A method for phase test of no-load line relay protection

Abstract

This disclosure relates to a method for testing the phase of relay protection on a no-load line, comprising the following steps: providing a predetermined current required for testing to the line under test and the line capable of carrying a load through a current booster; measuring whether the voltage wiring and the secondary circuit wiring of the current transformer of the corresponding relay protection device are consistent with those of the line under test and the line capable of carrying a load; after the line capable of carrying a load is energized, measuring whether the phase of the relay protection device of the line capable of carrying a load is correct; if the results of the above measurements are all correct or consistent, it indicates that the phase of the relay protection device of the line under test and the line capable of carrying a load is correct. This method solves the problem that in the past, due to insufficient load current or the inability to connect a load to the line, the phase of the relay protection device could not be tested, resulting in the relay protection device failing to perform normal line protection and affecting the commissioning of primary equipment.

Description

Technical Field

[0001] This disclosure relates to the field of power engineering technology, and in particular to a method for phase testing of relay protection for no-load lines. Background Technology

[0002] In new, upgraded, and expanded power system projects, when the wiring of the current and voltage secondary circuits of relay protection devices changes, relay protection devices with directional or differential current must undergo on-load phase testing. The conventional method for protection phase testing utilizes the current and operating voltage of the load on the transformer equipment. The angle relationship between the secondary current of the current transformer and the secondary voltage of the voltage transformer is measured using instruments. Based on the nature of the load and the principle of the protection device, the angle is judged to verify its correctness, thus verifying the correctness of the secondary wiring of the protection device and ensuring that the relay protection device can function normally. However, in actual operation, situations often arise where the load current is too small or the line cannot be connected to a load, making it impossible to complete the phase test of the relay protection device. This prevents the relay protection device's distance protection, bus differential protection, etc., from being activated, thus affecting the commissioning of primary equipment. Summary of the Invention

[0003] This disclosure proposes a phase testing method for relay protection of no-load lines to solve the problem that in the past, due to insufficient load current or the inability to connect a load to the line, the phase of the relay protection device could not be tested, which led to the relay protection device failing to perform normal line protection and affecting the commissioning of primary equipment.

[0004] According to one aspect of this disclosure, a method for phase testing of no-load line relay protection is provided, comprising:

[0005] Connect the busbar and the lines connected to the busbar, wherein at least one of the lines connected to the busbar is a load-bearing line;

[0006] Measure whether the voltage wiring of the circuit under test and the load-bearing circuit is consistent with the corresponding relay protection device.

[0007] Short-circuit the three-phase conductors of the circuit to be tested, and connect each pair of the three-phase conductors of the load-bearing circuit to the current booster in turn, so that the current booster provides the predetermined current required for the test to the load-bearing circuit.

[0008] Measure whether the secondary circuit wiring of the current transformers of the circuit under test and the circuit capable of carrying loads is consistent;

[0009] After the load-bearing line is energized, measure whether the phase of the relay protection device of the load-bearing line is correct;

[0010] If the results of the above measurements are all correct or consistent, it indicates that the phase of the relay protection device of the line under test and the line that can carry the load is correct.

[0011] Preferably, before providing the predetermined current required for testing to the load-bearing line through the current booster, the method further includes:

[0012] Determine the predetermined current value required for the test, wherein the method for determining the predetermined current value required for the test is as follows:

[0013] The predetermined current value is determined based on the current transformer ratio and the minimum allowable current of the phase table of the line.

[0014] Preferably, the method for determining the predetermined current value based on the current transformer ratio and the minimum allowable current value of the phase table of the line includes:

[0015] The predetermined current value is obtained by multiplying the current transformer ratio by the minimum allowable current value of the phase table.

[0016] Preferably, the method for measuring whether the voltage wiring of the circuit under test and the circuit capable of carrying a load is consistent with that of the corresponding relay protection device includes:

[0017] Connect the three-phase voltage of the relay protection device of the line under test to the corresponding phase of the three-phase voltage of the relay protection device of the line that can carry the load in sequence using a multimeter.

[0018] Measure whether the phase of the relay protection device of the line under test and the relay protection device of the line that can carry the load are in a conducting state. If they are, the voltage connection of the line under test and the line that can carry the load is consistent with the voltage connection of the corresponding relay protection device.

[0019] Preferably, the method for measuring whether the secondary circuit wiring of the current transformers of the circuit under test and the circuit capable of carrying loads is consistent includes:

[0020] The phase value and current value of the three-phase current of the current transformer corresponding to the line under test and the line that can carry the load are measured using a phase meter.

[0021] If the phase difference between the currents of the same phases of the current transformers corresponding to the circuit under test and the circuit capable of carrying a load is equal to a predetermined phase difference, and the currents of the same phases are the same, then the secondary circuit wiring of the current transformers corresponding to the circuit under test and the circuit capable of carrying a load is consistent.

[0022] Preferably, the method for measuring whether the phase of the relay protection device of the load-bearing line is correct after the load-bearing line is energized includes:

[0023] Measure the voltage amplitude and voltage phase of the relay protection device of the line that can carry the load, and determine whether the voltage amplitude and voltage phase meet the first predetermined condition. If they do, the voltage wiring of the relay protection device of the line that can carry the load is correct.

[0024] Measure the current amplitude and current phase of the relay protection device of the line that can carry the load, and determine whether the current amplitude and current phase meet the second predetermined condition. If they do, the three-phase current phase sequence and current transformer ratio of the relay protection device of the line that can carry the load are correct.

[0025] Measure the voltage and current angles of the same phases in the three phases between the relay protection devices of the line that can be subjected to load, and determine whether the voltage and current angles are equal to the primary voltage and current angles. If they are, the phase measurement of the relay protection device of the line that can be subjected to load is correct.

[0026] Preferably, the first predetermined condition includes:

[0027] The three-phase voltage amplitude of the relay protection device for the load-bearing line is equal to the first predetermined voltage amplitude, the three-phase phase-to-phase voltage amplitude is equal to the second predetermined voltage amplitude, and the zero-sequence voltage amplitude is equal to the third predetermined voltage amplitude.

[0028] Preferably, the second predetermined condition includes:

[0029] The phase difference of the three-phase voltage of the relay protection device for the load-bearing line is equal to the first predetermined phase difference.

[0030] This disclosure has at least the following beneficial effects:

[0031] This disclosure proposes a method for testing the phase of relay protection on no-load lines. By connecting the test line (which cannot carry a load) to a line that can carry a load, a current booster is used to provide test current to the line that can carry a load. The phase sequence of the connection between the terminals of the two lines and the corresponding relay protection devices, the phase sequence of the three-phase terminals of the two lines, and the phase sequence of the connection with the secondary circuit of the current transformer are all tested to ensure that they are completely consistent. After power is supplied, the phase of the relay protection on the line that can carry a load is tested, thereby verifying the correctness of the phase of the relay protection on the no-load line, ensuring the safety of the line equipment, and ensuring the timely and smooth commissioning of the primary equipment. Attached Figure Description

[0032] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the specification, serve to illustrate the technical solutions of this disclosure.

[0033] Figure 1 A flowchart is shown below illustrating a phase testing method for no-load line relay protection according to an embodiment of the present disclosure;

[0034] Figure 2 A circuit diagram is shown for a phase test method for no-load line relay protection according to an embodiment of the present disclosure. Detailed Implementation

[0035] Various exemplary embodiments, features, and aspects of this disclosure will now be described in detail with reference to the accompanying drawings. The same reference numerals in the drawings denote elements that have the same or similar functions. Although various aspects of the embodiments are shown in the drawings, they are not necessarily drawn to scale unless specifically indicated otherwise.

[0036] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments.

[0037] In this document, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A alone, A and B simultaneously, and B alone. Furthermore, the term "at least one" in this document means any combination of at least two of any one or more elements. For example, including at least one of A, B, and C can mean including any one or more elements selected from the set consisting of A, B, and C.

[0038] Furthermore, to better illustrate this disclosure, numerous specific details are set forth in the following detailed description. Those skilled in the art will understand that this disclosure can be practiced without certain specific details. In some instances, methods, means, components, and circuits well known to those skilled in the art have not been described in detail in order to highlight the main points of this disclosure.

[0039] Figure 1 This diagram shows a flowchart of a phase testing method for no-load line relay protection according to an embodiment of the present disclosure. Figure 2 A circuit diagram of a phase test method for no-load line relay protection according to an embodiment of this disclosure is shown, as follows: Figure 1 , 2As shown, the no-load line relay protection phase test method includes: Step S01: Connecting the busbar and the lines connected to the busbar, wherein at least one of the lines connected to the busbar is a load-carrying line; Step S02: Measuring whether the voltage wiring of the line under test and the load-carrying line is consistent with the corresponding relay protection device; Step S03: Short-circuiting the three-phase conductors of the line under test, and connecting each pair of the three-phase conductors of the load-carrying line to a current booster, providing the load-carrying line with the predetermined current required for testing through the current booster; Step S04: Measuring whether the secondary circuit wiring of the current transformers of the line under test and the load-carrying line is consistent; Step S05: After the load-carrying line is energized, measuring whether the phase of the relay protection device of the load-carrying line is correct; If the results of the above measurements are all correct or consistent, it indicates that the phase of the relay protection device of the line under test and the load-carrying line is correct.

[0040] The phase testing method for no-load line relay protection provided in this embodiment includes the following steps:

[0041] Step S01: Connect the busbar and the lines connected to the busbar, wherein at least one of the lines connected to the busbar is a load-bearing line.

[0042] In this embodiment of the disclosure, in a 110kV substation, after the relay protection device is modified, before commissioning, it is necessary to measure the relay protection phase of several lines connected to the busbar in the entire line. Among these lines, some lines have disconnected ends (without any equipment connected), making it impossible to connect to a load and measure phase under load. These lines are considered no-load lines, i.e., the lines to be tested in this method. To test the relay protection phase of these lines, it is necessary to use load-bearing lines connected to the busbar in the entire line for testing. During testing, if there are multiple lines to be tested among the several lines connected to the busbar, each line to be tested needs to be tested in conjunction with a load-bearing line.

[0043] Step S02: Measure whether the voltage wiring of the circuit under test and the circuit capable of carrying load is consistent with that of the corresponding relay protection device.

[0044] In this disclosure, the method for measuring whether the voltage wiring of the circuit under test and the circuit capable of carrying a load is consistent with the corresponding relay protection device includes: sequentially connecting the three-phase voltage of the relay protection device of the circuit under test and the corresponding phase of the three-phase voltage of the relay protection device of the circuit capable of carrying a load to the same phase of the circuit under test and the circuit capable of carrying a load, and measuring whether the corresponding phase of the relay protection device of the circuit under test and the relay protection device of the circuit capable of carrying a load is in a conducting state. If so, the voltage wiring of the circuit under test and the circuit capable of carrying a load is consistent with the corresponding relay protection device.

[0045] In this embodiment of the disclosure, if the three-phase terminals of the relay protection device of the circuit under test are a1, b1, and c1, and the three-phase terminals of the relay protection device of the circuit capable of carrying a load are a2, b2, and c2, a multimeter is used to measure whether terminals a1 and a2, b1 and b2, and c1 and c2 are all conductive. A1 and a2, b1 and b2, and c1 and c2 are the voltage phases of the relay protection device of the circuit under test and the relay protection device of the circuit capable of carrying a load. If the measurement results are all conductive in the three sets of measurements, it indicates that the voltage wiring of the relay protection devices of the circuit under test and the circuit capable of carrying a load is completely consistent.

[0046] Step S03: Short-circuit the three-phase conductors of the circuit to be tested, and connect each pair of the three-phase conductors of the load-bearing circuit to the current booster in turn, so as to provide the predetermined current required for the test to the load-bearing circuit through the current booster.

[0047] In this embodiment, short-circuiting means connecting the beginnings of the three-phase conductors of the circuit under test, namely phases A, B, and C, to each other; and connecting two of the three-phase conductors of the load-carrying circuit, namely phases A, B, and C, to the current booster. During the entire test, it is necessary to connect phases A and B of the load-carrying circuit to the current booster once, phases B and C to the current booster once, and phases A and C to the current booster once. After connection to the current booster, the current booster supplies the predetermined current required for the test to the connected two-phase conductors.

[0048] In this disclosure, before providing the predetermined current required for testing to the load-bearing line through the current booster, the method further includes: determining the predetermined current value required for testing, wherein the method for determining the predetermined current value required for testing is: determining the predetermined current value based on the current transformer ratio and the minimum allowable current of the phase table of the line.

[0049] In this disclosure, the method for determining the predetermined current value based on the current transformer ratio and the minimum allowable current value of the phase table of the line includes: multiplying the current transformer ratio by the minimum allowable current value of the phase table to obtain the predetermined current value.

[0050] In this embodiment, a phase meter is required for testing. The predetermined test current value provided by the current booster should be greater than the minimum allowable current value measured by the phase meter after passing through the current transformer ratio. For example, if the current transformer ratio in the line is 600 / 5 and the minimum allowable current value of the phase meter used during testing is 0.5A, then the predetermined test current value = 600 / 5 × 0.5 = 60A. The current booster converts the power supply current to 60A and transmits it to the load-bearing line.

[0051] Step S04: Measure whether the secondary circuit wiring of the current transformers of the circuit under test and the circuit capable of carrying loads is consistent.

[0052] In this disclosure, the method for measuring whether the secondary circuit wiring of the current transformers of the line under test and the line capable of carrying a load is consistent includes: using a phase meter to measure the phase value and current value of the three-phase current of the current transformers corresponding to the line under test and the line capable of carrying a load; determining whether the secondary circuit wiring of the current transformers corresponding to the line under test and the line capable of carrying a load is consistent if the phase difference of the currents of the same phases of the current transformers of the line under test and the line capable of carrying a load is equal to a predetermined phase difference value and the current values ​​of the same phases are the same.

[0053] In this embodiment of the disclosure, the secondary circuit wiring of the current transformer is the three-phase wiring of the current transformer and the relay protection device. To measure whether the wiring of the current transformer of the line under test and the line that can carry the load is consistent with that of the connected relay protection device, firstly, the three phases at the beginning of the line under test are short-circuited, and the A and B phases at the beginning of the line that can carry the load are connected to the current booster. The current booster outputs the predetermined current required for the test.

[0054] The measurement process for the secondary circuit wiring of the current transformers corresponding to the circuit under test and the circuit capable of carrying loads is as follows: If the three-phase wiring of the current transformer corresponding to the circuit under test is a5, b5, and c5, and the three-phase wiring of the current transformer corresponding to the circuit capable of carrying loads is a6, b6, and c6, then use a phase meter to measure the phase values ​​of the current transformers a5, b5, and c5 corresponding to the circuit under test and the current transformers a6, b6, and c6 corresponding to the circuit capable of carrying loads. Calculate and determine whether the phase difference between the corresponding phases of the two current transformers is equal to the predetermined phase difference. Among the three-phase wiring of the two current transformers, a5 and a6, b5 and b6, and c5 and c6 are corresponding phases, that is, calculate the phase difference between a5 and a6, b5 and b6, and c5 and c6 respectively.

[0055] After the above measurements are completed, disconnect phase B of the load-bearing line from the current booster, and connect phases A and C to the current booster. Repeat the above measurement process of the secondary circuit wiring of the current transformer corresponding to the line under test and the load-bearing line, that is, measure and calculate the phase difference values ​​of a5 and a6, b5 and b6, and c5 and c6 in sequence.

[0056] After the above measurements are completed, disconnect phase A of the load-bearing line from the current booster, and connect phases B and C to the current booster. Repeat the above process of measuring the phase sequence of the terminals of the line under test and the load-bearing line, that is, measure and calculate the phase difference values ​​of a5 and a6, b5 and b6, and c5 and c6 in sequence.

[0057] By connecting the three phases of the load-bearing line to the current booster in pairs, a total of three sets of measurements are performed. In each set, the phase difference of the current transformer corresponding to the line under test and the load-bearing line is measured. If the phase difference of the current of each corresponding phase in the three sets of measurements is equal to the predetermined phase difference and the current value of the corresponding phase is also the same, it indicates that the secondary circuit wiring of the current transformers corresponding to the line under test and the load-bearing line is consistent. The current of the corresponding phase is calculated based on the transformation ratio of the current transformers of the load-bearing line and the line under test.

[0058] Step S05: After the load-bearing line is energized, measure whether the phase of the relay protection device of the load-bearing line is correct.

[0059] In this disclosure, the method for measuring the phase of the relay protection device of the load-bearing line after the load-bearing line is energized includes: measuring the voltage amplitude and voltage phase of the relay protection device of the load-bearing line, determining whether the voltage amplitude and voltage phase meet a first predetermined condition, and if so, the voltage wiring of the relay protection device of the load-bearing line is correct; measuring the current amplitude and current phase of the relay protection device of the load-bearing line, determining whether the current amplitude and current phase meet a second predetermined condition, and if so, the three-phase current phase sequence and current transformer ratio of the relay protection device of the load-bearing line are correct; measuring the voltage and current angles of the same phases among the three phases of the relay protection device of the load-bearing line, determining whether the voltage and current angles are equal to the primary voltage and current angles, and if so, the phase measurement of the relay protection device of the load-bearing line under load is correct.

[0060] In this embodiment of the disclosure, after the substation is energized, the correctness of the wiring between the busbar, the load-bearing lines, and the relay protection device is measured.

[0061] In this disclosure, the first predetermined condition includes: the three-phase voltage amplitude of the relay protection device of the load-bearing line is equal to the first predetermined voltage amplitude, the three-phase phase-to-phase voltage amplitude is equal to the second predetermined voltage amplitude, and the zero-sequence voltage amplitude is equal to the third predetermined voltage amplitude.

[0062] In this embodiment of the disclosure, the voltage amplitude of the relay protection device for the load-bearing line includes the voltage amplitudes of phase a, phase b, phase c, phase-ab, phase-bc, phase-ca, and zero-sequence voltages. A multimeter is used to sequentially measure the voltage amplitudes of phase a, phase b, phase c, phase-ab, phase-bc, phase-ca, and zero-sequence voltages in the line connected to the relay protection device at the output terminal of the load-bearing line. The first predetermined condition is that the voltage amplitudes of phase a, phase b, and phase c are equal to the first predetermined voltage amplitude; the voltage amplitudes between phases a, b, and c are equal to the second predetermined voltage amplitude; and the zero-sequence voltage amplitude is equal to the third predetermined voltage amplitude. The first predetermined voltage amplitude is 57.7V, the second predetermined voltage amplitude is 100V, and the third predetermined voltage amplitude is 0V. That is, the voltage amplitude of phases A, B, and C should all be 57.7V, the voltage amplitude between phases A and B, between phases B and C, and between phases C and D should be 100V, and the zero-sequence voltage amplitude should be 0V. However, in reality, after the substation is energized, the actual measured voltage amplitude may fluctuate slightly around 57.7V, 100V, or 0V depending on the voltage supplied by different substations. It should be judged according to the specific actual situation.

[0063] In this disclosure, the second predetermined condition includes: the phase difference of the three-phase voltage of the relay protection device of the load-bearing line is equal to the first predetermined phase difference.

[0064] In this embodiment, the voltage phase of the relay protection device for a load-bearing line includes the voltage phases of phases a, b, and c. A phase meter is used to sequentially measure the voltage phases of phases a, b, and c in the line connected to the relay protection device at the output terminal of the load-bearing line (the phase is referenced to a specific phase voltage). A first predetermined condition includes that the voltage phase difference between phases a, b, and c is equal to a first predetermined phase difference, where the first predetermined phase difference is 120°. That is, phase a voltage leads phase b by 120°, phase b voltage leads phase c by 120°, and phase c voltage leads phase a by 120°. If the measured voltage amplitudes are equal to their predetermined voltage amplitudes, and the voltage phase difference between the three phases is equal to the predetermined phase difference, then the voltage wiring of the relay protection device is correct.

[0065] The current amplitude of the relay protection device includes the current amplitudes of phases A, B, and C. The current amplitudes of phases A, B, and C are measured sequentially at the terminal blocks of the protection panel using a clamp meter. A second predetermined condition is that the current amplitudes of phases A, B, and C are all equal to a predetermined current amplitude. The predetermined current amplitude is calculated by dividing the actual primary load current (e.g., 120A) by the current transformer ratio (e.g., 600 / 5 = 120), resulting in a predetermined current amplitude of 120 / 120 = 1A. That is, the current amplitudes of phases A, B, and C should all be 1A. Depending on the supply current, the actual measured current amplitude may fluctuate slightly around 1A and should be determined based on the specific circumstances.

[0066] The current phase of the relay protection device includes the current phases of phases a, b, and c. A phase meter is used to sequentially measure the current phases of phases a, b, and c in the line connected to the relay protection device at the output terminal of the load-bearing line on the protection panel (the phase is referenced to the current of one phase).

[0067] The second predetermined condition also includes: the current phase difference between phases a, b, and c is equal to the first predetermined phase difference. That is, the phase a current leads phase b by 120°, the phase b current leads phase c by 120°, and the phase c current leads phase a by 120°. If the measured current amplitudes are equal to their predetermined current amplitudes, and the current phase difference between the three phases is equal to the first predetermined phase difference, then it indicates that the three-phase current phase sequence relationship and the current transformer ratio of the relay protection device are correct.

[0068] The phase meter is used to measure the voltage and current angles of the same phase at the terminal blocks of the protection panel of the relay protection device. The primary voltage and current angles are calculated based on the active and reactive power values ​​in the line power flow. The measured current and voltage angles are then compared to determine the correctness of the direction. For example, if the busbar sends 7200kW of active power and 1000kVar of reactive power to the line, then the voltage-current lead angle of the primary phase of the line on that busbar is φ=arctag(1000 / 7200)=7.9°.

[0069] Since line protection devices only protect one side of the transmission line, the calculated voltage and current angles are equal to the measured voltage and current angles of the relay protection device on the load-bearing line. That is, the phase meter measures a 7.9° lead angle between the voltage and current of the same phase at the terminal block of the relay protection device on the load-bearing line, indicating that the phase measurement of the load-bearing relay protection device on the line is correct.

[0070] In this disclosure, if the measurement results of steps S02, S04 and S05 are all correct or consistent, it indicates that the phase of the relay protection device of the line under test and the line that can carry the load is correct.

[0071] In this embodiment of the disclosure, the above steps S02 to S04 are to test that all wiring of the circuit under test and the circuit capable of carrying load are completely consistent, that is, the voltage wiring of the circuit under test and the circuit capable of carrying load measured in step S02 is consistent with the voltage wiring of the corresponding relay protection device, and the secondary circuit wiring of the current transformer of the circuit under test and the circuit capable of carrying load measured in steps S03 and S04 is consistent.

[0072] Under this premise, step S05 is to measure the phase of the relay protection device of the load-bearing line after power is supplied. Since the above steps S02~S04 have already tested that the wiring of the line under test and the load-bearing line are completely consistent, if the phase measurement of the relay protection device of the load-bearing line is correct, it indirectly proves that the phase of the line under test is correct.

[0073] It is understood that the various method embodiments mentioned above in this disclosure can be combined with each other to form combined embodiments without violating the principle and logic. Due to space limitations, this disclosure will not elaborate further.

[0074] This disclosure primarily addresses the testing of directional line protection and bus differential protection phases when transmission lines cannot be connected to a load or have excessively low loads. Based on conventional protection phase testing principles, a test current is used to replace the load current. The phase of the line that cannot be connected to a load (the line under test) is compared with that of a line that can be connected to a load, thereby indirectly verifying the correct wiring of the protection device for the unloaded line under test. This disclosure is simple to operate, highly feasible, and achieves 100% accuracy in phase testing of relay protection for unloaded lines.

[0075] This disclosure was practically applied in the renovation of relay protection devices at a 110kV substation in Daqing Oilfield. Because one 110kV line was disconnected at its end, it could not be connected to a load, making it impossible to perform phase measurement under load. Consequently, the replaced relay protection device could not be put into operation, and the line could not be put into service. If the line remained unenergized for an extended period, the risk of theft would significantly increase. By adopting the testing method of this disclosure, the technical problem of relay protection being unable to measure phase under no-load conditions was successfully solved, enabling the unloaded line to operate normally.

[0076] Those skilled in the art will understand that, in the above-described method of the specific implementation, the order in which each step is written does not imply a strict execution order and does not constitute any limitation on the implementation process. The specific execution order of each step should be determined by its function and possible internal logic.

[0077] The various embodiments of this disclosure have been described above. These descriptions are exemplary and not exhaustive, and are not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical applications, or technical improvements to the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for testing the phase of a no-load line relay protection, characterized in that, include: Connect the busbar and the lines connected to the busbar, wherein at least one of the lines connected to the busbar is a load-bearing line; Measure whether the voltage wiring of the circuit under test and the load-bearing circuit is consistent with the corresponding relay protection device; Short-circuit the three-phase conductors of the circuit to be tested, and connect each pair of the three-phase conductors of the load-bearing circuit to the current booster in turn, so that the current booster provides the predetermined current required for the test to the load-bearing circuit. Measure whether the secondary circuit wiring of the current transformers of the circuit under test and the circuit capable of carrying loads is consistent. After the load-bearing line is energized, measure whether the phase of the relay protection device of the load-bearing line is correct; If the results of the above measurements are all correct or consistent, it indicates that the phase of the relay protection device of the line under test and the line that can carry the load is correct.

2. The method for phase testing of no-load line relay protection according to claim 1, characterized in that, Before providing the predetermined test current to the load-bearing line via the current booster, the method further includes: Determine the predetermined current value required for the test, wherein the method for determining the predetermined current value required for the test is as follows: The predetermined current value is determined based on the current transformer ratio and the minimum allowable current of the phase table of the line.

3. The method for phase testing of no-load line relay protection according to claim 2, characterized in that, The method for determining the predetermined current value based on the current transformer ratio and the minimum allowable current value of the phase table of the line includes: The predetermined current value is obtained by multiplying the current transformer ratio by the minimum allowable current value of the phase table.

4. The method for phase testing of no-load line relay protection according to claim 1, characterized in that, The method for measuring whether the voltage wiring of the circuit under test and the circuit capable of carrying load is consistent with the corresponding relay protection device includes: Connect the three-phase voltage of the relay protection device of the line under test to the corresponding phase of the three-phase voltage of the relay protection device of the line that can carry the load in sequence using a multimeter. Measure whether the phase of the relay protection device of the line under test and the relay protection device of the line that can carry the load are in a conducting state. If they are, the voltage connection of the line under test and the line that can carry the load is consistent with the voltage connection of the corresponding relay protection device.

5. The method for phase testing of no-load line relay protection according to claim 1, characterized in that, The method for measuring whether the secondary circuit wiring of the current transformers of the circuit under test and the circuit capable of carrying loads are consistent includes: The phase value and current value of the three-phase current of the current transformer corresponding to the line under test and the line that can carry the load are measured using a phase meter. If the phase difference between the current transformers of the same phase corresponding to the circuit under test and the circuit that can carry the load is equal to a predetermined phase difference, and the current values ​​of the same phase are the same, then the secondary circuit wiring of the current transformers of the circuit under test and the circuit that can carry the load is consistent.

6. The method for phase testing of no-load line relay protection according to any one of claims 1-5, characterized in that, The method for measuring the phase of the relay protection device of the load-bearing line after it is energized includes: Measure the voltage amplitude and voltage phase of the relay protection device of the line that can carry the load, and determine whether the voltage amplitude and voltage phase meet the first predetermined condition. If they do, the voltage wiring of the relay protection device of the line that can carry the load is correct. Measure the current amplitude and current phase of the relay protection device of the line that can carry the load, and determine whether the current amplitude and current phase meet the second predetermined condition. If they do, the three-phase current phase sequence and current transformer ratio of the relay protection device of the line that can carry the load are correct. Measure the voltage and current angles of the same phases in the three phases between the relay protection devices of the line that can be subjected to load, and determine whether the voltage and current angles are equal to the primary voltage and current angles. If they are, the phase measurement of the relay protection device of the line that can be subjected to load is correct.

7. The method for phase testing of no-load line relay protection according to claim 6, characterized in that, The first predetermined condition includes: The three-phase voltage amplitude of the relay protection device for the load-bearing line is equal to the first predetermined voltage amplitude, the three-phase phase-to-phase voltage amplitude is equal to the second predetermined voltage amplitude, and the zero-sequence voltage amplitude is equal to the third predetermined voltage amplitude.

8. The method for phase testing of no-load line relay protection according to claim 6, characterized in that, The second predetermined condition includes: The phase difference of the three-phase voltage of the relay protection device for the load-bearing line is equal to the first predetermined phase difference.

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