A transformer differential protection polarity test system and method

Abstract

The invention discloses a transformer differential protection polarity testing system and method, comprising a high-voltage standby transformer high-voltage side bus, a high-voltage standby transformer high-voltage side interval, a high-voltage standby transformer, a high-voltage plant bus standby power supply incoming line interval, a generator set high-voltage plant bus, a capacitor load combination, a high-voltage plant bus voltage transformer, a feeder circuit breaker group, a capacitor load combination, a first differential protection device and a second differential protection device. The high-voltage standby transformer high-voltage side interval comprises a first isolating knife switch, a high-voltage standby transformer high-voltage side circuit breaker, a first current transformer and a second current transformer. The high-voltage plant bus standby power supply incoming line interval comprises a high-voltage plant bus standby power supply incoming line circuit breaker, a fourth current transformer, a third current transformer and a high-voltage plant bus standby power supply incoming line voltage transformer. The system and method can realize transformer differential protection polarity testing, and have strong versatility and high safety.

Description

Technical Field

[0001] The invention belongs to the technical field of power commissioning and power testing, and relates to a transformer differential protection polarity testing system and method. Background Art

[0002] Power plants are usually equipped with high-voltage standby transformers as backup power sources for the power plants. The low-voltage side of the high-voltage standby transformer is connected to the high-voltage plant busbar through a backup power supply incoming switch. When the high-voltage plant transformer cannot provide power to the high-voltage plant busbar, the high-voltage standby transformer can provide power to it.

[0003] When the power plant's booster station reverses power for the first time and the plant receives power, a phasor test is required to test whether the polarity of each differential protection is correct. The line differential and bus differential can be tested through the grid-side system circulating current or the long line capacitive current. However, the high-voltage standby transformer does not meet the power transmission conditions because the plant load has not yet completed installation and commissioning. Therefore, during the first reverse power transmission process, the high-voltage standby transformer often does not meet the phasor test conditions due to insufficient plant load capacity. Therefore, it is of great significance to find a transformer differential protection polarity test system and method. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a transformer differential protection polarity testing system and method. The system and method can realize transformer differential protection polarity testing and have strong versatility and high safety.

[0005] To achieve the above-mentioned purpose, the transformer differential protection polarity test system described in the present invention includes a high-voltage standby transformer high-voltage side bus, a high-voltage standby transformer high-voltage side interval, a high-voltage standby transformer, a high-voltage plant bus standby power supply incoming line interval, a generator set high-voltage plant bus, a capacitor load combination, a high-voltage plant bus voltage transformer, a feeder circuit breaker group, a capacitor load combination, a first differential protection device and a second differential protection device, the high-voltage standby transformer high-voltage side interval includes a first isolation knife switch, a second isolation knife switch, a high-voltage standby transformer high-voltage side circuit breaker, a first current transformer and a second current transformer, and the high-voltage plant bus standby power supply incoming line interval includes a high-voltage plant bus standby power supply incoming line circuit breaker, a fourth current transformer, a third current transformer and a high-voltage plant bus standby power supply incoming line voltage transformer;

[0006] The high-voltage side busbar of the high-voltage standby transformer is connected to the high-voltage plant busbar of the generator set via the first isolating knife switch, the high-voltage side circuit breaker of the high-voltage standby transformer, the second isolating knife switch, the high-voltage standby transformer, and the high-voltage plant busbar standby power supply incoming line circuit breaker. The capacitor load combination is connected to the high-voltage plant busbar of the generator set through the feeder circuit breaker group. The high-voltage plant busbar voltage transformer is installed on the high-voltage plant busbar of the generator set. The first current transformer and the second current transformer are installed on the line between the first isolating knife switch and the high-voltage side circuit breaker of the high-voltage standby transformer. The high-voltage plant busbar standby power supply incoming line voltage transformer, the third current transformer and the fourth current transformer are installed on the line between the high-voltage plant busbar standby power supply incoming line circuit breaker and the high-voltage standby transformer.

[0007] The first differential protection device is connected to the secondary side of the first current transformer and the secondary side of the fourth current transformer, and the second differential protection device is connected to the secondary side of the second current transformer and the secondary side of the third current transformer.

[0008] The capacitor load combination includes a plurality of capacitor loads, and the feeder circuit breaker group includes a plurality of feeder circuit breakers, wherein one capacitor load corresponds to one feeder circuit breaker, and wherein the capacitor load is connected to the high-voltage plant busbar of the generator set via the corresponding feeder circuit breaker.

[0009] High voltage side protection level current transformer current of high voltage standby transformer Among them, S is the total capacity of the capacitor load combination; U is the voltage of the high-voltage side bus of the high-voltage standby transformer; n is the transformation ratio of the high-voltage side protection level current transformer of the high-voltage standby transformer.

[0010] The transformer differential protection polarity testing method of the present invention comprises the following steps:

[0011] 1) Carry out preliminary preparations for differential protection polarity testing;

[0012] 2) adjusting the high-voltage standby transformer high-voltage side interval to a hot standby state;

[0013] 3) Close the high-voltage side circuit breaker of the high-voltage standby transformer and perform a full-voltage impact test on the high-voltage standby transformer;

[0014] 4) Check and determine whether the voltage amplitude and phase sequence of the high-voltage plant busbar backup power supply incoming voltage transformer are correct. When the voltage amplitude and phase sequence of the high-voltage plant busbar backup power supply incoming voltage transformer are correct, go to step 5); otherwise, go to step 6);

[0015] 5) Close the high-voltage plant bus standby power supply incoming circuit breaker, perform a full-voltage impact on the high-voltage plant bus of the generator set, and then go to step 7);

[0016] 6) Disconnect the high voltage side circuit breaker of the high voltage standby transformer, check and eliminate the defects, and then go to step 3);

[0017] 7) Check and determine whether the voltage amplitude and phase sequence of the high-voltage plant bus voltage transformer are correct. When the voltage amplitude and phase sequence of the high-voltage plant bus voltage transformer are correct, go to step 8); otherwise, go to step 9);

[0018] 8) Close each feeder circuit breaker in turn, apply full voltage shock to the capacitor load combination, and then go to step 10);

[0019] 9) Disconnect the high-voltage plant busbar backup power supply incoming circuit breaker, check and eliminate the defects, and then go to step 5);

[0020] 10) Check whether the differential protection polarities of the first differential protection device and the second differential protection device are correct. When the differential protection polarities of the first differential protection device and the second differential protection device are correct, go to step 12); otherwise, go to step 11);

[0021] 11) Disconnect each feeder circuit breaker, the high-voltage plant busbar backup power supply incoming circuit breaker and the high-voltage backup transformer high-voltage side circuit breaker, check and eliminate the defects, and then go to step 3);

[0022] 12) The differential protection polarity test is completed.

[0023] The specific operations of step 1) are:

[0024] Complete the installation and commissioning of all primary and secondary equipment within the power receiving range; adjust the high-voltage side busbar of the high-voltage standby transformer to the energized operating state.

[0025] The specific operations of step 2) are:

[0026] Close the first isolating knife switch and the second isolating knife switch through remote control; ensure that the first isolating knife switch and the second isolating knife switch are in the closed position both locally and remotely.

[0027] The specific operation of checking and judging whether the voltage amplitude and phase sequence of the high-voltage plant bus standby power supply incoming voltage transformer are correct in step 4) is as follows:

[0028] Check the secondary side voltage amplitude of the high-voltage plant bus standby power supply incoming line voltage transformer, determine whether the three-phase voltage amplitude on the secondary side of the high-voltage plant bus standby power supply incoming line voltage transformer is the primary side voltage of the high-voltage plant bus standby power supply incoming line voltage transformer divided by the transformation ratio of the high-voltage plant bus standby power supply incoming line voltage transformer, and whether the zero-sequence voltage is zero; check the secondary side voltage phase sequence of the high-voltage plant bus standby power supply incoming line voltage transformer, and determine whether the three-phase voltage of the high-voltage plant bus standby power supply incoming line voltage transformer is a positive phase sequence.

[0029] The specific process of checking and judging whether the voltage amplitude and phase sequence of the high-voltage plant bus voltage transformer are correct in step 7) is as follows:

[0030] Check the secondary side voltage amplitude of the high-voltage plant bus voltage transformer, determine whether the three-phase voltage amplitude on the secondary side of the high-voltage plant bus voltage transformer is the primary side voltage of the high-voltage plant bus voltage transformer divided by the transformation ratio of the high-voltage plant bus voltage transformer, and whether the zero-sequence voltage is zero; check the secondary side voltage phase sequence of the high-voltage plant bus voltage transformer, and determine whether the three-phase voltage of the high-voltage plant bus voltage transformer is a positive phase sequence.

[0031] In step 10), when the differential protection differential current of the first differential protection device and the second differential protection device is zero, the differential protection polarities of the first differential protection device and the second differential protection device are correct.

[0032] The present invention has the following beneficial effects:

[0033] The transformer differential protection polarity test system and method described in the present invention, during specific operation, uses a capacitor load combination as a high-voltage plant load, and the capacitor load is connected to the high-voltage plant busbar of the generator set via a feeder circuit breaker. The first differential protection device and the second differential protection device are used to test whether the differential protection polarity of the high-voltage standby transformer is correct, wherein, after the entire capacitor load combination is put into operation, the high-voltage side current of the high-voltage standby transformer of the differential protection device is greater than 15mA. It should be noted that the present invention uses a capacitor load combination as a high-voltage plant load, and there is no need to organize the plant load to perform a high-voltage standby transformer differential protection polarity test, which speeds up the progress of the first reverse power transmission of the power plant, has strong practicality and versatility, is suitable for the test of the transformer differential protection polarity when the main transformer and the high-voltage plant transformer of the power plant are reversed, and is convenient for on-site promotion and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic diagram of the structure of the present invention;

[0035] Figure 2 It is a flow chart of the present invention.

[0036] Among them, 1 is the high-voltage side bus of the high-voltage standby transformer, 2 is the high-voltage side interval of the high-voltage standby transformer, 3 is the high-voltage standby transformer, 4 is the high-voltage plant bus standby power supply incoming line interval, 5 is the high-voltage plant bus of the generator set, 6 is the high-voltage plant bus voltage transformer, 7 is the capacitor load combination, 8 is the first differential protection device, 9 is the second differential protection device, 10 is the feeder circuit breaker, 2-1 is the first isolating knife switch, 2-2 is the first current transformer, 2-3 is the second current transformer, 2-4 is the high-voltage side circuit breaker of the high-voltage standby transformer, 2-5 is the second isolating knife switch, 4-1 is the high-voltage plant bus standby power supply incoming line voltage transformer, 4-2 is the third current transformer, 4-3 is the fourth current transformer, and 4-4 is the high-voltage plant bus standby power supply incoming line circuit breaker. DETAILED DESCRIPTION

[0037] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0038] refer to Figure 1The transformer differential protection polarity test system of the present invention comprises a high-voltage standby transformer high-voltage side bus 1, a high-voltage standby transformer high-voltage side interval 2, a high-voltage standby transformer 3, a high-voltage plant bus standby power supply incoming line interval 4, a generator set high-voltage plant bus 5, a capacitor load combination 7, a high-voltage plant bus voltage transformer 6, a feeder circuit breaker group, a capacitor load combination 7, a first differential protection device 8 and a second differential protection device 9, the high-voltage standby transformer high-voltage side interval 2 comprises a first isolating knife switch 2-1, a second isolating knife switch 2-5, a high-voltage standby transformer high-voltage side circuit breaker 2-4, a first current transformer 2-2 and a second current transformer 2-3, the high-voltage plant bus standby power supply incoming line interval 4 comprises a high-voltage plant bus standby power supply incoming line circuit breaker 4-4, a fourth current transformer 4-3, a third current transformer 4-2 and a high-voltage plant bus standby power supply incoming line voltage transformer 4-1; the high-voltage standby transformer high-voltage side bus 1 is connected via the first isolating knife switch 2-1, the high-voltage standby transformer high-voltage side circuit breaker 2-4, the second The isolating knife switch 2-5, the high-voltage standby transformer 3, and the high-voltage plant bus standby power supply incoming circuit breaker 4-4 are connected to the high-voltage plant bus 5 of the generator set, the capacitor load combination 7 is connected to the high-voltage plant bus 5 of the generator set through the feeder circuit breaker group, the high-voltage plant bus voltage transformer 6 is installed on the high-voltage plant bus 5 of the generator set, and the first current transformer 2-2 and the second current transformer 2-3 are installed on the line between the first isolating knife switch 2-1 and the high-voltage standby transformer high-voltage side circuit breaker 2-4 The high-voltage plant busbar backup power supply incoming line voltage transformer 4-1, the third current transformer 4-2 and the fourth current transformer 4-3 are installed on the line between the high-voltage plant busbar backup power supply incoming line circuit breaker 4-4 and the high-voltage standby transformer 3; the first differential protection device 8 is connected to the secondary side of the first current transformer 2-2 and the secondary side of the fourth current transformer 4-3, and the second differential protection device 9 is connected to the secondary side of the second current transformer 2-3 and the secondary side of the third current transformer 4-2.

[0039] The capacitor load combination 7 includes a plurality of capacitor loads, and the feeder circuit breaker group includes a plurality of feeder circuit breakers 10, wherein one capacitor load corresponds to one feeder circuit breaker 10, wherein the capacitor load is connected to the high-voltage plant bus 5 of the generator set via the corresponding feeder circuit breaker 10.

[0040] High voltage side protection level current transformer current of high voltage standby transformer 3 Among them, S is the total capacity of the capacitor load combination 7; U is the voltage of the high-voltage side bus 1 of the high-voltage standby transformer; n is the transformation ratio of the high-voltage side protection level current transformer of the high-voltage standby transformer 3.

[0041] refer to Figure 2 The transformer differential protection polarity testing method of the present invention comprises the following steps:

[0042] 1) Carry out preliminary preparations for differential protection polarity testing;

[0043] 2) adjusting the high-voltage standby transformer high-voltage side interval 2 to a hot standby state;

[0044] 3) Close the high-voltage side circuit breaker 2-4 of the high-voltage standby transformer and perform a full-voltage impact test on the high-voltage standby transformer 3;

[0045] 4) Check and determine whether the voltage amplitude and phase sequence of the high-voltage plant busbar backup power supply incoming line voltage transformer 4-1 are correct. When the voltage amplitude and phase sequence of the high-voltage plant busbar backup power supply incoming line voltage transformer 4-1 are correct, go to step 5); otherwise, go to step 6);

[0046] 5) Close the high-voltage plant bus standby power supply incoming line circuit breaker 4-4, perform full-voltage impact on the generator set high-voltage plant bus 5, and then go to step 7);

[0047] 6) Disconnect the high voltage standby transformer high voltage side circuit breaker 2-4, check and eliminate the defects, and then go to step 3);

[0048] 7) Check and determine whether the voltage amplitude and phase sequence of the high-voltage plant bus voltage transformer 6 are correct. When the voltage amplitude and phase sequence of the high-voltage plant bus voltage transformer 6 are correct, go to step 8); otherwise, go to step 9);

[0049] 8) Close each feeder circuit breaker 10 in sequence, perform full voltage impact on the capacitor load combination 7, and then go to step 10);

[0050] 9) Disconnect the high-voltage plant busbar backup power supply incoming circuit breaker 4-4, check and eliminate the defects, and then go to step 5);

[0051] 10) Check whether the differential protection polarities of the first differential protection device 8 and the second differential protection device 9 are correct. When the differential protection polarities of the first differential protection device 8 and the second differential protection device 9 are correct, go to step 12); otherwise, go to step 11);

[0052] 11) Disconnect each feeder circuit breaker 10, the high-voltage plant busbar backup power supply incoming circuit breaker 4-4 and the high-voltage backup transformer high-voltage side circuit breaker 2-4, check and eliminate the defects, and then go to step 3);

[0053] 12) The differential protection polarity test is completed.

[0054] The specific operation of step 1) is: complete the installation and commissioning of all primary and secondary equipment within the power receiving range; adjust the high-voltage side bus 1 of the high-voltage standby transformer to the energized operating state.

[0055] The specific operation of step 2) is: close the first isolating knife switch 2-1 and the second isolating knife switch 2-5 by remote control; ensure that the first isolating knife switch 2-1 and the second isolating knife switch 2-5 are in the closed position both locally and remotely.

[0056] The specific operation of checking and judging whether the voltage amplitude and phase sequence of the high-voltage plant bus standby power supply incoming line voltage transformer 4-1 are correct in step 4) is as follows: checking the secondary side voltage amplitude of the high-voltage plant bus standby power supply incoming line voltage transformer 4-1, judging whether the three-phase voltage amplitude of the secondary side of the high-voltage plant bus standby power supply incoming line voltage transformer 4-1 is the primary side voltage of the high-voltage plant bus standby power supply incoming line voltage transformer 4-1 divided by the transformation ratio of the high-voltage plant bus standby power supply incoming line voltage transformer 4-1, and whether the zero-sequence voltage is zero; checking the secondary side voltage phase sequence of the high-voltage plant bus standby power supply incoming line voltage transformer 4-1, and judging whether the three-phase voltage of the high-voltage plant bus standby power supply incoming line voltage transformer 4-1 is a positive phase sequence.

[0057] The specific process of checking and judging whether the voltage amplitude and phase sequence of the high-voltage plant bus voltage transformer 6 are correct in step 7) is as follows: checking the secondary side voltage amplitude of the high-voltage plant bus voltage transformer 6, judging whether the three-phase voltage amplitude on the secondary side of the high-voltage plant bus voltage transformer 6 is the primary side voltage of the high-voltage plant bus voltage transformer 6 divided by the transformation ratio of the high-voltage plant bus voltage transformer 6, and whether the zero-sequence voltage is zero; checking the secondary side voltage phase sequence of the high-voltage plant bus voltage transformer 6, and judging whether the three-phase voltage of the high-voltage plant bus voltage transformer 6 is a positive phase sequence.

[0058] In step 10), when the differential protection differential current of the first differential protection device 8 and the second differential protection device 9 is zero, the differential protection polarities of the first differential protection device 8 and the second differential protection device 9 are correct.

[0059] The first differential protection device 8 performs a transformer differential protection polarity test by detecting the current polarity detected by the first current transformer 2-2 and the current polarity detected by the fourth current transformer 4-3, and the second differential protection device 9 performs a transformer differential protection polarity test by detecting the current polarity detected by the second current transformer 2-3 and the current polarity detected by the third current transformer 4-2.

Claims

1. A transformer differential protection polarity test system, characterized in that: The invention comprises a high-voltage standby transformer high-voltage side busbar (1), a high-voltage standby transformer high-voltage side compartment (2), a high-voltage standby transformer (3), a high-voltage plant busbar standby power supply incoming line compartment (4), a generator set high-voltage plant busbar (5), a capacitor load combination (7), a high-voltage plant busbar voltage transformer (6), a feeder circuit breaker group, a capacitor load combination (7), a first differential protection device (8) and a second differential protection device (9); the high-voltage standby transformer high-voltage side compartment (2) comprises a first isolating knife switch (2-1), a second isolating knife switch (2-5), a high-voltage standby transformer high-voltage side circuit breaker (2-4), a first current transformer (2-2) and a second current transformer (2-3); the high-voltage plant busbar standby power supply incoming line compartment (4) comprises a high-voltage plant busbar standby power supply incoming line circuit breaker (4-4), a fourth current transformer (4-3), a third current transformer (4-2) and a high-voltage plant busbar standby power supply incoming line voltage transformer (4-1); The high-voltage standby transformer high-voltage side busbar (1) is connected to the generator set high-voltage plant busbar (5) via the first isolating switch (2-1), the high-voltage standby transformer high-voltage side circuit breaker (2-4), the second isolating switch (2-5), the high-voltage standby transformer (3), and the high-voltage plant busbar standby power supply incoming line circuit breaker (4-4); the capacitor load combination (7) is connected to the generator set high-voltage plant busbar (5) via the feeder circuit breaker group; the high-voltage plant busbar voltage transformer (6) is installed at the generator set high-voltage plant busbar voltage transformer (6). The first current transformer (2-2) and the second current transformer (2-3) are installed on the line between the first isolating switch (2-1) and the high-voltage standby transformer high-voltage side circuit breaker (2-4), and the high-voltage plant bus standby power supply incoming line voltage transformer (4-1), the third current transformer (4-2) and the fourth current transformer (4-3) are installed on the line between the high-voltage plant bus standby power supply incoming line circuit breaker (4-4) and the high-voltage standby transformer (3); The first differential protection device (8) is connected to the secondary side of the first current transformer (2-2) and the secondary side of the fourth current transformer (4-3), and the second differential protection device (9) is connected to the secondary side of the second current transformer (2-3) and the secondary side of the third current transformer (4-2); High voltage side protection level current transformer current of high voltage standby transformer (3) Wherein, S is the total capacity of the capacitor load combination (7); U is the voltage of the high-voltage side busbar (1) of the high-voltage standby transformer; and n is the transformation ratio of the high-voltage side protection-level current transformer of the high-voltage standby transformer (3).

2. The transformer differential protection polarity test system according to claim 1, characterized in that: The capacitor load combination (7) includes a plurality of capacitor loads, and the feeder circuit breaker group includes a plurality of feeder circuit breakers (10), wherein one capacitor load corresponds to one feeder circuit breaker (10), and wherein the capacitor load is connected to the high-voltage plant busbar (5) of the generator set via the corresponding feeder circuit breaker (10).

3. A transformer differential protection polarity testing method, characterized in that: The transformer differential protection polarity test system according to claim 1 comprises the following steps: 1) Carry out preliminary preparations for differential protection polarity testing; 2) adjusting the high-voltage standby transformer high-voltage side interval (2) to a hot standby state; 3) Close the high-voltage side circuit breaker (2-4) of the high-voltage standby transformer and perform a full-voltage impact test on the high-voltage standby transformer (3); 4) Check and determine whether the voltage amplitude and phase sequence of the high-voltage plant busbar backup power supply incoming line voltage transformer (4-1) are correct. When the voltage amplitude and phase sequence of the high-voltage plant busbar backup power supply incoming line voltage transformer (4-1) are correct, go to step 5); otherwise, go to step 6); 5) Close the high-voltage plant bus standby power supply incoming line circuit breaker (4-4), perform a full-voltage impact on the generator set high-voltage plant bus (5), and then go to step 7); 6) Disconnect the high voltage standby transformer high voltage side circuit breaker (2-4), check and eliminate the defects, and then go to step 3); 7) Check and determine whether the voltage amplitude and phase sequence of the high-voltage plant bus voltage transformer (6) are correct. If the voltage amplitude and phase sequence of the high-voltage plant bus voltage transformer (6) are correct, go to step 8); otherwise, go to step 9); 8) Close each feeder circuit breaker (10) in sequence, perform a full voltage impact on the capacitor load combination (7), and then go to step 10); 9) Disconnect the high-voltage plant busbar backup power supply incoming circuit breaker (4-4), check and eliminate the defects, and then go to step 5); 10) Check whether the differential protection polarities of the first differential protection device (8) and the second differential protection device (9) are correct. If the differential protection polarities of the first differential protection device (8) and the second differential protection device (9) are correct, go to step 12); otherwise, go to step 11); 11) Disconnect each feeder circuit breaker (10), the high-voltage plant busbar backup power supply incoming circuit breaker (4-4) and the high-voltage backup transformer high-voltage side circuit breaker (2-4), check and eliminate the defects, and then go to step 3); 12) The differential protection polarity test is completed.

4. The transformer differential protection polarity testing method according to claim 3, characterized in that: The specific operations of step 1) are: Complete the installation and commissioning of all primary and secondary equipment within the power receiving range; adjust the high-voltage side busbar (1) of the high-voltage standby transformer to the energized operating state.

5. The transformer differential protection polarity testing method according to claim 3, characterized in that: The specific operations of step 2) are: The first isolating knife switch (2-1) and the second isolating knife switch (2-5) are closed by remote control, ensuring that the first isolating knife switch (2-1) and the second isolating knife switch (2-5) are in the closed position both locally and remotely.

6. The transformer differential protection polarity testing method according to claim 3, characterized in that: The specific operation of checking and judging whether the voltage amplitude and phase sequence of the high-voltage plant bus standby power supply incoming voltage transformer (4-1) are correct in step 4) is as follows: Check the secondary side voltage amplitude of the high-voltage plant bus standby power supply incoming line voltage transformer (4-1), and determine whether the three-phase voltage amplitude of the secondary side of the high-voltage plant bus standby power supply incoming line voltage transformer (4-1) is the primary side voltage of the high-voltage plant bus standby power supply incoming line voltage transformer (4-1) divided by the transformation ratio of the high-voltage plant bus standby power supply incoming line voltage transformer (4-1), and whether the zero-sequence voltage is zero; check the secondary side voltage phase sequence of the high-voltage plant bus standby power supply incoming line voltage transformer (4-1), and determine whether the three-phase voltage of the high-voltage plant bus standby power supply incoming line voltage transformer (4-1) is a positive phase sequence.

7. The transformer differential protection polarity testing method according to claim 3, characterized in that: The specific process of checking and judging whether the voltage amplitude and phase sequence of the high-voltage plant bus voltage transformer (6) are correct in step 7) is as follows: Check the secondary side voltage amplitude of the high-voltage plant bus voltage transformer (6) to determine whether the three-phase voltage amplitude of the secondary side of the high-voltage plant bus voltage transformer (6) is the primary side voltage of the high-voltage plant bus voltage transformer (6) divided by the transformation ratio of the high-voltage plant bus voltage transformer (6), and whether the zero-sequence voltage is zero; check the secondary side voltage phase sequence of the high-voltage plant bus voltage transformer (6) to determine whether the three-phase voltage of the high-voltage plant bus voltage transformer (6) is a positive phase sequence.

8. The transformer differential protection polarity testing method according to claim 3, characterized in that: In step 10), when the differential protection differential current of the first differential protection device (8) and the second differential protection device (9) is zero, the differential protection polarity of the first differential protection device (8) and the second differential protection device (9) is correct.

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