required. The staffing requires the entire team, and regular shutdowns and maintenance are required. Once the generator has a minor problem, it may have to be inspected, and the cost of a short-circuit generator and the supporting civil engineering system requires hundreds of millions of funds. The oscillation circuit, because the charging capacitor cannot be charged wirelessly, due to the limitations of the capacitor and space and the influence of the voltage level, the capacity is limited, and the decay is also relatively fast. Summary of the invention

[0005] The purpose of the present invention is to provide an energy storage medium voltage switch test system and method. The present invention uses an energy storage power supply to replace the above three traditional power supply methods to design a medium voltage switch test system and method, thereby solving the problems existing in the above three power supplies during the medium voltage switch test.

[0006] To achieve this purpose, the energy storage medium voltage switch test system designed by the present invention is characterized in that it includes an energy storage power supply, a three-phase closing switch, a three-phase operating circuit breaker, an adjusting reactor, an adjusting resistor and a test circuit breaker, wherein the three-phase AC output end of the generator is connected to one wiring port of the three-phase closing switch, the other wiring port of the three-phase closing switch is connected to one wiring port of the three-phase operating circuit breaker, the other wiring port of the three-phase operating circuit breaker is connected to one wiring port of the adjusting reactor, the other wiring port of the adjusting reactor is connected to one wiring port of the adjusting resistor, the other wiring port of the adjusting resistor is connected to one wiring port of the test circuit breaker, and the other wiring port of the test circuit breaker is short-circuited.

[0007] A method for testing an energy storage medium voltage switch comprises the following steps:

[0008] Step 1: Calculate the preliminary resistance and reactance values ​​of the regulating reactor and regulating resistor according to the short-circuit current required to be tested by the circuit breaker under test;

[0009] Step 2: Use a vacuum circuit breaker to replace the test circuit breaker and connect it to the energy storage medium voltage switch test system. Apply the rated voltage of the test circuit breaker to the vacuum circuit breaker through the energy storage power supply. At the same time, adjust the resistance value and reactance value of the regulating reactor and the regulating resistor to the preliminary resistance value and reactance value of the regulating reactor and the regulating resistor calculated in step 1. At this time, the rated short-circuit current of the test circuit breaker is generated. The rated short-circuit current of the test circuit breaker is used to perform the breaking test of the vacuum circuit breaker. During the breaking test of the vacuum circuit breaker, adjust the parameters of the frequency modulation device and the capacitor, adjust the waveform that meets the standard transient recovery voltage, and record the actual resistance value and reactance value of the regulating reactor and the regulating resistor and the parameters of the frequency modulation device and the capacitor under the waveform;

[0010] Step 3: Connect the test circuit breaker to the energy storage medium voltage switch test system instead of the vacuum circuit breaker, control the three-phase closing switch to be in the disconnected state, and the three-phase operating circuit breaker to be in the closed state;

[0011] Step 4: According to the parameters of the frequency modulation device and capacitor under the waveform of the transient recovery voltage obtained by debugging in step 2, the frequency modulation device and the capacitor are switched on and off, and the waveform of the transient recovery voltage that meets the standard is adjusted when the test circuit breaker is connected to the energy storage medium voltage switch test system;

[0012] Step 5: In the energy storage power supply, the AC power supply is converted into a controllable DC power supply to charge the energy storage unit. When the charging voltage meets the medium voltage switch test requirements, the inverter unit operates to convert the DC power stored in the energy storage unit into a controllable square wave power output through SPWM pulse width modulation technology and series multi-level technology, and finally converts the square wave into a controllable AC power output through a sine wave filter;

[0013] Step 6: Close the three-phase closing switch, close the loop, and adjust the resistance and reactance values ​​of the regulating reactor and regulating resistor to the actual resistance and reactance values ​​of the regulating reactor and regulating resistor under the waveform of the standard transient recovery voltage. At this time, the energy storage medium voltage switch test system generates the required short-circuit current;

[0014] Step 7: Control the circuit breaker of the test product to open, and control the three-phase operating circuit breaker to open after the preset time;

[0015] Step 8: Record the transient recovery voltage and short-circuit current collected by the voltage divider U and the current divider I.

[0016] Beneficial effects of the present invention:

[0017] The present invention utilizes the above scheme to completely replace the short-circuit generator power supply with an energy storage power supply, and carries out the opening and closing of a 10kV circuit breaker. During the test, the power supply is completely disconnected from the mains, and there is no impact on the power grid. The operation is simple, the investment scale is small, and there is no need to build a supporting step-down station (the capacity required for the short-circuit test is very large, and the electric energy required for the test needs to be obtained from the high-voltage power grid. Directly obtaining the short-circuit test energy from the power grid line is equivalent to a short circuit in the system, which will seriously affect the quality of the electric energy and even affect the safety of the power grid. Therefore, when using the power grid for experiments, it is necessary to build a supporting step-down station to isolate the connection with the main grid to ensure that the short-circuit test does not affect the main grid power. The generator system also obtains the electric energy to drive the generator to rotate from the main grid, so a step-down station is also required for isolation), and the operation and maintenance cost is low.

[0018] Compared with the method of directly obtaining electric energy from the power grid, the present invention does not require the construction of a step-down station, does not require the operation and maintenance of the step-down station, requires little investment, and has no impact on the power grid; because a step-down station needs to be built and maintained, and the interference caused by the short circuit needs to be shielded, otherwise it will affect the power quality of the main grid.

[0019] Compared with the short-circuit generator, the present invention does not require generator operation and maintenance, is more convenient to use, has no operation and maintenance cost, and has low investment. Because the generator system is complex, including the traction motor, generator, variable frequency speed regulation, excitation, oil and water subsystems, operation and maintenance requires a lot of manpower, and the startup and shutdown takes a long time, which affects the test efficiency.

[0020] Compared with the oscillation circuit, the present invention occupies a smaller area and has higher equivalence. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the present invention;

[0022] Figure 2 It is a schematic diagram of the structure of the energy storage power supply in the present invention.

[0023] Among them, 1—energy storage power supply, 2—three-phase closing switch, 3—three-phase operating circuit breaker, 4—regulating reactor, 5—regulating resistor, 6—frequency modulation device, 7—capacitor, 8—test circuit breaker. DETAILED DESCRIPTION

[0024] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0025] like Figure 1 and 2 The energy storage medium voltage switch test system shown includes an energy storage power supply 1, a three-phase closing switch 2, a three-phase operating circuit breaker 3, an adjusting reactor 4, an adjusting resistor 5 and a test circuit breaker 8, wherein the three-phase AC output end of the generator 1 is connected to one end of the wiring port of the three-phase closing switch 2, the other end of the wiring port of the three-phase closing switch 2 is connected to one end of the wiring port of the three-phase operating circuit breaker 3, the other end of the wiring port of the three-phase operating circuit breaker 3 is connected to one end of the wiring port of the adjusting reactor 4, the other end of the wiring port of the adjusting reactor 4 is connected to one end of the wiring port of the adjusting resistor 5, the other end of the wiring port of the adjusting resistor 5 is connected to one end of the wiring port of the test circuit breaker 8, and the other end of the wiring port of the test circuit breaker 8 is short-circuited. The test circuit breaker 8 is a three-phase circuit breaker, one side of the three-phase circuit breaker is connected to the power supply, and the other side is short-circuited to form a short-circuit loop to verify the breaking capacity of the circuit breaker when encountering a rated short-circuit current.

[0026] In the above technical solution, the energy storage power supply 1 is used to provide the test power required for the breaking test of the test circuit breaker 8. The energy storage power supply can replace the traditional generator and substation solution, with a small investment scale and convenient operation and maintenance. During the test, the power supply from the power grid is disconnected, and there is no impact on the power grid.

[0027] In the above technical solution, the three-phase closing switch 2 is used to control whether the test current is connected to the test circuit breaker 8. Before the test, the closing switch is in a separate state. When the test is required, the closing switch is closed. At this time, the circuit is in a short-circuited state because one side of the test circuit breaker is in a short-circuited state, generating the required short-circuit current.

[0028] In the above technical solution, the three-phase closing switch 2 is used to close the energy storage medium voltage switch test system, and the three-phase operating circuit breaker 3 is used to disconnect the circuit after the test. The closing time of the closing switch is fast and the three-phase dispersion is low, so it is used for closing and only has the function of closing the short-circuit current, but not the ability to disconnect the short-circuit current. The operating circuit breaker can extinguish the arc and disconnect the short-circuit current. When the test circuit breaker 8 cannot disconnect, it serves as a protective device to cut off the circuit current.

[0029] In the above technical solution, the regulating reactor 4 and the regulating resistor 5 are respectively connected to each phase circuit, the regulating reactor 4 is used to adjust the required test current, and the regulating resistor 5 is used to adjust the peak factor of the test current. The total impedance value is calculated by adjusting the resistance value of the reactor L and the resistor R connected in series in the loop, and the effective value of the required test current is obtained by dividing the test voltage by the total impedance value. At the same time, the ratio of the reactor to the resistor determines the peak factor of the loop. The higher the impedance ratio, the greater the peak factor. In order to achieve the required effective value current and peak current, it is necessary to reasonably adjust the parameters of the reactor and the resistor.

[0030] The above technical solution also includes a frequency modulation device 6 and a capacitor 7, one end of each phase frequency modulation unit in the frequency modulation device 6 is respectively connected to the three-phase circuit between the other end wiring port of the regulating resistor 5 and the one end wiring port of the test circuit breaker 8, the other end of each phase frequency modulation unit in the frequency modulation device 6 is grounded, one end of each capacitor Cd in the capacitor 7 is respectively connected to the three-phase circuit between the other end wiring port of the regulating resistor 5 and the one end wiring port of the test circuit breaker 8, the other end of the capacitor 7 is grounded; the frequency modulation device is composed of a capacitor and a resistor, and is used to adjust the transient recovery voltage waveform required for the test;

[0031] Each phase frequency modulation unit in the frequency modulation device 6 includes a resistor Rs and a capacitor Cs, one end of the resistor Rs in each phase frequency modulation unit is connected to the other end of the adjustment resistor 5, the other end of the resistor Rs is connected to one end of the capacitor Cs, and the other end of the capacitor Cs in each phase frequency modulation unit is grounded; the capacitor and the frequency modulation device are used together to adjust the transient recovery voltage waveform that meets the standard requirements.

[0032] The resistor Rs is used to adjust the peak value of the transient recovery voltage generated by the test circuit breaker 8, the capacitor Cs is used to adjust the reference time of the transient recovery voltage generated by the test circuit breaker 8 (the time from the generation of the transient recovery voltage to the peak value of the transient recovery voltage), and the capacitor Cd is used to adjust the delay time of the transient recovery voltage generated by the test circuit breaker 8. The delay time reflects the influence of the rising rate of the transient recovery voltage in the first few microseconds on the arc extinction. The above scheme can generate the transient recovery voltage waveform required by the standard, which is used to assess whether the circuit breaker can withstand the transient recovery voltage required by the standard.

[0033] When the circuit breaker is disconnected, it will generate a transient recovery voltage higher than the rated voltage. The circuit breaker must withstand this voltage without breakdown to ensure that it does not reignite, otherwise the circuit breaker will fail to disconnect. The transient recovery voltage has detailed parameter requirements in the national standard GB1984 for high-voltage AC circuit breakers. The frequency modulation device and capacitor are equipped to adjust the transient recovery voltage that meets the requirements of the national standard GB1984 for high-voltage AC circuit breakers.

[0034] In the above technical solution, a voltage divider U and a shunt I are respectively connected in series in each phase circuit of the three-phase circuit between the other end connection port of the regulating resistor 5 and one end connection port of the test circuit breaker 8, the voltage divider U is used to measure the test voltage, and the shunt I is used to measure the test current.

[0035] In the above technical solution, the energy storage power supply 1 includes an input isolating switch, a DC charging unit, an energy storage unit, an inverter unit, a sine wave filter and a control unit. The input end of the input isolating switch is connected to the power supply network, the output end of the input isolating switch is connected to the input end of the DC charging unit, the output end of the DC charging unit is connected to the input end of the energy storage unit, the output end of the energy storage unit is connected to the input end of the inverter unit, the output end of the inverter unit is connected to the input end of the sine wave filter, and the output end of the sine wave filter is the three-phase AC output end of the energy storage power supply 1. The isolating switch control signal output end of the control unit is connected to the control signal input end of the input isolating switch, and the inverter control signal output end of the control unit is connected to the control signal input end of the inverter unit. The working process of controlling the inverter unit involves multiple components and steps, including the on-off switching of the switching power electronic thyristor, the generation of the modulation signal and the formation of the output voltage waveform. In the three-phase inverter circuit, the SPWM modulation technology is used to synchronously control three sets of SPWM modulation circuits to output three-phase AC. Since the SPWM waveform is composed of a square wave and contains more harmonic components, a sine filter is required to sinusoid the output waveform. The inverter unit generates a nearly sinusoidal output voltage by on-off control of electronic switches, and uses a sinusoidal filter to reduce harmonic components, thereby improving the quality and efficiency of the output voltage.

[0036] The sine filter is a bandpass filter. The function of the large-capacity energy storage filter is to pass the harmonic components of the inverter unit through the sine filter and output a standard sine wave that meets the national standard short-circuit test requirements (that is, the short-circuit power supply THD value should be less than 5%).

[0037] In the above technical solution, the DC charging unit is used to convert the input AC power into a controllable DC power to charge the energy storage unit. When the charging voltage meets the medium voltage switch test requirements, the inverter unit operates to convert the DC power stored in the energy storage unit into a controllable square wave power output through SPWM pulse width modulation technology and series multi-level technology, and finally converts the square wave into a controllable AC power output through a sine wave filter;

[0038] The control unit is used to send synchronous trigger signals to the disconnector and inverter unit respectively when the medium-voltage switch test starts, so that the disconnector and inverter unit start working synchronously when the medium-voltage switch test starts, trigger the energy storage power supply 1, and intervene in the medium-voltage switch test circuit to provide capacity support, so that the required short-circuit test voltage and current are released. The above design can realize the rapid release of energy of large-capacity power supply and quickly realize the release of rated voltage and rated short-circuit current.

[0039] In the above technical solution, the protection circuit of the three-phase test switch 7 is grounded through the protection resistor R1. When there is a problem with the test product, grounding through the resistor can reduce the grounding current and prevent excessive current from directly grounding.

[0040] A method for testing an energy storage medium voltage switch using the above system comprises the following steps:

[0041] Step 1: Calculate the preliminary resistance and reactance values ​​of the regulating reactor 4 and the regulating resistor 5 according to the short-circuit current to be tested by the test circuit breaker 8; the reactor and the resistor are a complete system composed of multiple devices connected in series, and each resistor and reactor is connected in parallel with an isolating switch. When the device needs to be connected, the isolating switch is separated, and the device is connected in series to the circuit; when it is not needed, the parallel switch is closed, and the device is connected in parallel and not connected to the circuit. For example, if a 10kV, 10kA short-circuit test is to be performed, the voltage of the energy storage power supply needs to be set to 10kv, and the square root of the sum of the squares of the resistance and inductance in the circuit is 1Ω, and the short-circuit current is 10kA at this time;

[0042] Step 2: Select a vacuum circuit breaker to replace the test circuit breaker 8 and connect it to the energy storage medium voltage switch test system. Apply the rated voltage of the test circuit breaker 8 to the vacuum circuit breaker through the energy storage power supply 1. At the same time, adjust the resistance value and reactance value of the regulating reactor 4 and the regulating resistor 5 to the preliminary resistance value and reactance value of the regulating reactor 4 and the regulating resistor 5 calculated in step 1. At this time, the rated short-circuit current of the test circuit breaker 8 is generated. The rated short-circuit current of the test circuit breaker 8 is used to perform the breaking test of the vacuum circuit breaker. During the breaking test of the vacuum circuit breaker, adjust the parameters of the frequency modulation device 6 and the capacitor 7, adjust the waveform that meets the standard transient recovery voltage, and record the actual resistance value and reactance value of the regulating reactor 4 and the regulating resistor 5 and the parameters of the frequency modulation device 6 and the capacitor 7 under the waveform;

[0043] Step 3: connect the test circuit breaker 8 to the energy storage medium voltage switch test system instead of the vacuum circuit breaker, control the three-phase closing switch 2 to be in the disconnected state, and the three-phase operating circuit breaker 3 to be in the closed state;

[0044] Step 4: According to the parameters of the frequency modulation device 6 and the capacitor 7 (peak value uc of the transient recovery voltage, reference time t3 and delay time td) under the waveform of the transient recovery voltage obtained by debugging in step 2, the frequency modulation device 6 and the capacitor 7 are switched on and off (the frequency modulation device and the capacitor are complete sets of devices, Rs is a number of resistors with different parameters connected in series, each resistor is connected in parallel with an isolating knife, the isolating knife is disconnected when it needs to be connected, and the isolating knife is closed when it is not connected. Cs and Cd are a number of capacitors connected in parallel.), and the waveform of the transient recovery voltage that meets the standard is adjusted when the test circuit breaker 8 is connected to the energy storage medium voltage switch test system;

[0045] Step 5: In the energy storage power supply 2, the AC power supply is converted into a controllable DC power supply to charge the energy storage unit. When the charging voltage meets the medium voltage switch test requirements (a 12kV circuit breaker in this embodiment has a voltage of ±5%), the inverter unit operates to convert the DC power stored in the energy storage unit into a controllable square wave power output through the SPWM pulse width modulation technology and the series multi-level technology, and finally converts the square wave into a controllable AC power output through a sine wave filter;

[0046] Step 6: Close the three-phase closing switch 2, close the loop, adjust the resistance value and reactance value of the regulating reactor 4 and the regulating resistor 5 to the actual resistance value and reactance value of the regulating reactor 4 and the regulating resistor 5 under the waveform of the standard transient recovery voltage, and then the energy storage medium voltage switch test system generates the required short-circuit current; this test is to verify whether the circuit breaker can be normally opened and closed under the rated short-circuit current. If the circuit breaker cannot open the short-circuit current, a major accident will occur in the system;

[0047] Step 7: Control the test circuit breaker 8 to open, and control the three-phase operating circuit breaker 3 to open after the preset time (0.3 seconds); after the test circuit breaker is disconnected, a transient recovery voltage will appear. After the transient recovery voltage phenomenon disappears, the power frequency recovery voltage will appear. The power frequency recovery voltage should be no less than 95% of the specified value and should be maintained for at least 0.3 seconds. Therefore, the operating circuit breaker should be opened again 0.3 seconds after the test circuit breaker is disconnected. If the test circuit breaker fails to open, the operating circuit breaker can cut off the system short-circuit current to ensure system safety. If the test circuit breaker does not open, the circuit breaker will basically explode, and the test product can be judged as unqualified and prohibited from entering the power grid;

[0048] Step 8: Record the transient recovery voltage and short-circuit current collected by the voltage divider U and the current divider I to determine whether they meet the national standard GB1984 for high-voltage AC circuit breakers.

[0049] The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

Claims

1. An energy storage medium voltage switch test system, characterized in that: The invention comprises an energy storage power source (1), a three-phase closing switch (2), a three-phase operating circuit breaker (3), an adjusting reactor (4), an adjusting resistor (5) and a test circuit breaker (8), wherein the three-phase AC output end of the generator (1) is connected to one wiring port of the three-phase closing switch (2), the other wiring port of the three-phase closing switch (2) is connected to one wiring port of the three-phase operating circuit breaker (3), the other wiring port of the three-phase operating circuit breaker (3) is connected to one wiring port of the adjusting reactor (4), the other wiring port of the adjusting reactor (4) is connected to one wiring port of the adjusting resistor (5), the other wiring port of the adjusting resistor (5) is connected to one wiring port of the test circuit breaker (8), and the other wiring port of the test circuit breaker (8) is short-circuited.

2. The energy storage medium voltage switch test system according to claim 1 is characterized in that: The energy storage power supply (1) is used to provide the test power required for the breaking test of the test circuit breaker (8).

3. The energy storage medium voltage switch test system according to claim 1 is characterized in that: The three-phase closing switch (2) is used to control whether the test current is connected to the test product circuit breaker (8).

4. The energy storage medium voltage switch test system according to claim 1 is characterized in that: The three-phase closing switch (2) is used for closing the energy storage type medium voltage switch test system, and the three-phase operating circuit breaker (3) is used for disconnecting the circuit after the test.

5. The energy storage medium voltage switch test system according to claim 1 is characterized in that: The regulating reactor (4) and the regulating resistor (5) are respectively connected to each phase circuit; the regulating reactor (4) is used to regulate the required test current, and the regulating resistor (5) is used to regulate the peak coefficient of the test current.

6. The energy storage medium voltage switch test system according to claim 1 is characterized in that: It also includes a frequency modulation device (6) and a capacitor (7), wherein one end of each phase frequency modulation unit in the frequency modulation device (6) is respectively connected to the three-phase circuit between the other end wiring port of the regulating resistor (5) and one end wiring port of the test circuit breaker (8), and the other end of each phase frequency modulation unit in the frequency modulation device (6) is grounded; one end of each capacitor Cd in the capacitor (7) is respectively connected to the three-phase circuit between the other end wiring port of the regulating resistor (5) and one end wiring port of the test circuit breaker (8), and the other end of the capacitor (7) is grounded; Each phase frequency modulation unit in the frequency modulation device (6) comprises a resistor Rs and a capacitor Cs, one end of the resistor Rs in each phase frequency modulation unit is connected to the other end of the adjustment resistor (5), the other end of the resistor Rs is connected to one end of the capacitor Cs, and the other end of the capacitor Cs in each phase frequency modulation unit is grounded; The resistor Rs is used to adjust the peak value of the transient recovery voltage generated by the test circuit breaker (8), the capacitor Cs is used to adjust the reference time of the transient recovery voltage generated by the test circuit breaker (8), and the capacitor Cd is used to adjust the delay time of the transient recovery voltage generated by the test circuit breaker (8).

7. The energy storage medium voltage switch test system according to claim 1 is characterized in that: A voltage divider U and a current divider I are respectively connected in series in each phase circuit of the three-phase circuit between the other end connection port of the regulating resistor (5) and one end connection port of the test circuit breaker (8), wherein the voltage divider U is used to measure the test voltage and the current divider I is used to measure the test current.

8. The energy storage medium voltage switch test system according to claim 1 is characterized in that: The energy storage power supply (1) comprises an input isolating switch, a DC charging unit, an energy storage unit, an inverter unit, a sine wave filter and a control unit, wherein the input end of the input isolating switch is connected to a power supply network, the output end of the input isolating switch is connected to the input end of the DC charging unit, the output end of the DC charging unit is connected to the input end of the energy storage unit, the output end of the energy storage unit is connected to the input end of the inverter unit, the output end of the inverter unit is connected to the input end of the sine wave filter, the output end of the sine wave filter is the three-phase AC output end of the energy storage power supply (1), the isolating switch control signal output end of the control unit is connected to the control signal input end of the input isolating switch, and the inverter control signal output end of the control unit is connected to the control signal input end of the inverter unit.

9. The energy storage medium voltage switch test system according to claim 8 is characterized in that: The DC charging unit is used to convert the input AC power into a controllable DC power to charge the energy storage unit. When the charging voltage meets the medium voltage switch test requirements, the inverter unit operates to convert the DC power stored in the energy storage unit into a controllable square wave power output through SPWM pulse width modulation technology and series multi-level technology, and finally converts the square wave into a controllable AC power output through a sine wave filter; The control unit is used to send synchronous trigger signals to the isolating switch and the inverter unit respectively when the medium voltage switch test starts, so that the isolating switch and the inverter unit start working synchronously when the medium voltage switch test starts, trigger the energy storage power supply (1), and intervene in the medium voltage switch test circuit to provide capacity support, so that the required short-circuit test voltage and current are released.

10. A method for testing an energy storage medium voltage switch using the system of claim 1, characterized in that: It includes the following steps: Step 1: Calculate the preliminary resistance value and reactance value of the regulating reactor (4) and the regulating resistor (5) according to the short-circuit current required to be tested by the test circuit breaker (8); Step 2: Select a vacuum circuit breaker to replace the test circuit breaker (8) and connect it to the energy storage medium voltage switch test system. Apply the rated voltage of the test circuit breaker (8) to the vacuum circuit breaker through the energy storage power supply (1). At the same time, adjust the resistance value and reactance value of the regulating reactor (4) and the regulating resistor (5) to the preliminary resistance value and reactance value of the regulating reactor (4) and the regulating resistor (5) calculated in step 1. At this time, the rated short-circuit current of the test circuit breaker (8) is generated. The rated short-circuit current of the test circuit breaker (8) is used to perform a breaking test of the vacuum circuit breaker. During the breaking test of the vacuum circuit breaker, the parameters of the frequency modulation device (6) and the capacitor (7) are adjusted to obtain a waveform that meets the standard transient recovery voltage, and the actual resistance value and reactance value of the regulating reactor (4) and the regulating resistor (5) and the parameters of the frequency modulation device (6) and the capacitor (7) under the waveform are recorded. Step 3: connect the test circuit breaker (8) to the energy storage medium voltage switch test system instead of the vacuum circuit breaker, control the three-phase closing switch (2) to be in the disconnected state, and the three-phase operating circuit breaker (3) to be in the closed state; Step 4: According to the parameters of the frequency modulation device (6) and the capacitor (7) under the waveform of the transient recovery voltage obtained by debugging in step 2, the frequency modulation device (6) and the capacitor (7) are switched on and off, and a waveform of the transient recovery voltage that meets the standard is obtained when the test circuit breaker (8) is connected to the energy storage medium voltage switch test system; Step 5: In the energy storage power supply (2), the AC power supply is converted into a controllable DC power supply to charge the energy storage unit. When the charging voltage meets the medium voltage switch test requirements, the inverter unit operates to convert the DC power stored in the energy storage unit into a controllable square wave power output through SPWM pulse width modulation technology and series multi-level technology, and finally converts the square wave into a controllable AC power output through a sine wave filter; Step 6: Close the three-phase closing switch (2), close the loop, adjust the resistance value and reactance value of the regulating reactor (4) and the regulating resistor (5) to the actual resistance value and reactance value of the regulating reactor (4) and the regulating resistor (5) under the waveform of the standard transient recovery voltage, and at this time, the energy storage medium voltage switch test system generates the required short-circuit current; Step 7: Control the circuit breaker (8) of the test product to open, and after a preset time, control the three-phase operating circuit breaker (3) to disconnect; Step 8: Record the transient recovery voltage and short-circuit current collected by the voltage divider U and the current divider I.

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