Insulation and voltage resistance test method and auxiliary device for high-voltage complete equipment

Abstract

The invention discloses a high-voltage complete equipment insulation and voltage withstand test method and an auxiliary device, relates to the technical field of electrical engineering, and can provide the high-voltage complete equipment insulation and voltage withstand test method and the auxiliary device. The resonant frequency is controlled in a standard allowable range, the electric reactor is reasonably selected to obtain the inductance value, and the equipment insulation voltage-withstanding test auxiliary device calculates to obtain the resonant frequency. The equipment insulation voltage-withstanding test auxiliary device calculates current according to a current calculation formula, selects a power supply inlet wire model, and matches a reasonable excitation transformer model. Automatic determination of insulation and voltage resistance test parameters of high-voltage complete equipment is realized, a large-voltage and small-current test effect is realized through frequency modulation type series resonance, resonance and loss of a test capacitor and a reactor are minimum, and test safety is guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of electrical engineering, and in particular to a method and an auxiliary device for testing the insulation and withstand voltage of a high-voltage complete set of equipment. Background Art

[0002] The insulation withstand voltage test of complete sets of high-voltage equipment in the power system is a very dangerous job, which requires a rigorous work attitude and the implementation of standardized operating procedures to avoid unnecessary accidents. In the insulation withstand voltage test, the AC withstand voltage test generally adopts the frequency modulation series resonance method. Therefore, the resonant frequency is the key to the entire test. The resonant frequency is mainly related to the capacitance of the test product. In conventional debugging, the debugging engineer generally determines the resonant frequency through empirical data and configures the corresponding reactor. In this way, it is often impossible to find the resonant frequency to stabilize at the test voltage, or the reactor cannot be raised to the test voltage, resulting in the failure of the AC withstand voltage test. Therefore, the essence of the present invention is to provide an accurate resonant frequency calculation device and recommend reasonable test equipment, and optimize the debugging method for different test products to achieve a successful insulation withstand voltage test at one time. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a method and auxiliary device for high-voltage complete equipment insulation withstand voltage test. The following technical solutions are adopted: A method for testing the insulation withstand voltage of a high-voltage complete set of equipment comprises the following steps: Step 1: Calculate the resonant frequency and select the test equipment. Search and calculate the test capacitance Cx in the complete set of high-voltage equipment database of the insulation withstand voltage test auxiliary device, control the resonant frequency within the allowable range of the specification, select the reactor to obtain the inductance L, calculate the resonant frequency and line current, and select the test equipment model; Step 2: Connect the test equipment and the test equipment, connect the variable frequency power supply equipment to the 380V incoming line, then connect the excitation transformer, reactor and test equipment, and connect the capacitor voltage divider in parallel at both ends of the reactor; Step 3, insulation test, the insulation resistance tester is connected to both ends of the test equipment, the insulation withstand voltage test auxiliary device and the insulation resistance tester exchange the resistance value of the test equipment, the insulation withstand voltage test auxiliary device checks whether the insulation resistance meets the requirements according to the power handover test specification, and the withstand voltage test is carried out after the insulation test is qualified; Step 4, voltage withstand test, after the variable frequency power supply is powered on, set the test voltage, and set the frequency range according to the resonant frequency calculated by the insulation voltage withstand test auxiliary device. The insulation voltage withstand test auxiliary device controls the voltage increase and detects whether the test equipment is abnormal. The timing starts after the voltage stabilizes at the test voltage. If there is no abnormality in the test equipment during the test timing period and the test voltage is stable, the test is judged to be qualified. After the voltage withstand test is completed, discharge to the ground.

[0004] Optionally, in step 1, according to the series resonance formula: , where f is the frequency, L is the inductance, Cx is the test capacitance, the insulation withstand voltage test auxiliary device queries the complete set of high-voltage equipment database and calculates the test capacitance Cx based on the series resonance formula, controls the resonant frequency at 50-200Hz, selects the inductor to obtain the inductance L, and the insulation withstand voltage test auxiliary device calculates the resonant frequency f.

[0005] Optionally, in step 1, according to the current calculation formula , where I is current and U is voltage. The insulation withstand voltage test auxiliary device calculates the current size, selects the power supply line model, and matches the excitation transformer model.

[0006] By adopting the above technical solution, the test capacitance Cx is queried and calculated in the complete set of high-voltage equipment database through the insulation withstand voltage test auxiliary device (the equipment has capacitance data that can be directly input), the resonant frequency is controlled within the allowable range of the specification (50-200Hz), the inductance L is reasonably selected from the reactor, and the equipment insulation withstand voltage test auxiliary device calculates the resonant frequency f. According to the current calculation formula (I: current, unit A, U: voltage, unit kV), the equipment insulation withstand voltage test auxiliary device calculates the current size, selects the power supply line model, and matches the reasonable excitation transformer model.

[0007] The automatic determination of insulation withstand voltage test parameters of high-voltage complete sets of equipment is realized. The test effect of high voltage and small current is achieved through frequency modulation series resonance. The test capacitor and reactor resonate with minimal loss, which ensures the safety of the test to a certain extent.

[0008] Optionally, in step 2, terminal 1 of the test equipment is connected to the A, B, and C ends of the high-voltage winding of the transformer, terminal 2 of the test equipment is connected to the a, b, and c ends of the low-voltage winding of the transformer, and terminal 3 of the test equipment is connected to the transformer core and clamp grounding wire.

[0009] Optionally, in step 3, the insulation withstand voltage test auxiliary device sets the insulation resistance threshold of the current test equipment according to the power handover test specification, and the insulation test is judged to be qualified when the insulation resistance values ​​within the duration of the insulation test are all less than the insulation resistance threshold.

[0010] Optionally, in step 4, the insulation withstand voltage test auxiliary device controls the excitation transformer to uniformly increase the voltage within a set time, so that the test voltage of the test equipment reaches the set withstand voltage test voltage, and the withstand voltage test time is set continuously.

[0011] Optionally, in step 4, a visual analysis method is used to determine the changes in physical damage of the test equipment before and after the test, and a sound analysis method is used to determine whether there is an abnormal discharge sound during the voltage test of the test equipment. If it is determined that there are physical damage changes and / or abnormal discharge sounds, the test equipment is judged to be abnormal; otherwise, the test equipment is judged to be normal.

[0012] By adopting the above technical solutions, the visual analysis method requires using a high-resolution camera to capture images of the test equipment before and after the test. Ensure that the shooting conditions are consistent, such as light, angle, and distance, to facilitate subsequent image comparison. Perform denoising, contrast enhancement, sharpening, etc. on the image to improve image quality. Correct the geometric distortion of the image to ensure the accuracy of the image. Extract key features such as edges, shapes, colors, textures, etc. from the image. Use image processing algorithms (such as SIFT, SURF, ORB, etc.) to identify and match key points in the image. Align the images before and after the test to ensure that they are spatially aligned for easy comparison. Apply change detection algorithms to identify differences between the images before and after the test.

[0013] The following methods can be used specifically: Difference image method: subtract the images before and after the test to highlight the changed areas.

[0014] Image segmentation method: divide the image into multiple regions and compare the changes in each region.

[0015] Machine learning approach: Train a classifier or neural network to recognize damage patterns.

[0016] Use pattern recognition techniques to identify and classify damage such as cracks, scorching, deformation, etc.

[0017] Deep learning models, such as convolutional neural networks (CNNs), can be trained to improve recognition accuracy and automation.

[0018] The sound analysis method requires the use of a highly sensitive microphone to collect sound signals during the withstand voltage test. The collected sound signals are denoised, such as using a bandpass filter to remove unnecessary frequency components. The sound signals are then standardized and normalized.

[0019] Extract features from the preprocessed sound signal. These features include: Frequency domain features: spectrum, spectrum centroid, spectrum bandwidth, spectrum flatness, etc.

[0020] Time domain characteristics: amplitude, energy, zero-crossing rate, autocorrelation function, etc.

[0021] Model-based features: such as Mel-frequency cepstral coefficients (MFCC), linear prediction coefficients (LPC), etc.

[0022] Use an acoustic event detection algorithm to identify abnormal discharge events in the acoustic signal.

[0023] Threshold detection: Set the energy or amplitude threshold. If the threshold is exceeded, abnormal discharge is detected.

[0024] Pattern matching: Match the collected sound with known abnormal discharge sound patterns.

[0025] Machine learning: Train classifiers (such as support vector machines, random forests, neural networks, etc.) to identify abnormal discharge sounds.

[0026] The machine learning model is applied to classify the extracted features to determine whether it is an abnormal discharge sound.

[0027] Deep learning models such as convolutional neural networks (CNN) or recurrent neural networks (RNN) can be used to improve recognition accuracy.

[0028] It can realize automatic judgment on whether there is any abnormality in the equipment and automatically output the test results.

[0029] A high-voltage complete set of equipment insulation withstand voltage test auxiliary device is used to implement a high-voltage complete set of equipment insulation withstand voltage test method. The insulation withstand voltage test auxiliary device comprises a calculation and analysis module, a complete set of high-voltage equipment database module, a control module and a display module. The calculation and analysis module pre-stores a calculation program designed using the steps of a high-voltage complete set of equipment insulation withstand voltage test method. The calculation and analysis module is communicatively connected with the complete set of high-voltage equipment database module, and the test capacitance Cx, the resonant frequency and the line current are calculated based on the query results of the complete set of high-voltage equipment database module. The control module is communicatively connected with the calculation and analysis module, and the test equipment is controlled to adjust the test parameters and execute actions based on the results of the calculation and analysis module. The display module is communicatively connected with the calculation and analysis module and the control module, and the test parameters and the test progress are displayed.

[0030] Optionally, it also includes a test result analysis module, which includes a visual analysis module, an abnormal sound analysis module and a test result judgment module. The visual analysis module includes a visual camera and a visual analysis module. The visual camera captures the visual picture of the test process of the test equipment. The visual analysis module is communicatively connected to the visual camera and adopts a visual feature recognition method to identify the physical damage changes during the test of the test equipment. The abnormal sound analysis module includes a radio microphone and an audio analysis module. The radio microphone collects audio data during the test of the test equipment. The audio analysis module is communicatively connected to the radio microphone and adopts an audio feature recognition method to identify the abnormal discharge sound during the test of the test equipment. The test result judgment module includes a buffer and a data analysis chip. The buffer is communicatively connected to the visual analysis module and the audio analysis module respectively. The data analysis chip is communicatively connected to the buffer. It is judged whether there is an abnormality in the test equipment according to the physical damage changes and the abnormal discharge sound analysis results, and the test result analysis results are interactively communicated with the data analysis chip and the display module.

[0031] Optionally, the calculation and analysis module is an industrial control computer, the complete set of high-voltage equipment database module is a memory for storing the complete set of high-voltage equipment database, the control module is a controller based on a control chip, and the display module is a display.

[0032] In summary, the present invention includes at least one of the following beneficial technical effects: The present invention can provide a method and auxiliary device for high-voltage complete equipment insulation withstand voltage test. The auxiliary device for insulation withstand voltage test can query and calculate the capacitance of the test product in the complete high-voltage equipment database, control the resonant frequency within the allowable range of the specification, reasonably select the inductance of the reactor, and calculate the resonant frequency. The auxiliary device for insulation withstand voltage test of the equipment calculates the current size according to the current calculation formula, selects the power supply line model, and matches the reasonable excitation transformer model.

[0033] The automatic determination of insulation withstand voltage test parameters of high-voltage complete sets of equipment is realized. The test effect of high voltage and small current is achieved through frequency modulation series resonance. The test capacitor and reactor resonate with minimal loss, ensuring the safety of the test. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic diagram of the wiring principle of a high-voltage complete set of equipment insulation withstand voltage test method of the present invention; Figure 2 It is a principle diagram of a high-voltage complete set equipment insulation withstand voltage test method of the present invention; Figure 3 It is a schematic diagram of the component connection principle of a high-voltage complete equipment insulation withstand voltage test device of the present invention; Figure 4The present invention is a schematic diagram of a test piece wiring terminal of a high-voltage complete set of equipment insulation withstand voltage test method.

[0035] Explanation of the accompanying drawings: 1. Calculation and analysis module; 2. Complete high-voltage equipment database module; 3. Control module; 4. Display module; 5. Visual analysis module; 6. Abnormal sound analysis module; 61. Radio microphone; 62. Audio analysis module; 7. Test result judgment module; 71. Buffer; 72. Data analysis chip. DETAILED DESCRIPTION

[0036] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0037] The embodiment of the invention discloses a method for testing the insulation and withstand voltage of a high-voltage complete set of equipment and an auxiliary device.

[0038] Reference Figure 1-Figure 4 , a high-voltage complete set of equipment insulation withstand voltage test method, comprising the following steps: Step 1: Calculate the resonant frequency and select the test equipment. Search and calculate the test capacitance Cx in the complete set of high-voltage equipment database of the insulation withstand voltage test auxiliary device, control the resonant frequency within the allowable range of the specification, select the reactor to obtain the inductance L, calculate the resonant frequency and line current, and select the test equipment model; Step 2: Connect the test equipment and the test equipment, connect the variable frequency power supply equipment to the 380V incoming line, then connect the excitation transformer, reactor and test equipment, and connect the capacitor voltage divider in parallel at both ends of the reactor; Step 3, insulation test, the insulation resistance tester is connected to both ends of the test equipment, the insulation withstand voltage test auxiliary device and the insulation resistance tester exchange the resistance value of the test equipment, the insulation withstand voltage test auxiliary device checks whether the insulation resistance meets the requirements according to the power handover test specification, and the withstand voltage test is carried out after the insulation test is qualified; Step 4, voltage withstand test, after the variable frequency power supply is powered on, set the test voltage, and set the frequency range according to the resonant frequency calculated by the insulation voltage withstand test auxiliary device. The insulation voltage withstand test auxiliary device controls the voltage increase and detects whether the test equipment is abnormal. The timing starts after the voltage stabilizes at the test voltage. If there is no abnormality in the test equipment during the test timing period and the test voltage is stable, the test is judged to be qualified. After the voltage withstand test is completed, discharge to the ground.

[0039] In step 1, according to the series resonance formula: , where f is the frequency, L is the inductance, Cx is the test capacitance, the insulation withstand voltage test auxiliary device queries the complete set of high-voltage equipment database and calculates the test capacitance Cx based on the series resonance formula, controls the resonant frequency at 50-200Hz, selects the inductor to obtain the inductance L, and the insulation withstand voltage test auxiliary device calculates the resonant frequency f.

[0040] In step 1, according to the current calculation formula , where I is current and U is voltage. The insulation withstand voltage test auxiliary device calculates the current size, selects the power supply line model, and matches the excitation transformer model.

[0041] Through the insulation withstand voltage test auxiliary device, the test capacitance Cx is queried and calculated in the complete set of high-voltage equipment database (the equipment has capacitance data that can be directly input), the resonant frequency is controlled within the allowable range of the specification (50-200Hz), the inductance L is reasonably selected from the reactor, and the equipment insulation withstand voltage test auxiliary device calculates the resonant frequency f. According to the current calculation formula (I: current, unit A, U: voltage, unit kV), the equipment insulation withstand voltage test auxiliary device calculates the current size, selects the power supply line model, and matches the reasonable excitation transformer model.

[0042] The automatic determination of insulation withstand voltage test parameters of high-voltage complete sets of equipment is realized. The test effect of high voltage and small current is achieved through frequency modulation series resonance. The test capacitor and reactor resonate with minimal loss, which ensures the safety of the test to a certain extent.

[0043] In step 2, the test equipment terminal 1 is connected to the A, B, and C ends of the transformer high-voltage winding, the test equipment terminal 2 is connected to the a, b, and c ends of the transformer low-voltage winding, and the test equipment terminal 3 is connected to the transformer core and clamp grounding wire.

[0044] In step 3, the insulation withstand voltage test auxiliary device sets the insulation resistance threshold of the current test equipment according to the power handover test specification. When the insulation resistance values ​​within the insulation test duration are all less than the insulation resistance threshold, the insulation test is judged to be qualified.

[0045] In step 4, the insulation withstand voltage test auxiliary device controls the excitation transformer to uniformly increase the voltage within the set time, so that the test voltage of the test equipment reaches the set withstand voltage test voltage, and continues the set withstand voltage test time.

[0046] In step 4, a visual analysis method is used to determine the physical damage changes of the test equipment before and after the test, and a sound analysis method is used to determine whether there is an abnormal discharge sound during the voltage test of the test equipment. If it is determined that there are physical damage changes and / or abnormal discharge sounds, the test equipment is judged to be abnormal, otherwise it is judged that the test equipment is normal.

[0047] Visual analysis methods require the use of a high-resolution camera to capture images of the test equipment before and after the test. Ensure that the shooting conditions are consistent, such as lighting, angle, and distance, to facilitate subsequent image comparison. Perform denoising, contrast enhancement, and sharpening on the images to improve image quality. Correct the geometric distortion of the image to ensure image accuracy. Extract key features from the image, such as edges, shapes, colors, textures, etc. Use image processing algorithms (such as SIFT, SURF, ORB, etc.) to identify and match key points in the image. Register the images before and after the test to ensure that they are spatially aligned for easy comparison. Apply change detection algorithms to identify differences between the images before and after the test.

[0048] The following methods can be used specifically: Difference image method: subtract the images before and after the test to highlight the changed areas.

[0049] Image segmentation method: divide the image into multiple regions and compare the changes in each region.

[0050] Machine learning approach: Train a classifier or neural network to recognize damage patterns.

[0051] Use pattern recognition techniques to identify and classify damage such as cracks, scorching, deformation, etc.

[0052] Deep learning models, such as convolutional neural networks (CNNs), can be trained to improve recognition accuracy and automation.

[0053] The sound analysis method requires the use of a highly sensitive microphone to collect sound signals during the withstand voltage test. The collected sound signals are denoised, such as using a bandpass filter to remove unnecessary frequency components. The sound signals are then standardized and normalized.

[0054] Extract features from the preprocessed sound signal. These features include: Frequency domain features: spectrum, spectrum centroid, spectrum bandwidth, spectrum flatness, etc.

[0055] Time domain characteristics: amplitude, energy, zero-crossing rate, autocorrelation function, etc.

[0056] Model-based features: such as Mel-frequency cepstral coefficients (MFCC), linear prediction coefficients (LPC), etc.

[0057] Use an acoustic event detection algorithm to identify abnormal discharge events in the acoustic signal.

[0058] Threshold detection: Set the energy or amplitude threshold. If the threshold is exceeded, abnormal discharge is detected.

[0059] Pattern matching: Match the collected sound with known abnormal discharge sound patterns.

[0060] Machine learning: Train classifiers (such as support vector machines, random forests, neural networks, etc.) to identify abnormal discharge sounds.

[0061] The machine learning model is applied to classify the extracted features to determine whether it is an abnormal discharge sound.

[0062] Deep learning models such as convolutional neural networks (CNN) or recurrent neural networks (RNN) can be used to improve recognition accuracy.

[0063] It can realize automatic judgment on whether there is any abnormality in the equipment and automatically output the test results.

[0064] A high-voltage complete set of equipment insulation withstand voltage test auxiliary device is used to implement a high-voltage complete set of equipment insulation withstand voltage test method. The insulation withstand voltage test auxiliary device comprises a calculation and analysis module 1, a complete set of high-voltage equipment database module 2, a control module 3 and a display module 4. The calculation and analysis module 1 pre-stores a calculation program designed using step 1 of a high-voltage complete set of equipment insulation withstand voltage test method. The calculation and analysis module 1 is communicated with the complete set of high-voltage equipment database module 2, and the test capacitance Cx, the resonant frequency and the line current are calculated based on the query result of the complete set of high-voltage equipment database module 2. The control module 3 is communicated with the calculation and analysis module 1, and the test equipment is controlled to adjust the test parameters and execute actions based on the result of the calculation and analysis module 1. The display module 4 is communicated with the calculation and analysis module 1 and the control module 3, and the test parameters and the test progress are displayed.

[0065] The test result analysis module also includes a test result analysis module, which includes a visual analysis module 5, an abnormal sound analysis module 6 and a test result determination module 7. The visual analysis module 5 includes a visual camera 51 and a visual analysis module 52. The visual camera 51 captures the visual picture of the test process of the test equipment. The visual analysis module 52 is connected to the visual camera 51 in communication, and a visual feature recognition method is used to identify the physical damage changes during the test of the test equipment. The abnormal sound analysis module 6 includes a radio microphone 61 and an audio analysis module 62. The radio microphone 61 collects audio data during the test of the test equipment. The audio analysis module 62 is connected to the radio microphone 61 in communication, and an audio feature recognition method is used to identify the abnormal discharge sound during the test of the test equipment. The test result determination module 7 includes a buffer 71 and a data analysis chip 72. The buffer 71 is connected to the visual analysis module 52 and the audio analysis module 62 in communication, respectively. The data analysis chip 72 is connected to the buffer 71 in communication, and whether there is an abnormality in the test equipment is determined according to the physical damage changes and the abnormal discharge sound analysis results, and the test result analysis results are interactively communicated with the data analysis chip 72 and the display module 4.

[0066] The calculation and analysis module 1 is an industrial control computer, the complete set of high-voltage equipment database module 2 is a memory for storing the complete set of high-voltage equipment database, the control module 3 is a controller based on a control chip, and the display module 4 is a display.

[0067] The following uses a specific embodiment to illustrate the implementation principle of a high-voltage complete set of equipment insulation withstand voltage test method and auxiliary device: Taking 35kV high-voltage cable as test equipment: 3×(ZR-YJV62-26 / 35kV-1×630) 650 meters, 35kV oil-immersed transformer, and 10kV row and set high-voltage cabinet as examples, the specific test method includes the following steps: 35kV high voltage cable insulation withstand voltage test 1) Calibration: Use a multimeter to check the continuity of the circuit and verify that the three phases A / B / C correspond correctly. Disconnect one side of the double ground wire, measure the continuity from the other side, and check the spacing between the steel layer and the copper shielding layer.

[0068] 2) Outer sheath insulation: Figure 4 , one end of the insulation resistance tester is connected to the double ground wire (N1, N2), the other end is grounded, and the opposite side is suspended. Select the 500V gear to test the outer sheath insulation. The insulation resistance is not less than 0.5MΩ.

[0069] 3) Conductor insulation: such as Figure 4 , one end of the insulation resistance tester is connected to the conductor M end, and the other end is connected to the double ground wire (N1, N2). The opposite side is suspended. Select the 5kV gear to test the conductor insulation. The insulation resistance is not less than 1GΩ.

[0070] 4) Calculation of resonant frequency and selection of test equipment: The database query shows that the capacitance of the ZR-YJV62-26 / 35kV-1×630 cable is 0.256μF / km and the length is 650m. The capacitance of the test product is calculated to be 0.1664μF. Select a reactor of 90H, 2A, according to the frequency formula The calculated resonant frequency is 60.54HZ, which meets the specification requirements. The test voltage is 2U0, i.e. 52kV. According to the current calculation formula The line current is 1.52A. According to the current, a 2.5m2 three-core incoming cable is selected to meet the requirement. According to the line current and test voltage, the excitation transformer capacity is selected to be 100kVA.

[0071] 5) Connect the test equipment and the test equipment: Figure 1 :The variable frequency power supply equipment is connected to the 380V incoming line, and then connected to the excitation transformer and reactor, and a capacitor voltage divider is connected in parallel at both ends of the reactor, such as Figure 1 . Test equipment terminal 1 connection as follows Figure 4The high-voltage cable conductor end M, terminal 2 is connected to the double ground wires (N1, N2), and terminal 3 is grounded nearby on site.

[0072] 6) Withstand voltage test: After the variable frequency power supply is powered on, set the test voltage to 52kV and the frequency to 60HZ. As the voltage rises slowly, check that there is no abnormality in the high-voltage cable. Start timing after the voltage stabilizes at 52kV. The withstand voltage time is 1h. During this period, observe that there is no abnormality in the cable and the test voltage is stable. The test is considered qualified. After the withstand voltage test is completed, discharge to the ground should be performed.

[0073] (2) 35kV oil-immersed transformer insulation withstand voltage test 1) Disconnect the transformer from the 10kV busbar soft connection, check the transformer core and clamp grounding, equipment casing grounding, and secondary grounding has been completed.

[0074] 2) Check the oil analysis report (oil chromatography analysis) of 35kV oil-immersed transformer. The withstand voltage test can be carried out only if the test is qualified.

[0075] 3) Transformer insulation test: Figure 4 One end of the insulation resistance tester is connected to the A, B, and C ends of the transformer high-voltage winding, and the other end is connected to the a, b, and c ends of the transformer low-voltage winding and grounded. The 5kV gear is selected to test the main insulation of the high and low voltage windings of the transformer. The insulation resistance is not less than 1GΩ.

[0076] 4) Resonance frequency calculation and test equipment selection: Query the database to obtain the capacitance of the 35kV oil-immersed transformer as 0.0104μF, select two reactors in series with 180H and 4A, and use the frequency formula The calculated resonant frequency is 116.32HZ, which meets the specification requirements. The test voltage is 80% of the transformer insulation level, that is, 85*80%=68kV. According to the current calculation formula The line current is 0.52A. According to the current, a 2.5m2 three-core incoming cable is selected to meet the requirement. According to the line current and test voltage, the excitation transformer capacity is selected to be 50kVA.

[0077] 5) Connect the test equipment and the test equipment: Figure 1 , Figure 4 , terminal 1 of the test equipment is connected to the A, B, and C ends of the transformer high-voltage winding, terminal 2 is connected to the a, b, and c ends of the transformer low-voltage winding, and terminal 3 is connected to the transformer core and clamp grounding wire.

[0078] 6) Withstand voltage test: After the variable frequency power supply is powered on, set the test voltage to 68kV and the frequency to 113.50HZ. As the voltage rises slowly, check that the transformer is normal. Start timing after the voltage stabilizes at 68kV. The withstand voltage time is 1min. During this period, observe that the transformer is normal and the test voltage is stable. This means that the test is qualified. After the withstand voltage test is completed, discharge to the ground.

[0079] (3) 10kV high-voltage cabinet insulation withstand voltage test 1) Preparation: Short-circuit the secondary PT terminals to the ground to protect the secondary side, and short-circuit the secondary side to the ground in series at the busbar isolation cabinet. Drag the incoming PT and busbar PT out of the cabinet to avoid damage to the PT due to excessive voltage.

[0080] Release the three-in-two function and close the circuit breakers of the high-voltage switch cabinets in a row.

[0081] 2) Break insulation test: Figure 4 , short-circuit (thin copper wire) the lower ports of all switch cabinet circuit breakers (A2, B2, C2) to the ground, connect one end of the insulation resistance tester to the upper port of the circuit breaker (A1, B1, C1), and the other end to the lower port of the circuit breaker, short-circuit the busbar on the transformer side, and use the 2.5kV gear to test the conductor insulation. The insulation resistance is not less than 1GΩ.

[0082] 3) Break voltage test: After the insulation resistance is qualified, the voltage test is carried out. Terminal 1 of the test equipment is connected to the upper port of the circuit breaker (A1, B1, C1), terminal 2 is connected to the lower port of the circuit breaker (A2, B2, C2), and terminal 3 is connected to the switch cabinet ground bar. Through database query calculation, the capacitance of the 10kV high-voltage switch cabinet is 0.01556μF, two reactors of 180H, 4A are selected, the resonant frequency is calculated to be 95.08HZ, the insulation level of the 10kV complete high-voltage cabinet is 42kV, and the test is performed at 80%, that is, 33.6kV. The calculated line current is 0.31A, which meets the requirements. After the variable frequency power supply is powered on, set the test voltage to 33.6kV and the frequency to 95HZ. As the voltage rises slowly, check that there is no abnormality in the switch cabinet. Start timing after the voltage stabilizes at 33.6kV. The withstand voltage time is 1min. During this period, observe that there is no abnormality in the switch cabinet and the test voltage is stable. The test is considered to be qualified. After the withstand voltage test is completed, discharge to the ground and remove all short-circuited copper wires.

[0083] 4) Phase-to-phase and phase-to-ground insulation test: When testing phase A, phases B and C are short-circuited (thin copper wire) to ground; when testing phase B, phases A and C are short-circuited to ground; when testing phase C, phases A and B are short-circuited to ground. This connection method can be used to test both phase-to-ground and phase-to-phase. Figure 1 , Figure 4 , connect terminal 1 of the insulation resistance tester to the upper port A1 of the circuit breaker, and the other end to the lower port (B2, C2) of the circuit breaker. The same is true for the transformer side. The phase to be tested is suspended, and the other two phases are short-circuited to the ground. Use the 2.5kV gear to test the conductor insulation, and the insulation resistance is not less than 1GΩ. Similarly, test the B1 and C1 phases.

[0084] 5) Phase-to-phase and phase-to-ground withstand voltage test: After the insulation resistance is qualified, the withstand voltage test is carried out. After the insulation resistance is qualified, the withstand voltage test is carried out. Terminal 1 of the test equipment is connected to the upper port A1 of the circuit breaker, terminal 2 is connected to the lower port (B2, C2) of the circuit breaker, and terminal 3 is connected to the switch cabinet ground bar. Through database query and calculation, the capacitance of the 10kV high-voltage switch cabinet is 0.01903μF, two reactors of 180H, 4A are selected, the resonant frequency is calculated to be 86HZ, and the insulation level of the 10kV complete high-voltage cabinet is 42kV. According to the 80% test, that is, 33.6kV, the calculated line current is 0.35A, which meets the requirements. After the frequency conversion power supply is powered on, the test voltage is set to 33.6kV and the frequency is 86HZ. As the voltage rises slowly, check that there is no abnormality in the switch cabinet. After the voltage stabilizes at 33.6kV, start timing. The withstand voltage time is 1min. During this period, observe that there is no abnormality in the switch cabinet and the test voltage is stable, which means that the test is qualified. After the withstand voltage test is completed, discharge to the ground and remove all short-circuited copper wires. Similarly, test phases B1 and C1.

[0085] The above are all preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for insulation withstand voltage testing of high voltage complete equipment, characterized in that: The following steps are involved: Step 1: Calculate the resonant frequency and select the test equipment. Search and calculate the test capacitance Cx in the complete set of high-voltage equipment database of the insulation withstand voltage test auxiliary device, control the resonant frequency within the allowable range of the specification, select the reactor to obtain the inductance L, calculate the resonant frequency and line current, and select the test equipment model; Step 2: Connect the test equipment and the test equipment, connect the variable frequency power supply equipment to the 380V incoming line, then connect the excitation transformer, reactor and test equipment, and connect the capacitor voltage divider in parallel at both ends of the reactor; Step 3, insulation test, the insulation resistance tester is connected to both ends of the test equipment, the insulation withstand voltage test auxiliary device and the insulation resistance tester exchange the resistance value of the test equipment, the insulation withstand voltage test auxiliary device checks whether the insulation resistance meets the requirements according to the power handover test specification, and the withstand voltage test is carried out after the insulation test is qualified; Step 4, voltage withstand test, after the variable frequency power supply is powered on, set the test voltage, and set the frequency range according to the resonant frequency calculated by the insulation voltage withstand test auxiliary device. The insulation voltage withstand test auxiliary device controls the voltage increase and detects whether the test equipment is abnormal. The timing starts after the voltage stabilizes at the test voltage. If there is no abnormality in the test equipment during the test timing period and the test voltage is stable, the test is judged to be qualified. After the voltage withstand test is completed, discharge to the ground.

2. A high voltage complete set insulation withstand voltage test method according to claim 1, characterized in that: In step 1, according to the series resonance formula: , where f is the frequency, L is the inductance, Cx is the test capacitance, the insulation withstand voltage test auxiliary device queries the complete set of high-voltage equipment database and calculates the test capacitance Cx based on the series resonance formula, controls the resonant frequency at 50-200Hz, selects the inductor to obtain the inductance L, and the insulation withstand voltage test auxiliary device calculates the resonant frequency f.

3. A high-voltage complete equipment insulation withstand voltage test method according to claim 2, characterized in that: In step 1, according to the current calculation formula , where I is current and U is voltage. The insulation withstand voltage test auxiliary device calculates the current size, selects the power supply line model, and matches the excitation transformer model.

4. A high-voltage complete equipment insulation withstand voltage test method according to claim 3, characterized in that: In step 2, the test equipment terminal 1 is connected to the A, B, and C ends of the transformer high-voltage winding, the test equipment terminal 2 is connected to the a, b, and c ends of the transformer low-voltage winding, and the test equipment terminal 3 is connected to the transformer core and clamp grounding wire.

5. A high-voltage complete equipment insulation withstand voltage test method according to claim 4, characterized in that: In step 3, the insulation withstand voltage test auxiliary device sets the insulation resistance threshold of the current test equipment according to the power handover test specification. When the insulation resistance values ​​within the insulation test duration are all less than the insulation resistance threshold, the insulation test is judged to be qualified.

6. A high-voltage complete equipment insulation withstand voltage test method according to claim 5, characterized in that: In step 4, the insulation withstand voltage test auxiliary device controls the excitation transformer to uniformly increase the voltage within the set time, so that the test voltage of the test equipment reaches the set withstand voltage test voltage, and continues the set withstand voltage test time.

7. A high voltage complete equipment insulation withstand voltage test method according to claim 6, characterized in that: In step 4, a visual analysis method is used to determine the physical damage changes of the test equipment before and after the test, and a sound analysis method is used to determine whether there is an abnormal discharge sound during the voltage test of the test equipment. If it is determined that there are physical damage changes and / or abnormal discharge sounds, the test equipment is judged to be abnormal, otherwise it is judged that the test equipment is normal.

8. An auxiliary device for insulation withstand voltage test of high-voltage complete equipment, characterized in that: The insulation withstand voltage test auxiliary device is used to implement a high-voltage complete set of equipment insulation withstand voltage test method as described in any one of claims 1 to 7, and comprises a calculation and analysis module (1), a complete set of high-voltage equipment database module (2), a control module (3) and a display module (4), wherein the calculation and analysis module (1) pre-stores a calculation program designed according to step 1 of the high-voltage complete set of equipment insulation withstand voltage test method as described in any one of claims 1 to 7, the calculation and analysis module (1) is communicatively connected with the complete set of high-voltage equipment database module (2), and calculates the test capacitance Cx, the resonant frequency and the line current based on the query result of the complete set of high-voltage equipment database module (2), the control module (3) is communicatively connected with the calculation and analysis module (1), and controls the test equipment to adjust the test parameters and execute actions based on the result of the calculation and analysis module (1), and the display module (4) is communicatively connected with the calculation and analysis module (1) and the control module (3), and displays the test parameters and the test progress.

9. The auxiliary device for insulation withstand voltage test of high-voltage complete equipment according to claim 8, characterized in that: The device also includes a test result analysis module, the test result analysis module including a visual analysis module (5), an abnormal sound analysis module (6) and a test result determination module (7), the visual analysis module (5) including a visual camera (51) and a visual analysis module (52), the visual camera (51) capturing visual images of the test equipment during the test, the visual analysis module (52) communicating with the visual camera (51) and using a visual feature recognition method to identify physical damage changes during the test of the test equipment, the abnormal sound analysis module (6) including a sound receiving microphone (61) and an audio analysis module (62), the sound receiving microphone (61) capturing visual images of the test equipment during the test, The audio analysis module (62) is connected in communication with the sound receiving microphone (61), and an audio feature recognition method is used to identify abnormal discharge sounds during the test of the test equipment. The test result determination module (7) includes a buffer (71) and a data analysis chip (72). The buffer (71) is connected in communication with the visual analysis module (52) and the audio analysis module (62), respectively. The data analysis chip (72) is connected in communication with the buffer (71), and determines whether there is an abnormality in the test equipment based on the physical damage change and the abnormal discharge sound analysis results, and communicates with the data analysis chip (72) and the display module (4) to exchange the test result analysis results.

10. The auxiliary device for insulation withstand voltage test of high-voltage complete equipment according to claim 9, characterized in that: The calculation and analysis module (1) is an industrial control computer, the complete set of high-voltage equipment database module (2) is a memory for storing the complete set of high-voltage equipment database, the control module (3) is a controller based on a control chip, and the display module (4) is a display.

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