Differential Coordination Testing Method and System for AC Circuit Breakers Based on Impedance Angle Offset

Abstract

This application is applicable to the technical field of power systems, and provides a method and system for testing the differential coordination of AC circuit breakers based on impedance angle offset. The method includes: obtaining a first voltage value, a second voltage value, and a second current value of the circuit under test; calculating an offset time according to the first voltage value, the second voltage value, and the second current value; simulating a maximum short-circuit fault of the short-circuit current in the circuit under test according to the offset time; detecting a first state of the AC circuit breaker under test and a second state of the upper-level AC circuit breaker under test in the circuit under test during the maximum short-circuit fault of the short-circuit current; if the first state is tripped and the second state is closed, the differential coordination is qualified. This application can improve the accuracy of test results and accurately determine whether the differential coordination is qualified.

Description

Technical Field

[0001] The present application relates to the technical field of power systems, and in particular to an AC circuit breaker differential coordination testing method and system based on impedance angle offset. Background Art

[0002] In the power system, AC power is the most basic power source for substations. At present, the feeder network of the AC power system for substations mostly adopts a tree structure, and uses AC circuit breakers as the main protective electrical appliances. However, if the protection action characteristics of the upper and lower AC circuit breakers do not match, when a short circuit occurs in the lower power equipment, it will cause the upper AC circuit breaker to trip, thereby causing power outages in other feeder lines and expanding the scope of the accident.

[0003] In order to prevent potential safety hazards caused by mismatched action characteristics of upper and lower AC circuit breakers, a new substation AC power system must undergo an AC circuit breaker differential coordination test before commissioning and during its subsequent use to detect whether the AC circuit breaker differential coordination is qualified.

[0004] In the prior art, a parameter verification method is usually used to perform a differential coordination test on an AC circuit breaker in an AC power system. However, this method involves many parameters, is difficult to find the parameters, and has certain errors, resulting in low accuracy of the test results. Summary of the invention

[0005] In view of this, an embodiment of the present application provides an AC circuit breaker differential coordination test method and system based on impedance angle offset to solve the technical problem that the existing test method has certain errors when performing AC circuit breaker differential coordination test on the AC power supply system, resulting in low test result accuracy.

[0006] In order to achieve the above objectives, this application adopts the following technical solutions:

[0007] In a first aspect, an embodiment of the present application provides an AC circuit breaker differential coordination test method based on impedance angle offset, comprising:

[0008] In a possible implementation manner of the first aspect, obtaining a first voltage value, a second voltage value, and a second current value of the circuit under test includes:

[0009] When the circuit under test is unloaded, obtaining a first voltage value of the circuit under test;

[0010] The test resistance values ​​at both ends of the circuit under test are changed to obtain a second voltage value and a second current value of the circuit under test.

[0011] In a possible implementation manner of the first aspect, calculating the offset time according to the first voltage value, the second voltage value, and the second current value includes:

[0012] Calculate the equivalent complex impedance of the circuit under test according to the first voltage value, the second voltage value and the second current value;

[0013] Perform an arctangent process on the equivalent complex impedance to determine the phase difference between the AC voltage and the AC current of the circuit under test;

[0014] Determine the offset time according to the phase difference.

[0015] In a possible implementation manner of the first aspect, the simulating the maximum short-circuit fault of the short-circuit current for the circuit under test according to the offset time includes:

[0016] Detect the moment when the AC voltage of the circuit under test is maximum;

[0017] Determine the moment when the AC current of the circuit under test is maximum according to the moment when the AC voltage of the circuit under test is maximum and the offset time;

[0018] Simulate the maximum short-circuit fault of the short-circuit current for the circuit under test at the moment when the AC current of the circuit under test is maximum.

[0019] In a possible implementation manner of the first aspect, the AC circuit breaker grading cooperation test method based on impedance angle offset further includes: if both the first state and the second state are open, the grading cooperation is unqualified.

[0020] In a second aspect, an embodiment of the present application provides an AC circuit breaker grading cooperation test system based on impedance angle offset, including: an intelligent control module, a voltage acquisition module, a current acquisition module, an adjustable impedance load module, a short-circuit fault simulation module, and a switch state sensing module;

[0021] The intelligent control module is respectively communicatively connected to the voltage acquisition module, the current acquisition module, the adjustable impedance load module, the short-circuit fault simulation module, and the switch state sensing module;

[0022] Wherein, the voltage acquisition module is used to acquire the first voltage value and the second voltage value of the circuit under test;

[0023] The current acquisition module is used to acquire the second current value of the circuit under test;

[0024] The adjustable impedance load module is used to change the test resistance value at both ends of the circuit under test;

[0025] The short-circuit fault simulation module is used to simulate the maximum short-circuit fault of the short-circuit current for the circuit under test;

[0026] The switch state sensing module is used to detect the first state of the AC circuit breaker under test and the second state of its upper-level AC circuit breaker under test in the circuit under test;

[0027] The intelligent control module is used to execute the differential coordination test method of the AC circuit breaker based on impedance angle offset as described in any item of the first aspect.

[0028] In a possible implementation manner of the second aspect, the differential coordination test system of the AC circuit breaker based on impedance angle offset further includes: a data processing module communicatively connected to the voltage acquisition module and the current acquisition module respectively;

[0029] The data processing module is used to receive the first voltage value and the second voltage value sent by the voltage acquisition module, and to receive the second current value sent by the current acquisition module;

[0030] The data processing module is further used to calculate the offset time according to the first voltage value, the second voltage value and the second current value.

[0031] In a possible implementation manner of the second aspect, the differential coordination test system of the AC circuit breaker based on impedance angle offset further includes: a first wiring terminal and a second wiring terminal;

[0032] The first wiring terminal and the second wiring terminal are used to respectively connect the live wire terminal and the neutral wire terminal of the measured AC circuit breaker in the measured circuit when executing the differential coordination test method of the AC circuit breaker based on impedance angle offset as described in any item of the first aspect;

[0033] The first wiring terminal is respectively electrically connected to the voltage acquisition module, the current acquisition module, the adjustable impedance load module and the short-circuit fault simulation module;

[0034] The second wiring terminal is respectively electrically connected to the voltage acquisition module, the current acquisition module, the adjustable impedance load module and the short-circuit fault simulation module.

[0035] In a possible implementation manner of the second aspect, the differential coordination test system of the AC circuit breaker based on impedance angle offset further includes: a display module communicatively connected to the intelligent control module;

[0036] The display module is used to receive the differential coordination result sent by the intelligent control module and display the differential coordination result.

[0037] In a possible implementation manner of the second aspect, the differential coordination test system of the AC circuit breaker based on impedance angle offset further includes: an alarm module communicatively connected to the intelligent control module;

[0038] The alarm module is used to receive the differential coordination result sent by the intelligent control module and perform alarm processing according to the differential coordination result.

[0039] It can be understood that the beneficial effects of the above second aspect can be referred to the relevant descriptions in the above first aspect, and will not be elaborated here.

[0040] The AC circuit breaker grading coordination test method and system based on impedance angle offset provided by the embodiments of the present application obtain the first voltage value, the second voltage value and the second current value of the circuit under test, calculate the offset time according to the first voltage value, the second voltage value and the second current value, simulate the maximum short-circuit fault of the short-circuit current for the circuit under test according to the above offset time, and detect the first state of the AC circuit breaker under test and the second state of its upper-level AC circuit breaker under test in the case of the maximum short-circuit fault of the short-circuit current, and then judge whether the grading coordination is qualified according to the above first state and the second state, which can improve the accuracy of the test result and accurately judge whether the grading coordination is qualified.

[0041] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit this specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0043] Figure 1 is a schematic diagram of an application scenario provided by an embodiment of the present application;

[0044] Figure 2 is a schematic flowchart of an AC circuit breaker grading coordination test method based on impedance angle offset provided by an embodiment of the present application;

[0045] Figure 3 is a schematic flowchart of an AC circuit breaker grading coordination test method based on impedance angle offset provided by an embodiment of the present application;

[0046] Figure 4 is a schematic flowchart of an AC circuit breaker grading coordination test method based on impedance angle offset provided by an embodiment of the present application;

[0047] Figure 5 is a schematic flowchart of an AC circuit breaker grading coordination test method based on impedance angle offset provided by an embodiment of the present application;

[0048] Figure 6 is a schematic structural diagram of an AC circuit breaker grading coordination test system based on impedance angle offset provided by an embodiment of the present application;

[0049] Figure 7 It is an application connection diagram of an AC circuit breaker grading cooperation test system based on impedance angle offset provided by an embodiment of the present application. Specific embodiments

[0050] The present application will be described more clearly below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the role of the present application, but do not limit the present application in any form. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several deformations and improvements can be made. These all belong to the protection scope of the present application.

[0051] It should be understood that when used in the description of the present application specification and the appended claims, the term "comprising" indicates the presence of the described features, wholes, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or their combinations.

[0052] It should also be understood that the term "and / or" used in the description of the present application specification and the appended claims refers to any combination and all possible combinations of one or more of the related listed items, and includes these combinations.

[0053] In the description of the present application specification and the appended claims, the terms "first", "second", "third", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0054] The reference to "an embodiment" or "some embodiments" etc. described in the present application specification means that a specific feature, structure or characteristic described in combination with the embodiment is included in one or more embodiments of the present application. Thus, the statements "in an embodiment", "in some embodiments", "in other some embodiments", "in still other embodiments", etc. that appear in different places in this specification do not necessarily all refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "comprising", "including", "having" and their variants all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0055] In addition, the "plurality" mentioned in the embodiments of the present application should be construed as two or more.

[0056] In the power system, AC power is the most basic power supply for substations. It continuously and reliably supplies power to primary and secondary equipment and production activities in substations, and is the basic guarantee for the reliable operation of substations. At present, the feeder network of the AC power supply system for substations mostly adopts a tree structure, with a large power supply load and a wide distribution of circuits. From the station transformer to the power equipment, it generally goes through three or four levels of power distribution. Usually, AC circuit breakers are used as the main protective electrical appliances for overcurrent or short-circuit faults of the outgoing lines. The AC circuit breaker plays the role of disconnecting and isolating the feeder line. However, if the protection action characteristics of the upper and lower AC circuit breakers do not match, when a short-circuit fault occurs in the lower power equipment, it will cause the upper AC circuit breaker to trip, thereby causing the power outage of other feeder lines and expanding the scope of the accident.

[0057] In order to prevent hidden dangers caused by mismatched action characteristics of upper and lower AC circuit breakers, the AC power supply system of a newly built substation needs to undergo a differential coordination test of the AC circuit breaker before it is put into operation. It can only be put into operation after passing the test. At the same time, during the use of the AC power supply system, the AC circuit breaker differential coordination test also needs to be performed regularly. In the prior art, the parameter verification method is usually used to perform differential coordination test on the AC power supply system. However, this method involves many parameters, making it difficult to find the parameters, and there is a certain error that leads to low accuracy of the test results.

[0058] Based on the above problems, the inventors have discovered through research that the maximum AC current moment can be determined based on the phase difference between the AC voltage and the AC current of the tested circuit and the maximum AC current moment of the tested circuit. When the AC current is maximum, the short-circuit current maximum short-circuit fault simulation is performed on the tested circuit, and then the status of the upper and lower AC circuit breakers in the tested circuit is detected to test whether the differential coordination is qualified.

[0059] That is to say, the embodiment of the present application obtains the first voltage value, the second voltage value and the second current value of the circuit under test, and calculates the offset time according to the first voltage value, the second voltage value and the second current value. According to the above offset time, a short-circuit current maximum short-circuit fault is simulated for the circuit under test, and the first state of the AC circuit breaker under test in the circuit under test and the second state of its upstream AC circuit breaker under test are detected when the short-circuit current is the maximum short-circuit fault. Then, whether the differential coordination is qualified is judged according to the above first state and second state, thereby improving the accuracy of the test results and accurately judging whether the differential coordination is qualified.

[0060] Figure 1 Schematic diagram of an application scenario provided by an embodiment of the present application. Figure 1As shown, the differential coordination test system 10 for AC circuit breakers based on impedance angle offset connects the live wire connection end and the neutral wire connection end of the lower-level AC circuit breaker 20 in the AC power supply system, is used to collect the voltage and current at both ends of the lower-level AC circuit breaker 20, and analyze and process the above voltage and current to determine the moment when the AC current is the largest. At this moment, a short-circuit current maximum short-circuit fault is simulated, and then it is determined whether the differential coordination is qualified according to the states of the lower-level AC circuit breaker 20 and its upper-level AC circuit breaker collected.

[0061] Figure 2 It is a schematic flowchart of a method for differential coordination test of an AC circuit breaker based on impedance angle offset provided by an embodiment of the present application. As Figure 2 shown, the method in the embodiment of the present application may include:

[0062] Step 101, obtain a first voltage value, a second voltage value and a second current value of the circuit under test.

[0063] In this embodiment, the circuit under test is the AC power supply side of the AC power supply system, and the circuit under test includes the AC circuit breaker to be tested and the upper-level AC circuit breaker of the AC circuit breaker to be tested. Among them, the AC circuit breaker to be tested is the lower-level AC circuit breaker. Obtaining the first voltage value and the second voltage value of the circuit under test is actually obtaining the voltage across the AC circuit breaker to be tested in the circuit under test, and obtaining the second current of the circuit under test is actually obtaining the current flowing through the AC circuit breaker to be tested.

[0064] In a possible implementation manner, referring to Figure 3 , step 101 of obtaining the first voltage value, the second voltage value and the second current value of the circuit under test may specifically include:

[0065] Step 1011, when the circuit under test is no-load, obtain the first voltage value of the circuit under test.

[0066] Step 1012, change the test resistance value at both ends of the circuit under test, and obtain the second voltage value and the second current value of the circuit under test.

[0067] Optionally, according to Thevenin's theorem, the circuit under test, that is, the AC power supply side of the AC power supply system, can be equivalent to a single-port network in series with an equivalent voltage source and an equivalent complex impedance.

[0068] Exemplarily, when the circuit under test is no-load, that is, when the single-port network is no-load, obtain the first voltage value of the circuit under test, and this first voltage value is the voltage value of the equivalent voltage source of the single-port network.

[0069] Change the test resistance value at both ends of the circuit under test, that is, change the test resistance value at the output end of the single-port network, and obtain the second voltage value and the second current value of the circuit under test.

[0070] Optionally, the first voltage value and the second voltage value are the effective values of alternating voltages, and the second current value is the effective value of an alternating current.

[0071] Step 102: Calculate the offset time according to the first voltage value, the second voltage value, and the second current value.

[0072] In a possible implementation, referring to Figure 4 , in step 102, calculating the offset time according to the first voltage value, the second voltage value, and the second current value may specifically include:

[0073] Step 1021: Calculate the equivalent complex impedance of the circuit under test according to the first voltage value, the second voltage value, and the second current value.

[0074] Optionally, perform complex number conversion on the first voltage value, the second voltage value, and the second current value to respectively obtain corresponding first complex voltage value, second complex voltage value, and second complex current value.

[0075] The formula for the equivalent complex impedance is:

[0076]

[0077] In the formula, is the equivalent complex impedance, is the first complex voltage value, is the second complex voltage value, is the second complex current value, R is the resistance, X is the reactance, and j is the imaginary unit.

[0078] Step 1022: Perform arctangent processing on the equivalent complex impedance to determine the phase difference between the alternating voltage and the alternating current of the circuit under test.

[0079] Optionally, perform arctangent processing on the equivalent complex impedance to obtain the impedance angle, and the impedance angle is the phase difference between the alternating voltage and the alternating current of the circuit under test.

[0080] The formula for the impedance angle is:

[0081]

[0082] In the formula, is the impedance angle.

[0083] Step 1023: Determine the offset time according to the phase difference.

[0084] Exemplarily, the offset time can be calculated according to the phase difference and the alternating current cycle. For example, if the alternating current frequency of the power grid in China is 50 Hz and the alternating current cycle is 20 milliseconds, then the offset time can be calculated as milliseconds.

[0085] Step 103: Simulate the maximum short-circuit fault of the short-circuit current for the circuit under test according to the offset time.

[0086] In a possible implementation, referring to Figure 5 , in step 103, calculating the offset time according to the first voltage value, the second voltage value and the second current value may specifically include:

[0087] Step 1031: Detect the moment when the AC voltage of the circuit under test is maximum.

[0088] Step 1032: Determine the moment when the AC current of the circuit under test is maximum according to the moment when the AC voltage of the circuit under test is maximum and the offset time.

[0089] Step 1033: Simulate the maximum short-circuit fault of the short-circuit current for the circuit under test at the moment when the AC current of the circuit under test is maximum.

[0090] Among them, since the moment when the AC current of the circuit under test is maximum cannot be directly determined by detection, while the moment when the AC voltage of the circuit under test is maximum can be directly detected, therefore, by detecting the moment when the AC voltage of the circuit under test is maximum and according to the offset time determined based on the phase difference, the moment when the AC current of the circuit under test is maximum can be determined.

[0091] Exemplarily, collect the AC voltage waveform of the circuit under test, determine the moment when the AC voltage of the circuit under test is maximum according to the above AC voltage waveform, and then offset the above offset time at this moment when the AC voltage is maximum, that is, the moment when the AC current of the circuit under test is maximum is obtained.

[0092] Specifically, simulating a short-circuit fault for the circuit under test at the moment when the AC current of the circuit under test is maximum can simulate the fault of the circuit under test to the greatest extent, so that it can be determined that if the grading coordination of the AC circuit breaker is qualified in this fault situation, then when other faults occur in the circuit under test, the grading coordination of the AC circuit breaker is qualified. That is to say, simulating a short-circuit fault for the circuit under test at the moment when the AC current of the circuit under test is maximum, and then detecting whether the grading matching of the measured AC circuit breaker and its upper-level measured AC circuit breaker is qualified in this fault situation can achieve precise verification of the grading coordination of the AC circuit breaker and improve the accuracy of the test results.

[0093] Step 104: Detect the first state of the measured AC circuit breaker and the second state of its upper-level measured AC circuit breaker in the circuit under test during the maximum short-circuit fault of the short-circuit current.

[0094] Optionally, the states of the measured AC circuit breaker and its upper-level measured AC circuit breaker may be opening or closing, and a non-contact acquisition method is used to detect the states of the measured AC circuit breaker and its upper-level measured AC circuit breaker.

[0095] Specifically, if no electrical signal is detected at the lower port of the tested AC circuit breaker, the state of the tested AC circuit breaker is open, otherwise, the state of the tested AC circuit breaker is closed. If no electrical signal is detected at the upper port of the tested AC circuit breaker, the state of the upper-level tested AC circuit breaker of the tested AC circuit breaker is open, otherwise, the state of the tested AC circuit breaker is closed.

[0096] Step 105: If the first state is open and the second state is closed, the differential coordination is qualified.

[0097] Optionally, if both the first state and the second state are open, the differential coordination is unqualified.

[0098] Specifically, if the first state of the tested AC circuit breaker is open and the second state of its upper-level tested AC circuit breaker is closed, it indicates that when a short-circuit fault with maximum short-circuit current occurs, the tested AC circuit breaker normally opens to disconnect and isolate the tested circuit, while its upper-level tested AC circuit breaker is not affected, and the step-difference coordination is qualified.

[0099] If the first state of the tested AC circuit breaker and the second state of its upstream tested AC circuit breaker are both open, it indicates that when a short-circuit fault with maximum short-circuit current occurs, the tested AC circuit breaker opens normally, while its upstream AC circuit breaker trips across levels, and the level difference coordination is unqualified.

[0100] Optionally, if the first state of the tested AC circuit breaker is closed, it indicates that the tested AC circuit breaker or other components in the tested circuit are faulty, which also poses a safety hazard and requires further maintenance.

[0101] The above-mentioned AC circuit breaker differential coordination test method based on impedance angle offset obtains the first voltage value, the second voltage value and the second current value of the circuit under test, and calculates the offset time according to the first voltage value, the second voltage value and the second current value. According to the above-mentioned offset time, a short-circuit current maximum short-circuit fault is simulated for the circuit under test, and the first state of the AC circuit breaker under test in the circuit under test and the second state of its upper-level AC circuit breaker under test are detected when the short-circuit current is the maximum short-circuit fault. Whether the differential coordination is qualified is judged according to the above-mentioned first state and second state, which can improve the accuracy of the test result and accurately judge whether the differential coordination is qualified.

[0102] It should be understood that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0103] Figure 6 1 is a schematic diagram of the structure of an AC circuit breaker differential coordination test system based on impedance angle offset provided by an embodiment of the present application. Figure 6As shown in the figure, the differential coordination test system 10 for AC circuit breakers based on impedance angle offset includes: an intelligent control module 11, a voltage acquisition module 12, a current acquisition module 13, an adjustable impedance load module 14, a short-circuit fault simulation module 15, and a switch state sensing module 16;

[0104] The intelligent control module 11 is communicatively connected to the voltage acquisition module 12, the current acquisition module 13, the adjustable impedance load module 14, the short-circuit fault simulation module 15, and the switch state sensing module 16 respectively;

[0105] The intelligent control module 11 is used to execute the differential coordination test method for AC circuit breakers based on impedance angle offset.

[0106] Among them, the above differential coordination test method for AC circuit breakers based on impedance angle offset can be the differential coordination test method for AC circuit breakers based on impedance angle offset provided by any embodiment of the present application.

[0107] Optionally, the voltage acquisition module 12 is used to acquire the first voltage value and the second voltage value of the circuit under test; the current acquisition module 13 is used to acquire the second current value of the circuit under test; the adjustable impedance load module 14 is used to change the test resistance value at both ends of the circuit under test; the short-circuit fault simulation module 15 is used to simulate the maximum short-circuit fault of short-circuit current in the circuit under test; the switch state sensing module 16 is used to detect the first state of the AC circuit breaker under test and the second state of its upper-level AC circuit breaker under test in the circuit under test.

[0108] Exemplarily, the voltage acquisition module 12 is further used to acquire the AC voltage waveform of the circuit under test and can be a voltage transmitter. The current acquisition module 13 can be a current transmitter. The adjustable impedance load module 14 can be a parallel circuit of several resistors. The short-circuit fault simulation module 15 can be a thyristor. The switch state sensing module 16 can be a line break detection circuit, where the line break detection circuit detects the states of the AC circuit breaker under test and its upper-level AC circuit breaker under test in a non-contact manner, with simple wiring and convenient use.

[0109] The above voltage acquisition module 12, current acquisition module 13, adjustable impedance load module 14, short-circuit fault simulation module 15, and switch state sensing module 16 can all be implemented by existing technologies and will not be elaborated here.

[0110] The above differential coordination test system 10 for AC circuit breakers based on impedance angle offset can realize the on-line test of whether the differential coordination between the AC circuit breaker under test and its upper-level AC circuit breaker under test in the circuit under test is qualified, and has simple line connection and high test accuracy.

[0111] Optionally, the differential coordination test system 10 for AC circuit breakers based on impedance angle offset further includes a data processing module (not shown in the figure).

[0112] Specifically, the above data processing module is communicatively connected to the voltage acquisition module and the current acquisition module respectively, and is used to receive the first voltage value and the second voltage value sent by the voltage acquisition module 12, and is also used to receive the second current value sent by the current acquisition module 13.

[0113] The above data processing module is further used to calculate the offset time according to the first voltage value, the second voltage value and the second current value.

[0114] Optionally, the AC circuit breaker grading coordination test system 10 based on impedance angle offset further includes a first terminal and a second terminal (not shown in the figure).

[0115] Specifically, the first terminal and the second terminal are used to respectively connect the live wire terminal and the neutral wire terminal of the measured AC circuit breaker in the circuit to be measured when performing the AC circuit breaker grading coordination test method based on impedance angle offset.

[0116] Optionally, the first terminal is electrically connected to the voltage acquisition module 12, the current acquisition module 13, the adjustable impedance load module 14 and the short-circuit fault simulation module 15 respectively.

[0117] The second terminal is electrically connected to the voltage acquisition module 12, the current acquisition module 13, the adjustable impedance load module 14 and the short-circuit fault simulation module 15 respectively.

[0118] Optionally, the AC circuit breaker grading coordination test system 10 based on impedance angle offset further includes a display module (not shown in the figure) communicatively connected to the intelligent control module 11.

[0119] The display module is used to receive the grading coordination result sent by the intelligent control module 11 and display the grading coordination result, so that the staff can directly observe the grading coordination result in time.

[0120] Optionally, the AC circuit breaker grading coordination test system 10 based on impedance angle offset may further include an alarm module (not shown in the figure) communicatively connected to the intelligent control module 11.

[0121] The alarm module is used to receive the grading coordination result sent by the intelligent control module 11 and perform alarm processing according to the grading coordination result. For example, an alarm message is sent when the above grading coordination result is unqualified, so that the staff can receive the unqualified grading coordination result in time. The above alarm module may be a buzzer or an indicator light, etc., and is not specifically limited here. For example, when the alarm module is an indicator light, the indicator light turns red when receiving the unqualified grading coordination result.

[0122] Figure 7It is an application connection diagram of an AC circuit breaker grading coordination test system based on impedance angle offset provided by an embodiment of the present application. As Figure 7 shown, in a single-phase station AC power supply system, an AC circuit breaker is used as a protective electrical appliance. The single-phase station AC power supply system is powered by the neutral line N and the live line L of the station transformer to the AC busbar. The current feeder panel supplies power to the AC load panel or distribution box via the in-panel AC circuit breakers S11, S12... S1n. The above-mentioned AC load panel or distribution box then supplies power to the AC load via the in-panel AC circuit breakers SK1, SK2... SKn.

[0123] Taking the example of testing whether the grading coordination between the AC circuit breaker SK2 and its upper-level AC circuit breaker S12 is qualified, disconnect the AC circuit breaker SK2, and disconnect the actual load wiring of the live wire connection terminal and the neutral wire connection terminal at its lower port. Connect the first wiring terminal of the AC circuit breaker grading coordination test system based on impedance angle offset in the present application to the above-mentioned live wire wiring terminal, and connect the second wiring terminal to the above-mentioned neutral wire wiring terminal; close the AC circuit breaker SK2, and ensure that all other AC circuit breakers in the single-phase station AC power supply system are in the closed state.

[0124] Use the AC circuit breaker grading coordination test system based on impedance angle offset described in the foregoing embodiments of the present application, and test the AC circuit breaker SK2 according to the AC circuit breaker grading coordination test method described in the foregoing embodiments of the present application to obtain the grading coordination result.

[0125] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. An AC circuit breaker grading coordination test method based on impedance angle offset, characterized in that, Including: Obtain a first voltage value, a second voltage value, and a second current value of the circuit under test; Calculate an offset time according to the first voltage value, the second voltage value, and the second current value; Simulate a maximum short-circuit fault of the short-circuit current for the circuit under test according to the offset time; Detect a first state of the AC circuit breaker under test and a second state of its upper-level AC circuit breaker under test during the maximum short-circuit fault of the short-circuit current; If the first state is open and the second state is closed, the grading coordination is qualified; Among them, the obtaining of the first voltage value, the second voltage value, and the second current value of the circuit under test includes: When the circuit under test is no-load, obtain the first voltage value of the circuit under test; change the test resistance value at both ends of the circuit under test, and obtain the second voltage value and the second current value of the circuit under test; The calculating of the offset time according to the first voltage value, the second voltage value, and the second current value includes: Calculate the equivalent complex impedance of the circuit under test according to the first voltage value, the second voltage value, and the second current value; perform an arctangent process on the equivalent complex impedance to determine the phase difference between the AC voltage and the AC current of the circuit under test; determine the offset time according to the phase difference; among them, the phase difference between the AC voltage and the AC current of the circuit under test is the impedance angle.

2. The differential coordination test method of the AC circuit breaker based on impedance angle offset according to claim 1, characterized in that The simulating of the maximum short-circuit fault of the short-circuit current for the circuit under test according to the offset time includes: Detect the moment when the AC voltage of the circuit under test is maximum; Determine the moment when the AC current of the circuit under test is maximum according to the moment when the AC voltage of the circuit under test is maximum and the offset time; Simulate a maximum short-circuit fault of the short-circuit current for the circuit under test at the moment when the AC current of the circuit under test is maximum.

3. The differential coordination test method for AC circuit breakers based on impedance angle offset according to claim 1 or 2, characterized in that It also includes: If both the first state and the second state are open, the grading coordination is unqualified.

4. An alternating current circuit breaker grading cooperation test system based on impedance angle offset, characterized in that Including: An intelligent control module, a voltage acquisition module, a current acquisition module, an adjustable impedance load module, a short-circuit fault simulation module, and a switch state sensing module; The intelligent control module is respectively communicatively connected to the voltage acquisition module, the current acquisition module, the adjustable impedance load module, the short-circuit fault simulation module, and the switch state sensing module; Among them, the voltage acquisition module is used to acquire the first voltage value and the second voltage value of the circuit under test; The current acquisition module is used to acquire the second current value of the circuit under test; The adjustable impedance load module is used to change the test resistance value at both ends of the circuit under test; The short-circuit fault simulation module is used to simulate a maximum short-circuit fault of the short-circuit current for the circuit under test; The switch state sensing module is used to detect the first state of the AC circuit breaker under test and the second state of its upper-level AC circuit breaker under test in the circuit under test; The intelligent control module is used to execute the AC circuit breaker grading coordination test method based on impedance angle offset as described in any one of claims 1-3.

5. The differential coordination test system for AC circuit breakers based on impedance angle offset according to claim 4, wherein It also includes: a data processing module communicatively connected to the voltage acquisition module and the current acquisition module respectively; The data processing module is used to receive the first voltage value and the second voltage value sent by the voltage acquisition module, and is used to receive the second current value sent by the current acquisition module; The data processing module is further configured to calculate an offset time according to the first voltage value, the second voltage value, and the second current value.

6. The differential coordination test system for AC circuit breakers based on impedance angle offset according to claim 4, characterized in that, It further includes: a first terminal and a second terminal; The first terminal and the second terminal are used to connect to the live wire terminal and the neutral wire terminal of the AC circuit breaker under test in the circuit under test respectively; The first terminal is electrically connected to the voltage acquisition module, the current acquisition module, the adjustable impedance load module, and the short-circuit fault simulation module respectively; The second terminal is electrically connected to the voltage acquisition module, the current acquisition module, the adjustable impedance load module, and the short-circuit fault simulation module respectively.

7. The differential coordination test system for AC circuit breakers based on impedance angle offset according to claim 6, wherein It further includes: a display module communicatively connected to the intelligent control module; The display module is configured to receive the grading coordination result sent by the intelligent control module and display the grading coordination result.

8. The differential coordination test system for AC circuit breakers based on impedance angle offset according to claim 6, characterized in that, It further includes: an alarm module communicatively connected to the intelligent control module; The alarm module is configured to receive the grading coordination result sent by the intelligent control module and perform alarm processing according to the grading coordination result.

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