Station AC power system protection device differential coordination test device and test method

Abstract

The present invention provides a differential coordination test device and a test method for a station AC power system protective electrical appliance. The device comprises an A-phase terminal, a B-phase terminal, a C-phase terminal, a first branch and a second branch connected in parallel, and a first bridge arm, a second bridge arm, a third bridge arm and a fourth bridge arm that are selectively turned on or off; the first branch comprises an adjustable load and a switch connected in series; the second branch comprises a first thyristor; the first ends of the first branch and the second branch are respectively connected to the first end of the first bridge arm and the first end of the second bridge arm, and the second ends are respectively connected to the first end of the third bridge arm and the first end of the fourth bridge arm; the second end of the first bridge arm is connected to the A-phase terminal, the second ends of the second bridge arm and the third bridge arm are both connected to the B-phase terminal, and the second end of the fourth bridge arm is connected to the C-phase terminal. The present invention can realize the differential coordination test of the station AC power system protective electrical appliance, reduce the false operation caused by the incompatible differential, and avoid the expansion of accidents.

Description

Technical Field

[0001] The present invention relates to the technical field of differential coordination testing, and in particular to a differential coordination testing device and a testing method for protection electrical appliances of a station AC power supply system. Background Art

[0002] In the power system, AC power is the basic power supply of the substation. It is used as the power supply for transformer cooling fans, domestic electricity, fire pumps, charging devices, and power distribution maintenance. It is the basic guarantee for the safe and reliable operation of the substation.

[0003] At present, the AC feeder network of the substation mostly adopts a tree structure, and uses AC circuit breakers as the main protection elements for overcurrent and short-circuit faults of each outgoing line of the AC system, which plays the role of disconnecting and isolating the feeder loop power supply network. From the station transformer to the power equipment in the station, it generally goes through three or four levels of power distribution, and each level of power distribution mostly uses AC circuit breakers as protective electrical appliances; if the protection action characteristics of the upper and lower level AC circuit breakers do not match, when a short-circuit fault occurs in the lower level power equipment, it will cause the upper level AC circuit breaker to trip, thereby causing power outages in other feeder lines, and even causing AC power outages in the entire station, expanding the scope of the accident.

[0004] However, there is currently a lack of effective means to test the differential coordination of protective devices in station AC power systems. Summary of the invention

[0005] The embodiment of the present invention provides a station AC power system protection device differential coordination test device and a test method to solve the problem of lack of effective means for testing the station AC power system protection device differential coordination.

[0006] In a first aspect, an embodiment of the present invention provides a station-used AC power system protection device differential coordination test device, comprising an A-phase terminal, a B-phase terminal, a C-phase terminal, a first branch and a second branch connected in parallel, and a first bridge arm, a second bridge arm, a third bridge arm, and a fourth bridge arm that are selectively turned on or off; the first branch comprises an adjustable load and a switch connected in series; the second branch comprises a first thyristor;

[0007] The A-phase terminal, the B-phase terminal and the C-phase terminal are used to connect the outlet terminal of the protective electrical appliance to be tested; the first ends of the first branch and the second branch are respectively connected to the first end of the first bridge arm and the first end of the second bridge arm, the second ends of the first branch and the second branch are respectively connected to the first end of the third bridge arm and the first end of the fourth bridge arm, the second end of the first bridge arm is connected to the A-phase terminal, the second end of the second bridge arm and the second end of the third bridge arm are both connected to the B-phase terminal, and the second end of the fourth bridge arm is connected to the C-phase terminal.

[0008] In a possible implementation, the second branch further includes an emergency stop button connected in series with the first thyristor.

[0009] In a possible implementation, the first bridge arm includes a second thyristor, the second bridge arm includes a third thyristor, the third bridge arm includes a fourth thyristor, and the fourth bridge arm includes a fifth thyristor.

[0010] In a possible implementation, the switch is a contactor.

[0011] In a possible implementation, the station AC power system protection device differential coordination test device further includes a controller;

[0012] The first bridge arm, the second bridge arm, the third bridge arm, the fourth bridge arm, the switch and the first thyristor are all controlled by a controller.

[0013] In a second aspect, an embodiment of the present invention provides a method for testing the differential coordination of a station-used AC power system protection device, which is applied to a station-used AC power system protection device differential coordination testing device of the first aspect or any possible implementation of the first aspect;

[0014] The test method for the differential coordination of the protection devices of the AC power system for the above-mentioned station includes:

[0015] Control the first bridge arm and the third bridge arm to be turned on, control the second bridge arm and the fourth bridge arm to be turned off, and perform a differential coordination test on the A phase and the B phase of the protection device to be tested, and obtain a differential coordination test result on the A phase and the B phase of the protection device to be tested;

[0016] Control the second bridge arm and the fourth bridge arm to be turned on, control the first bridge arm and the third bridge arm to be turned off, and perform a differential coordination test on the B phase and the C phase of the protection device to be tested, and obtain a differential coordination test result on the B phase and the C phase of the protection device to be tested;

[0017] Control the first bridge arm and the fourth bridge arm to be turned on, control the second bridge arm and the third bridge arm to be turned off, and perform a differential coordination test on the A phase and the C phase of the protection device to be tested, and obtain a differential coordination test result on the A phase and the C phase of the protection device to be tested;

[0018] Determine the differential coordination test result of the protection device to be tested based on the differential coordination test results of phase A and phase B of the protection device to be tested, the differential coordination test results of phase B and phase C of the protection device to be tested, and the differential coordination test results of phase A and phase C of the protection device to be tested.

[0019] In a possible implementation, performing a differential matching test on phases A and B of the protection device to be tested to obtain a differential matching test result on phases A and B of the protection device to be tested includes:

[0020] Obtaining the voltage across the first branch when the switch and the first thyristor are both disconnected, recorded as a first voltage;

[0021] The control switch is closed, and the size of the adjustable load is adjusted so that the current of the first branch is a preset current value, and the current voltage across the first branch is obtained and recorded as the second voltage;

[0022] Calculate the equivalent impedance of phase A and phase B of the protection device to be tested according to the first voltage, the second voltage and the preset current value;

[0023] Calculate the first short-circuit current of phase A and phase B of the protection device to be tested according to the first voltage and the equivalent impedance, and estimate the differential coordination probability according to the first short-circuit current and the ampere-second characteristic curves of the upper and lower level protection devices;

[0024] Controlling the first thyristor to conduct to simulate a short circuit fault between phase A and phase B;

[0025] When simulating a short-circuit fault of phases A and B, if it is detected that the protective device to be tested has tripped, and the superior protective device of the protective device to be tested has also tripped, then the differential coordination test result of phases A and B of the protective device to be tested is determined to be unqualified; if it is detected that the protective device to be tested has tripped, and the superior protective device of the protective device to be tested has not tripped, then the differential coordination test result of phases A and B of the protective device to be tested is determined to be qualified.

[0026] In a possible implementation, the emergency stop button is used to control the disconnection of the second branch when a short circuit fault between phases A and B is simulated and the protective device to be tested does not trip.

[0027] In a possible implementation, performing a differential matching test on phases A and B of the protection device to be tested to obtain a differential matching test result of phases A and B of the protection device to be tested further includes:

[0028] When simulating the short-circuit fault of phase A and phase B, record the breaking time and the second short-circuit current of the protective device to be tested.

[0029] In a possible implementation, according to the differential coordination test result of the A phase and the B phase of the protection device to be tested, the differential coordination test result of the B phase and the C phase of the protection device to be tested, and the differential coordination test result of the A phase and the C phase of the protection device to be tested, the differential coordination test result of the protection device to be tested is determined, including:

[0030] If the differential coordination test results of the A-phase and B-phase of the protection device to be tested, the differential coordination test results of the B-phase and C-phase of the protection device to be tested, and the differential coordination test results of the A-phase and C-phase of the protection device to be tested are all qualified, then the differential coordination test result of the protection device to be tested is determined to be qualified;

[0031] If at least one of the differential coordination test results of phase A and phase B of the protection device to be tested, the differential coordination test results of phase B and phase C of the protection device to be tested, and the differential coordination test results of phase A and phase C of the protection device to be tested are unqualified, then the differential coordination test result of the protection device to be tested is determined to be unqualified.

[0032] The embodiment of the present invention provides a differential coordination test device and a test method for a station-used AC power supply system protective electrical appliance. The test device includes an A-phase terminal, a B-phase terminal, a C-phase terminal, a first branch and a second branch connected in parallel, and a first bridge arm, a second bridge arm, a third bridge arm and a fourth bridge arm that are selectively turned on or off; the first branch includes an adjustable load and a switch connected in series; the second branch includes a first thyristor; the A-phase terminal, the B-phase terminal and the C-phase terminal are used to connect the outlet terminal of the protective electrical appliance to be tested; the first ends of the first branch and the second branch are respectively connected to the first end of the first bridge arm and the first end of the second bridge arm, the second ends of the first branch and the second branch are respectively connected to the first end of the third bridge arm and the first end of the fourth bridge arm, the second end of the first bridge arm is connected to the A-phase terminal, the second end of the second bridge arm and the second end of the third bridge arm are both connected to the B-phase terminal, and the second end of the fourth bridge arm is connected to the C-phase terminal. The test device can be used to test the coordination of the protection devices of the station AC power supply system, which can effectively reduce the false operation caused by inconsistent level differences, especially the false operation due to overstepping, and avoid the expansion of accidents. Moreover, only one wiring is required to complete the test between any two phases among the three phases without repeated wiring. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, 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 invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0034] Figure 1 It is a structural schematic diagram of a station AC power system protection device differential coordination test device provided by an embodiment of the present invention;

[0035] Figure 2 It is a circuit diagram of a station AC power system protection device differential coordination test device provided by an embodiment of the present invention;

[0036] Figure 3 It is a flow chart of a method for testing the differential coordination of protection devices of a station AC power system provided by an embodiment of the present invention;

[0037] Figure 4It is a schematic diagram of on-site wiring of a station AC power system protection device differential coordination test device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0038] In order to enable people in the technical field to better understand the present solution, the technical solution in the embodiment of the present solution will be clearly described below in conjunction with the drawings in the embodiment of the present solution. Obviously, the described embodiment is an embodiment of a part of the present solution, not all of the embodiments. Based on the embodiments in the present solution, all other embodiments obtained by ordinary technicians in the field without creative work should fall within the scope of protection of the present solution.

[0039] The term "including" and any other variations in the specification and claims of this solution and the above drawings mean "including but not limited to", and is intended to cover non-exclusive inclusions and is not limited to the examples listed in the text. In addition, the terms "first" and "second" are used to distinguish different objects, not to describe a specific order.

[0040] Figure 1 A schematic diagram of a station AC power system protection device differential coordination test device provided by an embodiment of the present invention. Figure 1 The station-use AC power system protection device differential coordination test device includes an A-phase terminal A, a B-phase terminal B, a C-phase terminal C, a first branch and a second branch connected in parallel, and a first bridge arm, a second bridge arm, a third bridge arm and a fourth bridge arm that are selectively turned on or off; the first branch includes an adjustable load LR and a switch K1 connected in series; the second branch includes a first thyristor LN;

[0041] The A-phase terminal A, the B-phase terminal B and the C-phase terminal C are used to connect the outlet terminal of the protection device to be tested; the first ends of the first branch and the second branch are respectively connected to the first end of the first bridge arm and the first end of the second bridge arm, the second ends of the first branch and the second branch are respectively connected to the first end of the third bridge arm and the first end of the fourth bridge arm, the second end of the first bridge arm is connected to the A-phase terminal A, the second end of the second bridge arm and the second end of the third bridge arm are both connected to the B-phase terminal B, and the second end of the fourth bridge arm is connected to the C-phase terminal C.

[0042] Among them, the A-phase terminal A, the B-phase terminal B and the C-phase terminal C are respectively used to connect the A-phase outlet terminal, the B-phase outlet terminal and the C-phase outlet terminal of the protection device to be tested. The first bridge arm, the second bridge arm, the third bridge arm and the fourth bridge arm are used for automatic switching control of any two-phase test, and can be selectively turned on or off. The first branch is used to calculate the loop impedance and estimate the short-circuit current by controlling the adjustable load LR to generate a small current. The second branch is used for short-circuit fault simulation and verification of the differential coordination of the upper and lower protection devices. The first branch and the second branch can also be selectively turned on or off.

[0043] The protective device to be tested may be a circuit breaker to be tested.

[0044] This embodiment can realize the differential coordination test of the station AC power system protection electrical appliance through the station AC power system protection electrical appliance differential coordination test device, thereby effectively reducing the false operation caused by inconsistent differentials, especially the over-level false operation, avoiding the expansion of accidents, and only requires one wiring to complete the test between any two phases among the three phases, without the need for repeated wiring.

[0045] In some embodiments, see Figure 1 and Figure 2 The second branch also includes an emergency stop button ESB connected in series with the first thyristor LN.

[0046] The emergency stop button ESB can be used to cut off the second branch circuit to ensure the safety of the test when the protection device refuses to operate during the short circuit fault simulation. The emergency stop button ESB can be controlled manually to cut off the second branch circuit when the above situation occurs.

[0047] In some embodiments, see Figure 2 The first bridge arm includes a second thyristor LA, the second bridge arm includes a third thyristor LB, the third bridge arm includes a fourth thyristor LD, and the fourth bridge arm includes a fifth thyristor LC.

[0048] In some embodiments, the switch K1 is a contactor.

[0049] In some embodiments, the station AC power system protection device differential coordination test device further includes a controller;

[0050] The first bridge arm, the second bridge arm, the third bridge arm, the fourth bridge arm, the switch K1 and the first thyristor LN are all controlled by a controller.

[0051] In this embodiment, see Figure 2 The first thyristor LN, the second thyristor LA, the third thyristor LB, the fourth thyristor LD, the fifth thyristor LC and the switch K1 are all controlled by the controller. The controller can control the first thyristor LN, the second thyristor LA, the third thyristor LB, the fourth thyristor LD, the fifth thyristor LC and the switch K1 to be turned on or off.

[0052] Corresponding to the above-mentioned station AC power system protection device differential coordination test device, an embodiment of the present invention also provides a station AC power system protection device differential coordination test method, which is applied to any station AC power system protection device differential coordination test device as described above, and specifically can be applied to the controller of the test device.

[0053] See also Figure 3The test method for the differential coordination of the above-mentioned station AC power system protection devices includes:

[0054] In S301, the first bridge arm and the third bridge arm are controlled to be turned on, the second bridge arm and the fourth bridge arm are controlled to be turned off, and a differential coordination test of phases A and B of the protection device to be tested is performed to obtain a differential coordination test result of phases A and B of the protection device to be tested.

[0055] In S302, the second bridge arm and the fourth bridge arm are controlled to be turned on, the first bridge arm and the third bridge arm are controlled to be turned off, and a differential coordination test of the B phase and the C phase of the protection device to be tested is performed to obtain a differential coordination test result of the B phase and the C phase of the protection device to be tested.

[0056] In S303, the first bridge arm and the fourth bridge arm are controlled to be turned on, the second bridge arm and the third bridge arm are controlled to be turned off, and a differential coordination test of phases A and C of the protection device to be tested is performed to obtain a differential coordination test result of phases A and C of the protection device to be tested.

[0057] In S304, the differential coordination test result of the protection device to be tested is determined according to the differential coordination test result of phase A and phase B of the protection device to be tested, the differential coordination test result of phase B and phase C of the protection device to be tested, and the differential coordination test result of phase A and phase C of the protection device to be tested.

[0058] In this embodiment, after the station AC power system protection device differential coordination test device is connected to the terminal of the protection device to be tested, the differential coordination test of phase A and phase B, the differential coordination test of phase B and phase C, and the differential coordination test of phase A and phase C are performed in sequence to obtain the corresponding differential coordination test results. Finally, the differential coordination test results of the protection device to be tested are determined based on the corresponding differential coordination test results.

[0059] The differential coordination test of the A phase and the B phase of the protection device to be tested can be performed by controlling the first bridge arm and the third bridge arm to be turned on and controlling the second bridge arm and the fourth bridge arm to be turned off. Figure 2 Specifically, the second thyristor LA and the fourth thyristor LD are controlled to be turned on, and the third thyristor LB and the fifth thyristor LC are controlled to be turned off, so that the A and B two-phase voltages are added to the L and N terminals, and the differential coordination test of the A phase and the B phase of the protection device to be tested is performed to obtain the differential coordination test result of the A phase and the B phase of the protection device to be tested.

[0060] The B-phase and C-phase differential coordination test of the protection device to be tested can be performed by controlling the second bridge arm and the fourth bridge arm to be turned on and the first bridge arm and the third bridge arm to be turned off. Figure 2Specifically, the third thyristor LB and the fifth thyristor LC are controlled to be turned on, and the second thyristor LA and the fourth thyristor LD are controlled to be turned off, so that the B and C two-phase voltages are added to the L and N ends, and the B-phase and C-phase differential coordination test of the protection device to be tested is performed to obtain the B-phase and C-phase differential coordination test results of the protection device to be tested.

[0061] The differential coordination test of phase A and phase C of the protection device to be tested can be performed by controlling the first bridge arm and the fourth bridge arm to be turned on and the second bridge arm and the third bridge arm to be turned off. Figure 2 Specifically, the second thyristor LA and the fifth thyristor LC are controlled to be turned on, and the third thyristor LB and the fourth thyristor LD are controlled to be turned off, so that the A and C two-phase voltages are added to the L and N terminals, and the A-phase and C-phase differential coordination test of the protection device to be tested is performed to obtain the A-phase and C-phase differential coordination test results of the protection device to be tested.

[0062] In some embodiments, the above S301: performing a differential matching test on the A phase and the B phase of the protection device to be tested to obtain a differential matching test result of the A phase and the B phase of the protection device to be tested includes:

[0063] Obtaining the voltage across the first branch when the switch K1 and the first thyristor LN are both disconnected, recorded as a first voltage;

[0064] The control switch K1 is closed, and the size of the adjustable load LR is adjusted so that the current of the first branch is a preset current value, and the current voltage across the first branch is obtained, which is recorded as the second voltage;

[0065] Calculate the equivalent impedance of phase A and phase B of the protection device to be tested according to the first voltage, the second voltage and the preset current value;

[0066] Calculate the first short-circuit current of phase A and phase B of the protection device to be tested according to the first voltage and the equivalent impedance, and estimate the differential coordination probability according to the first short-circuit current and the ampere-second characteristic curves of the upper and lower level protection devices;

[0067] Controlling the first thyristor LN to be turned on to simulate a short circuit fault between phases A and B;

[0068] When simulating a short-circuit fault of phases A and B, if it is detected that the protective device to be tested has tripped, and the superior protective device of the protective device to be tested has also tripped, then the differential coordination test result of phases A and B of the protective device to be tested is determined to be unqualified; if it is detected that the protective device to be tested has tripped, and the superior protective device of the protective device to be tested has not tripped, then the differential coordination test result of phases A and B of the protective device to be tested is determined to be qualified.

[0069] In this embodiment, when the differential coordination test of the A phase and the B phase of the protection device to be tested is performed, after the first bridge arm and the third bridge arm are controlled to be turned on, and the second bridge arm and the fourth bridge arm are controlled to be turned off, at this time, the A and B two-phase voltages of the protection device to be tested are added to the L and N ends, and the first branch and the second branch are both in a disconnected state. The voltage at both ends of the first branch at this time is obtained, which is also the voltage at both ends of the second branch, and is also the voltage at both ends of L and N, and is recorded as the first voltage U AB1 After obtaining the first voltage, the control switch K1 is closed, that is, the first branch is controlled to be turned on, and the size of the adjustable load LR is adjusted so that the current of the first branch is the preset current value I AB At this time, the voltage across the first branch, that is, the voltage across L and N, is obtained again and recorded as the second voltage U AB2 The preset current value is a small test current value, which can be set according to actual needs, for example, it can be 10A.

[0070] According to the formula Z AB =(U AB1 -U AB2 ) / I AB , calculate the equivalent impedance Z of phase A and phase B of the protection device to be tested AB , which can also be called the equivalent impedance at the test point of phases A and B of the station AC power supply.

[0071] According to formula I AB0 =U AB1 / Z AB , calculate the first short-circuit current at the test point, that is, the first short-circuit current I of phase A and phase B of the protection device to be tested AB0 The first short-circuit current is the estimated short-circuit current of the A phase and the B phase of the protection device to be tested. Based on the first short-circuit current and the ampere-second characteristic curves of the upper and lower level protection devices, the existing method can be used to estimate the upper and lower level differential matching probability of the A and B phases of the protection device to be tested. At this time, the small current estimation test of the A phase and the B phase of the protection device to be tested is completed.

[0072] After completing the small current estimation test of phase A and phase B of the protection device to be tested, a short-circuit fault simulation test of phase A and phase B of the protection device to be tested is performed, that is, the first thyristor LN is controlled to be turned on to simulate the short-circuit fault of phases A and B of the protection device to be tested. At this time, if it is detected that the protection device to be tested is tripped, and the superior protection device of the protection device to be tested is also tripped, then it is determined that the differential coordination test result of phase A and phase B of the protection device to be tested is unqualified; if it is detected that the protection device to be tested is tripped, and the superior protection device of the protection device to be tested is not tripped, then it is determined that the differential coordination test result of phase A and phase B of the protection device to be tested is qualified.

[0073] When conducting a short-circuit fault simulation test on phases A and B of the protective device under test, if the protective device under test refuses to operate, the emergency stop button ESB can be used to control the short-circuit circuit to be disconnected to ensure test safety.

[0074] A voltmeter may be connected in parallel to L and N to obtain the voltage across L and N, or other existing methods may be used to obtain the voltage across L and N. An ammeter may be connected in series to the second branch to obtain the current of the second branch, or other existing methods may be used to obtain the current of the second branch.

[0075] In a possible implementation, the above S302: performing a differential matching test on the B phase and the C phase of the protection device to be tested to obtain a differential matching test result of the B phase and the C phase of the protection device to be tested may include:

[0076] The voltage across the first branch when the switch K1 and the first thyristor LN are both disconnected is obtained, and is recorded as the third voltage U BC1 ;

[0077] The control switch K1 is closed, and the size of the adjustable load LR is adjusted so that the current of the first branch is the preset current value, and the current voltage across the first branch is obtained, which is recorded as the fourth voltage U BC2 ;

[0078] According to the third voltage, the fourth voltage and the preset current value, the equivalent impedance Z of the B phase and the C phase of the protection device to be tested is calculated. BC ;

[0079] According to the third voltage and equivalent impedance, calculate the third short-circuit current I of phase B and phase C of the protection device to be tested BC0 , and according to the third short-circuit current and the ampere-second characteristic curves of the upper and lower level protection devices, estimate the level difference coordination probability of the B and C phases of the protection device to be tested;

[0080] Controlling the first thyristor LN to be turned on to simulate a short circuit fault of phase B and phase C;

[0081] When simulating a short-circuit fault of phases B and C, if it is detected that the protective device to be tested has tripped, and the superior protective device of the protective device to be tested has also tripped, then the differential coordination test result of phases B and C of the protective device to be tested is determined to be unqualified; if it is detected that the protective device to be tested has tripped, and the superior protective device of the protective device to be tested has not tripped, then the differential coordination test result of phases B and C of the protective device to be tested is determined to be qualified.

[0082] In the above S303, performing a differential matching test on the A phase and the C phase of the protection device to be tested to obtain a differential matching test result of the A phase and the C phase of the protection device to be tested may include:

[0083] The voltage across the first branch when the switch K1 and the first thyristor LN are both disconnected is obtained, and is recorded as the fifth voltage U AC1 ;

[0084] The control switch K1 is closed, and the size of the adjustable load LR is adjusted so that the current of the first branch is the preset current value, and the current voltage across the first branch is obtained, which is recorded as the sixth voltage U AC2 ;

[0085] According to the fifth voltage, the sixth voltage and the preset current value, the equivalent impedance Z of the A phase and the C phase of the protection device to be tested is calculated. AC ;

[0086] According to the third voltage and the equivalent impedance, the fifth short-circuit current I of phase A and phase C of the protection device to be tested is calculated. AC0 , and according to the fifth short-circuit current and the ampere-second characteristic curves of the upper and lower level protection devices, estimate the differential coordination probability of the A and C phases of the protection device to be tested;

[0087] Controlling the first thyristor LN to be turned on to simulate a short circuit fault of phase A and phase C;

[0088] When simulating a short-circuit fault of phases A and C, if it is detected that the protective device to be tested has tripped, and the superior protective device of the protective device to be tested has also tripped, then the differential coordination test result of phases A and C of the protective device to be tested is determined to be unqualified; if it is detected that the protective device to be tested has tripped, and the superior protective device of the protective device to be tested has not tripped, then the differential coordination test result of phases A and C of the protective device to be tested is determined to be qualified.

[0089] Among them, the steps for performing differential coordination test on the B and C phases and the A and C phases of the protection device to be tested are similar to the steps for performing differential coordination test on the A and B phases of the protection device to be tested, and will not be repeated here. Please refer to the above description.

[0090] In some embodiments, the emergency stop button ESB is used to control the disconnection of the second branch when a short circuit fault between phases A and B is simulated and the protective device to be tested does not trip.

[0091] Among them, the emergency stop button ESB can also be used to control the disconnection of the second branch when simulating a short-circuit fault of phase B and phase C and the protective device to be tested does not trip, and to control the disconnection of the second branch when simulating a short-circuit fault of phase A and phase C and the protective device to be tested does not trip.

[0092] In some embodiments, the above S301: performing a differential matching test on the A phase and the B phase of the protection device to be tested to obtain a differential matching test result of the A phase and the B phase of the protection device to be tested, further includes:

[0093] When simulating the short-circuit fault of phase A and phase B, record the breaking time and the second short-circuit current of the protective device to be tested.

[0094] When performing a short-circuit fault simulation test on phases A and B of the protection device to be tested, it is also necessary to record the disconnection time of the protection device to be tested, that is, the tripping time, and obtain the current of the short-circuit circuit at this time, which is recorded as the second short-circuit current. Optionally, the waveform of the current of the circuit, the waveform of the voltage of the circuit, etc. can also be recorded at this time.

[0095] In a possible implementation, the above S302: performing a differential matching test on the B phase and the C phase of the protection device to be tested to obtain a differential matching test result of the B phase and the C phase of the protection device to be tested may also include:

[0096] When simulating the short-circuit fault of phase B and phase C, the breaking time and the fourth short-circuit current of the protective device to be tested are recorded.

[0097] In the above S303, the step of performing a differential matching test on the A phase and the C phase of the protection device to be tested to obtain a differential matching test result of the A phase and the C phase of the protection device to be tested may also include:

[0098] When simulating the short-circuit fault of phase A and phase C, the breaking time and the sixth short-circuit current of the protective device to be tested are recorded.

[0099] Among them, the steps for performing short-circuit fault simulation test on the B and C phases and the A and C phases of the protection device to be tested are similar to the steps for performing short-circuit fault simulation test on the A and B phases of the protection device to be tested, and will not be repeated here. Please refer to the above description.

[0100] In some embodiments, according to the differential matching test results of the A phase and the B phase of the protection device to be tested, the differential matching test results of the B phase and the C phase of the protection device to be tested, and the differential matching test results of the A phase and the C phase of the protection device to be tested, the differential matching test results of the protection device to be tested are determined, including:

[0101] If the differential coordination test results of the A-phase and B-phase of the protection device to be tested, the differential coordination test results of the B-phase and C-phase of the protection device to be tested, and the differential coordination test results of the A-phase and C-phase of the protection device to be tested are all qualified, then the differential coordination test result of the protection device to be tested is determined to be qualified;

[0102] If at least one of the differential coordination test results of phase A and phase B of the protection device to be tested, the differential coordination test results of phase B and phase C of the protection device to be tested, and the differential coordination test results of phase A and phase C of the protection device to be tested are unqualified, then the differential coordination test result of the protection device to be tested is determined to be unqualified.

[0103] In a specific application scenario, the AC differential coordination test device on-site wiring is as follows Figure 4 The station AC power supply system is powered by the station-use inverter AC busbars W, U, and V. The AC feeder panel supplies power to the AC load panel or distribution box via the AC circuit breakers S11, S12, ..., S1n in the panel, and the AC load panel or distribution box supplies power to the AC load via the AC circuit breakers SK1, SK2, SK3, ..., SKn in it.

[0104] Take the verification of the AC circuit breaker S12 and SK3 as an example to illustrate. During the test, disconnect the AC circuit breaker SK3 of the feeder circuit to be tested in the on-site AC system, untie the actual load wiring at its lower port, and connect the A, B, and C phase terminals of the test device to the lower port of the circuit breaker SK3; then close the AC circuit breaker SK3, and ensure that all other AC protective devices (including fuses and circuit breakers) on the AC feeder circuit to be tested are in the closed position.

[0105] According to the above test method, the following tests are performed:

[0106] (1) A and B phase differential coordination verification test:

[0107] 1) Small current estimation test: The test device controls the thyristor LA and LD to conduct, then closes the contactor K1 and adjusts the adjustable load LR to generate a suitable small test current, calculates the equivalent impedance of the A and B phases through the voltage and current, and then calculates the short-circuit current based on the bus voltage and impedance. Finally, the extreme difference coordination probability is estimated based on the ampere-second action characteristic curves of the upper and lower level protection devices.

[0108] 2) Short circuit simulation test: The test device controls the conduction of thyristors LA and LD, and then controls the conduction of thyristor LN, simulating the short circuit fault of phases A and B, recording the breaking time, short circuit current and waveform. At this time, the circuit breaker SK3 is instantaneous. If the circuit breaker S12 also trips, it means that the over-level tripping occurs and the differential coordination is unqualified. If S12 does not act, it means that the differential coordination of circuit breakers S12 and SK3 meets the requirements.

[0109] (2) B and C phase differential coordination verification test:

[0110] 1) Small current estimation test: The test device controls the thyristor LB and LC to conduct, then closes the contactor K1 and adjusts the adjustable load LR to generate a suitable small test current. The equivalent impedance at the B and C phases is calculated by the voltage and current, and the short-circuit current is calculated based on the bus voltage and impedance. Finally, the extreme difference coordination probability is estimated based on the ampere-second action characteristic curves of the upper and lower level protection devices.

[0111] 2) Short circuit simulation test: The test device controls the conduction of thyristors LB and LC, and then controls the conduction of thyristor LN, simulating the short circuit fault of phases B and C, recording the breaking time, short circuit current and waveform. At this time, the circuit breaker SK3 is instantaneous. If the circuit breaker S12 also trips, it means that the over-level tripping occurs and the differential coordination is unqualified. If S12 does not act, it means that the differential coordination of circuit breakers S12 and SK3 meets the requirements.

[0112] (3) A and C phase differential coordination verification test:

[0113] 1) Small current estimation test: the test device controls the thyristor LA and LC to conduct, then closes the contactor K1 and adjusts the adjustable load LR to generate a suitable small test current. The equivalent impedance at the A and C phases is calculated by the voltage and current, and the short-circuit current is calculated based on the bus voltage and impedance. Finally, the extreme difference coordination probability is estimated based on the ampere-second action characteristic curves of the upper and lower level protection devices.

[0114] 2) Short circuit simulation test, the test device controls the thyristor LA and LC to conduct, and then controls the thyristor LN to conduct, simulates the short circuit fault of phases A and C, records the breaking time, short circuit current and records the waveform. At this time, the circuit breaker SK3 is instantaneous. If the circuit breaker S12 also trips, it means that the over-level tripping occurs and the differential coordination is unqualified. If S12 does not act, it means that the differential coordination of circuit breakers S12 and SK3 meets the requirements.

[0115] Among them, the test data is shown in Table 1.

[0116] Table 1 Test data

[0117]

[0118]

[0119] This embodiment uses the differential coordination test device and test method for station AC power system protection devices, which can automatically complete the test of any two phases between three phases through one wiring, without repeated wiring; it can complete small current estimation test, test feeder line impedance, and estimate loop short-circuit current. The test has high safety and can perform online test on station AC power protection devices; it can complete short-circuit simulation test, simulate short-circuit test between any two phases, display the disconnection time and disconnection current of the protection device to be tested, and record the disconnection waveform curve of the protection device to be tested. The test conclusion is objective, true and reliable.

[0120] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A station-used AC power system protection device differential coordination test device, characterized in that: It includes an A-phase terminal, a B-phase terminal, a C-phase terminal, a first branch and a second branch connected in parallel, and a first bridge arm, a second bridge arm, a third bridge arm and a fourth bridge arm that are selectively turned on or off; the first branch includes an adjustable load and a switch connected in series; the second branch includes a first thyristor; The A-phase terminal, the B-phase terminal and the C-phase terminal are used to connect the outlet terminal of the protective electrical appliance to be tested; the first ends of the first branch and the second branch are respectively connected to the first end of the first bridge arm and the first end of the second bridge arm, the second ends of the first branch and the second branch are respectively connected to the first end of the third bridge arm and the first end of the fourth bridge arm, the second end of the first bridge arm is connected to the A-phase terminal, the second end of the second bridge arm and the second end of the third bridge arm are both connected to the B-phase terminal, and the second end of the fourth bridge arm is connected to the C-phase terminal.

2. The station AC power system protection device differential coordination test device according to claim 1, characterized in that: The second branch also includes an emergency stop button connected in series with the first thyristor.

3. The station AC power system protection device differential coordination test device according to claim 1, characterized in that: The first bridge arm includes a second thyristor, the second bridge arm includes a third thyristor, the third bridge arm includes a fourth thyristor, and the fourth bridge arm includes a fifth thyristor.

4. The station AC power system protection device differential coordination test device according to claim 1, characterized in that: The switch is a contactor.

5. The station AC power system protection device differential coordination test device according to any one of claims 1 to 4, characterized in that: The station-used AC power system protection electrical appliance differential coordination test device also includes a controller; The first bridge arm, the second bridge arm, the third bridge arm, the fourth bridge arm, the switch and the first thyristor are all controlled by the controller.

6. A method for testing the differential coordination of protective devices for a station AC power system, characterized in that: Applicable to the station AC power system protection device differential coordination test device as claimed in any one of claims 1 to 5; the station AC power system protection device differential coordination test method comprises: Control the first bridge arm and the third bridge arm to be turned on, control the second bridge arm and the fourth bridge arm to be turned off, and perform a differential coordination test on the A phase and the B phase of the protection device to be tested, and obtain a differential coordination test result on the A phase and the B phase of the protection device to be tested; Controlling the second bridge arm and the fourth bridge arm to be turned on, controlling the first bridge arm and the third bridge arm to be turned off, and performing a differential coordination test of the B phase and the C phase of the protection device to be tested, to obtain a differential coordination test result of the B phase and the C phase of the protection device to be tested; Controlling the first bridge arm and the fourth bridge arm to be turned on, controlling the second bridge arm and the third bridge arm to be turned off, and performing a differential coordination test of the A phase and the C phase of the protection device to be tested, to obtain a differential coordination test result of the A phase and the C phase of the protection device to be tested; The differential coordination test result of the protection device to be tested is determined according to the differential coordination test result of phase A and phase B of the protection device to be tested, the differential coordination test result of phase B and phase C of the protection device to be tested, and the differential coordination test result of phase A and phase C of the protection device to be tested.

7. The station AC power system protection device differential coordination test method according to claim 6, characterized in that: The step of performing a differential matching test on the A phase and the B phase of the protection device to be tested to obtain a differential matching test result of the A phase and the B phase of the protection device to be tested includes: Obtaining the voltage across the first branch when the switch and the first thyristor are both disconnected, recorded as a first voltage; Controlling the switch to close, and adjusting the size of the adjustable load so that the current of the first branch is a preset current value, and obtaining the current voltage across the first branch, which is recorded as a second voltage; Calculating the equivalent impedance of phase A and phase B of the protection device to be tested according to the first voltage, the second voltage and the preset current value; Calculate the first short-circuit current of the A-phase and the B-phase of the protection device to be tested according to the first voltage and the equivalent impedance, and estimate the differential coordination probability according to the first short-circuit current and the ampere-second characteristic curves of the upper and lower level protection devices; Controlling the first thyristor to conduct to simulate a short circuit fault between phase A and phase B; When simulating a short-circuit fault of phases A and B, if it is detected that the protection electrical appliance to be tested trips, and the superior protection electrical appliance of the protection electrical appliance to be tested also trips, then it is determined that the differential coordination test result of phases A and B of the protection electrical appliance to be tested is unqualified; if it is detected that the protection electrical appliance to be tested trips, and the superior protection electrical appliance of the protection electrical appliance to be tested does not trip, then it is determined that the differential coordination test result of phases A and B of the protection electrical appliance to be tested is qualified.

8. The station AC power system protection device differential coordination test method according to claim 7, characterized in that: The emergency stop button is used to control the disconnection of the second branch when a short circuit fault of phase A and phase B is simulated and the protective electrical device to be tested does not trip.

9. The station AC power system protection device differential coordination test method according to claim 7, characterized in that: The step of performing a differential matching test on the A phase and the B phase of the protection device to be tested to obtain a differential matching test result of the A phase and the B phase of the protection device to be tested further includes: When simulating the short-circuit fault of phase A and phase B, the breaking time and the second short-circuit current of the protective device to be tested are recorded.

10. The station AC power system protection device differential coordination test method according to any one of claims 6 to 9, characterized in that: Determining the differential coordination test result of the protection device to be tested according to the differential coordination test result of the A phase and the B phase of the protection device to be tested, the differential coordination test result of the B phase and the C phase of the protection device to be tested, and the differential coordination test result of the A phase and the C phase of the protection device to be tested, comprises: If the differential coordination test results of the A-phase and B-phase of the protection device to be tested, the differential coordination test results of the B-phase and C-phase of the protection device to be tested, and the differential coordination test results of the A-phase and C-phase of the protection device to be tested are all qualified, then the differential coordination test result of the protection device to be tested is determined to be qualified; If at least one of the differential coordination test results of phases A and B of the protection device to be tested, the differential coordination test results of phases B and C of the protection device to be tested, and the differential coordination test results of phases A and C of the protection device to be tested are unqualified, then it is determined that the differential coordination test result of the protection device to be tested is unqualified.

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