Device and method for detecting one-point grounding of voltage loop

Abstract

The invention discloses equipment and a method for detecting one-point grounding of a voltage loop. The equipment comprises a processing control unit and a test loop, the processing control unit is in communication connection with the test loop; the signal input end and the signal output end are respectively in communication connection with the processing control unit; the adjustable equivalent resistor is also in communication connection with the processing control unit; the processing control unit is used for receiving a first feedback signal output by the signal output end, determining actual equivalent resistance according to the test signal and the first feedback signal, adjusting the resistance value of the adjustable equivalent resistor according to the actual equivalent resistance and receiving a second feedback signal; and judging whether the to-be-tested voltage loop has a grounding fault according to the second feedback signal and the test signal. According to the technical scheme, the problem that a universal meter cannot be used for measurement at one-point grounding position is solved, and operation interval protection maloperation is not prone to being caused. Meanwhile, the adjustable equivalent resistor is arranged to change the parallel resistance of the distributed capacitors according to the feedback signal, thereby achieving the effect of enhancing the signal.

Description

Technical Field

[0001] The present invention relates to the technical field of power grid detection, and in particular to a device and method for detecting single-point grounding of a voltage loop. Background Art

[0002] The existing detection method is to judge whether the secondary circuit is grounded at one point based on the empirical value of the voltage or to use the resistance range of the multimeter for measurement. However, the use of a multimeter has disadvantages, which will cause two points of grounding, which is easy to cause false protection. During daily operation inspections, the equipment is not powered off, and only experience can be relied on for investigation, which is not effective. Existing drone inspections, robot inspections, manual inspections, etc. cannot directly detect whether there is a single point of grounding, which is a blind spot that has long plagued secondary circuit inspections. Summary of the invention

[0003] The invention provides a device and method for detecting single-point grounding of a voltage loop, so as to solve the problem of poor safety and accuracy of the method for detecting single-point grounding of a secondary loop in the prior art.

[0004] According to one aspect of the present invention, there is provided a device for detecting a single-point grounding of a voltage loop, comprising: a processing control unit and a test loop; the processing control unit is in communication connection with the test loop;

[0005] The test circuit includes a signal input terminal, a signal output terminal, an adjustable equivalent resistor, a first test terminal and a second test terminal;

[0006] The signal input terminal and the signal output terminal are respectively connected to the processing control unit for communication; the first test terminal is used to connect the ground wire of the voltage loop to be tested, the second test terminal is used for grounding and the adjustable equivalent resistor is connected in series between the first test terminal and the second test terminal; the adjustable equivalent resistor is also connected to the processing control unit for communication;

[0007] The processing control unit is used to input a test signal to the signal input end, and is also used to receive a first feedback signal output from the signal output end and determine the actual equivalent resistance according to the test signal and the first feedback signal and adjust the resistance value of the adjustable equivalent resistance according to the actual equivalent resistance and receive a second feedback signal output from the signal output end, and determine whether a ground fault occurs in the voltage circuit to be tested according to the second feedback signal and the test signal.

[0008] Optionally, the test circuit also includes an input optocoupler and an output optocoupler;

[0009] The second end of the input optical coupler is electrically connected to the signal input end, and the third end of the input optical coupler is electrically connected to the first test end;

[0010] The first end of the output optical coupler is electrically connected to the second test end, and the fourth end of the output optical coupler is electrically connected to the signal output end.

[0011] Optionally, the test circuit further includes a first resistor, a second resistor, a third resistor and a fourth resistor;

[0012] The first resistor is arranged in series between the second test terminal and the first terminal of the output optical coupler;

[0013] The second resistor is electrically connected to the fourth end of the output optical coupler;

[0014] The third resistor is arranged in series between the signal input terminal and the second terminal of the input optical coupler;

[0015] The fourth resistor is arranged in series between the first test terminal and the third terminal of the input optical coupler.

[0016] Optionally, the processing control unit includes a data processing subunit and a single chip microcomputer;

[0017] The single chip microcomputer is respectively connected to the data processing sub-unit, the signal input terminal and the adjustable equivalent resistor for communication;

[0018] The data processing subunit is communicatively connected with the signal output terminal.

[0019] Optionally, the device further comprises a power supply;

[0020] The power supply is electrically connected to the processing control unit and is used to supply power to the processing control unit.

[0021] Optionally, the device further comprises a display screen;

[0022] The processing control unit is connected to the display screen for communication, and is used for outputting a detection result signal to the display screen after determining whether a ground fault occurs in the voltage circuit to be tested.

[0023] Optionally, the device further comprises a housing;

[0024] The display screen is arranged on the surface of the shell;

[0025] The processing control unit, the signal input terminal, the signal output terminal and the adjustable equivalent resistor are arranged in the accommodating space of the shell; the first test terminal and the second test terminal are arranged outside the shell.

[0026] According to another aspect of the present invention, a method for detecting a single-point grounding of a voltage loop is provided, which is applied to a device for detecting a single-point grounding of a voltage loop; the method comprises:

[0027] Input a test signal to the signal input terminal;

[0028] receiving a first feedback signal outputted from the signal output terminal and determining an actual equivalent resistance according to the test signal and the first feedback signal;

[0029] The resistance value of the equivalent resistor can be adjusted according to the actual equivalent resistor;

[0030] A second feedback signal outputted from the receiving signal output terminal;

[0031] It is determined whether a ground fault occurs in the voltage circuit to be tested according to the second feedback signal and the test signal.

[0032] Optionally, judging whether a ground fault occurs in the voltage circuit to be tested according to the second feedback signal and the test signal includes:

[0033] When the second feedback signal and the test signal are the same, a ground normal signal is output;

[0034] When the second feedback signal is different from the test signal, a ground abnormality signal is output.

[0035] Optionally, the test circuit also includes an input optocoupler and an output optocoupler;

[0036] Determining an actual equivalent resistance according to the test signal and the first feedback signal includes:

[0037] Acquire a first current transfer ratio of the input optocoupler and a second current transfer ratio of the output optocoupler;

[0038] An actual equivalent resistance is determined according to the test signal, the first feedback signal, the first current transfer ratio, and the second current transfer ratio.

[0039] The technical solution of the present invention solves the problem that it is not possible to use a multimeter to measure at the single-point grounding of the N600 of the entire station during technical transformation and regular inspection, and it is not easy to cause malfunction of the running interval protection. At the same time, the adjustable equivalent resistor is set to change the resistance value of the distributed capacitor in parallel according to the feedback signal, thereby achieving the effect of enhancing the signal, so that the measurement result is not easily interfered by the capacitance of the non-fault branch to the ground, and the result is accurate.

[0040] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. 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 creative work.

[0042] Figure 1This is a test connection diagram of a single-point grounding device for detecting a voltage loop provided according to an embodiment of the present invention;

[0043] Figure 2 is a circuit connection diagram of a test loop provided according to an embodiment of the present invention;

[0044] Figure 3 is a connection diagram of a single-point grounding device for detecting a voltage loop provided according to an embodiment of the present invention;

[0045] Figure 4 is a schematic diagram of simulation results of a test loop provided according to an embodiment of the present invention;

[0046] Figure 5 This is a flow chart of a first method for detecting single-point grounding in a voltage loop provided according to an embodiment of the present invention;

[0047] Figure 6 is a flow chart of a second method for detecting single-point grounding of a voltage loop provided according to an embodiment of the present invention;

[0048] Figure 7 It is a flow chart of a third method for detecting single-point grounding of a voltage loop provided according to an embodiment of the present invention. DETAILED DESCRIPTION

[0049] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0050] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0051] The single-point grounding of the N-line voltage loop of the power system is a very typical wiring form, especially for double-busbar wiring plants and 500kV stations. The existing detection method is to judge whether the secondary loop is single-point grounded based on the empirical value of the voltage or to use the resistance range of a multimeter for measurement. However, since the impedance output by the resistance range of the multimeter is relatively small, it is easy to cause two-point grounding, which makes it impossible to use the resistance range of the multimeter to measure the voltage for judgment. Once a system failure occurs, a large current may flow through the substation grounding network, resulting in a neutral point potential shift, causing voltage-related protection malfunctions. Therefore, an embodiment of the present invention provides a device for detecting single-point grounding of a voltage loop. Figure 1 This is a test connection diagram of a single-point grounding device for detecting a voltage loop according to an embodiment of the present invention. Figure 2 is a circuit connection diagram of a test loop provided according to an embodiment of the present invention, Figure 3 1 is a connection diagram of a single-point grounding device for detecting a voltage loop according to an embodiment of the present invention. Figure 1 , Figure 2 and Figure 3 As shown, the device 1 comprises:

[0052] Processing control unit 11 and test loop 12; Processing control unit 11 is in communication connection with test loop 12;

[0053] The test loop 12 includes a signal input terminal A, a signal output terminal B, an adjustable equivalent resistor R6, a first test terminal C and a second test terminal D;

[0054] The signal input terminal A and the signal output terminal B are respectively connected to the processing control unit 11 for communication; the first test terminal C is used to connect the ground wire of the voltage loop to be tested, the second test terminal D is used for grounding and the adjustable equivalent resistor R6 is connected in series between the first test terminal C and the second test terminal D; the adjustable equivalent resistor R6 is also connected to the processing control unit 11 for communication;

[0055] The processing control unit 11 is used to input a test signal to the signal input terminal A, and is also used to receive a first feedback signal output by the signal output terminal B and determine the actual equivalent resistance according to the test signal and the first feedback signal and adjust the resistance value of the adjustable equivalent resistance R6 according to the actual equivalent resistance and receive a second feedback signal output by the signal output terminal B, and determine whether a ground fault occurs in the voltage circuit to be tested according to the second feedback signal and the test signal.

[0056] Among them, the processing control unit 11 can be used for data processing, transmission, calculation and control, and is communicated with the test loop 12. Specifically, it can be used to input test signals to the test loop 12 and receive feedback signals passing through the test loop 12, and perform calculation processing control.

[0057] Among them, the test loop 12 can be used to connect with the voltage loop to be tested and transmit a test signal to the voltage loop to be tested. The test loop 12 includes a signal input terminal A, a signal output terminal B, an adjustable equivalent resistor R6, a first test terminal C and a second test terminal D. The signal input terminal A is connected to the processing control unit 11, so that the processing control unit 11 can input a test signal along the signal output terminal B. The signal output terminal B is connected to the processing control unit 11, so that the processing control unit 11 can receive the first feedback signal or the second feedback signal after passing through the voltage loop to be tested. The first test terminal C can be used to connect the ground wire connected to the voltage loop to be tested, and the second test terminal D can be used for grounding, so that the signal input terminal A, the first test terminal C, the voltage loop to be tested, the second test terminal D and the signal output terminal B form a loop, so that the test signal flows in the loop and outputs a feedback signal.

[0058] Among them, the adjustable equivalent resistor R6 is connected in series between the first test terminal C and the second test terminal D, and is connected in parallel with the voltage loop to be tested. When there is distributed capacitance in the voltage loop to be tested, the distributed capacitance will interfere with the test signal and the feedback signal, causing the accuracy of the processing and control unit 11 in judging the grounding to decrease. Therefore, by connecting the adjustable equivalent resistor R6 in parallel with the voltage loop to be tested, the resistance value of the adjustable equivalent resistor R6 can be adjusted by the processing and control unit 11 and the resistance value of the adjustable equivalent resistor R6 meets the condition that the total resistance value can be increased after parallel connection. The purpose of setting the adjustable equivalent resistance is: due to the existence of distributed capacitance, the distributed capacitance of the voltage loop to be measured can be equivalent to an RC parallel circuit, that is, the C0 and R0 parallel circuit in the figure. The larger the distributed capacitance, the smaller the capacitive reactance, and the smaller the total impedance. When the voltage loop to be measured is connected to the first test terminal C, the total resistance between the first test terminal C and the second test terminal D, that is, the voltage value, can be increased by adjusting the resistance value of the adjustable equivalent resistor R6. Therefore, the processing control unit 11 inputs a test signal into the voltage loop to be measured and receives a first feedback signal. Since the resistance value of the adjustable equivalent resistor R6 is known, the resistance value of the distributed capacitance of the voltage loop to be measured, that is, the resistance value of the actual equivalent resistor, can be calculated through the test signal and the first feedback signal. The resistance value of the adjustable equivalent resistor R6 is adjusted according to the resistance value of the actual equivalent resistor to increase the total resistance between the first test terminal C and the second test terminal D, enhance the amplitude of the second feedback signal, and then improve the quality of the second feedback signal, so that the processing control unit 11 is more accurate and more precise when judging whether the voltage loop to be measured is grounded based on the test signal and the second feedback signal.

[0059] The reason why the amplitude of the second feedback signal can be enhanced by increasing the total resistance between the first test terminal C and the second test terminal D is that, according to the model simulation analysis, fixed parameters of the simulation model are set, the amplitude of the test signal is set to U=3.3V, the frequency of the test signal is set to f=5KHz, the distributed capacitance is set to C0=2uF, and the resistance R=20Ω in parallel with the distributed capacitance is set. Figure 4 Schematic diagram of simulation results of a test loop provided according to an embodiment of the present invention. Figure 4 , the red line is the test signal waveform amplitude V = 3.3V, frequency f = 5KHz; the green line is the first feedback signal waveform frequency of 5KHz, peak amplitude Vh = 3.3V, trough amplitude Vl = 1.78V. Since the resistance and capacitance will not affect the frequency of the signal, but only the signal amplitude and phase shift, the control variable method is used to change the resistance value of the adjustable equivalent resistor R6 and then change the resistance value R after R6 and R0 are connected in parallel to observe the impact on the signal amplitude. The results are shown in Table 1. It can be seen that the larger the resistance value R after R6 and R0 are connected in parallel, the peak value of the received signal will not be changed, but the trough value will increase accordingly, showing a positive correlation. It is concluded that the larger the equivalent capacitance, the larger the trough amplitude will be, achieving the effect of enhancing the signal.

[0060] Table 1

[0061]

[0062] For example, continue to refer to Figure 1 As shown, the voltage circuit to be tested includes a PT ground terminal box, an electric energy meter, a protection module, a recording module and a measurement and control module. The N lines of the PT ground terminal box, the electric energy meter, the protection module, the recording module and the measurement and control module are all grounded uniformly at N600 of the entire station. When the device 1 in the embodiment of the present invention is tested, the first test terminal C can be connected to any N line, and the second test terminal D is grounded. A test signal is sent to the corresponding N line and a first feedback signal is received. The processing control unit 11 further calculates the equivalent resistance value corresponding to the distributed capacitance in the corresponding N line circuit, and adjusts the resistance value of the adjustable equivalent resistor R6 through the equivalent resistance value. The resistance value of the adjustable equivalent resistor R6 can be adjusted to be much smaller than the equivalent resistance value, thereby increasing the total resistance value after the two are connected in parallel, and increasing the resistance in parallel with the distributed capacitance, thereby achieving the effect of enhancing the signal. After the adjustment is completed, continue to output the test signal and receive the second feedback signal, compare the test signal with the stable second feedback signal, when the test signal is consistent with the second feedback signal, it means that the N line is grounded normally at this time; when the test signal is inconsistent with the second feedback signal, it means that the N line is grounded abnormally at this time.

[0063] The technical solution of the embodiment of the present invention is to set a processing control unit and a test circuit in the device for detecting the grounding of a voltage loop, and set a signal input terminal, a signal output terminal, an adjustable equivalent resistor, a first test terminal and a second test terminal in the test circuit, so as to solve the problem that it is impossible to use a multimeter to measure at the grounding point of the N600 of the whole station during technical transformation and regular inspection, and it is not easy to cause the operation interval protection to malfunction. At the same time, the adjustable equivalent resistor is set to change the resistance value of the distributed capacitor in parallel according to the feedback signal, thereby achieving the effect of enhancing the signal, so that the measurement result is not easily interfered by the capacitance of the non-fault branch to the ground, and the result is accurate.

[0064] Optional, continue to refer to Figure 1 and Figure 2 As shown, the test circuit 12 also includes an input optocoupler U1 and an output optocoupler U2;

[0065] The second terminal a2 of the input optical coupler U1 is electrically connected to the signal input terminal A, and the third terminal a3 of the input optical coupler U1 is electrically connected to the first test terminal C;

[0066] The first terminal a1 of the output optical coupler U2 is electrically connected to the second test terminal D, and the fourth terminal a4 of the output optical coupler U2 is electrically connected to the signal output terminal B.

[0067] The input optocoupler U1 and the output optocoupler U2 may be devices that transmit electrical signals through optical signals. The input optocoupler U1 is arranged between the signal input terminal A and the first test terminal C, and can be used to isolate the input and output terminals of the test signal; the output optocoupler U2 is arranged between the signal output terminal B and the second test terminal D, and can be used to isolate the input and output terminals of the feedback signal.

[0068] Specifically, the first end a1 of the input optical coupler U1 is the VCC end, the second end a2 is electrically connected to the signal input end A, the third end a3 is electrically connected to the first test end C, and the fourth end a4 is the VDD end. The first end a1 of the output optical coupler U2 is electrically connected to the second test end D, the second end a2 is the VSS end, the third end a3 is grounded, and the fourth end a4 is electrically connected to the signal output end B, thereby ensuring the operational safety of the device 1 in the embodiment of the present invention.

[0069] The technical solution of the embodiment of the present invention achieves isolation and anti-interference by arranging an input optical coupler between the signal input terminal and the first test terminal and an output optical coupler between the signal output terminal and the second test terminal.

[0070] Optional, continue to refer to Figure 1 and Figure 2 As shown, the test circuit 12 also includes a first resistor R1, a second resistor R2, a third resistor R3 and a fourth resistor R4;

[0071] The first resistor R1 is arranged in series between the second test terminal D and the first terminal a1 of the output optical coupler U2;

[0072] The second resistor R2 is electrically connected to the fourth terminal a4 of the output optical coupler U2;

[0073] The third resistor R3 is arranged in series between the signal input terminal A and the second terminal a2 of the input optical coupler U1;

[0074] The fourth resistor R4 is connected in series between the first test terminal C and the third terminal a3 of the input optical coupler U1 .

[0075] Among them, the second resistor R2 and the third resistor R3 can be set as primary resistors, and the first resistor R1 and the fourth resistor R4 can be set as secondary resistors. The first resistor R1 is set in series between the second test terminal D and the first end a1 of the output optical coupler U2, the second resistor R2 is electrically connected to the fourth end a4 of the output optical coupler U2, and the other end is the VCC end, the third resistor R3 is set in series between the signal input terminal A and the second end a2 of the input optical coupler U1, and the fourth resistor R4 is set in series between the first test terminal C and the third end a3 of the input optical coupler U1, which plays the role of voltage division and current limiting.

[0076] In some embodiments, the second resistor R2 and the third resistor R3 may both be set to 1000Ω, the first resistor R1 may be set to 1000Ω, and the fourth resistor R4 may be set to 2000Ω, thereby achieving the purpose of voltage division and current limiting.

[0077] Optional, continue to refer to Figure 3 As shown, the processing control unit 11 includes a data processing subunit 111 and a single chip microcomputer 112;

[0078] The single chip computer 112 is respectively connected to the data processing sub-unit 111, the signal input terminal A and the adjustable equivalent resistor R6 for communication;

[0079] The data processing subunit 111 is connected to the signal output terminal B in communication.

[0080] The data processing subunit 111 can be used to process and transmit feedback signals, and the single chip microcomputer 112 can be used to perform calculation control.

[0081] Specifically, the single-chip microcomputer 112 is respectively connected to the data processing subunit 111, the signal input terminal A and the adjustable equivalent resistor R6 for communication. The single-chip microcomputer 112 can input a test signal to the signal input terminal A according to an instruction, and can also receive a feedback signal transmitted by the data processing subunit 111, and can also control the resistance value of the adjustable equivalent resistor R6 according to the calculated actual equivalent resistance. The data processing subunit 111 can be used to receive the first feedback signal or the second feedback signal and process and transmit it to the single-chip microcomputer 112.

[0082] In some embodiments, the data processing unit further includes a digital-to-analog conversion subunit and a storage unit for converting and storing feedback signals.

[0083] The technical solution of the embodiment of the present invention ensures the normal operation of the device by arranging a data processing subunit and a single chip microcomputer in the processing control unit.

[0084] Optional, continue to refer to Figure 3 As shown, the device 1 also includes a power supply 13;

[0085] The power supply 13 is electrically connected to the processing control unit 11 and is used to supply power to the processing control unit 11 .

[0086] The device 1 may include an independent power supply 13 to improve the convenience of operation and the mobility of the device 1. The power supply 13 is electrically connected to the processing control unit 11 to supply power to the processing control unit 11 and ensure the normal operation of the device 1.

[0087] Optional, continue to refer to Figure 3 As shown, the device 1 also includes a display screen 14; the processing control unit 11 is in communication connection with the display screen 14, and is used to output a detection result signal to the display screen 14 after determining whether a ground fault occurs in the voltage circuit to be tested.

[0088] The display screen 14 can be used to display the detection result of the voltage circuit to be tested. The processing control unit 11 is connected to the display screen 14 for communication. After the processing control unit 11 determines that the voltage circuit to be tested has a ground fault, it outputs a ground abnormality signal to the display screen 14, which is displayed on the display screen 14 to remind the detection personnel; after the processing control unit 11 determines that the voltage circuit to be tested has not a ground fault, it outputs a ground abnormality signal to the display screen 14, which is displayed on the display screen 14 to remind the detection personnel, thereby improving the timeliness and convenience of the device 1 during use.

[0089] In some embodiments, the device 1 further includes a housing; a display screen 14 is disposed on the surface of the housing; a processing control unit 11, a signal input terminal A, a signal output terminal B and an adjustable equivalent resistor R6 are disposed in the housing space of the housing; and a first test terminal C and a second test terminal D are disposed outside the housing. Figure 3 The housing is not shown)

[0090] Among them, the display screen 14 can be set on the surface of the shell, which is convenient for the test personnel to view the received test results. The processing control unit 11, the signal input terminal A, the signal output terminal B and the adjustable equivalent resistor R6 are arranged in the accommodating space of the shell to avoid the exposure of the signal transmission process and affect the test safety. The first test terminal C and the second test terminal D are arranged outside the shell, which is convenient for quickly connecting the first test terminal C and the second test terminal D to the voltage circuit to be tested, ensuring the convenience of operation of the device 1.

[0091] The technical solution of the embodiment of the present invention is to set a display screen and a shell so that the device for detecting the single-point grounding of the voltage loop is integrated, thereby ensuring the convenience and safety of the operation of the device.

[0092] Based on the same inventive concept, an embodiment of the present invention further provides a method for detecting a single-point grounding of a voltage loop, which is applied to a device 1 for detecting a single-point grounding of a voltage loop; Figure 5 is a flow chart of a method for detecting a single-point grounding of a voltage loop according to an embodiment of the present invention, Figure 1 , Figure 2 and Figure 5 As shown, the method includes:

[0093] S10. Input a test signal to the signal input terminal.

[0094] The signal input terminal A is connected to the processing control unit 11 , so that the processing control unit 11 can input a test signal along the signal output terminal B.

[0095] S11 , receiving a first feedback signal outputted from a signal output terminal and determining an actual equivalent resistance according to a test signal and the first feedback signal.

[0096] Among them, the signal output terminal B is connected to the processing control unit 11, so that the processing control unit 11 can receive the first feedback signal after passing through the voltage loop to be tested. Due to the existence of distributed capacitance, the distributed capacitance of the voltage loop to be tested can be equivalent to an RC parallel loop. The larger the distributed capacitance, the smaller the capacitive reactance, and the smaller the total impedance. The total resistance between the first test terminal C and the second test terminal D, that is, the voltage value, can be increased by adjusting the resistance value of the adjustable equivalent resistor R6. Therefore, by inputting a test signal into the voltage loop to be tested and receiving the first feedback signal, since the resistance value of the adjustable equivalent resistor R6 is known, the resistance value of the distributed capacitance of the voltage loop to be tested, that is, the resistance value of the actual equivalent resistor, can be calculated through the test signal and the first feedback signal.

[0097] S12, adjusting the resistance value of the adjustable equivalent resistor according to the actual equivalent resistor.

[0098] Among them, the resistance value of the equivalent resistor R6 can be adjusted according to the resistance value of the actual equivalent resistor to increase the total resistance between the first test terminal C and the second test terminal D, enhance the amplitude of the second feedback signal, and then improve the quality of the second feedback signal, so that the processing control unit 11 can judge whether the voltage loop to be tested is grounded with higher precision and accuracy when judging the test signal and the second feedback signal.

[0099] S13, receiving a second feedback signal outputted by the signal output terminal.

[0100] The second feedback signal is continuously received, and the second feedback signal may be a signal after increasing the total resistance between the first test terminal C and the second test terminal D, so the second feedback signal is more stable and has a stronger signal effect.

[0101] S14. Determine whether a ground fault occurs in the voltage circuit to be tested according to the second feedback signal and the test signal.

[0102] The test signal is compared with the stable second feedback signal to determine whether the N line is grounded normally or abnormally.

[0103] Specifically, first, the processing control unit 11 inputs a test signal to the signal input terminal A and receives a first feedback signal output by the signal output terminal B and determines the actual equivalent resistance according to the test signal and the first feedback signal, and adjusts the resistance value of the adjustable equivalent resistor R6 according to the actual equivalent resistance to be much smaller than the equivalent resistance value, thereby increasing the total resistance value after the two are connected in parallel, and increasing the resistance in parallel with the distributed capacitance, thereby achieving the effect of enhancing the signal; after the adjustment is completed, continue to receive the second feedback signal output by the signal output terminal B; and determine whether a ground fault occurs in the voltage circuit to be tested according to the second feedback signal and the test signal.

[0104] The technical solution of the embodiment of the present invention determines the actual equivalent resistance in advance based on the test signal and the first feedback signal, and then adjusts the resistance value in the test loop based on the actual equivalent resistance to ensure that the resistance in parallel with the distributed capacitance becomes larger, thereby achieving the effect of enhancing the signal, making the measurement result less susceptible to interference from the capacitance to ground of the non-fault branch, and the result is accurate.

[0105] Based on the same inventive concept, Figure 6 is a flow chart of a second method for detecting a single-point grounding of a voltage loop provided according to an embodiment of the present invention, combined with Figure 1 , Figure 2 and Figure 6 As shown, an embodiment of the present invention also provides a method for detecting a single-point grounding of a voltage loop, the method comprising:

[0106] S20, input a test signal to the signal input terminal.

[0107] S21 , receiving a first feedback signal outputted from a signal output terminal and determining an actual equivalent resistance according to a test signal and the first feedback signal.

[0108] S22, adjusting the resistance value of the adjustable equivalent resistor according to the actual equivalent resistor.

[0109] S23, receiving a second feedback signal outputted by the signal output terminal.

[0110] S24. When the second feedback signal and the test signal are the same, a ground normal signal is output.

[0111] S25. When the second feedback signal and the test signal are different, output a grounding abnormality signal.

[0112] Among them, after the adjustment is completed, the test signal continues to be output and the second feedback signal is received, and the test signal is compared with the stable second feedback signal. When the test signal is consistent with the second feedback signal, it means that the N line is grounded normally at this time; when the test signal is inconsistent with the second feedback signal, it means that the N line is grounded abnormally at this time, which realizes the judgment of grounding of any voltage loop and ensures the safety and reliability of power system operation.

[0113] The technical solution of the embodiment of the present invention determines whether the voltage loop to be tested is grounded at one point by comparing the test signal with the stable second feedback signal, thereby ensuring the safety and reliability of the power system operation.

[0114] Based on the same inventive concept, Figure 7 is a flow chart of a third method for detecting a single-point grounding of a voltage loop provided according to an embodiment of the present invention, combined with Figure 1 , Figure 2 and Figure 7 As shown, the embodiment of the present invention also provides a method for detecting a single-point grounding of a voltage loop, wherein the test loop 12 further includes an input optical coupler U1 and an output optical coupler U2; the method includes:

[0115] S30, input a test signal to the signal input terminal.

[0116] S31, receiving a first feedback signal outputted from a signal output terminal and acquiring a first current transfer ratio of an input optocoupler and a second current transfer ratio of an output optocoupler.

[0117] When there are input optocoupler U1 and output optocoupler U2 in the test loop 12, since the optocouplers have a current transfer ratio CTR, the actual equivalent resistance can be determined by obtaining the first current transfer ratio of the input optocoupler U1 and the second current transfer ratio of the output optocoupler U2.

[0118] S32, determining an actual equivalent resistance according to the test signal, the first feedback signal, the first current transfer ratio, and the second current transfer ratio.

[0119] Among them, the current transfer ratio is the ratio of the output current of the optocoupler to the input current. When the input current of the input optocoupler U1, that is, the test signal, is known, the output current can be determined. When the output current of the output optocoupler U2, that is, the first feedback signal, is known, the input current can be determined. When the output current of the input optocoupler U1 is fixed, the actual equivalent resistance changes, causing the input current of the output optocoupler U2 to change. Therefore, the actual equivalent resistance can be determined based on the output current of the input optocoupler U1 and the input current of the output optocoupler U2.

[0120] It can be understood that the actual equivalent resistance is the total resistance of the current adjustable equivalent resistance R6 and the resistance corresponding to the partial capacitance in parallel. Subsequently, the total resistance of the adjustable equivalent resistance R6 and the resistance corresponding to the partial capacitance in parallel can be increased by reducing the resistance of the adjustable equivalent resistance R6, thereby increasing the resistance in parallel with the distributed capacitance, thereby achieving the effect of enhancing the signal.

[0121] S33, adjusting the resistance value of the adjustable equivalent resistor according to the actual equivalent resistor.

[0122] S34, receiving a second feedback signal outputted by the signal output terminal.

[0123] The technical solution of the embodiment of the present invention, by simultaneously obtaining the first current transfer ratio of the input optocoupler and the second current transfer ratio of the output optocoupler when receiving the first feedback signal output from the signal output end, determines the actual equivalent resistance according to the test signal, the first feedback signal, the first current transfer ratio and the second current transfer ratio, thereby ensuring the accuracy of the subsequent adjustment of the adjustable equivalent resistance value according to the actual equivalent resistance and enhancing the effect of the signal.

[0124] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0125] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A device for detecting a single point grounding of a voltage loop, characterized in that: include: A processing control unit and a test loop; the processing control unit is communicatively connected with the test loop; The test loop includes a signal input terminal, a signal output terminal, an adjustable equivalent resistor, a first test terminal and a second test terminal; The signal input terminal and the signal output terminal are respectively connected to the processing control unit for communication; the first test terminal is used to connect the ground wire of the voltage loop to be tested, the second test terminal is used for grounding and the adjustable equivalent resistor is connected in series between the first test terminal and the second test terminal; the adjustable equivalent resistor is also connected to the processing control unit for communication; The processing control unit is used to input a test signal to the signal input end, and is also used to receive a first feedback signal output by the signal output end and determine an actual equivalent resistance according to the test signal and the first feedback signal and adjust the resistance value of the adjustable equivalent resistance according to the actual equivalent resistance and receive a second feedback signal output by the signal output end, and determine whether a ground fault occurs in the voltage circuit to be tested according to the second feedback signal and the test signal.

2. The device according to claim 1, characterized in that The test circuit also includes an input optical coupler and an output optical coupler; The second end of the input optical coupler is electrically connected to the signal input end, and the third end of the input optical coupler is electrically connected to the first test end; The first end of the output optical coupler is electrically connected to the second test end, and the fourth end of the output optical coupler is electrically connected to the signal output end.

3. The device according to claim 2, characterized in that The test loop also includes a first resistor, a second resistor, a third resistor and a fourth resistor; The first resistor is arranged in series between the second test terminal and the first terminal of the output optical coupler; The second resistor is electrically connected to the fourth end of the output optical coupler; The third resistor is arranged in series between the signal input terminal and the second terminal of the input optocoupler; The fourth resistor is arranged in series between the first test terminal and the third terminal of the input optocoupler.

4. The device according to claim 1, characterized in that The processing control unit includes a data processing subunit and a single chip microcomputer; The single chip microcomputer is respectively connected to the data processing sub-unit, the signal input terminal and the adjustable equivalent resistor for communication; The data processing subunit is communicatively connected to the signal output terminal.

5. The device according to claim 1, characterized in that The device also includes a power supply; The power supply is electrically connected to the processing control unit and is used to supply power to the processing control unit.

6. The device according to claim 1, characterized in that The device also includes a display screen; The processing control unit is in communication connection with the display screen, and is used for outputting a detection result signal to the display screen after determining whether a ground fault occurs in the voltage circuit to be tested.

7. The device according to claim 6, characterized in that The device also includes a housing; The display screen is arranged on the surface of the housing; The processing control unit, the signal input terminal, the signal output terminal and the adjustable equivalent resistor are arranged in the accommodating space of the shell; the first test terminal and the second test terminal are arranged outside the shell.

8. A method for detecting a single point grounding of a voltage loop, characterized in that: Applicable to the device for detecting single-point grounding of a voltage loop according to any one of claims 1 to 7; the method comprises: Input a test signal to the signal input terminal; receiving a first feedback signal outputted from a signal output terminal and determining an actual equivalent resistance according to the test signal and the first feedback signal; adjusting the resistance value of the adjustable equivalent resistor according to the actual equivalent resistor; receiving a second feedback signal output by the signal output terminal; It is determined whether a ground fault occurs in the voltage circuit to be tested according to the second feedback signal and the test signal.

9. The method according to claim 8, characterized in that Determining whether a ground fault occurs in the voltage circuit to be tested according to the second feedback signal and the test signal includes: When the second feedback signal is the same as the test signal, outputting a ground normal signal; When the second feedback signal is different from the test signal, a ground abnormality signal is output.

10. The method according to claim 8, characterized in that The test circuit also includes an input optical coupler and an output optical coupler; Determining an actual equivalent resistance according to the test signal and the first feedback signal includes: Acquire a first current transfer ratio of the input optocoupler and a second current transfer ratio of the output optocoupler; An actual equivalent resistance is determined according to the test signal, the first feedback signal, the first current transfer ratio, and the second current transfer ratio.

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