Device and method for testing short circuit bearing capacity of transformer

Abstract

The invention discloses a transformer short-circuit bearing capacity testing device, which adopts a three-phase test that a high-voltage side is then pressurized and a low-voltage side is firstly short-circuited to test the short-circuit bearing capacity of a tested transformer, and comprises field equipment and a testing circuit which is connected with a primary line of the tested transformer and forms a short circuit with the tested transformer through closing and opening matching operation. And the control room equipment is in control connection with the field equipment, controls closing and opening of the field equipment through an upper computer control program to form test current, calculates switching parameters of the test circuit according to the capacity of the tested transformer, and is also used for collecting and storing voltage data and current data in the test circuit. The control room equipment remotely controls the no-load power-on of the field equipment and the switching-on and switching-off cooperation operation of the switch, completes the short-circuit current test of the tested transformer, assesses the stability of the tested transformer, checks whether the transformer is qualified, and guarantees the reliable and stable operation of a power grid. The invention further discloses a testing method of the testing device for the short-circuit bearing capacity of the transformer.

Description

Technical Field

[0001] The present invention relates to the technical field of short - circuit capacity testing of transformers, and particularly to a method for testing the short - circuit capacity of transformers. Background Art

[0002] The reliability and stability of the power grid are directly related to the national economy, production and daily life. Once a fault occurs, there will be economic losses or even personal accidents. Distribution transformers are an important part of the terminal of the distribution network. Most short - circuit faults in the power grid will directly cause short - circuit faults in transformers, resulting in transformer damage accidents, expanding the power grid accidents, and seriously affecting the safe operation of the power system.

[0003] Therefore, the short - circuit capacity test of transformers is crucial in national economic production and daily life, and a test system that can evaluate the quality of transformers must be designed. Summary of the Invention

[0004] In order to solve the above - mentioned technical problems, the present invention provides a method for testing the short - circuit capacity of transformers, which automatically tests the transformer under test through control room equipment and on - site equipment.

[0005] In order to achieve the above object, the present invention is realized through the following technical solutions:

[0006] A device for testing the short - circuit capacity of a transformer uses a three - phase test with post - pressurization on the high - voltage side and pre - short - circuit on the low - voltage side to test the short - circuit capacity of the transformer under test, including:

[0007] On - site equipment, connected to the primary circuit of the transformer under test, forms a short - circuit test circuit with the transformer under test through switching - on and switching - off operations.

[0008] Control room equipment, connected to the on - site equipment for control, controls the switching - on and switching - off of the on - site equipment through the upper - computer control program to form a test current, calculates the switching parameters of the test circuit according to the capacity of the transformer under test, and is also used to collect and save the voltage data and current data in the test circuit.

[0009] Compared with the prior art, the present invention has the following advantages:

[0010] The control room equipment remotely controls the no - load power - on of the on - site equipment and the switching - on and switching - off operations of the switch to complete the short - circuit current test of the transformer under test, and the three - phase test with post - pressurization on the high - voltage side and pre - short - circuit on the low - voltage side of the transformer under test, so as to evaluate the stability of the transformer under test, check whether the structure and production process of the transformer are qualified, improve the product quality, and ensure the reliable and stable operation of the power grid.

[0011] Further preferably, the on - site equipment includes:

[0012] A transformer is arranged in the test circuit of the transformer under test and is connected to the control room equipment, and is used to output a test voltage that meets the test requirements.

[0013] A switch unit is arranged in the test circuit and is connected to the grid power supply. The transformer is connected in series to the switch unit. The switch unit is used to connect the grid power supply to the transformer to power on the transformer under no-load condition. It is also used to connect the transformer under test to the test circuit for short-circuit test through the coordinated operation of closing and opening the switch.

[0014] An adjustment unit is electrically connected in series with the switch unit and is used to adjust and output switching parameters. The switching parameters are the adjusted reactance value L and the adjusted resistance value R during the switching of the test circuit.

[0015] An acquisition unit is arranged between the adjustment unit and the transformer under test and is connected to the control room equipment, and is used to acquire the voltage and current in the test circuit and transmit them to the control room equipment.

[0016] Adopting the above technical solution, a test circuit is composed of a transformer, a switch unit, an adjustment unit and an acquisition unit to realize the three-phase test of the transformer under test with post-pressure on the high-voltage side and pre-short-circuit on the low-voltage side.

[0017] Further preferably, the switch unit includes:

[0018] An outgoing line switch is arranged in the test circuit, one end of which is connected to the grid power supply and is used to power on the transformer under no-load condition through closing.

[0019] An operation switch is connected in series with the transformer, one end of which is connected to the test transformer and the other end is connected to the phase-selection closing switch, and the secondary control end is connected to the control of the control room equipment.

[0020] The phase-selection closing switch is connected in series between the other electrical end of the operation switch and the adjustment unit and is also connected to the control room equipment, and is used to be switched in the test circuit through the coordinated operation of closing and opening the switch with the operation switch.

[0021] Adopting the above technical solution, after the transformer is powered on normally under no-load condition through the outgoing line switch, the operation switch and the phase-selection closing switch cooperate to complete the short-circuit current test of the transformer under test.

[0022] Further preferably, the adjustment unit includes:

[0023] An adjustment reactor is arranged in the test circuit, located between the phase-selection closing switch and the acquisition unit, and is electrically connected to the phase-selection closing switch, and is used to output the adjusted reactor value.

[0024] An adjustment resistor is connected in series with the adjustment reactor, and its secondary control end is connected to the control of the control room equipment, and is used to output the adjusted resistor value.

[0025] With the above technical solution, the regulating reactor and the regulating resistor are connected in series, and different reactances and resistance values are output by switching the on / off of the switching switch, so as to realize the regulation of the effective value and peak value of different test currents.

[0026] It is further optimized that the acquisition unit includes:

[0027] A current sensor, which is connected in series on the line at the rear end of the regulating resistor, and its data terminal is electrically connected to the equipment in the control room, and is used to collect the current in the short-circuit circuit during the test.

[0028] A voltage sensor, which is connected in parallel between the current sensor and the transformer under test, and its data terminal is connected to the equipment in the control room, and is used to collect the voltage in the short-circuit circuit.

[0029] With the above technical solution, the collection of current and voltage during the experiment is completed, which is convenient for subsequent processing and storage.

[0030] It is further optimized that the equipment in the control room includes:

[0031] A control and protection system, which is connected to the switch unit and the regulating unit for control, and is used to remotely and statically control the on / off of the on-site equipment to form a test circuit.

[0032] A data acquisition system, which is connected to the current sensor and the voltage sensor, and is used to collect, process and store the voltage and current in the test circuit.

[0033] With the above technical solution, the remote control operation of the outgoing line switch, the operating switch and the phase-selection closing switch is completed through the control and protection system to form a test circuit, and the short-circuit test of the low-voltage side and the high-voltage side voltage application of the transformer under test is realized.

[0034] It is further optimized that the control and protection system includes:

[0035] A control cabinet, which is arranged in the control room and is connected to the outgoing line switch, the operating switch, the transformer and the phase-selection closing switch for control, and is used to remotely and statically control the on-site equipment to form a test circuit.

[0036] A control host computer, which is installed on the console in the control room and is connected to the control cabinet. It has a test control program built in, and is used to control the control cabinet to send control signals to the on-site equipment through automatically running the test timing process. Among them, the control signal is an electrical signal for controlling the on-site equipment to form a test circuit.

[0037] A microcomputer integrated protection device, which is arranged in the control room and is connected to the on-site equipment, and is used to protect the normal operation of the on-site equipment.

[0038] With the above technical solution, the functions of remote static control of on-site equipment, automatic operation of test timing process and equipment protection are realized.

[0039] Further optimized to, the data acquisition system includes:

[0040] A data acquisition cabinet, which is arranged in the control room and electrically connected to the voltage sensor and the current sensor, and is used to convert the voltage signal and the current signal into voltage data and current data.

[0041] A data acquisition upper computer, which is arranged on the console and data-connected to the data acquisition host, and is used to record and save the voltage data and the current data.

[0042] Adopting the above technical solution, the acquisition, processing and saving of the voltage data and the current data during the test are completed accordingly.

[0043] The present invention also discloses a test method for a transformer short-circuit withstand capacity test device based on claim 1, which is characterized by including:

[0044] S901 Connect the test transformer to the test circuit.

[0045] S902 Adjust impedance switching calculation and static switching: According to the capacity of the test transformer, control the upper computer to calculate the switching regulating reactor value L and the regulating resistor value R, and perform switching.

[0046] S903 Set the closing angle and the energization time: Set the closing phase and angle of the phase selection closing switch through the control upper computer, and set the closing and opening cooperation time of the short-circuit test, that is, the cooperation time between the operating switch and the phase selection closing switch.

[0047] S904 Static switching of the transformer tap changer: Adjust the tap changer position of the transformer on the control upper computer.

[0048] S905 Data acquisition system acquisition setting: Set the parameters of the data acquisition upper computer, the voltage sensor and the current sensor.

[0049] S906 Power on the test transformer without load: Close the outgoing line switch to power on the transformer without load, and close the operating switch.

[0050] S907 Start the test: Start the three-phase short-circuit withstand capacity test of the test transformer.

[0051] S908 The data acquisition system completes data recording and saving: The voltage sensor collects the voltage, the current sensor collects the current, and the data acquisition upper computer records and saves the test voltage data and the current data.

[0052] S909 Sequentially disconnect the outgoing line switch, the operating switch and the phase selection closing switch through the control upper computer to end the test.

[0053] Adopting the above technical solution, a three-phase test method of short-circuiting the low-voltage side and applying voltage to the high-voltage side of the transformer under test is realized through the above steps to test the bearing capacity of the transformer under test during short-circuit and check whether the structure and production process of the transformer are qualified, so as to improve product quality and ensure the reliable and stable operation of the power grid.

[0054] Further optimized, S902 calculates the regulated reactor value L and regulated resistor value R to be switched according to the capacity of the transformer under test by controlling the upper computer, including:

[0055] S1001 calculates the test current:

[0056] S1002 calculates the regulated impedance value to be switched according to the test current:

[0057] S1003 solves the following equation according to the K value of the transformer under test to calculate the regulated reactor value L and regulated resistor value R to be switched:

[0058] Among them, U is the no-load voltage of the test system, I is the expected test current, Zs is the short-circuit impedance of the power grid system connected to the transformer under test, U T is the voltage at the current tap position of the transformer under test, Z T is the impedance value at the current tap position of the transformer under test, XT is the reactance value at the current tap position of the transformer under test, and RT is the resistance value at the current tap position of the transformer under test. Z LR is the impedance value of the regulated impedance switching of the test system, X is the reactance value of the regulated impedance switching of the test system, and R is the resistance value of the regulated impedance switching of the test system. K is a coefficient, equal to the ratio of reactance to resistance.

[0059] Adopting the above technical solution, accurately calculating the regulated reactor value L and regulated resistor value R during the switching process of the test circuit can accurately test the ability of the transformer under test to withstand short-circuit. Description of the Drawings

[0060] Figure 1 It is the single-line electrical schematic diagram of Embodiment 1.

[0061] Figure 2 It is the single-line electrical connection schematic diagram of the regulated reactor L and regulated resistor R in Embodiment 1.

[0062] Figure 3 It is the principle block diagram of the control and data acquisition system of Embodiment 1.

[0063] Figure 4 It is the method flow block diagram of Embodiment 2.

[0064] Reference numerals: 1QF - outgoing switch; TM - transformer; 2QF - operating switch; HK - phase - selection closing switch; L - regulating reactor; L1 - first reactance - value coil; L2 - second reactance - value coil; L3 - third reactance - value coil; L4 - fourth reactance - value coil; R - regulating resistor; R1 - first resistance - value element; R2 - second resistance - value element; R3 - third resistance - value element; TA - current sensor; TV - voltage sensor; SP - transformer under test. Detailed implementation manners

[0065] The following further introduces the present invention in conjunction with the Figures 1 - 4 accompanying drawings.

[0066] Embodiment 1

[0067] A short - circuit withstand capacity test device for transformer TM, as Figure 1 shown, adopts a three - phase test with the high - voltage side being pressurized later and the low - voltage side being short - circuited first to test the short - circuit withstand capacity of the transformer under test SP, including:

[0068] On - site equipment, connected to the primary circuit of the transformer under test SP, and forms a short - circuit test circuit with the transformer under test SP through closing and opening operations in coordination.

[0069] Control - room equipment, connected to the on - site equipment for control, controls the closing and opening of the on - site equipment through a control program of the upper - computer to form a test current, calculates the switching parameters of the test circuit according to the capacity of the transformer under test SP, and is also used to collect and save the voltage data and current data in the test circuit.

[0070] The control - room equipment remotely controls the no - load power - on of the on - site equipment and the coordinated operation of switch closing and opening to complete the short - circuit current test of the transformer under test SP, and the three - phase test with the high - voltage side of the transformer under test SP being pressurized later and the low - voltage side being short - circuited first, so as to evaluate the stability of the transformer under test SP and check whether its structure and production process are qualified, thereby improving the product quality and ensuring the reliable and stable operation of the power grid.

[0071] Specifically, as Figure 1 and Figure 3 shown, the on - site equipment in this embodiment includes:

[0072] Transformer TM, arranged in the test circuit of the transformer under test SP, connected to the control - room equipment, and used to output a test voltage meeting the test requirements.

[0073] Switch unit, arranged in the test circuit, connected to the grid power supply, with the transformer TM connected in series to the switch unit. The switch unit is used to connect the grid power supply to the transformer TM to make the transformer TM power - on under no - load. It is also used to connect the transformer under test SP to the test circuit through the coordinated operation of closing and opening for short - circuit testing.

[0074] An adjustment unit, electrically connected in series with the switch unit, is used to adjust the switching parameters. The switching parameters are the adjusted reactance value L and the adjusted resistance value R during the switching of the test circuit.

[0075] A collection unit, arranged between the adjustment unit and the transformer under test, is data-connected to the control room equipment, and is used to collect the voltage and current in the test circuit and transmit them to the control room equipment.

[0076] A test circuit is composed of a transformer TM, a switch unit, an adjustment unit, and a collection unit to realize a three-phase test in which the high-voltage side of the transformer under test SP is pressurized later and the low-voltage side is short-circuited first.

[0077] Specifically, as Figure 1 and Figure 3 shown, in this embodiment, the switch unit includes:

[0078] The outgoing line switch 1QF is arranged in the test circuit, one end is connected to the grid power supply, and is used to energize the transformer TM no-load by closing the switch.

[0079] The operation switch 2QF is connected in series with the transformer TM, one end is connected to the transformer, the other end is connected to the phase-selection closing switch, and the secondary control end is connected to the control of the control room equipment.

[0080] The phase-selection closing switch HK is connected in series between the other electrical end of the operation switch 2QF and the adjustment unit, and is also connected to the control room equipment, and is used to switch on and off in the test circuit in cooperation with the operation switch 2QF through the switch.

[0081] After the transformer TM is normally energized no-load through the outgoing line switch 1QF, the operation switch 2QF and the phase-selection closing switch HK cooperate to complete the short-circuit current test of the transformer under test SP.

[0082] Specifically, as Figure 2 shown, in this embodiment, the adjustment unit includes:

[0083] The adjustment reactor L is arranged in the test circuit, located between the phase-selection closing switch HK and the collection unit, and is electrically connected to the phase-selection closing switch HK, and is used to output the adjusted reactor value. In a specific embodiment, the adjustment reactor L is composed of a series of coils with different reactance values connected in series, and each coil is configured with a parallel switching switch. In this embodiment, the adjustment reactor L is composed of 4 coils with reactance values, namely the first reactance value coil L1, the second reactance value coil L2, the third reactance value coil L3, and the fourth reactance value coil L4 connected in series, and each reactance value coil is respectively connected with parallel switching switches QS1, QS2, QS3, and QS4.

[0084] The regulating resistor R is connected in series with the regulating reactor L and is used to output the value of the regulating resistor R. In a specific embodiment, the regulating resistor is formed by a series connection of a series of elements with different resistance values, and each element is configured with a parallel switching switch. In this embodiment, the regulating resistor is formed by a series connection of three resistance value elements, namely the first resistance value element R1, the second resistance value element R2, and the third resistance value element R3. Moreover, the first resistance value element R1 is connected in series with the fourth regulating reactor L4, and each regulating resistor is configured with parallel switching switches QS5, QS6, and QS7.

[0085] The regulating reactor L is connected in series with the regulating resistor R. By switching the on / off of the switching switch, different reactances and resistance values are output, realizing the regulation of the effective value and peak value of different test currents.

[0086] As Figure 1 shown, the acquisition unit in this embodiment includes:

[0087] The current sensor TA is connected in series on the line at the rear end of the regulating resistor, and its data terminal is electrically connected to the equipment in the control room, and is used to collect the current in the short - circuit circuit during the test.

[0088] The voltage sensor TV is connected in parallel between the current sensor TA and the test transformer SP, and its data terminal is connected to the equipment in the control room, and is used to collect the voltage in the short - circuit circuit, completing the acquisition of the current and voltage during the experiment, facilitating subsequent processing and storage.

[0089] Specifically, as Figure 1 and Figure 3 shown, the equipment in the control room in this embodiment includes:

[0090] The control and protection system is connected to the switch unit and the regulating unit for remote static and sequential control of the on / off of the on - site equipment to form a test circuit.

[0091] The data acquisition system is connected to the current sensor and the voltage sensor, and is used to collect, process the voltage and current.

[0092] Through the control and protection system, the remote control operations of the outgoing line switch 1QF, the operating switch 2QF, and the phase - selection closing switch HK are completed to form a test circuit, realizing the short - circuit test of the low - voltage side short - circuit and high - voltage side pressurization of the test transformer SP.

[0093] Specifically, as Figure 1 shown, the control and protection system in this embodiment of the present embodiment includes:

[0094] The control cabinet is arranged in the control room and is connected to the outgoing line switch 1QF, the operating switch 2QF, the transformer TM, and the phase - selection closing switch HK for remote static control of the on - site equipment to form a test circuit.

[0095] The control upper computer is installed on the console in the control room and is connected to the control cabinet. It has a test control program built-in, which is used to control the control cabinet to send control signals to the on-site equipment by automatically running the test timing process. Among them, the control signal is an electrical signal for controlling the on-site equipment to form a test circuit.

[0096] The microcomputer integrated protection device is set in the control room and is connected to the on-site equipment, which is used to protect the on-site equipment to operate normally.

[0097] Functions such as remote static control of on-site equipment, automatic operation of test timing process, and equipment protection are now available.

[0098] Specifically, as Figure 1 and Figure 3 shown, the data acquisition system in this embodiment includes:

[0099] The data acquisition cabinet is set in the control room and is electrically connected to the voltage sensor TV and the current sensor TA, which is used to convert the voltage signal and current signal into voltage data and current data.

[0100] The data acquisition upper computer is set on the console and is data-connected to the data acquisition host, which is used to record and save the voltage data and current data, so as to complete the acquisition, processing and saving of the voltage data and current data during the test.

[0101] Embodiment 2

[0102] The present invention also discloses a test method for a test device for the short-circuit withstand capacity of a transformer TM. As Figure 4 shown, it includes:

[0103] S901 Test preparation, wiring the test transformer SP and connecting it to the test circuit: The high-voltage side of the test transformer SP is connected to the test station, and the low-voltage side is short-circuited in three phases. A three-phase test method of applying voltage to the high-voltage side first and short-circuiting the low-voltage side first is adopted to connect into a test circuit.

[0104] S902 Adjust the impedance switching calculation and static switching: According to the capacity of the test transformer SP, the control upper computer calculates the switching regulating reactor value L and the regulating resistor value R, and performs the switching.

[0105] S903 Set the closing angle and energization time: Set the closing phase and angle of the phase-selection closing switch HK through the control upper computer, and set the short-circuit test current-carrying time, that is, the cooperation time of the operating switch 2QF and the phase-selection closing switch HK. In a specific embodiment, the short-circuit test current-carrying time is set to 0.5 s. It should be noted that setting the closing phase and angle of the phase-selection closing switch HK is a function inherent in the control upper computer and belongs to the prior art, so it will not be elaborated here.

[0106] S904 Static Tap-changing Transformer TM Tap-changer: Adjust the tap-changer position of transformer TM on the control upper computer.

[0107] S905 Data Acquisition System Acquisition Settings: Set the parameters of the data acquisition upper computer, voltage sensor TV, and current sensor TA.

[0108] S906 No-load Energization of Test Transformer TM: Close the outgoing line switch 1QF to energize transformer TM without load, and operate switch 2QF to close.

[0109] S907 Start the Test: Initiate the three-phase short-circuit withstand capacity test of the test transformer SP. The program in the control upper computer automatically gives commands to the phase-selection closing switch HK in the background to control its closing. After 0.5 s, a command is issued to operate switch 2QF to open, thus automatically completing the short-circuit current-carrying test of the test transformer SP.

[0110] S908 Data Acquisition System Completes Data Recording and Saving: The voltage sensor TV collects voltage, the current sensor TA collects current, and the data acquisition upper computer records and saves the test voltage data and current data.

[0111] S909 Give commands to the switch unit through the control upper computer to open, successively open the outgoing line switch 1QF, the operating switch 2QF, and the phase-selection closing switch HK to end the test.

[0112] Through the above steps, a three-phase test method of short-circuiting the low-voltage side and applying voltage to the high-voltage side of the test transformer SP is realized, testing the withstand capacity of the test transformer SP during short-circuit, checking whether the structure and production process of transformer TM are qualified, thereby improving product quality and ensuring the reliable and stable operation of the power grid.

[0113] Specifically, in this embodiment, S902 calculates the switched shunt reactor value L and the switched resistor value R according to the capacity of the test transformer SP through the control upper computer, including:

[0114] S1001 Calculate the test current:

[0115] S1002 Deduce the switched impedance value according to the test current:

[0116] S1003 According to the K value of the test transformer SP, solve the following equation to calculate the switched shunt reactor value L and the switched resistor value R:

[0117] Where, U is the no-load voltage of the test system, I is the expected test current, Zs is the short-circuit impedance of the power grid system connected to the test transformer SP, UT is the voltage at the current tap position of the test transformer SP, ZT Z is the impedance value at the current tap position of the test transformer SP, XT is the reactance value at the current tap position of the test transformer SP, and RT is the resistance value at the current tap position of the test transformer SP. ZLR is the impedance value for adjusting the impedance switching of the test system, X is the reactance value for adjusting the impedance switching of the test system, and R is the resistance value for adjusting the impedance switching of the test system. K is a coefficient equal to the ratio of reactance to resistance.

[0118] Accurately calculating the value of the regulating reactor L and the regulating resistor R during the switching process of the test circuit can accurately test the ability of the test transformer SP to withstand short circuits.

[0119] In summary, through the short-circuit withstand capacity test device and test method of the transformer TM, a three-phase test of the test transformer SP with the high-voltage side pressurized first and the low-voltage side short-circuited first is completed, so as to evaluate the stability ability of the test transformer SP, and it can accurately check whether the structure and production process of the transformer TM are qualified, improve product quality, and ensure the reliable and stable operation of the power grid.

[0120] This specific embodiment is only an explanation of the invention, and it is not a limitation of the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without creative contributions as needed, but as long as they are within the protection scope of the invention, they are protected by the patent law.

Claims

1. A transformer short-circuit withstand capacity test device, which uses a three-phase test in which the high-voltage side is pressurized later and the low-voltage side is short-circuited first to test the short-circuit withstand capacity of the tested transformer (SP), characterized in that: include: The field equipment is connected to the primary circuit of the transformer under test (SP), and forms a short-circuit test circuit with the transformer under test (SP) through the coordinated operation of closing and opening switches; The control room equipment is connected to the control of the field equipment, controls the field equipment to close and open the switch to form a test current through the upper computer control program, calculates the switching parameters of the test circuit according to the capacity of the tested transformer (SP), and is also used to collect and save the voltage data and current data in the test circuit.

2. The transformer short-circuit withstand capability test device according to claim 1, characterized in that: The field equipment includes: A transformer (TM), arranged in the test circuit of the transformer under test (SP), connected to the control room equipment, and used for outputting a test voltage that meets the test requirements; A switch unit is arranged in the test circuit and connected to the grid power supply. The transformer (TM) is connected in series to the switch unit. The switch unit is used to connect the grid power supply to the transformer (TM) so that the transformer (TM) is powered on without load; and is also used to connect the tested transformer (SP) to the test circuit for a short-circuit test through the coordinated operation of closing and opening the switch; An adjusting unit, electrically connected in series with the switch unit, for adjusting and outputting the switching parameters, wherein the switching parameters are an adjusting reactance value L and an adjusting resistance value R when the test circuit is switched; The collecting unit is arranged between the regulating unit and the transformer under test (SP), connected to the control room equipment, and used for collecting the voltage and current in the test circuit.

3. The transformer short-circuit withstand capability test device according to claim 2, characterized in that: The switch unit comprises: An outgoing line switch (1QF), arranged in the test circuit, one end of which is connected to the grid power supply, and used to power on the transformer (TM) in a no-load state by closing the switch; An operating switch (2QF) is connected in series with the transformer (TM), one end of which is connected to the transformer (TM), the other end of which is connected to the phase selection closing switch (HK), and the secondary control end of which is connected to the control room equipment control; The phase selection closing switch (HK) is connected in series between the other electrical end of the operating switch (2QF) and the regulating unit, and is also connected to the control room equipment, and is used to cooperate with the operating switch (2QF) to switch in the test circuit through switch closing and opening.

4. The transformer short-circuit withstand capability test device according to claim 3, characterized in that: The adjustment unit comprises: A regulating reactor (L) is arranged in the test circuit, located between the phase selection closing switch (HK) and the acquisition unit, and is electrically connected to the phase selection closing switch (HK) for outputting a regulating reactor value; The regulating resistor (R) is connected in series with the regulating reactor (L), and its secondary control end is connected to the control room equipment control for outputting the regulating resistor value.

5. The transformer short-circuit withstand capability test device according to claim 4, characterized in that: The acquisition unit comprises: A current sensor (TA), which is serially connected to the rear end line of the regulating resistor (R), and the data end is electrically connected to the control room equipment, and is used to collect the current in the short-circuit circuit during the test; A voltage sensor (TV) is connected in parallel between the current sensor (TA) and the tested transformer (TM), and its data end is connected to the control room equipment for collecting the voltage in the short-circuit circuit.

6. The transformer short-circuit withstand capability test device according to claim 5, characterized in that: The control room equipment includes: A control protection system, connected to the switch unit and the adjustment unit, for remotely controlling the switching of the field equipment into a test circuit in a static and sequential manner; The data acquisition system is connected to the current sensor and the voltage sensor and is used for acquiring, processing and storing the voltage and current in the test circuit.

7. The transformer short-circuit withstand capability test device according to claim 6, characterized in that: The control and protection system comprises: A control cabinet is arranged in the control room, and is connected to the outlet switch (1QF), the operation switch (2QF), the transformer (TM), and the phase selection closing switch (HK) for remote static control of the field equipment to form a test circuit; A control host computer, installed on a control console in a control room, connected to the control cabinet, having a built-in test control program, for controlling the control cabinet to send a control signal to the field device by automatically running a test sequence process, wherein the control signal is an electrical signal for controlling the field device to form a test circuit; A microcomputer comprehensive protection device is arranged in the control room and connected to the field equipment to protect the normal operation of the field equipment.

8. The transformer short-circuit withstand capability test device according to claim 6, characterized in that: The data acquisition system comprises: A data acquisition cabinet is arranged in the control room, electrically connected to the voltage sensor (TV) and the current sensor (TA), and is used to convert the voltage signal and the current signal into voltage data and current data; The data acquisition host computer is arranged on the console and is data-connected to the data acquisition host computer, and is used to record and save the voltage data and the current data.

9. A test method based on the transformer short-circuit withstand capability test device according to claim 1, characterized in that: include: S901 Test preparation: Connect the transformer under test (SP) to the test circuit; S902 Regulating impedance switching calculation and static switching: According to the capacity of the tested transformer (SP), the host computer is controlled to calculate the switching regulating reactor value L and regulating resistor value R, and perform switching; S903 sets the closing angle and power-on time: sets the closing phase and angle of the phase-selective closing switch (HK) and sets the closing and opening coordination time of the short-circuit test through the control host computer; S904 static switching transformer tap changer: adjusting the tap changer position of the transformer (TM) on the control host computer; S905 data acquisition system acquisition settings: set the parameters of the data acquisition host computer, voltage sensor (TV) and current sensor (TA); S906 Test transformer no-load power-up: close the outgoing line switch (1QF) to power up the transformer (TM) no-load, and close the operating switch (2QF); S907 start-up test: start the three-phase short-circuit withstand capacity test of the tested transformer (TM); The S908 data acquisition system completes data recording and storage: the voltage sensor (TV) collects voltage, the current sensor (TA) collects current, and the data acquisition host computer records and saves the test voltage data and current data; S909 Test ends: by controlling the upper computer, the outgoing line switch (1QF), the operating switch (2QF) and the phase selection closing switch (HK) are disconnected in sequence to end the test.

10. The test method of the transformer short-circuit withstand capability test device according to claim 9, characterized in that: The S902 controls the upper computer to calculate the switching regulating reactor (L) value and regulating resistor (R) value according to the capacity of the tested transformer (SP), including: S1001 calculates the test current: S1002 calculates the switching adjustment impedance value based on the test current: S1003 can calculate the switching regulating reactor (L) value and regulating resistor (R) value by solving the following equation according to the K value of the tested transformer (TM): Where, U is the no-load voltage of the test system, I is the expected test current, Zs is the short-circuit impedance of the power grid system to which the tested transformer (SP) is connected, UT is the voltage at the current tap position of the tested transformer (SP), and Z T is the impedance value of the test transformer (SP) at the current tap position, XT is the reactance value of the test transformer (SP) at the current tap position, RT is the resistance value of the test transformer (SP) at the current tap position; ZLR is the impedance value of the test system adjusting the impedance switching, X is the reactance value of the test system adjusting the impedance switching, R is the resistance value of the test system adjusting the impedance switching; K is the coefficient, which is equal to the ratio of reactance to resistance.

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