A method for controlling short-circuit current peak value of a power transformer with delta-connected windings

Abstract

The short-circuit current peak value control method of the triangle-connected winding power transformer of the present invention comprises the following steps: step 1, test preparation; step 2, measuring the effective value of the power supply voltage; step 3, measuring and determining the phase sequence of the power supply; step 4, connecting the primary side of the voltage measuring device; step 5, connecting the secondary side of the voltage measuring device; step 6, adjusting the synchronization of the phase-selective closing switch; step 7, adjusting the closing angle of the phase-selective closing switch; step 8, connecting the short-circuit test system to the transformer; step 9-1, adjusting the short-circuit current peak value of the positive phase sequence of the power supply; step 9-2, adjusting the short-circuit current peak value of the negative phase sequence of the power supply. The present invention omits the voltage measuring device of the B phase and the C phase of the short-circuit test system and the voltage measuring module of the B phase and the C phase of the phase-selective closing switch, thereby reducing the construction cost of the short-circuit test system and the cost of the phase-selective closing switch.

Description

Technical Field

[0001] The invention relates to the field of power transformer testing related to measuring electric variables, and in particular to a short-circuit current peak value control method for a power transformer with a delta-connected winding. Background Art

[0002] When conducting short-circuit tests on power transformers in accordance with GB 1094.5-2008 "Power Transformers Part 5: Ability to Withstand Short Circuits", special requirements are placed on the apparent short-circuit capacity of the system, so it is necessary to conduct the test in a professional short-circuit test system. When conducting short-circuit tests on star / delta-connected power transformers, the star-connected side can be short-circuited and the delta-connected side can be connected to the short-circuit test system.

[0003] Clause 4.2.5.2 of GB 1084.5-2008 stipulates the short-circuit test of power transformers with delta-connected windings: "In order to obtain the maximum asymmetric current on one of the three phase windings", "For three-phase tests of delta-connected windings, this condition can be obtained by closing the circuit breaker when the line voltage passes through zero." and "Another method for determining the phase current of the delta-connected winding is to appropriately connect the secondary windings of each current transformer that measures the line current. The phase current value can be recorded using an oscilloscope." The above content describes the short-circuit current peak control method of the power transformer with delta-connected windings. In order to meet the above test conditions, it is necessary to install voltage measuring devices on the A-phase, B-phase and C-phase lines of the short-circuit test system respectively, and connect the primary side of the voltage measuring devices; the secondary side of the voltage measuring devices is linearly connected and connected to the voltage measuring module of the phase-selective closing switch. At this time, the short-circuit test system needs to install 3 voltage measuring devices, the phase-selective closing switch needs to be equipped with 3 voltage measuring modules, and the phase-selective closing switch needs to collect the line voltage on the secondary side of the voltage measuring device.

[0004] How to achieve short-circuit current peak control of delta-connected winding power transformers while reducing the number of voltage measuring devices and the number of voltage measuring modules of the phase-selective closing switch to meet the technical requirements of Article 4.2.5.2 of GB 1084.5-2008 is a technical problem that can both reduce the cost of test equipment and improve work efficiency.

[0005] The prior art does not involve the research on the short-circuit test method of the delta-connected winding power transformer, and in particular, does not involve the research on the short-circuit current peak value regulation method. Therefore, it is necessary to conduct research on the short-circuit current peak value regulation method of the delta-connected winding power transformer. Summary of the invention

[0006] In order to make up for the deficiencies of the prior art, the present invention provides a short-circuit current peak value control method for a delta-connected winding power transformer, which is applied to the short-circuit test of the delta-connected winding power transformer, can reduce two-thirds of the voltage measuring devices and two-thirds of the voltage measuring modules of the phase-selective closing switch, and at the same time meet the technical requirements of GB1084.5-2008 on the short-circuit test current peak value.

[0007] The present invention is achieved through the following technical solutions:

[0008] An optimized short-circuit current peak value control method for a delta-connected winding power transformer comprises the following steps:

[0009] Step 1. Test preparation: Check the short-circuit test system according to the test requirements, and supply power to the short-circuit test system after the test requirements are met;

[0010] Step 2: Measure the effective value of the power supply voltage: Measure the effective value of the line voltage of the short-circuit test system power supply to meet the test requirements;

[0011] Step 3, measure and determine the phase sequence of the power supply: measure the phase sequence of the short-circuit test system power supply, and determine whether the phase sequence of the power supply is positive phase sequence or negative phase sequence;

[0012] Step 4, connect the primary side of the voltage measuring device: the primary side high voltage end of phase A of the voltage measuring device is connected to the phase A line of the short-circuit test system, and the primary side low voltage end of the voltage measuring device is connected to the ground terminal;

[0013] Step 5, connect the secondary side of the voltage measuring device: the secondary side of the A phase of the voltage measuring device is connected to the voltage measuring module of the A phase of the phase selection closing switch;

[0014] Step 6, adjusting the synchronization of the phase selection closing switch: the short-circuit test system is in an open circuit state, that is, the delta-connected winding power transformer under test is not connected to the short-circuit test system; adjusting the parameters of the phase selection closing switch to achieve the three-pole asynchronism of the phase A, phase B, and phase C of the phase selection closing switch within the specified error range;

[0015] Step 7, adjusting the closing angle of the phase-selective closing switch: the short-circuit test system is in an open circuit state, that is, the delta-connected winding power transformer under test is not connected to the short-circuit test system; adjusting the parameters of the phase-selective closing switch, inputting the closing angle α into the phase-selective closing switch, measuring the initial voltage angle β of the A phase at the rear end of the phase-selective closing switch, and achieving α≈β within the specified error range;

[0016] Step 8. Connect the short-circuit test system to the transformer: Phase A, Phase B, and Phase C of the power transformer with a delta-connected winding correspond to Phase A, Phase B, and Phase C of the short-circuit test system and are connected with wires of sufficient cross-sectional area; Phase A, Phase B, and Phase C of the star-connected winding of the power transformer are short-circuited with wires of sufficient cross-sectional area;

[0017] Step 9-1, when the power supply of the short-circuit test system is in positive phase sequence, short-circuit current peak value adjustment: first adjust the parameters of the adjustable resistor and reactor in the short-circuit test system to meet the test requirements, and then input the closing angle of -30 degrees, 90 degrees, and 210 degrees in the voltage measurement module of the phase selection closing switch phase A, so that the maximum current peak value can be achieved in the phase A, phase B, and phase C of the power transformer;

[0018] Step 9-2, when the power supply of the short-circuit test system is a negative phase sequence, short-circuit current peak value adjustment: first adjust the parameters of the adjustable resistors and reactors in the short-circuit test system to meet the test requirements, and then input the closing angles of 30 degrees, -90 degrees, and 150 degrees in the voltage measurement module of phase A of the phase selection closing switch, so as to achieve the maximum current peaks in phases A, B, and C of the power transformer.

[0019] The short-circuit test system comprises a power supply, an adjustable resistor and a reactor, a current measuring device, a voltage measuring device, a trip circuit breaker, a phase-selecting closing switch and a voltage waveform collecting and measuring device which are connected in sequence.

[0020] The primary side high voltage end of phase A of the voltage measuring device is connected to the phase A line of the short-circuit test system and is located at the front end of the opening circuit breaker, and the primary side low voltage end of phase A of the voltage measuring device is connected to the ground terminal;

[0021] The secondary side of phase A of the voltage measuring device is connected to the voltage measuring module of phase A of the phase selection closing switch.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The present invention proposes to install a voltage measuring device only on phase A of the short-circuit test system, and connect the voltage measuring module of phase A of the phase-selective closing switch; in order to meet the closing angle when the line voltage passes through zero required by clause 4.2.5.2 of GB 1084.5-2008, three voltage measuring devices and three voltage measuring modules of the phase-selective closing switches are required; in comparison, the voltage measuring devices of phases B and C of the short-circuit test system and the voltage measuring modules of phases B and C of the phase-selective closing switch are omitted, thereby reducing the construction cost of the short-circuit test system and the cost of the phase-selective closing switch;

[0024] The present invention proposes that by changing the closing angle of the phase-selecting closing switch A phase, the maximum current peak value can be achieved in the phases A, B and C of the transformer; the closing angle when the line voltage passes through zero as required by clause 4.2.5.2 of GB 1084.5-2008 can achieve the maximum current peak value in the phases A, B and C of the transformer; the line voltage refers to the positive phase sequence voltage AB phase, BC phase, CA phase or the negative phase sequence power supply AC phase, CB phase, BA phase. In comparison, the present invention only involves the A phase, reducing the measurement of voltage parameters;

[0025] The present invention proposes to determine the positive phase sequence power supply or the negative phase sequence power supply, but does not need to add additional equipment, and can be manually or automatically identified in the power supply system. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention will be further described below in conjunction with the accompanying drawings.

[0027] Figure 1 It is a structural schematic diagram of the short circuit test system of the present invention;

[0028] Figure 2 It is a wiring diagram of the secondary side of the voltage measuring device of the present invention and the voltage module of the phase selection closing switch;

[0029] Figure 3 FIG. 4 is a flowchart of the experimental method of the present invention.

[0030] As shown in the figure: 1 power supply, 2-1 adjustable resistor and reactor A phase, 2-2 adjustable resistor and reactor B phase, 2-3 adjustable resistor and reactor C phase, 3-1 current measuring device A phase, 3-2 current measuring device B phase, 3-3 current measuring device C phase, 4-1 voltage measuring device A phase, 4-1-1 secondary side of voltage measuring device A phase, 5 opening circuit breaker, 6-1 phase selection closing switch A phase, 6-2 phase selection closing switch B phase, 6-3 phase selection closing switch C phase, 6-1-1 voltage measurement module of phase selection closing switch A phase, 7-1 voltage waveform acquisition and measurement device A phase, 7-2 voltage waveform acquisition and measurement device B phase, 7-3 voltage waveform acquisition and measurement device C phase, 8 tested delta-connected winding power transformer.

[0031] Among them, the adjustable resistors and reactors are composed of: adjustable resistor and reactor A phase 2-1, adjustable resistor and reactor B phase 2-2, and adjustable resistor and reactor C phase 2-3; the A phase, B phase, and C phase of the above adjustable resistors and reactors can be adjusted separately to meet the test requirements.

[0032] The current measuring device comprises: a current measuring device for phase A 3-1, a current measuring device for phase B 3-2, and a current measuring device for phase C 3-3; the phase A, phase B, and phase C of the above-mentioned current measuring devices can be used separately.

[0033] Composition of the voltage measuring device: Voltage measuring device A phase 4-1.

[0034] The phase-selective closing switch is composed of: phase-selective closing switch A phase 6-1, phase-selective closing switch B phase 6-2, and phase-selective closing switch C phase 6-3; the closing time of phase A, phase B, and phase C of the above-mentioned phase-selective closing switches can be adjusted separately, thereby realizing the function of the phase-selective closing switch.

[0035] The voltage waveform acquisition and measurement device comprises: a voltage waveform acquisition and measurement device for phase A 7-1, a voltage waveform acquisition and measurement device for phase B 7-2, and a voltage waveform acquisition and measurement device for phase C 7-3; the A phase, B phase, and C phase of the above-mentioned voltage waveform acquisition and measurement device can be used separately. DETAILED DESCRIPTION

[0036] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention are clearly and completely described below.

[0037] Figure 1 This is a schematic diagram of the structure of the short circuit test system of the present invention, which is specifically implemented as follows:

[0038] The short-circuit test system consists of: a power supply 1, an adjustable resistor and reactor, a current measuring device, a voltage measuring device, a trip circuit breaker 5, a phase selection and closing switch, a voltage waveform acquisition and measurement device, and a delta-connected winding power transformer 8 to be tested, which are connected in sequence.

[0039] The primary side high voltage end of the voltage measuring device A phase 4-1 is connected to the A phase line of the short-circuit test system, which is located at the front end of the opening circuit breaker, and the primary side low voltage end of the voltage measuring device A phase 4-1 is connected to the grounding terminal.

[0040] Figure 2 The wiring diagram of the secondary side of the voltage measuring device of the present invention and the voltage module of the phase selection closing switch is as follows:

[0041] The connection between the secondary side 4-1-1 of the voltage measuring device phase A and the voltage measuring module 6-1-1 of the phase selection closing switch phase A.

[0042] Figure 3 The following is a workflow diagram of the test method of the present invention, and the specific implementation steps are as follows:

[0043] Step 1. Test preparation: Check the short-circuit test system according to the test requirements, and supply power to the short-circuit test system after the test requirements are met;

[0044] Step 2: Measure the effective value of the power supply voltage: Measure the effective value of the line voltage of the short-circuit test system power supply to meet the test requirements;

[0045] Step 3, measure and determine the phase sequence of the power supply: measure the phase sequence of the short-circuit test system power supply, and determine whether the phase sequence of the power supply is positive phase sequence or negative phase sequence;

[0046] Step 4, connect the primary side of the voltage measuring device: the primary side high voltage end of the voltage measuring device A phase 4-1 is connected to the A phase line of the short circuit test system, and the primary side low voltage end of the voltage measuring device A phase 4-1 is connected to the ground terminal;

[0047] Step 5, connect the secondary side of the voltage measuring device: the secondary side 4-1-1 of the A phase of the voltage measuring device is connected to the voltage measuring module 6-1-1 of the A phase of the phase selection closing switch;

[0048] Step 6, adjusting the synchronization of the phase-selective closing switch: the short-circuit test system is in the open circuit state, that is, the tested delta-connected winding power transformer 8 is not connected to the short-circuit test system; the opening circuit breaker 5 is in the closed state, and the parameters of the phase-selective closing switch A phase 6-1, the phase-selective closing switch B phase 6-2, and the phase-selective closing switch C phase 6-3 are adjusted. After the phase-selective closing switch A phase 6-1, the phase-selective closing switch B phase 6-2, and the phase-selective closing switch C phase 6-3 are closed, the voltage waveform acquisition and measurement device A phase 7-1, the voltage waveform acquisition and measurement device B phase 7-2, and the voltage waveform acquisition and measurement device C phase 7-3 are measured. The voltage signals collected need to meet the requirement that the three-pole asynchronism is less than 0.1ms;

[0049] Step 7, adjusting the closing angle of the phase-selective closing switch: the short-circuit test system is in an open circuit state, that is, the delta-connected winding power transformer 8 under test is not connected to the short-circuit test system; adjusting the parameters of the phase-selective closing switch A phase 6-1, the phase-selective closing switch B phase 6-2, and the phase-selective closing switch C phase 6-3, when the closing angle α is input into the phase-selective closing switch, and the voltage initial angle β of the voltage waveform acquisition and measurement device A phase 7-1 is measured, the difference between α and β needs to be within the specified error range;

[0050] Step 8. Connect the short-circuit test system to the power transformer with delta-connected windings: Phase A, Phase B, and Phase C of the delta-connected windings of the transformer correspond to Phase A, Phase B, and Phase C of the short-circuit test system and are connected with wires of sufficient cross-sectional area; Phase A, Phase B, and Phase C of the star-connected windings of the transformer are short-circuited with wires of sufficient cross-sectional area;

[0051] Step 9-1, when the power supply of the short-circuit test system is in positive phase sequence, short-circuit current peak value adjustment: According to the technical requirements of GB 1094.5-2008, first adjust the parameters of the adjustable resistor and reactor A phase 2-1, the adjustable resistor and reactor B phase 2-2, and the adjustable resistor and reactor C phase 2-3 in the short-circuit test system, and then input the closing angles of -30 degrees, 90 degrees, and 210 degrees in the voltage measurement module 6-1-1 of the phase selection closing switch A phase, and finally measure the corresponding transformer A phase, B phase, C phase to see the maximum current peak to meet the test requirements;

[0052] Step 9-2, short-circuit current peak value adjustment when the power supply of the short-circuit test system is a negative phase sequence: According to the technical requirements of GB 1094.5-2008, first adjust the parameters of the adjustable resistor and reactor A phase 2-1, the adjustable resistor and reactor B phase 2-2, and the adjustable resistor and reactor C phase 2-3 in the short-circuit test system, and then input the closing angles of 30 degrees, -90 degrees, and 150 degrees in the voltage measurement module 6-1-1 of the phase selection closing switch A phase, and finally measure the corresponding transformer A phase, B phase, and C phase to see the maximum current peak to meet the test requirements.

[0053] An embodiment is described by taking a certain type of power transformer as an example.

[0054] The high voltage side of the power transformer is connected in a triangle, and the low voltage side is connected in a star; the rated voltage of the high voltage side is 10kV, and the rated voltage of the low voltage side is 0.4kV; the high voltage side is connected to the short circuit test system, and the low voltage side is short-circuited; the measurement results show that X / R=4.

[0055] Step 1. Test preparation: Check the short-circuit test system according to the test requirements, and supply power to the short-circuit test system after the test requirements are met;

[0056] Step 2: Measure the effective value of the power supply voltage: Measure the effective value of the line voltage of the short-circuit test system power supply, 10.1 kV, which meets the test requirements;

[0057] Step 3, measure and determine the phase sequence of the power supply: measure the phase sequence of the short-circuit test system power supply, and determine whether the phase sequence of the power supply is positive phase sequence or negative phase sequence;

[0058] Step 4, connect the primary side of the voltage measuring device: the primary side high voltage end of the voltage measuring device A phase 4-1 is connected to the A phase line of the short circuit test system, and the primary side low voltage end of the voltage measuring device A phase 4-1 is connected to the ground terminal;

[0059] Step 5, connect the secondary side of the voltage measuring device: the secondary side 4-1-1 of the A phase of the voltage measuring device is connected to the voltage measuring module 6-1-1 of the A phase of the phase selection closing switch;

[0060] Step 6, adjust the synchronization of the phase-selective closing switch: the short-circuit test system is in the open circuit state, that is, the tested delta-connected winding power transformer 8 is not connected to the short-circuit test system; the 5-opening circuit breaker is in the closed state, adjust the parameters of the phase-selective closing switch A phase 6-1, the phase-selective closing switch B phase 6-2, and the phase-selective closing switch C phase 6-3, and after the phase-selective closing switch A phase 6-1, the phase-selective closing switch B phase 6-2, and the phase-selective closing switch C phase 6-3 are closed, measure the voltage waveform acquisition and measurement device A phase 7-1, the voltage waveform acquisition and measurement device B phase 7-2, and the voltage waveform acquisition and measurement device C phase 7-3. The voltage signals collected, the three-pole asynchronism is 0.06ms;

[0061] Step 7, adjust the closing angle of the phase-selective closing switch: the short-circuit test system is in the open-circuit state, that is, the tested delta-connected winding power transformer 8 is not connected to the short-circuit test system; adjust the parameters of the phase-selective closing switch A phase 6-1, the phase-selective closing switch B phase 6-2, and the phase-selective closing switch C phase 6-3, so that the closing angle of 0° is input into the phase-selective closing switch A phase 6-1, the phase-selective closing switch B phase 6-2, and the phase-selective closing switch C phase 6-3, and the voltage initial angle of 1.7° of the voltage waveform acquisition and measurement device A phase 7-1 is measured, which meets the specified error range of ±3.6°.

[0062] Step 8. Connect the short-circuit test system to the transformer: Phase A, Phase B, and Phase C of the triangle-connected winding on the high-voltage side of the transformer correspond to Phase A, Phase B, and Phase C of the short-circuit test system, and are connected with wires of sufficient cross-sectional area; Phase a, Phase b, and Phase c of the star-connected winding of the transformer are short-circuited with wires of sufficient cross-sectional area.

[0063] Step 9-1, short-circuit current peak value adjustment of the positive phase sequence of the power supply: If the phase sequence of the power supply is determined to be positive phase sequence in the above step 3, short-circuit current peak value adjustment: According to the technical requirements of GB 1094.5-2008, first adjust the parameters of the adjustable resistor and reactor A phase 2-1, the adjustable resistor and reactor B phase 2-2, and the adjustable resistor and reactor C phase 2-3 in the short-circuit test system, and then input the closing angles of -30 degrees, 90 degrees, and 210 degrees in the voltage measurement module 6-1-1 of the phase selection closing switch A phase, and finally measure the corresponding A phase current peak factor 2.10, B phase current peak factor 2.11, and C phase current peak factor 2.10 of the transformer to meet the test requirements.

[0064] Step 9-2, power supply negative phase sequence short-circuit current peak adjustment: If the power supply phase sequence is determined to be negative phase sequence in the above step 3, short-circuit current peak adjustment: According to the technical requirements of GB 1094.5-2008, first adjust the parameters of the adjustable resistor and reactor A phase 2-1, the adjustable resistor and reactor B phase 2-2, and the adjustable resistor and reactor C phase 2-3 in the short-circuit test system, and then input the closing angles of 30 degrees, -90 degrees, and 150 degrees in the voltage measurement module 6-1-1 of the phase selection closing switch A phase, and finally measure the corresponding transformer A phase current peak factor 2.11, B phase current peak factor 2.10, and C phase current peak factor 2.10 to meet the test requirements.

[0065] The above description is not limited to the above examples. Technical features not described in the present invention can be achieved by or by using existing technologies, which will not be described herein. The above embodiments and drawings are only used to illustrate the technical scheme of the present invention and are not limitations of the present invention. The present invention is described in detail with reference to the preferred implementation modes. Ordinary technicians in this field should understand that changes, modifications, additions or substitutions made by ordinary technicians in this technical field within the essential scope of the present invention do not depart from the purpose of the present invention and should also fall within the scope of protection of the claims of the present invention.

Claims

1. A method for controlling the short-circuit current peak value of a triangular-connected winding power transformer, characterized in that: The steps include: Step 1. Test preparation: Check the short-circuit test system according to the test requirements, and supply power to the short-circuit test system after the test requirements are met; Step 2: Measure the effective value of the power supply voltage: Measure the effective value of the line voltage of the short-circuit test system power supply to meet the test requirements; Step 3, measure and determine the phase sequence of the power supply: measure the phase sequence of the short-circuit test system power supply, and determine whether the phase sequence of the power supply is positive phase sequence or negative phase sequence; Step 4, connect the primary side of the voltage measuring device: the primary side high voltage end of phase A of the voltage measuring device is connected to the phase A line of the short-circuit test system, and the primary side low voltage end of the voltage measuring device is connected to the ground terminal; Step 5, connect the secondary side of the voltage measuring device: the secondary side of the A phase of the voltage measuring device is connected to the voltage measuring module of the A phase of the phase selection closing switch; Step 6, adjusting the synchronization of the phase selection closing switch: the short-circuit test system is in an open circuit state, that is, the delta-connected winding power transformer under test is not connected to the short-circuit test system; adjusting the parameters of the phase selection closing switch to achieve the three-pole asynchronism of the phase A, phase B, and phase C of the phase selection closing switch within the specified error range; Step 7, adjusting the closing angle of the phase-selective closing switch: the short-circuit test system is in an open circuit state, that is, the delta-connected winding power transformer under test is not connected to the short-circuit test system; adjusting the parameters of the phase-selective closing switch, inputting the closing angle α into the phase-selective closing switch, and measuring the initial voltage angle β of the A phase of the voltage waveform acquisition and measurement device, and the difference between α and β needs to be within the specified error range; Step 8. Connect the short-circuit test system to the transformer: Phase A, phase B, and phase C of the delta-connected winding of the power transformer correspond to phase A, phase B, and phase C of the short-circuit test system, and are connected with wires of sufficient cross-sectional area; The a, b and c phases of the star-connected winding of the power transformer are short-circuited with wires of sufficient cross-sectional area; Step 9-1, when the power supply of the short-circuit test system is in positive phase sequence, short-circuit current peak value adjustment: first, adjust the parameters of the adjustable resistor and reactor in the short-circuit test system to meet the test requirements, and input the closing angles of -30 degrees, 90 degrees, and 210 degrees in the voltage measurement module of the phase selection closing switch phase A in sequence, and after measurement, the maximum current peak values ​​of the phases A, B, and C of the power transformer can be achieved; Step 9-2, when the power supply of the short-circuit test system is a negative phase sequence, the short-circuit current peak value is adjusted: first, the parameters of the adjustable resistors and reactors in the short-circuit test system are adjusted to meet the test requirements, and the closing angles of 30 degrees, -90 degrees, and 150 degrees are successively input into the voltage measurement module of the phase selection closing switch phase A. After measurement, the maximum current peak values ​​can be achieved in the phases A, B, and C of the power transformer.

2. The short-circuit current peak value control method of a delta-connected winding power transformer according to claim 1 is characterized in that: In step 6: Adjust the synchronization of the phase-selective closing switch: the short-circuit test system is in the open circuit state, that is, the delta-connected winding power transformer under test is not connected to the short-circuit test system; the opening circuit breaker is in the closed state, and the parameters of the phase-selective closing switch are adjusted. After the adjusted phase-selective closing switch is closed, the voltage signals collected by the voltage waveform acquisition measuring device phase A, the voltage waveform acquisition measuring device phase B, and the voltage waveform acquisition measuring device phase C need to meet the three-pole asynchronism of less than 0.1ms.

3. The short-circuit current peak value control method of a delta-connected winding power transformer according to claim 1 is characterized in that: In step 7: achieve α≈β within the specified error range.

4. The short-circuit test system used in the short-circuit current peak value control method of the delta-connected winding power transformer according to claim 1 is characterized in that: It comprises a power supply (1), an adjustable resistor and a reactor, a current measuring device, a voltage measuring device, a tripping circuit breaker (5), a phase selection closing switch and a voltage waveform acquisition and measurement device which are connected in sequence; The primary high-voltage end of the voltage measuring device phase A (4-1) is connected to the phase A line of the short-circuit test system and is located at the front end of the opening circuit breaker, and the primary low-voltage end of the voltage measuring device phase A (4-1) is connected to the grounding terminal; the secondary side (4-1-1) of the voltage measuring device phase A is connected to the voltage measuring module (6-1-1) of the phase selection closing switch phase A.

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