A new high-safety plant system load test method

Abstract

The present application discloses a novel high-safety on-load test method for a factory system, comprising a high-voltage side primary current-passing method, a low-voltage side primary current-passing method and a high-voltage side boosted primary current-passing method; wherein the high-voltage side primary current-passing method uses a 400V test power supply to perform a short-circuit test, uses the short-circuit current to verify the polarity of the current transformer and the correctness of the secondary cable installation, and completes the on-load test; the low-voltage side primary current-passing method uses a single-phase relay protection tester, adopts a phase detection method, and takes the first low-voltage branch as a reference to complete the on-load test of all low-voltage branches; the high-voltage side boosted primary current-passing method uses a boosted test transformer as a test power supply, increases the secondary current of the current transformer to observe the differential current on the protection device; the present application avoids dependence on and influence on the auxiliary system of the unit, and can safely and efficiently complete the on-load test of the start-up and standby transformer interval.

Description

Technical Field

[0001] The present application belongs to the technical field of on-load testing methods for factory systems, and in particular, relates to a novel high-safety on-load testing method for factory systems. Background Art

[0002] In power infrastructure projects or after the protection device is modified, bus differential protection (starting and standby transformer interval), starting and standby transformer differential protection, etc. need to be tested with load before commissioning. Observe whether there is differential current on the protection device to ensure that the polarity of the current transformer and the secondary cable are installed correctly. The conventional load test method is to use the starting and standby transformer to power auxiliary machines such as high-power fans and water pumps to generate a large load current. If it is an infrastructure project, these high-power auxiliary machines are often not installed, do not meet the starting conditions, and cannot provide a large enough load current for differential protection verification; if it is after the protection modification, the high-power auxiliary machines of the operating units need to be switched to standby, and the on-site operation workload is large, the time is long, and there are great safety risks.

[0003] Therefore, it is imperative to study a new high-safety plant system load test method to calibrate the differential protection. Summary of the invention

[0004] In view of the above problems, the embodiment of the present application provides a new high-safety plant system load test method, which avoids the dependence and influence on the auxiliary system of the unit, and can safely and efficiently complete the load test of the start-up and standby interval. The technical solution is as follows:

[0005] The present application provides a novel high-safety plant system load test method, including a high-voltage side primary current-passing method, a low-voltage side primary current-passing method and a high-voltage side boosted primary current-passing method; wherein, the high-voltage side primary current-passing method uses a 400V test power supply to perform a short-circuit test, uses the short-circuit current to verify the polarity of the current transformer and the correctness of the secondary cable installation, and completes the load test; the low-voltage side primary current-passing method uses a single-phase relay protection tester, adopts a phase detection method, and takes the first low-voltage branch as a reference to complete the load test of all low-voltage branches; the high-voltage side boosted primary current-passing method uses a boost test transformer as a test power supply, increases the secondary current of the current transformer to observe the differential current on the protection device.

[0006] For example, in the new high-safety plant system load test method provided in one embodiment, the high-voltage side primary current flow method includes the following steps: Step 1: Disconnect the high-voltage side switch and the isolating switch of the standby transformer and switch it to cold standby; Step 2: Pull all the branch standby incoming line switch trolleys of the low-voltage side of the standby transformer out of the warehouse, and use the short-circuit bar to short-circuit the three phases on the power supply side; Step 3: Add a 400V test power supply to the high-voltage side incoming line of the standby transformer; Step 4: Calculate the theoretical values ​​of the high and low voltage side currents.

[0007] For example, in the novel high-safety plant system load test method provided in one embodiment, in step 4, the theoretical values ​​of the high and low voltage side currents are calculated, and at this time, the secondary current on the high voltage side is:

[0008]

[0009] Among them, I n U is the rated current of the high voltage side when the standby transformer is in full-ride operation; 0.4 is the applied 400V test voltage; U ng X is the rated voltage of the high voltage side of the standby transformer; 1-23 To start the full through impedance; n TAg is the current transformer ratio on the high voltage side;

[0010] At this time, the secondary current I d1 for:

[0011]

[0012] Among them, U nd is the rated voltage of the low voltage side; n TAd is the current transformer ratio on the low voltage side.

[0013] For example, in the novel high-safety plant system load test method provided in one embodiment, the high-voltage side primary current passing method further includes: Step 5: Connecting the multi-turn coil to the secondary circuit of the current transformer, and using a phase volt-ampere meter current clamp to clamp the total current of the multi-turn coil: I t =n×I0, which can multiply the secondary current.

[0014] For example, in the new high-safety plant system load test method provided in one embodiment, all low-voltage branches in the high-voltage side primary current flow method use a short-circuit bar to perform three-phase short-circuiting, and the short-circuit current is used to check whether the current transformer polarity and the secondary cable are installed correctly.

[0015] For example, in the novel high-safety plant system load test method provided in one embodiment, the low-voltage side primary current flow method includes the following steps: Step 1: Select the first low-voltage side branch as a reference, pull the first low-voltage side branch spare incoming line switch trolley out of the warehouse; pull the second low-voltage side branch spare incoming line switch trolley out of the warehouse; connect the live wire of the primary current flow device to the first low-voltage side branch A phase, and the neutral wire to the ground; the other spare branch switch and the current transformer are grounded; adjust the current of the primary current flow device to an appropriate value; observe the current of the two low-voltage branches on the protection device. Flow, and should meet the requirements of equal size and 180 degrees phase difference; Step 2: Repeat the test process of step 1 on the first low-voltage side branch phase B; Step 3: Repeat the test process of step 1 on the first low-voltage side branch phase C; Step 4: Taking the first low-voltage side branch as the reference, repeat the test process of steps 1 to 3 with all other low-voltage side branches to complete a current flow test on all branches; Put the high-voltage side of the standby transformer into operation, and only put the first reference branch into the low-voltage side, organize the factory auxiliary machine to carry out load test, and verify whether the polarity of the reference branch current transformer and the secondary cable installation are correct.

[0016] For example, in the new high-safety plant system load test method provided in one embodiment, in the low-voltage side primary current flow method, the first low-voltage side branch is selected as the reference branch, and the phase-splitting primary current flow method is used to confirm that the polarity of all other branch current transformers and the secondary circuits are installed correctly and are consistent with the reference branch.

[0017] For example, in the new high-safety plant system load test method provided in one embodiment, in the low-voltage side primary current flow method, a load test method is used to confirm that the polarity of the current transformer on the high-voltage side of the standby transformer and the reference branch and the secondary circuit are installed correctly.

[0018] For example, in the novel high-safety plant system load test method provided in one embodiment, the high-voltage side boost primary current flow method includes the following steps: Step 1: disconnect the high-voltage side switch and the isolating switch of the standby transformer, and switch to cold standby; Step 2: pull all the standby transformer low-voltage side branch standby incoming line switch trolleys out of the warehouse, and use the short-circuit bar to short-circuit the three phases on the power supply side; Step 3: add the output of the test transformer to the high-voltage side incoming line of the standby transformer; Step 4: determine the expected high-voltage side secondary current I according to the accuracy level of the protection device. g ; Step 5: Reverse calculation of the required test transformer voltage U T , and U T satisfy:

[0019]

[0020] At this time, the secondary current I d1 for:

[0021]

[0022] Step 6: Check the current on the high and low voltage sides directly in the protection device to confirm that the amplitude and phase are correct and the differential current is zero.

[0023] For example, in the new high-safety plant system load test method provided in one embodiment, in the high-voltage side boost primary current method, all low-voltage branches use a short-circuit bar to perform a three-phase short-circuit, and the short-circuit current is used to verify the polarity of the current transformer and the correct installation of the secondary cable.

[0024] The beneficial effects brought about by the new high-safety plant system load test method of the present application are: the new high-safety plant system load test method of the present application includes a high-pressure side primary flow method, a low-pressure side primary flow method and a high-pressure side boost primary flow method, which avoids dependence on and influence on the auxiliary system of the unit, and can safely and efficiently complete the load test of the start-up and standby interval. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 Schematic diagram of the primary flow method on the high-pressure side of the present application;

[0027] Figure 2 Schematic diagram of the low-pressure side primary flow method of the present application;

[0028] Figure 3 Schematic diagram of the high-pressure side boosting primary flow method of the present application. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0030] Unless otherwise defined, the technical terms or scientific terms used in the present disclosure should be understood by people with ordinary skills in the field to which the present disclosure belongs. The "first", "second" and similar words used in the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0031] This application provides a new high-safety plant system load test method, such as Figure 1-3 As shown, it includes a primary current-passing method on the high-voltage side, a primary current-passing method on the low-voltage side and a primary current-passing method on the high-voltage side; wherein, the primary current-passing method on the high-voltage side uses a 400V test power supply to perform a short-circuit test, uses the short-circuit current to verify the polarity of the current transformer and the correctness of the secondary cable installation, and completes the load test; the primary current-passing method on the low-voltage side uses a single-phase relay protection tester, adopts a phase-splitting detection method, and takes the first low-voltage branch as a reference to complete the load test of all low-voltage branches; the primary current-passing method on the high-voltage side uses a step-up test transformer as a test power supply, increases the secondary current of the current transformer to observe the differential current on the protection device. According to the above embodiments, the primary current-carrying method on the high-voltage side of the present application does not need to use a start-up transformer to power the high-power auxiliary machine, and does not need to adjust the auxiliary machine operation mode. A 400V test power supply can be used directly for a short-circuit test, and the short-circuit current is used to verify the polarity of the current transformer and the correct installation of the secondary cable to complete the load test; the primary current-carrying method on the low-voltage side has a lower test voltage, and a single-phase relay protection tester can be used to complete the test. The phase detection method is adopted, and the first low-voltage branch is used as the reference to complete the load test of all low-voltage branches; the high-voltage side boost primary current-carrying method uses a boost test transformer as a test power supply, which can effectively increase the secondary current of the current transformer, making it convenient to directly observe the differential current on the protection device.

[0032] For example, in the novel high-safety plant system load test method provided in one embodiment, as Figure 1 As shown, the high-pressure side primary flow method comprises the following steps:

[0033] Step 1: Disconnect the high-voltage side switch and the isolating switch of the standby transformer and switch it to cold standby;

[0034] Step 2: Pull all the standby transformer low-voltage side branch standby incoming line switch trolleys out of the warehouse, and use the short-circuit bar to short-circuit the three phases on the power supply side;

[0035] Step 3: Add 400V test power to the high voltage side of the standby transformer;

[0036] Step 4: Calculate the theoretical current values ​​of the high and low voltage sides.

[0037] For example, in the novel high-safety plant system load test method provided in one embodiment, in step 4, the theoretical values ​​of the high and low voltage side currents are calculated, and at this time, the secondary current on the high voltage side is:

[0038]

[0039] Among them, I n U is the rated current of the high voltage side when the standby transformer is in full-ride operation; 0.4 is the applied 400V test voltage; U ng X is the rated voltage of the high voltage side of the standby transformer; 1-23 To start the full through impedance; n TAg is the current transformer ratio on the high voltage side;

[0040] At this time, the secondary current I d1 for:

[0041]

[0042] Among them, U nd is the rated voltage of the low voltage side; n TAd is the current transformer ratio on the low voltage side.

[0043] For example, in the novel high-safety plant system load test method provided in one embodiment, as Figure 1 As shown, the high-voltage side primary current passing method also includes: Step 5: Connect the multi-turn coil to the secondary circuit of the current transformer, and use a phase volt-ampere meter current clamp to clamp the total current of the multi-turn coil: I t =n×I0, which can multiply the secondary current.

[0044] For example, in the novel high-safety plant system load test method provided in one embodiment, as Figure 1As shown, in the high-voltage side primary current-passing method, all low-voltage branches use a short-circuit bar for three-phase short-circuiting, and the short-circuit current is used to check whether the polarity of the current transformer and the secondary cable are correctly installed. According to the above embodiment, the high-voltage side primary current-passing method of the present application is changed from standby to cold standby state; there is no need to use the standby state to power the high-power auxiliary machine, and there is no need to adjust the auxiliary machine operation mode, the test voltage is low, and the safety is strong; all low-voltage branches use a short-circuit bar for three-phase short-circuiting, and the short-circuit current is used to check whether the polarity of the current transformer and the secondary cable are correctly installed; it is suitable for the case where the current transformer on the high-voltage side is relatively small, and the multi-turn coil can be connected in series to the secondary circuit of the current transformer, and the phase volt-ampere meter current clamp is used to clamp the total current of the multi-turn coil, which doubles the detection sensitivity.

[0045] For example, in the novel high-safety plant system load test method provided in one embodiment, as Figure 2 As shown, the low-voltage side primary current passing method includes the following steps: Step 1: Select the first low-voltage side branch as a reference, pull the first low-voltage side branch standby incoming line switch trolley out of the warehouse; pull the second low-voltage side branch standby incoming line switch trolley out of the warehouse; connect the live wire of the primary current passing device to the first low-voltage side branch phase A, and the neutral wire is grounded; the other standby branch switch and the current transformer are grounded; adjust the current of the primary current passing device to an appropriate value; observe the current of the two low-voltage branches on the protection device, and they should be equal in magnitude and have a phase difference of 1 80 degrees; Step 2: Repeat the test process of step 1 on the first low-voltage side branch B phase; Step 3: Repeat the test process of step 1 on the first low-voltage side branch C phase; Step 4: Take the first low-voltage side branch as the reference, and repeat the test process of step 1-step 3 with all other low-voltage side branches to complete a current flow test on all branches; Put the high-voltage side of the standby transformer into operation, and only put the first reference branch into the low-voltage side, organize the factory auxiliary equipment to carry out load test, and verify whether the polarity of the reference branch current transformer and the secondary cable installation are correct.

[0046] For example, in the novel high-safety plant system load test method provided in one embodiment, as Figure 2 As shown, in the low-voltage side primary current-passing method, the first low-voltage side branch is selected as the reference branch, and the phase-splitting primary current-passing method is used to confirm that the polarity of all other branch current transformers and the secondary circuits are installed correctly and are consistent with the reference branch.

[0047] For example, in the novel high-safety plant system load test method provided in one embodiment, as Figure 2As shown, in the low-voltage side primary current-passing method, a load test method is used to confirm that the polarity of the current transformers on the high-voltage side of the standby transformer and the reference branch and the secondary circuit are correctly installed. According to the above embodiment, the low-voltage side primary current-passing method of the present application selects a low-voltage side branch as the reference branch; the phase-splitting primary current-passing method is used to confirm that the polarity of the current transformers and the secondary circuits of all other branches are correctly installed and consistent with the reference branch; since the primary current-passing circuit does not pass through the transformer winding, the circuit impedance is very low, the test voltage is very low, and it has the highest safety; the traditional load test method is used to confirm that the polarity of the current transformers on the high-voltage side of the standby transformer and the reference branch and the secondary circuit are correctly installed; the workload and time of the traditional method of switching the high-power auxiliary machine of the running unit to the standby one can be greatly reduced, and the safety risk of the load test can be reduced.

[0048] For example, in the novel high-safety plant system load test method provided in one embodiment, as Figure 3 As shown, the high-pressure side boosting primary flow method comprises the following steps:

[0049] Step 1: Disconnect the high-voltage side switch and the isolating switch of the standby transformer and switch it to cold standby;

[0050] Step 2: Pull all the standby transformer low-voltage side branch standby incoming line switch trolleys out of the warehouse, and use the short-circuit bar to short-circuit the three phases on the power supply side;

[0051] Step 3: Add the output of the test transformer to the high-voltage side of the standby transformer;

[0052] Step 4: Determine the expected high-voltage side secondary current I according to the accuracy level of the protection device g ;

[0053] Step 5: Reverse calculation of the required test transformer voltage U T , and U T satisfy:

[0054]

[0055] At this time, the secondary current I d1 for:

[0056]

[0057] Step 6: Check the current on the high and low voltage sides directly in the protection device to confirm that the amplitude and phase are correct and the differential current is zero.

[0058] For example, in the novel high-safety plant system load test method provided in one embodiment, as Figure 3As shown, in the high-voltage side boost primary current flow method, all low-voltage branches use a short-circuit bar for three-phase short-circuiting, and the short-circuit current is used to verify that the current transformer polarity and the secondary cable are correctly installed. According to the above embodiment, the high-voltage side boost primary current flow method of the present application is in a cold standby state; there is no need to use a standby transformer to power a high-power auxiliary machine, and there is no need to adjust the auxiliary machine operation mode, and an adjustable test transformer is used to power the high-voltage side of the standby transformer; all low-voltage branches use a short-circuit bar for three-phase short-circuiting, and the short-circuit current is used to verify that the current transformer polarity and the secondary cable are correctly installed; according to the performance of the protection device, the test transformer voltage is flexibly adjusted to obtain a more obvious secondary current, which is suitable for the case where the current transformer on the high-voltage side is relatively large.

[0059] 1. Application cases of the high-pressure side primary flow method of this application

[0060] Taking the relevant parameters of a 220kV standby transformer in a power plant as an example, the parameters of the standby transformer are shown in Table 1:

[0061] Table 1 High-pressure side primary flow method start-up parameter table

[0062]

[0063] The transformer connection type is Yy0, and the current transformers on the high and low voltage sides are connected at 180 degrees; the current transformer ratio on the high voltage side is 1000 / 5A, and the current transformer ratio on the low voltage side is 4000 / 5A. The primary current flow method on the high voltage side includes the following steps:

[0064] 1) Disconnect the high-voltage side switch and isolating switch of the standby transformer and switch it to cold standby;

[0065] 2) Pull all the standby incoming line switch trolleys on the low-voltage side of the standby transformer out of the warehouse, and use the short-circuit bar to short-circuit the three phases on the power supply side;

[0066] 3) Add 400V test power to the high voltage side of the standby transformer;

[0067] 4) Calculate the theoretical value of high and low voltage side current:

[0068] At this time, the secondary current on the high-voltage side is:

[0069]

[0070] At this time, the secondary current on the low-voltage side is:

[0071]

[0072] By using a 5-turn coil to access the secondary circuit of the high-voltage side current transformer, the high-voltage side current can be amplified to 0.050A, meeting the precise measurement requirements of commonly used phase volt-ampere meters.

[0073] Taking the high voltage side current as the reference, the low voltage side current phase is 180 degrees.

[0074] 2. Application cases of the low-pressure side primary flow method of this application

[0075] Taking a 500kV standby transformer in a certain plant as an example, the 10kV 1A section 9110 standby power supply incoming line switch, the 10kV1B section 9120 standby power supply incoming line switch, the 6kV 1A section 6110 standby power supply incoming line switch, the 6kV1B section 6120 standby power supply incoming line switch, the 10kV 2A section 9210 standby power supply incoming line switch, and the 10kV 2B section 9220 standby power supply incoming line switch are in the test opening state, and each standby branch PT is in the test position. The low-voltage side primary current passing method includes the following steps:

[0076] 1) Disconnect the high-voltage side switch and isolating switch of the standby transformer and switch it to cold standby;

[0077] 2) Select the 10kV 1A branch of unit #1 as the reference, pull the 9110 spare incoming line switch trolley out of the warehouse, connect the live wire of the primary current-carrying equipment to phase A on the power supply side, and ground the neutral wire;

[0078] 3) Pull the 10kV1B branch 9120 spare incoming line switch trolley out of the warehouse and ground phase A on the power supply side;

[0079] 4) Operate the primary current-carrying device to increase the current to 100A. Since the ratio of the standby incoming current transformer is 3000 / 5, the secondary current is calculated as:

[0080]

[0081] 5) Use a phase volt-ampere meter to detect the secondary current of the current transformers of the 9110 and 9120 backup power supply lines. The amplitude is consistent with the calculated value, and the phase difference is 180 degrees;

[0082] 6) Then conduct current flow between phases B and C. After the three-phase current flow is completed, remove the grounding point at the 9120 switch;

[0083] 7) Carry out a primary current flow between each branch and the 10kV 1A branch of 10kV 2A (in the order of C, B, A phases), 10kV 2B (in the order of A, B, C phases), 10kV 3A (in the order of C, B, A phases), 10kV 3B (in the order of A, B, C phases), 10kV 4A (in the order of C, B, A phases), 10kV 4B (in the order of A, B, C phases) in sequence. After completion, remove all branch grounding wires and remove the primary current flow equipment test circuit;

[0084] 8) Put the high-voltage side of the standby transformer into operation, and only put the 10kV 1A branch into operation on the low-voltage side. Organize the factory auxiliary equipment to carry out load tests, verify that the polarity of the reference branch current transformer and the secondary cable are installed correctly, and then the load test can be completed.

[0085] 3. Application cases of the high-voltage side boosting primary flow method of this application

[0086] Taking the relevant parameters of a 220kV standby transformer in a power plant as an example, the parameters of the standby transformer are shown in Table 2:

[0087] Table 2 High-voltage side boost primary flow method standby transformer parameter table

[0088]

[0089] The current transformer ratio on the high-voltage side is 1000 / 5A, and the current transformer ratio on the low-voltage side is 4000 / 5A. The high-voltage side boosting primary current flow method includes the following steps:

[0090] 1) Disconnect the high-voltage side switch and isolating switch of the standby transformer and switch it to cold standby;

[0091] 2) Pull all the standby incoming line switch trolleys on the low-voltage side of the standby transformer out of the warehouse, and use the short-circuit bar to short-circuit the three phases on the power supply side;

[0092] 3) Add the output of the test transformer to the high-voltage side of the standby transformer;

[0093] 4) According to the accuracy level of the protection device, the expected secondary current on the high-voltage side is determined as: I g =0.1A

[0094] 5) Reverse calculation of the required test transformer voltage U T ;

[0095]

[0096] 6) At this time, the secondary current on the low voltage side is:

[0097]

[0098] 7) Check the current on the high and low voltage sides directly in the protection device to confirm that the amplitude and phase are correct and the differential current is zero.

[0099] Although the embodiments of the present application have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims

1. A new high-security plant system load test method, characterized in that: include: A high-pressure side primary flow method, a low-pressure side primary flow method, and a high-pressure side boosted primary flow method; Among them, the primary current-carrying method on the high-voltage side uses a 400V test power supply to perform a short-circuit test, uses the short-circuit current to verify the polarity of the current transformer and the correctness of the secondary cable installation, and completes the load test; the primary current-carrying method on the low-voltage side uses a single-phase relay protection tester, adopts a phase detection method, and takes the first low-voltage branch as a reference to complete the load test of all low-voltage branches; the primary current-carrying method on the high-voltage side uses a step-up test transformer as a test power supply to increase the secondary current of the current transformer to observe the differential current on the protection device. The primary current-carrying method on the high-voltage side includes the following steps: Step 1: Disconnect the high-voltage side switch and the isolating switch of the standby transformer and switch it to cold standby; Step 2: Pull all the standby transformer low-voltage side branch standby incoming line switch trolleys out of the warehouse, and use the short-circuit bar to short-circuit the three phases on the power supply side; Step 3: Add 400V test power to the high voltage side of the standby transformer; Step 4: Calculate the theoretical values ​​of the high and low voltage side currents. In step 4, the theoretical values ​​of the high and low voltage side currents are calculated. At this time, the secondary current on the high voltage side is: Among them, I n U is the rated current of the high voltage side when the standby transformer is in full-ride operation; 0.4 is the applied 400V test voltage; U ng X is the rated voltage of the high voltage side of the standby transformer; 1-23 To start the full through impedance; n TAg is the current transformer ratio on the high voltage side; At this time, the secondary current I d1 for: Among them, U nd is the rated voltage of the low voltage side; n TAd is the transformation ratio of the current transformer on the low voltage side, and the primary current passing method on the high voltage side further comprises: Step 5: Connect the multi-turn coil to the secondary circuit of the current transformer and use the phase volt-ampere meter current clamp to obtain the total current of the multi-turn coil: I t =n×I0, the secondary current can be multiplied. In the primary current passing method on the high-voltage side, all low-voltage branches use a short-circuit bar for three-phase short-circuiting, and the short-circuit current is used to check whether the polarity of the current transformer and the secondary cable are installed correctly.

2. According to the new high-safety plant system load test method of claim 1, it is characterized in that: The low-pressure side primary flow method comprises the following steps: Step 1: Select the first low-voltage side branch as a reference, pull the first low-voltage side branch standby incoming line switch trolley out of the warehouse; pull the second low-voltage side branch standby incoming line switch trolley out of the warehouse; connect the live wire of the primary current-carrying device to the first low-voltage side branch phase A, and the neutral wire to ground; ground the other standby branch switch and the current transformer; adjust the current of the primary current-carrying device to an appropriate value; observe the current of the two low-voltage branches on the protection device, and they should be equal in magnitude and 180 degrees out of phase; Step 2: Repeat the test process of step 1 on the first low-voltage side branch phase B; Step 3: Repeat the test process of step 1 on the first low-voltage side branch phase C; Step 4: Taking the first low-voltage branch as the reference, repeat the test process of step 1 to step 3 with all other low-voltage branches to complete a current flow test on all branches; put the high-voltage side of the standby transformer into operation, and only put the first reference branch into operation on the low-voltage side. Organize the factory auxiliary equipment to carry out load tests to verify whether the polarity of the reference branch current transformer and the secondary cable installation are correct.

3. According to the new high-safety plant system load test method of claim 2, it is characterized in that: In the low-voltage side primary current-passing method, the first low-voltage side branch is selected as the reference branch, and the phase-splitting primary current-passing method is used to confirm that the polarity of all other branch current transformers and the secondary circuits are correctly installed and consistent with the reference branch.

4. The new high-safety plant system load test method according to claim 3 is characterized in that: In the primary current passing method on the low-voltage side, a load test method is used to confirm that the polarity of the current transformer on the high-voltage side of the standby transformer and the reference branch and the secondary circuit are correctly installed.

5. According to the new high-safety plant system load test method of claim 1, it is characterized in that: The high-pressure side boosting primary flow method comprises the following steps: Step 1: Disconnect the high-voltage side switch and the isolating switch of the standby transformer and switch it to cold standby; Step 2: Pull all the standby transformer low-voltage side branch standby incoming line switch trolleys out of the warehouse, and use the short-circuit bar to short-circuit the three phases on the power supply side; Step 3: Add the output of the test transformer to the high-voltage side of the standby transformer; Step 4: Determine the expected high-voltage side secondary current I according to the accuracy level of the protection device g ; Step 5: Reverse calculation of the required test transformer voltage U T , and U T satisfy: At this time, the secondary current I d1 for: Step 6: Check the current on the high and low voltage sides directly in the protection device to confirm that the amplitude and phase are correct and the differential current is zero.

6. The new high-security plant system load test method according to claim 5 is characterized in that: In the high-voltage side boost primary current method, all low-voltage branches are short-circuited in three phases using a short-circuit bar, and the short-circuit current is used to verify that the polarity of the current transformer and the secondary cable are correctly installed.

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