Insulation performance detection circuit, device and method for high-voltage switch cabinet based on partial discharge

Abstract

The invention provides a partial discharge-based high-voltage switch cabinet insulation performance detection circuit, device and method, and the circuit comprises an adjusting circuit which comprises a power supply, a variable-frequency power supply and a control box, the variable-frequency power supply is connected with the power supply, and the control box is connected with the variable-frequency power supply; the test circuit comprises a voltage regulation mechanism, a voltage divider, a coupling capacitor and a regulation feedback mechanism, the voltage divider, the coupling capacitor and the voltage regulation mechanism are arranged in parallel, the voltage divider is connected with the output end of the variable-frequency power supply, the regulation feedback mechanism is connected with the coupling capacitor in series, and the tested switch cabinet is connected between the voltage regulation mechanism and the voltage divider in parallel. According to the invention, the insulation performance of the tested switch cabinet can be efficiently and accurately detected through the high cooperation between the adjusting circuit and the testing circuit, and the insulation performance of the tested switch cabinet can be detected and evaluated according to the magnitude of the partial discharge capacity. Therefore, the device is of great significance in improving the operation reliability of the switch cabinet and improving the overall safety and stability of a power grid.

Description

Technical Field

[0001] The present invention relates to the technical field of insulation detection, and in particular to a circuit, device and method for detecting insulation performance of a high-voltage switch cabinet based on partial discharge. Background Art

[0002] As an indispensable equipment in the power system, high-voltage switchgear (hereinafter referred to as switchgear) is widely used in power transmission and distribution systems due to its modular design, high adaptability and convenient operation. However, among the many switchgear models and manufacturers, the product quality varies, resulting in differences in the performance and reliability of switchgear in actual operation. Especially in terms of insulation performance, poor-quality insulation materials and designs may lead to internal insulation degradation and reduced insulation strength, thus causing equipment failure and even posing a threat to personnel and equipment safety.

[0003] At present, partial discharge is a key indicator for evaluating the insulation performance of switchgear in the industry, which reflects whether there are potential insulation defects inside the switchgear. However, there is a lack of dedicated devices and methods for evaluating the insulation performance of switchgear in the market, making it difficult for users to effectively evaluate the insulation performance of switchgear. Most of the existing detection methods have poor compatibility, low efficiency and limited accuracy. In actual use, they often increase the equipment failure rate due to the inability to detect and solve insulation problems in a timely manner. Summary of the invention

[0004] To this end, the technical problem to be solved by the present invention is to overcome the problem that it is difficult to detect potential insulation defects in the prior art, and to provide a circuit, device and method for detecting insulation performance of a high-voltage switch cabinet based on partial discharge.

[0005] In order to solve the above technical problems, the present invention provides an insulation performance detection circuit of a high-voltage switch cabinet based on partial discharge, which includes: a regulation circuit, the regulation circuit includes a supply power supply, a variable frequency power supply and a control box, the input end of the variable frequency power supply is connected to the supply power supply, and the control box is connected to the variable frequency power supply signal; a test circuit, the test circuit includes a voltage regulation mechanism, a voltage divider, a coupling capacitor and a regulation feedback mechanism, the voltage divider, the coupling capacitor and the voltage regulation mechanism are arranged in parallel, wherein the voltage divider is connected to the output end of the variable frequency power supply, the regulation feedback mechanism and the coupling capacitor are arranged in series, and the switch cabinet under test is connected in parallel between the voltage regulation mechanism and the voltage divider.

[0006] In one embodiment of the present invention, the voltage regulating mechanism includes a transformer, a corona-free pressurized wire and a grounding shielding wire, wherein the low-voltage input end of the transformer is connected to the variable frequency power supply, the high-voltage output end of the transformer is connected in parallel with the voltage divider through the corona-free pressurized wire, one end of the corona-free pressurized wire is connected to the high-voltage terminal of the test switch cabinet, and the other end is connected to the grounding shielding wire.

[0007] In one embodiment of the present invention, the adjustment feedback mechanism includes a detection impedance and a partial discharge analyzer, wherein the detection impedance is connected in series with the coupling capacitor, and the partial discharge analyzer signal is connected to the detection impedance via a coaxial cable.

[0008] In one embodiment of the present invention, the adjustment feedback mechanism further includes a grounding terminal, and the ground end of the voltage divider, the ground end of the detection impedance and the housing of the switch cabinet under test are all connected to the grounding terminal.

[0009] In one embodiment of the present invention, the test circuit further includes a voltage peak meter, and the voltage divider is connected to the voltage peak meter via a coaxial cable.

[0010] In one embodiment of the present invention, the regulating circuit includes a low-voltage input cable, a low-voltage output cable and a control optical fiber, the two ends of the low-voltage input cable are respectively connected to the supply power supply and the input end of the variable frequency power supply, the two ends of the low-voltage output cable are respectively connected to the output end of the variable frequency power supply and the voltage regulating mechanism, and the control box is connected to the variable frequency power supply signal through the control optical fiber.

[0011] The present invention also provides a high-voltage switch cabinet insulation performance detection device based on partial discharge, which includes the above-mentioned high-voltage switch cabinet insulation performance detection circuit based on partial discharge.

[0012] The present invention also provides a method for detecting the insulation performance of a high-voltage switch cabinet based on partial discharge, characterized in that: the insulation performance detection circuit of a high-voltage switch cabinet based on partial discharge as described in any one of claims 1 to 6 is used to detect the insulation performance of the high-voltage switch cabinet, and the method comprises the following steps: step S1, calibrating the adjustment circuit and the test circuit respectively in a stable detection environment; step S2, starting the adjustment circuit, and gradually increasing the output frequency of the variable frequency power supply according to a preset uniform gradient until the output voltage of the adjustment feedback mechanism reaches the experimental voltage of the switch cabinet under test; step S3, after the switch cabinet under test is operated for a preset time, recording the partial discharge amount Q displayed by the adjustment feedback mechanism, and detecting the switch cabinet under test through the partial discharge amount Q: when Q>50pC, the switch cabinet under test is an unqualified product; when Q≤50pC, the switch cabinet under test is a qualified product.

[0013] In one embodiment of the present invention, step S1 is specifically as follows: the stable detection environment is in a fully sealed state, the detection environment temperature and humidity are constant, the power supply environment is good, and multiple pre-detections are performed to ensure that the detection environment and power supply quality data remain unchanged; the voltage divider is connected to the voltage peak meter using a coaxial cable, and the high voltage display of the voltage peak meter and the voltage display of the control box are calibrated to ensure the correctness of the test output voltage; the detection impedance is connected to the partial discharge analyzer using a coaxial cable to detect the partial discharge amount of the test loop; the partial discharge signal is input into the coupling capacitor to calibrate the partial discharge amount of the test circuit through the partial discharge analyzer.

[0014] In one embodiment of the present invention, step S3 also includes: rating the switch cabinet under test according to the partial discharge quantity Q: when 20pC<Q≤50pC, the switch cabinet under test is of qualified grade; when 10pC<Q≤20pC, the switch cabinet under test is of good grade; when Q≤10pC, the switch cabinet under test is of excellent grade.

[0015] The above technical solution of the present invention has the following advantages compared with the prior art:

[0016] The circuit, device and method for detecting the insulation performance of the high-voltage switch cabinet based on partial discharge described in the present invention can detect the insulation performance of the switch cabinet under test efficiently and accurately through the high degree of coordination between the regulating circuit and the test circuit, wherein, by changing the output voltage of the variable frequency power supply in the regulating circuit and the voltage regulating mechanism in the test circuit, the output voltage of the regulating feedback mechanism reaches the experimental voltage of the switch cabinet under test, thereby performing insulation performance detection and evaluation on the switch cabinet under test according to the magnitude of the partial discharge. This makes it of great significance in improving the reliability of switch cabinet operation and improving the overall safety and stability of the power grid. In addition, the present application also has the advantages of strong practicality, simple operation, and accurate and efficient detection process, and has broad application prospects in this industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to make the contents of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings.

[0018] Figure 1 It is a circuit diagram of a high-voltage switch cabinet insulation performance detection device for partial discharge in a preferred embodiment of the present invention.

[0019] Explanation of the reference numerals in the accompanying drawings in the specification: 1. Power supply; 2. Low-voltage input cable; 3. Variable-frequency power supply; 4. Control optical fiber; 5. Control box; 6. Low-voltage output cable; 7. Transformer; 8. Corona-free pressurized wire; 9. Grounding shielding wire; 10. Test switch cabinet; 11. Voltage divider; 12. Voltage peak meter; 13. Coupling capacitor; 14. Detection impedance; 15. Grounding terminal; 16. Coaxial cable; 17. Partial discharge analyzer. DETAILED DESCRIPTION

[0020] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0021] Embodiment 1

[0022] See also Figure 1 As shown, this embodiment provides a local discharge high-voltage switch cabinet insulation performance detection circuit, which includes: a regulation circuit, the regulation circuit includes a power supply 1, a variable frequency power supply 3 and a control box 5, the input end of the variable frequency power supply 3 is connected to the power supply 1, and the control box 5 is connected to the variable frequency power supply 3 signal; a test circuit, the test circuit includes a voltage regulation mechanism, a voltage divider 11, a coupling capacitor 13 and a regulation feedback mechanism, the voltage divider 11, the coupling capacitor 13 and the voltage regulation mechanism are arranged in parallel, wherein the voltage divider 11 is connected to the output end of the variable frequency power supply 3, the regulation feedback mechanism and the coupling capacitor 13 are arranged in series, and the switch cabinet 10 under test is connected in parallel between the voltage regulation mechanism and the voltage divider 11.

[0023] The insulation performance detection circuit of the high-voltage switch cabinet based on partial discharge described in this embodiment can efficiently and accurately detect the insulation performance of the switch cabinet 10 under test through the high degree of coordination between the adjustment circuit and the test circuit, wherein, by changing the output voltage of the variable frequency power supply 3 in the adjustment circuit and the voltage adjustment mechanism in the test circuit, the output voltage of the adjustment feedback mechanism reaches the experimental voltage of the switch cabinet 10 under test, thereby performing insulation performance detection and evaluation on the switch cabinet 10 under test according to the magnitude of the partial discharge. This makes it of great significance in improving the reliability of switch cabinet operation and improving the overall safety and stability of the power grid. In addition, the present application also has the advantages of strong practicality, simple operation, and accurate and efficient detection process, and has broad application prospects in this industry.

[0024] See also Figure 1As shown, in this embodiment, the supply power 1 is preferably a 380V power supply system, and the regulating circuit includes a low-voltage input cable 2, a low-voltage output cable 6 and a control optical fiber 4. The two ends of the low-voltage input cable 2 are respectively connected to the supply power 1 and the input end of the variable frequency power supply 3, and the two ends of the low-voltage output cable 6 are respectively connected to the output end of the variable frequency power supply 3 and the voltage regulating mechanism. The control box 5 is connected to the variable frequency power supply 3 through the control optical fiber 4. The low-voltage input cable 2 is used to connect the 380V power supply system and the input end of the variable frequency power supply 3. It is responsible for transmitting electric energy to ensure that the current and voltage are stably transmitted from the power supply system to the variable frequency power supply 3; the variable frequency power supply 3 can convert the three-phase power supply into a single-phase power supply with adjustable voltage and frequency; the low-voltage output cable 6 is connected to the output end of the variable frequency power supply 3 and the low-voltage input side of the transformer 7, and it is responsible for transmitting the electric energy output by the variable frequency power supply 3.

[0025] Furthermore, in this embodiment, the control signal is transmitted from the control box 5 to the variable frequency power supply 3 by controlling the signal transmission of the optical fiber 4, so as to realize the remote control of the output voltage and frequency, wherein the control box 5 is the control center of the variable frequency power supply 3, which is responsible for receiving the control signal from the remote operating system and performing corresponding operations, such as adjusting the output voltage and frequency. Under the control of the control box 5, the variable frequency power supply 3 can remotely adjust the output voltage and frequency to meet the power supply requirements of different electrical equipment. Specifically, in this embodiment, by controlling the remote control of the optical fiber 4 and the control box 5 of the variable frequency power supply 3, a complete isolation between low voltage and high voltage can be achieved. During the operation, the operator does not need to directly contact the high voltage power supply, thereby improving the safety of the operation. At the same time, the anti-interference characteristics of the control optical fiber 4 also ensure the stable transmission of the control signal, avoiding signal interference and errors.

[0026] See also Figure 1 As shown, the voltage regulating mechanism includes a transformer 7, a corona-free pressurized wire 8 and a grounding shielding wire 9, wherein the low-voltage input end of the transformer 7 is connected to the variable frequency power supply 3, and the high-voltage output end of the transformer 7 is connected in parallel with the voltage divider 11 through the corona-free pressurized wire 8, one end of the corona-free pressurized wire 8 is connected to the high-voltage terminal of the tested switch cabinet 10, and the other end is connected to the grounding shielding wire 9. In this embodiment, the transformer 7 is preferably a non-partial discharge isolation transformer 7, which is used to convert low-voltage input into high-voltage output. Furthermore, the transformer 7 can also increase the voltage and provide electrical isolation to prevent direct contact with high voltage, thereby ensuring the safety of the operator and avoiding additional interference or damage to the tested switch cabinet 10 during the test; the corona-free pressurized wire 8 is preferably 4 square mm in diameter. 2The corona-free conductor can connect various high-voltage test equipment to form a complete test loop. The cross-sectional area of ​​the corona-free pressurized wire 8 is large enough, so that it can withstand the current and thermal effects under high voltage, while reducing the occurrence of corona phenomenon and improving the accuracy of the test; the grounding shield wire 9 is used to provide safe and reliable grounding to prevent electric shock and arc that may occur during the test, while ensuring the accuracy and stability of the test signal.

[0027] Furthermore, the adjustment feedback mechanism in this embodiment includes a detection impedance 14 and a partial discharge analyzer 17, wherein the detection impedance 14 is connected in series with the coupling capacitor 13, and the signal of the partial discharge analyzer 17 is connected to the detection impedance 14 through a coaxial cable 16, wherein the adjustment feedback mechanism also includes a grounding terminal 15, and the ground end of the voltage divider 11, the ground end of the detection impedance 14, and the shell of the tested switch cabinet 10 are all connected to the grounding terminal 15. In this embodiment, the detection impedance 14 is used to detect the voltage and current during the insulation test to evaluate the insulation performance of the tested switch cabinet 10, which has high sensitivity and accuracy and can accurately measure the voltage and current values ​​under high voltage; the partial discharge analyzer 17 is a device capable of analyzing partial discharge signals, which displays the amplitude, frequency, phase and other parameters of partial discharge in real time, and analyzes the mode and characteristics of partial discharge through software to judge the insulation state and predict the development trend of faults. The voltage divider 11 is used to reduce the high voltage output by the non-partial discharge isolation transformer 7 to a safe level for easy measurement and recording; the coupling capacitor 13 can provide electrical connection and reduce electromagnetic interference generated during the test to ensure the quality and stability of the test signal. Specifically, the test circuit also includes a voltage peak meter 12, and the voltage divider 11 is connected to the voltage peak meter 12 via a coaxial cable 16.

[0028] Based on the above structure, the local discharge high-voltage switchgear insulation performance detection circuit described in this embodiment connects the high-voltage test equipment with the switchgear under test 10 through the non-corona pressurized line 8 to form a closed test loop. The non-partial discharge isolation transformer 7 provides high-voltage power supply, the voltage divider 11 reduces the voltage, the coupling capacitor 13 reduces interference, and the switchgear under test 10 is used as the object to be tested. Through this configuration, the insulation performance of the switchgear can be comprehensively evaluated to ensure its safe operation under high voltage conditions.

[0029] Embodiment 2

[0030] This embodiment provides a high-voltage switch cabinet insulation performance detection device based on partial discharge, which includes the high-voltage switch cabinet insulation performance detection circuit based on partial discharge described in the first embodiment.

[0031] Embodiment 3

[0032] This embodiment provides a method for detecting the insulation performance of a high-voltage switch cabinet based on partial discharge, which: uses the high-voltage switch cabinet insulation performance detection circuit based on partial discharge described in Example 1 to detect the insulation performance of the high-voltage switch cabinet, and includes the following steps:

[0033] Step S1, calibrate the adjustment circuit and the test circuit separately in a stable detection environment; in this embodiment, step S1 is specifically as follows: the stable detection environment is in a fully sealed state, the detection environment temperature and humidity are constant, the power supply environment is good, and multiple pre-detections are performed to ensure that the detection environment and power supply quality data remain unchanged; use a coaxial cable 16 to connect the voltage divider 11 with the voltage peak meter 12, and calibrate the high voltage display of the voltage peak meter 12 and the voltage display of the control box 5 to ensure the correctness of the test output voltage; use a coaxial cable 16 to connect the detection impedance 14 with the partial discharge analyzer 17 to detect the partial discharge amount of the test loop; input the partial discharge signal into the coupling capacitor 13 to calibrate the partial discharge amount of the test circuit through the partial discharge analyzer 17.

[0034] Step S2, starting the regulating circuit, and gradually increasing the output frequency of the variable frequency power supply 3 according to a preset uniform gradient, until the output voltage of the regulating feedback mechanism reaches the experimental voltage of the tested switch cabinet 10;

[0035] Step S3: after the switch cabinet 10 under test is operated for a preset time, the partial discharge amount Q displayed by the adjustment feedback mechanism is recorded, and the switch cabinet 10 under test is tested by the partial discharge amount Q:

[0036] When Q>50pC, the switch cabinet 10 under test is a defective product;

[0037] When Q≤50pC, the switch cabinet 10 under test is a qualified product.

[0038] Furthermore, in this embodiment, step S3 further includes: rating the switch cabinet 10 under test according to the partial discharge quantity Q:

[0039] When 20pC<Q≤50pC, the switch cabinet 10 under test is of qualified grade;

[0040] When 10pC<Q≤20pC, the tested switch cabinet 10 is of good grade.

[0041] When Q≤10pC, the tested switch cabinet 10 is of excellent grade.

[0042] After the above detection process is completed, the output voltage of the frequency conversion power supply 3 is reduced and disconnected through the frequency conversion control box 5, and a complete detection and evaluation process is completed.

[0043] In summary, the insulation performance detection circuit, device and method of the high-voltage switch cabinet based on partial discharge described in the present invention can efficiently and accurately detect the insulation performance of the tested switch cabinet 10 through the high degree of coordination between the adjustment circuit and the test circuit, wherein, by changing the output voltage of the variable frequency power supply 3 in the adjustment circuit and the voltage adjustment mechanism in the test circuit, the output voltage of the adjustment feedback mechanism reaches the experimental voltage of the tested switch cabinet 10, thereby performing insulation performance detection and evaluation on the tested switch cabinet 10 according to the magnitude of the partial discharge. This makes it of great significance in improving the reliability of switch cabinet operation and improving the overall safety and stability of the power grid. In addition, the present application also has the advantages of strong practicality, simple operation, and accurate and efficient detection process, and has broad application prospects in this industry.

[0044] Obviously, the above embodiments are merely examples for clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the protection scope of the invention.

Claims

1. A partial discharge high-voltage switch cabinet insulation performance detection circuit, characterized in that: include: A regulating circuit, the regulating circuit comprising a supply power supply, a variable frequency power supply and a control box, the input end of the variable frequency power supply is connected to the supply power supply, and the control box is connected to the variable frequency power supply signal; A test circuit, the test circuit includes a voltage regulating mechanism, a voltage divider, a coupling capacitor and an adjustment feedback mechanism, the voltage divider, the coupling capacitor and the voltage regulating mechanism are arranged in parallel, wherein the voltage divider is connected to the output end of the variable frequency power supply, the adjustment feedback mechanism and the coupling capacitor are arranged in series, and the switch cabinet under test is connected in parallel between the voltage regulating mechanism and the voltage divider.

2. The partial discharge high-voltage switch cabinet insulation performance detection circuit according to claim 1 is characterized in that: The voltage regulating mechanism includes a transformer, a corona-free pressurized wire and a grounding shielding wire, wherein the low-voltage input end of the transformer is connected to the variable frequency power supply, the high-voltage output end of the transformer is connected in parallel with the voltage divider through the corona-free pressurized wire, one end of the corona-free pressurized wire is connected to the high-voltage terminal of the test switch cabinet, and the other end is connected to the grounding shielding wire.

3. The partial discharge high-voltage switch cabinet insulation performance detection circuit according to claim 1 is characterized in that: The regulating feedback mechanism comprises a detection impedance and a partial discharge analyzer, wherein the detection impedance is connected in series with the coupling capacitor, and the partial discharge analyzer signal is connected to the detection impedance via a coaxial cable.

4. The partial discharge-based high-voltage switch cabinet insulation performance detection circuit according to claim 3 is characterized in that: The regulating feedback mechanism further comprises a grounding terminal, and the ground end of the voltage divider, the ground end of the detection impedance and the housing of the switch cabinet under test are all connected to the grounding terminal.

5. The partial discharge-based high-voltage switch cabinet insulation performance detection circuit according to claim 1 is characterized in that: The test circuit also includes a voltage peak meter, and the voltage divider is connected to the voltage peak meter via a coaxial cable.

6. The partial discharge-based high-voltage switch cabinet insulation performance detection circuit according to claim 1 is characterized in that: The regulation circuit includes a low-voltage input cable, a low-voltage output cable and a control optical fiber. The two ends of the low-voltage input cable are respectively connected to the supply power and the input end of the variable frequency power supply. The two ends of the low-voltage output cable are respectively connected to the output end of the variable frequency power supply and the voltage regulation mechanism. The control box is connected to the variable frequency power supply signal through the control optical fiber.

7. A high-voltage switchgear insulation performance detection device based on partial discharge, characterized in that: The invention comprises the insulation performance detection circuit of a high-voltage switch cabinet based on partial discharge as described in any one of claims 1 to 6.

8. A method for detecting insulation performance of a high-voltage switchgear based on partial discharge, characterized in that: The insulation performance detection circuit of a high-voltage switch cabinet based on partial discharge as described in any one of claims 1 to 6 is used to detect the insulation performance of a high-voltage switch cabinet, which comprises the following steps: Step S1, calibrating the adjustment circuit and the test circuit respectively in a stable detection environment; Step S2, starting the regulating circuit, and gradually increasing the output frequency of the variable frequency power supply according to a preset uniform gradient until the output voltage of the regulating feedback mechanism reaches the experimental voltage of the switch cabinet under test; Step S3: after the switch cabinet under test is operated for a preset time, the partial discharge amount Q displayed by the regulating feedback mechanism is recorded, and the switch cabinet under test is tested by the partial discharge amount Q: When Q>50pC, the switch cabinet under test is unqualified; When Q≤50pC, the switch cabinet under test is qualified.

9. The method for detecting insulation performance of a high-voltage switch cabinet based on partial discharge according to claim 8 is characterized in that: Step S1 is specifically as follows: the stable detection environment is in a fully sealed state, the detection environment temperature and humidity are constant, the power supply environment is good, and multiple pre-detections are performed to ensure that the detection environment and power supply quality data remain unchanged; the voltage divider is connected to the voltage peak meter using a coaxial cable, and the high voltage display of the voltage peak meter and the voltage display of the control box are calibrated to ensure the correctness of the test output voltage; the detection impedance is connected to the partial discharge analyzer using a coaxial cable to detect the partial discharge amount of the test loop; the partial discharge signal is input into the coupling capacitor to calibrate the partial discharge amount of the test circuit through the partial discharge analyzer.

10. The method for detecting insulation performance of a high-voltage switch cabinet based on partial discharge according to claim 8, characterized in that: Step S3 also includes: rating the switch cabinet under test according to the partial discharge quantity Q: When 20pC<Q≤50pC, the switchgear under test is of qualified grade; When 10pC<Q≤20pC, the switchgear under test is of good grade; When Q≤10pC, the tested switchgear is of excellent grade.

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