Method, system and medium for partial discharge diagnosis during GIS multi-aging stage pressure test

Abstract

This invention discloses a method, system, and medium for partial discharge diagnosis during multi-stage withstand voltage testing of GIS, relating to the field of GIS partial discharge diagnosis technology. By simultaneously acquiring monitoring signals from various measuring points during the AC withstand voltage test of GIS, and after filtering and noise reduction, displaying the test voltage and partial discharge monitoring signals on the same time axis, and through abnormal signal source analysis and location calculation, obtaining effective UHF and ultrasonic signals characterizing internal defects of the GIS, and plotting phase spectra of various effective signals in each voltage boosting / buckling stage and voltage holding stage, this invention combines the multi-stage voltage application process during the GIS withstand voltage test to extract multi-dimensional signal feature quantities, comprehensively analyze and diagnose internal defects and their severity in the GIS, support the formulation of GIS post-AC withstand voltage test handling strategies, and improve the effectiveness of GIS fault prediction and health management.

Description

Technical Field

[0001] This invention relates to the field of partial discharge diagnostic technology for GIS, specifically to a method, system, and medium for partial discharge diagnostics during the withstand voltage test of GIS at multiple aging stages. Background Technology

[0002] According to the requirements of standards such as DL / T 618 "Field Acceptance Test Procedure for Gas-Insulated Metal-Enclosed Switchgear" and DL / T 555 "Field Withstand Voltage and Insulation Test Guidelines for Gas-Insulated Metal-Enclosed Switchgear," partial discharge testing must be conducted simultaneously with the AC withstand voltage test for newly built GIS. This tests whether the tested GIS has penetrating insulation defects caused by non-compliance of materials, environment, processes, and procedures during production, transportation, and installation, as well as local insulation defects such as floating potential discharge, solid insulation discharge, free particle discharge, and point discharge. Extensive operational experience shows that even if newly built GIS passes the AC withstand voltage test, it may still have non-penetrating insulation defects that can develop and even worsen during long-term operation, threatening the safe operation of the equipment. Therefore, conducting comprehensive and effective partial discharge testing during the GIS construction phase to promptly detect latent insulation defects within the GIS is a necessary means to ensure the defect-free and safe commissioning of newly built GIS.

[0003] Due to the complex grounding of the tested GIS and the difficulty in obtaining signals, the pulse current method, which can accurately calibrate the discharge quantity, is difficult to implement during the AC withstand voltage test of GIS. Currently, the ultra-high frequency (UHF) method and ultrasonic method are the main means of partial discharge detection in GIS. Although there are mature detection, analysis, and diagnostic evaluation methods for operating GIS, there are no dedicated analysis and diagnostic methods for UHF and ultrasonic partial discharge detection of GIS during AC withstand voltage tests. In many cases, the UHF / ultrasonic partial discharge detectors used for operating GIS cannot synchronize with the test voltage frequency, resulting in inaccurate characteristic spectra. Furthermore, the currently recommended method of reducing the test voltage to 1.2 times the highest operating voltage of the tested GIS after one minute of withstand voltage testing cannot provide the tested GIS with a prolonged pressurized state, making it unsuitable for analyzing and diagnosing the internal state of the GIS based on long-term monitoring data. Moreover, existing technologies cannot perform dedicated partial discharge detection and analysis on the tested GIS for the voltage fluctuations and different voltage maintenance states during multiple aging stages, potentially missing certain partial discharge defects or characteristic information.

[0004] In summary, existing partial discharge diagnostic technologies during GIS withstand voltage tests rely directly on monitored discharge signals for fault diagnosis, neglecting the impact of AC withstand voltage tests at different voltage maintenance stages. This raises questions about the accuracy of the monitoring data, leading to potential omissions or misdiagnoses that affect GIS construction, installation, and subsequent operation. Summary of the Invention

[0005] To address the shortcomings of existing partial discharge diagnosis techniques during GIS withstand voltage testing, which rely solely on monitored discharge signals for fault diagnosis, neglecting the impact of different voltage maintenance stages in the AC withstand voltage test, the accuracy of monitoring data is questionable, leading to missed detections or misdiagnoses, thus affecting GIS construction, installation, and subsequent operation. This invention aims to provide a method, system, and medium for partial discharge diagnosis during GIS multi-stage withstand voltage testing. By simultaneously acquiring monitoring signals from various measuring points during the GIS AC withstand voltage test, and after filtering and noise reduction, displaying the test voltage and partial discharge monitoring signals on the same time axis, and through abnormal signal source analysis and location calculation, effective UHF and ultrasonic signals characterizing internal defects of the GIS are obtained. Phase maps of various effective signals in each voltage boosting / buckling stage and voltage maintenance stage are plotted. This allows for the extraction of multi-dimensional signal characteristics based on the multi-stage voltage application process during the GIS withstand voltage test, enabling comprehensive analysis and diagnosis of internal defects and their severity. This supports the formulation of GIS post-AC withstand voltage test handling strategies, improving the effectiveness of GIS fault prediction and health management.

[0006] The above-mentioned technical objective of the present invention is achieved through the following technical solution:

[0007] This solution provides a method for partial discharge diagnosis during the multi-stage withstand voltage test of GIS. The method includes:

[0008] Multiple measuring points were set up on the tested GIS, and monitoring signals from each measuring point were collected synchronously during the AC withstand voltage test of the tested GIS; the measuring points included monitoring points and background points; the monitoring points included UHF measuring points and ultrasonic measuring points; the background points included UHF background points and ultrasonic background points;

[0009] The monitoring signals are preprocessed by plotting them on the same time axis and performing adaptive filtering to filter out abnormal signals and record the basic information of each abnormal signal. The basic information includes: monitoring time, test voltage amplitude and test voltage phase at the monitoring time.

[0010] All anomalous signals were subjected to homology analysis, and the results of the homology analysis were used to locate each anomalous signal to determine the valid anomalous signal.

[0011] The AC withstand voltage test is divided into multiple voltage holding stages according to the test frequency, and the phase spectrum of the effective abnormal signal is plotted according to each voltage holding stage.

[0012] Partial discharge diagnosis is performed based on the phase spectrum, and the severity of defects in the tested GIS is assessed.

[0013] The severity assessment results of defects guide the operation and maintenance process of the GIS in the subjects.

[0014] A further optimized solution is that the method for arranging the measuring points includes:

[0015] The internal or non-metallic shielded locations of the tested GIS were used as UHF measurement points; the outer surface of the metal casing of the tested GIS was used as ultrasonic measurement points.

[0016] The ultra-high frequency and ultrasonic testing points cover the circuit breakers, disconnect switches, voltage transformers, current transformers, surge arresters, and busbars of the tested GIS.

[0017] An ultra-high frequency background point was placed between two adjacent GIS subjects, and an ultrasonic background point was placed on the surface of the metal frame connecting the two adjacent GIS subjects.

[0018] A further optimized solution is that the method for filtering abnormal signals includes:

[0019] The monitoring signals of each monitoring point are compared with the monitoring signals of the background point: an abnormal threshold is set. If the monitoring signal of the current monitoring point exceeds the monitoring signal of the background point and reaches the abnormal threshold, the monitoring signal of the current monitoring point is determined to be an abnormal signal.

[0020] A further optimized approach is that the method for homology analysis includes:

[0021] S31, based on the trigger time alignment and the same number of sampling points, extract the abnormal signals during the AC withstand voltage test in the multi-aging stage and obtain the time domain waveform of each abnormal signal;

[0022] S32, calculate the waveform similarity, phase distribution similarity, and test voltage dependence similarity of any two abnormal signals from adjacent monitoring points of the same type:

[0023] Waveform similarity between abnormal signals x and y from adjacent monitoring points of the same type for:

[0024] ;

[0025] Where N represents the total number of sampling points, ranging from [-1, 1]; x i This represents the value of the i-th sampling point of the abnormal signal x; y represents the mean of the abnormal signal x across the total sampling points N; i This represents the value of the i-th sampling point of the abnormal signal y; This represents the mean of the abnormal signal y across all sampling points N;

[0026] Waveform similarity between abnormal signals x and y from adjacent monitoring points of the same type for:

[0027] ;

[0028] Where j represents the j-th phase window uniformly divided by the AC withstand voltage test frequency period; M represents the total phase window uniformly divided by the AC withstand voltage test frequency period; H x (j) represents the proportion of the number of pulses in the j-th phase window of the abnormal signal x to the total number of pulses in the phase window; H y (j) represents the normalized frequency of the abnormal signal y in the j-th phase window;

[0029] Test voltage-dependent similarity between anomalous signals x and y from adjacent monitoring points of the same type for:

[0030] ;

[0031] Among them, V x (U i ) indicates that the test voltage is U i At that time, the amplitude of the abnormal signal x; V y (U i The value of the abnormal signal y is represented by y when the test voltage is Ui.

[0032] S33, set a first threshold, a second threshold and a third threshold. If the waveform similarity of the two current abnormal signals is greater than the first threshold, the phase distribution similarity is greater than the second threshold, and the test voltage dependence similarity is greater than the third threshold, then the two current abnormal signals are determined to be signals from the same source.

[0033] S34, repeat S32-S33 to obtain multiple groups of signals from the same source.

[0034] A further optimized solution is that the method for determining the valid abnormal signal includes:

[0035] T31, Scenario 1 is defined as a single monitoring point having an abnormal signal, while adjacent similar monitoring points do not have abnormal signals; Scenario 2 is at least

[0036] Two adjacent monitoring points of the same type have abnormal signals;

[0037] For scenario one: If there are similar monitoring points on both sides of the current monitoring point, then it is determined that the abnormal signal at the current monitoring point originates from the subject.

[0038] Internal GIS;

[0039] For scenario two: if only monitoring point a is classified as a signal group A from the same source, and there are similar monitoring points on both sides of monitoring point a, then the judgment is...

[0040] The abnormal signal at monitoring point a originates from within the subject's GIS; if at least two monitoring points are classified as signal group A, then dual-channel signal delay positioning is performed on the monitoring points classified as signal group A.

[0041] T32: Among all the anomalous signals located inside the subject's GIS, the anomalous signals belonging to Case 1 are extracted as valid signals, and the anomalous signals with the largest amplitude belonging to Case 2 are extracted as valid signals.

[0042] A further optimized solution is that the dual-channel signal delay positioning method includes:

[0043] Perform dual-channel signal delay calculations for any two monitoring points belonging to Case 2 and the same source signal group A:

[0044] ;

[0045] Where L represents the distance between monitoring point a and monitoring point b; v represents the signal propagation speed; Δt represents the time difference between the abnormal signal propagating to monitoring point a and monitoring point b; and m represents the distance between the abnormal signal source and monitoring point a or monitoring point b.

[0046] If m < L, the abnormal signal is determined to originate from within the subject's GIS; otherwise, if monitoring point a or monitoring point b has adjacent monitoring points, the abnormal signal is determined to originate from within the subject's GIS.

[0047] A further optimized approach is to include the following methods for plotting the phase spectrum of valid anomalous signals:

[0048] Based on the GIS withstand pressure test frequency, each pressurization or depressurization process is divided into a pressurization stage or a depressurization stage, and the holding process after each pressurization or depressurization is divided into a holding stage.

[0049] Phase diagrams of each effective abnormal signal were plotted according to the time periods of the boost and hold phases.

[0050] A further optimized approach is to include the following methods for assessing the severity of GIS defects:

[0051] Defect features are extracted based on the phase spectrum of each valid anomaly signal;

[0052] Set up multi-dimensional evaluation indicators; the multi-dimensional evaluation indicators include at least: defect type, signal type, excitation voltage, extinction voltage, discharge pulse number, phase distribution, and defect location;

[0053] The multidimensional evaluation index is calculated based on the defect characteristics, and the severity of GIS defects is classified according to the calculation results of the multidimensional evaluation index.

[0054] This solution also provides a partial discharge diagnostic system for GIS during multi-aging stage withstand voltage tests, used to implement the aforementioned partial discharge diagnostic method for GIS during multi-aging stage withstand voltage tests. The system includes:

[0055] The acquisition module is used to deploy multiple measuring points on the tested GIS and synchronously acquire monitoring signals from each measuring point during the AC withstand voltage test of the tested GIS; the measuring points include monitoring points and background points; the monitoring points include UHF measuring points and ultrasonic measuring points; the background points include UHF background points and ultrasonic background points;

[0056] The preprocessing module is used to preprocess the monitoring signals: plotting the monitoring signals on the same time axis and performing adaptive filtering to filter out abnormal signals from the monitoring signals and record the basic information of each abnormal signal; the basic information includes: monitoring time, test voltage amplitude and test voltage phase at the monitoring time;

[0057] The analysis and localization module is used to perform source analysis on all abnormal signals and, in combination with the source analysis results, locate each abnormal signal to determine the valid abnormal signal.

[0058] The plotting module is used to divide the AC withstand voltage test into multiple voltage holding stages according to the test frequency, and plot the phase spectrum of the effective abnormal signal according to each voltage holding stage.

[0059] An evaluation module is used to perform partial discharge diagnosis based on the phase spectrum and to assess the severity of defects in the tested GIS.

[0060] The application module is used to guide the operation and maintenance process of the tested GIS based on the assessment results of defect severity.

[0061] This solution also provides a computer-readable medium having a computer program stored thereon, which, when executed by a processor, can implement the partial discharge diagnosis method during the multi-aging stage withstand voltage test of GIS as described above.

[0062] Compared with the prior art, the present invention has the following beneficial effects:

[0063] 1. This solution provides a method, system, and medium for partial discharge diagnosis during the multi-stage withstand voltage test of GIS. By synchronously acquiring monitoring signals from various measuring points during the AC withstand voltage test of GIS, and displaying the test voltage and partial discharge monitoring signals on the same time axis after filtering and noise reduction, the solution obtains effective UHF and ultrasonic signals characterizing internal defects of GIS through abnormal signal source analysis and location calculation. It also plots the phase spectrum of various effective signals in each voltage boosting and voltage holding stage. In combination with the multi-stage voltage application process during the GIS withstand voltage test, multi-dimensional signal feature quantities are extracted, and the internal defects and severity of GIS are comprehensively analyzed and diagnosed. This supports the formulation of GIS handling strategies after AC withstand voltage test and improves the effectiveness of GIS fault prediction and health management.

[0064] 2. This solution provides a partial discharge diagnosis method, system, and medium for GIS multi-stage withstand voltage tests; it improves the similarity calculation method by combining waveform similarity, phase distribution similarity, and test voltage dependence to quantify the correlation between abnormal signals and the test voltage at that time, so as to more accurately determine whether abnormal signals have the same source. Attached Figure Description

[0065] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:

[0066] Figure 1 This is a schematic diagram of the partial discharge diagnosis method during the multi-stage withstand voltage test of GIS.

[0067] Figure 2 This is a schematic diagram of the partial discharge diagnostic system during the multi-stage withstand voltage test of GIS.

[0068] Figure 3 This is a schematic diagram of the phase spectrum of the GIS defect signal in Example 1;

[0069] Figure 4 This is a schematic diagram of the partial discharge diagnostic system during the multi-stage withstand voltage test of GIS. Detailed Implementation

[0070] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0071] Existing partial discharge diagnostic techniques during GIS withstand voltage testing rely directly on monitored discharge signals for fault diagnosis, neglecting the impact of different voltage maintenance phases in the AC withstand voltage test. This raises questions about the accuracy of the monitoring data, leading to missed detections or misdiagnoses, which negatively impacts GIS construction, installation, and subsequent operation. Therefore, this solution provides the following embodiments to address these technical problems:

[0072] Example 1

[0073] This embodiment provides a method for partial discharge diagnosis during the multi-aging stage withstand voltage test of GIS, such as... Figure 1 As shown, the method includes:

[0074] Step 1: Multiple measuring points are set up on the GIS under test, and monitoring signals from each measuring point are collected synchronously during the AC withstand voltage test of the GIS under test; the measuring points include monitoring points and background points; the monitoring points include UHF measuring points and ultrasonic measuring points; the background points include UHF background points and ultrasonic background points.

[0075] The method for arranging the measuring points includes:

[0076] The internal or non-metallic shielded locations of the tested GIS were used as UHF measurement points; the outer surface of the metal casing of the tested GIS was used as ultrasonic measurement points.

[0077] The ultra-high frequency and ultrasonic testing points cover the circuit breakers, disconnect switches, voltage transformers, current transformers, surge arresters, and busbars of the tested GIS.

[0078] An ultra-high frequency background point was placed between two adjacent GIS subjects, and an ultrasonic background point was placed on the surface of the metal frame connecting the two adjacent GIS subjects.

[0079] Under the above rules, monitoring points and background points can be arranged. Specifically, the built-in UHF sensor installed in the GIS under test can be used as the UHF measurement point. If the GIS under test does not have a built-in UHF sensor, the UHF sensor can be arranged in non-metallic shielded positions such as the basin insulator and observation window of the GIS under test as the UHF measurement point. The ultrasonic sensor can be arranged on the outer surface of the metal shell of the GIS under test as the ultrasonic measurement point.

[0080] The low-voltage capacitor output of the capacitor divider in the series resonant withstand voltage test device is connected to a unified acquisition device. All outputs from the UHF measurement points, UHF background points, ultrasonic measurement points, and ultrasonic background points are also connected to this unified acquisition device. During the AC withstand voltage test of the tested GIS, the unified acquisition device simultaneously acquires the monitoring signals from each output at a preset sampling rate. These signals are then pre-amplified and converted from analog to digital to form a digital signal sequence with time intervals between adjacent sampling points. For example, the sampling rate can be set to 200 MS / s, corresponding to a digital signal sequence time interval of 50 ns.

[0081] Step 2: Preprocess the monitoring signals: Plot the monitoring signals on the same time axis and perform adaptive filtering to filter out abnormal signals and record the basic information of each abnormal signal; the basic information includes: monitoring time, test voltage amplitude and test voltage phase at the monitoring time;

[0082] In step two, the adaptive filtering process aligns the digital signal sequence of similar background points within the interval containing the monitoring signal to be processed with the digital signal sequence of the monitoring signal to be processed at the point of maximum amplitude, and then performs adaptive differential processing. The expression is:

[0083] ;

[0084] In the formula, X m (t) represents the output signal of the m-th monitoring point after adaptive filtering, T m (t) represents the raw signal collected at the m-th monitoring point, B k (t) represents the original signal collected from a background point of the same type at the k-th interval, which is at the same interval as the m-th measurement point; α represents the differential coefficient for compensating for the amplitude difference between the background point and the measurement point; R m (t) represents the estimated residual noise signal, based on X m (t)-R m The error mean square error of (t) is adjusted in real time according to the principle of minimizing the mean square error.

[0085] The method for filtering abnormal signals includes:

[0086] The monitoring signals of each monitoring point are compared with the monitoring signals of the background point: an abnormal threshold is set. If the monitoring signal of the current monitoring point exceeds the monitoring signal of the background point and reaches the abnormal threshold, the monitoring signal of the current monitoring point is determined to be an abnormal signal.

[0087] Specifically, any monitoring signal at each monitoring point that reaches or exceeds twice the amplitude of the background monitoring signal is marked as an abnormal signal. During the entire test, the occurrence time of all abnormal signals at all monitoring points, the voltage value of the corresponding test voltage, and the phase are recorded.

[0088] Step 3: Perform source analysis on all abnormal signals, and locate each abnormal signal based on the source analysis results to determine the valid abnormal signal;

[0089] The methods for homology analysis include:

[0090] S31, based on the trigger time alignment and the same number of sampling points, extract the abnormal signals during the AC withstand voltage test in the multi-aging stage and obtain the time domain waveform of each abnormal signal;

[0091] Specifically, in this multi-stage AC withstand voltage test, the GIS is subjected to a specified maximum withstand voltage for approximately one minute, followed by at least four aging stages with voltages lower than the maximum withstand voltage and maintained for a certain period. These stages are used for ablation of foreign matter, particle removal, and partial discharge detection. The voltage is increased and decreased, and the voltage is maintained at each stage, according to the established GIS multi-stage withstand voltage test procedure. Figure 2As shown, this embodiment takes the 1100kV GIS AC withstand voltage test procedure as an example. The test voltage is increased from 0 to 200kV and held for 10 minutes, increased from 200kV to 300kV and held for 10 minutes, increased from 300kV to 577kV and the PT no-load current is measured, increased from 577kV to 635kV and held for 10 minutes, increased from 635kV to 762kV and held for 20 minutes, increased from 762kV to 1100kV and withstand voltage for 1 minute, decreased from 1100kV to 762kV and held for 30 minutes to carry out partial discharge measurement, decreased from 762kV to 577kV and the PT no-load current is measured, and decreased from 577kV to 0. Reaching four aging stages constitutes a multi-aging stage. According to current standards, GIS withstand voltage tests must withstand a specified voltage value for one minute; failure to break down is considered a pass, while breakdown is considered a fail. However, based on long-term experience, it is necessary to apply and maintain other voltage values ​​before and after the one-minute withstand voltage stage. The purpose is to drive away ablation particles and foreign matter, making it easier to pass the withstand voltage test. After the withstand voltage test, the equipment that has undergone the withstand voltage test is reduced to a certain aging voltage and held for a certain period of time for a partial discharge test. The purpose is to detect latent insulation defects in the equipment through partial discharge. Figure 2 The pressurization process of the 1000 kV GIS test is a typical GIS withstand voltage test process with multiple aging stages. Since many GIS partial discharges occur at a certain voltage for a certain period of time, by monitoring the partial discharge throughout the withstand voltage test and correlating the partial discharge signal with the test voltage at which it occurs, we can first identify at what test voltage the partial discharge signal is triggered and at what test voltage it disappears under the voltage reduction condition. This is a key indicator for evaluating the severity of the equipment in this invention.

[0092] S32, calculate the waveform similarity, phase distribution similarity, and test voltage dependence similarity of any two abnormal signals from adjacent monitoring points of the same type:

[0093] Waveform similarity between abnormal signals x and y from adjacent monitoring points of the same type for:

[0094] ;

[0095] Where N represents the total number of sampling points, ranging from [-1, 1]; x i This represents the value of the i-th sampling point of the abnormal signal x; y represents the mean of the abnormal signal x across the total sampling points N; i This represents the value of the i-th sampling point of the abnormal signal y; This represents the mean of the abnormal signal y across all sampling points N;

[0096] Waveform similarity between abnormal signals x and y from adjacent monitoring points of the same type for:

[0097] ;

[0098] Where j represents the j-th phase window uniformly divided by the AC withstand voltage test frequency period; M represents the total phase window uniformly divided by the AC withstand voltage test frequency period; H x (j) represents the proportion of the number of pulses in the j-th phase window of the abnormal signal x to the total number of pulses in the phase window; H y (j) represents the normalized frequency of the abnormal signal y in the j-th phase window; specifically, in this embodiment, the AC withstand voltage test frequency is 0~360°;

[0099] Test voltage-dependent similarity between anomalous signals x and y from adjacent monitoring points of the same type for:

[0100] ;

[0101] Among them, V x (U i ) indicates that the test voltage is U i At that time, the amplitude of the abnormal signal x; V y (U i The value of the abnormal signal y is represented by y when the test voltage is Ui.

[0102] In this embodiment, waveform similarity is a conventional calculation method for time-domain signals. However, the conventional similarity calculation method for time-domain signals is directly applied during the AC withstand voltage test in multiple aging stages and cannot capture the correlation between the test voltage and abnormal signals. In order to better capture the correlation between the test voltage and abnormal signals, this scheme improves the similarity calculation method by combining waveform similarity, phase distribution similarity, and test voltage dependence to quantify the correlation between abnormal signals and the test voltage at that time, so as to more accurately determine whether the abnormal signals are from the same source.

[0103] S33, set a first threshold, a second threshold, and a third threshold. If the waveform similarity of the two current abnormal signals is greater than the first threshold, the phase distribution similarity is greater than the second threshold, and the test voltage dependence similarity is greater than the third threshold, then the two current abnormal signals are determined to be signals from the same source. Specifically, the first threshold, the second threshold, and the third threshold are set to the same value, which is 0.8.

[0104] S34, repeat S32-S33 to obtain multiple groups of signals from the same source.

[0105] The method for determining the valid abnormal signal includes:

[0106] T31 defines scenario one as a single monitoring point having an abnormal signal while adjacent monitoring points of the same type do not have abnormal signals, and scenario two as at least two adjacent monitoring points of the same type having abnormal signals.

[0107] For scenario one: if there are similar monitoring points on both sides of the current monitoring point, it is determined that the abnormal signal of the current monitoring point comes from inside the subject GIS; if the current monitoring point is located at the end of the subject GIS, that is, there is only a similar monitoring point on one side, it is impossible to determine that the abnormal signal comes from inside the subject GIS.

[0108] For scenario two: if only monitoring point a is classified as a signal group A, and there are similar monitoring points on both sides of monitoring point a, then the abnormal signal of monitoring point a is determined to originate from inside the subject's GIS; if at least two monitoring points are classified as a signal group A, then dual-channel signal delay positioning is performed on the monitoring points classified as a signal group A.

[0109] The dual-channel signal delay positioning method includes:

[0110] T311, perform dual-channel signal delay calculation for any two monitoring points belonging to Case 2 and the same source signal group A:

[0111] ;

[0112] Where L represents the distance between monitoring point a and monitoring point b; v represents the signal propagation speed; Δt represents the time difference between the abnormal signal propagating to monitoring point a and monitoring point b; and m represents the distance between the abnormal signal source and monitoring point a or monitoring point b.

[0113] T312, if m < L, the abnormal signal is determined to originate from within the subject's GIS; otherwise, if monitoring point a or monitoring point b has adjacent monitoring points, the abnormal signal is determined to originate from within the subject's GIS.

[0114] T32, among all the abnormal signals located inside the subject's GIS, extract the abnormal signals belonging to Case 1 as valid signals, and extract the abnormal signals with the largest amplitude in Case 2 as valid signals, and further obtain the excitation voltage or extinguishing voltage of each valid signal.

[0115] Step four: Divide the AC withstand voltage test into multiple voltage holding stages according to the test frequency, and draw the phase spectrum of the effective abnormal signal according to each voltage holding stage; the phase spectrum can reflect the effective signal amplitude, discharge pulse number and phase distribution of each monitoring point in different time periods.

[0116] The method for plotting the phase spectrum of the effective abnormal signal includes:

[0117] S41, based on the GIS withstand pressure test frequency, divide each pressure increase or decrease process into a pressure increase stage or a pressure decrease stage, and divide the holding process after each pressure increase or decrease into a holding stage;

[0118] Specifically, such as Figure 3 As shown, the voltage increase from 0 to 200kV is divided into one voltage increase phase, followed by a 10-minute holding phase after reaching 200kV; the voltage increase from 200kV to 300kV is also divided into one voltage increase phase, followed by a 10-minute holding phase after reaching 300kV; the voltage increase from 300kV to 577kV is divided into one voltage increase phase, after which the PT no-load current measurement is completed; the voltage increase from 577kV to 635kV is divided into one voltage increase phase, followed by a 10-minute holding phase after reaching 635kV; and the voltage increase from 635kV to 762kV is divided into... The voltage is divided into several stages: a boost stage (762kV, held for 20 minutes), a holding stage (762kV to 1100kV, with a withstand voltage of 1 minute), a step-down stage (1100kV to 762kV, with a hold voltage of 30 minutes), a step-down stage (762kV to 577kV, with a PT no-load current measurement), and a step-down stage (577kV to 0).

[0119] S42, plot the phase spectrum of each effective abnormal signal according to the time periods of the boost phase and the hold phase. The phase spectrum of the effective abnormal signal plotted in this embodiment is as follows: Figure 3 As shown, it includes GIS tip discharge, GIS free particle discharge, GIS suspension discharge, GIS solid insulation discharge, and GIS abnormal vibration.

[0120] Step 5: Perform partial discharge diagnosis based on the phase spectrum and assess the severity of defects in the tested GIS;

[0121] Specific evaluation methods include:

[0122] S51, extract defect features based on the phase spectrum of each valid abnormal signal; specifically, in this embodiment, defect features include excitation voltage, extinction voltage, amplitude, number of discharge pulses, phase distribution, etc.

[0123] S52, set multi-dimensional evaluation indicators; the multi-dimensional evaluation indicators include at least: defect type, signal type, excitation voltage, extinction voltage, discharge pulse number, phase distribution and defect location;

[0124] S53, calculate the multidimensional evaluation index based on the defect characteristics, and classify the severity of GIS defects according to the calculation results of the multidimensional evaluation index.

[0125] Specifically, the evaluation indicators are first coded:

[0126] The defect type is one of floating potential discharge, free particle discharge, or solid insulation discharge, coded as A11;

[0127] The defect type is tip discharge, coded as A12;

[0128] The defect type is equipment vibration, coded as A13;

[0129] The defect signal contains both ultra-high frequency and ultrasonic signals, coded as A21.

[0130] The defect signal is only encoded as A22 using ultra-high frequency signals.

[0131] The defect signal is only an ultrasonic signal, coded as A23;

[0132] The excitation voltage should not exceed 1.2 times the highest operating voltage of the tested GIS, coded as A31;

[0133] The excitation voltage is 1.2 times higher than but less than 1.8 times the highest operating voltage of the tested GIS, coded as A32;

[0134] The excitation voltage shall not be less than 1.8 times the maximum operating voltage of the GIS, coded as A33;

[0135] The shutdown voltage is lower than the rated operating voltage of the GIS, coded as A41.

[0136] The shutdown voltage shall not be lower than the rated operating voltage of the GIS, coded as A42;

[0137] The number of discharge pulses with an amplitude exceeding -60dBm at 1.2 times the highest operating voltage of the tested GIS shall not be less than 2.0 pulses / minute or the rate of change shall be greater than 10.0%, which shall be coded as A51.

[0138] If the number of discharge pulses with an amplitude exceeding -60dBm is less than 2.0 pulses / minute and the rate of change is not greater than 10.0% at 1.2 times the highest operating voltage of the tested GIS, it is coded as A52.

[0139] The phase distribution in each cycle is greater than 180° at 1.2 times the highest operating voltage of the tested GIS, which is coded as A61;

[0140] Under the highest operating voltage of the tested GIS, the phase distribution of each cycle is no greater than 180°, coded as A62;

[0141] Defects located in solid insulation, circuit breakers, disconnectors / grounding switches and their vicinity are coded as A71.

[0142] Defects located in low field strength regions with increased insulation clearance are coded as A73; otherwise, they are coded as A72.

[0143] Based on the table below, GIS defects are classified into three categories: minor, moderate, and severe.

[0144]

[0145] Step 6: Guide the GIS operation and maintenance process based on the GIS defect severity assessment results.

[0146] For GIS defects assessed as minor, normal operation can be resumed after other tests are passed, with enhanced monitoring during operation. For GIS defects assessed as ordinary, insulation testing should be strengthened to further analyze the equipment status. For GIS defects assessed as serious, the equipment should be disassembled immediately to locate and eliminate the defects.

[0147] Example 2

[0148] This embodiment provides a partial discharge diagnostic system during the multi-aging stage withstand voltage test of GIS, such as... Figure 4 As shown, the system for implementing the partial discharge diagnosis method during the multi-aging stage withstand voltage test of GIS according to Embodiment 1 includes:

[0149] The acquisition module is used to deploy multiple measuring points on the tested GIS and synchronously acquire monitoring signals from each measuring point during the AC withstand voltage test of the tested GIS; the measuring points include monitoring points and background points; the monitoring points include UHF measuring points and ultrasonic measuring points; the background points include UHF background points and ultrasonic background points;

[0150] The preprocessing module is used to preprocess the monitoring signals: plotting the monitoring signals on the same time axis and performing adaptive filtering to filter out abnormal signals from the monitoring signals and record the basic information of each abnormal signal; the basic information includes: monitoring time, test voltage amplitude and test voltage phase at the monitoring time;

[0151] The analysis and localization module is used to perform source analysis on all abnormal signals and, in combination with the source analysis results, locate each abnormal signal to determine the valid abnormal signal.

[0152] The plotting module is used to divide the AC withstand voltage test into multiple voltage holding stages according to the test frequency, and plot the phase spectrum of the effective abnormal signal according to each voltage holding stage.

[0153] An evaluation module is used to perform partial discharge diagnosis based on the phase spectrum and to assess the severity of defects in the tested GIS.

[0154] The application module is used to guide the operation and maintenance process of the tested GIS based on the assessment results of defect severity.

[0155] Example 2

[0156] This embodiment provides a computer-readable medium having a computer program stored thereon. The computer program, when executed by a processor, can implement the partial discharge diagnosis method during the multi-aging stage withstand voltage test of GIS as described in Embodiment 1; specifically, it performs the following steps:

[0157] Step 1: Multiple measuring points are set up on the GIS under test, and monitoring signals from each measuring point are collected synchronously during the AC withstand voltage test of the GIS under test; the measuring points include monitoring points and background points; the monitoring points include UHF measuring points and ultrasonic measuring points; the background points include UHF background points and ultrasonic background points.

[0158] Step 2: Preprocess the monitoring signals: Plot the monitoring signals on the same time axis and perform adaptive filtering to filter out abnormal signals and record the basic information of each abnormal signal; the basic information includes: monitoring time, test voltage amplitude and test voltage phase at the monitoring time;

[0159] Step 3: Perform source analysis on all abnormal signals, and locate each abnormal signal based on the source analysis results to determine the valid abnormal signal;

[0160] Step 4: Divide the AC withstand voltage test into multiple voltage holding stages according to the test frequency, and draw the phase spectrum of the effective abnormal signal according to each voltage holding stage;

[0161] Step 5: Perform partial discharge diagnosis based on the phase spectrum and assess the severity of defects in the tested GIS;

[0162] Step 6: Guide the operation and maintenance process of the subject's GIS based on the severity assessment results of the defects.

[0163] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for partial discharge diagnosis during the withstand voltage test of GIS at multiple aging stages, characterized in that, The method includes: Multiple measuring points were set up on the test GIS, and monitoring signals from each measuring point were collected synchronously during the AC withstand voltage test of the test GIS; the measuring points included monitoring points and background points; the monitoring points included UHF measuring points and ultrasonic measuring points; the background points included UHF background points and ultrasonic background points; The monitoring signals are preprocessed by plotting them on the same time axis and performing adaptive filtering to filter out abnormal signals and record the basic information of each abnormal signal. The basic information includes: monitoring time, test voltage amplitude and test voltage phase at the monitoring time. All anomalous signals were subjected to homology analysis, and the results of the homology analysis were used to locate each anomalous signal to determine the valid anomalous signal. The AC withstand voltage test is divided into multiple voltage holding stages according to the test frequency, and the phase spectrum of the effective abnormal signal is plotted according to each voltage holding stage. Partial discharge diagnosis is performed based on the phase spectrum, and the severity of defects in the tested GIS is assessed. The severity assessment results of defects guide the operation and maintenance process of the GIS in the subjects.

2. The method for partial discharge diagnosis during the multi-aging stage withstand voltage test of GIS according to claim 1, characterized in that, The method for arranging the measuring points includes: The internal or non-metallic shielded locations of the tested GIS were used as UHF measurement points; the outer surface of the metal casing of the tested GIS was used as ultrasonic measurement points. The ultra-high frequency and ultrasonic testing points cover the circuit breakers, disconnect switches, voltage transformers, current transformers, surge arresters, and busbars of the tested GIS. An ultra-high frequency background point was placed between two adjacent GIS subjects, and an ultrasonic background point was placed on the surface of the metal frame connecting the two adjacent GIS subjects.

3. The partial discharge diagnosis method during the multi-aging stage withstand voltage test of GIS according to claim 2, characterized in that, The method for filtering abnormal signals includes: The monitoring signals of each monitoring point are compared with the monitoring signals of the background point: an abnormal threshold is set. If the monitoring signal of the current monitoring point exceeds the monitoring signal of the background point and reaches the abnormal threshold, the monitoring signal of the current monitoring point is determined to be an abnormal signal.

4. The partial discharge diagnosis method during the multi-aging stage withstand voltage test of GIS according to claim 3, characterized in that, The methods for homology analysis include: S31, based on the trigger time alignment and the same number of sampling points, extract the abnormal signals during the AC withstand voltage test in the multi-aging stage and obtain the time domain waveform of each abnormal signal; S32, calculate the waveform similarity, phase distribution similarity, and test voltage dependence similarity of any two abnormal signals from adjacent monitoring points of the same type: Waveform similarity between abnormal signals x and y from adjacent monitoring points of the same type for: ； Where N represents the total number of sampling points, ranging from [-1, 1]; x i This represents the value of the i-th sampling point of the abnormal signal x; y represents the mean of the abnormal signal x across the total sampling points N; i This represents the value of the i-th sampling point of the abnormal signal y; This represents the mean of the abnormal signal y across all sampling points N; Waveform similarity between abnormal signals x and y from adjacent monitoring points of the same type for: ； Where j represents the j-th phase window uniformly divided by the AC withstand voltage test frequency period; M represents the total phase window uniformly divided by the AC withstand voltage test frequency period; H x (j) represents the proportion of the number of pulses in the j-th phase window of the abnormal signal x to the total number of pulses in the phase window; H y (j) represents the normalized frequency of the abnormal signal y in the j-th phase window; Test voltage-dependent similarity between anomalous signals x and y from adjacent monitoring points of the same type for: ； Among them, V x (U i ) indicates that the test voltage is U i At that time, the amplitude of the abnormal signal x; V y (U i ) indicates that the test voltage is U i The amplitude of the abnormal signal y at that time; S33, set a first threshold, a second threshold and a third threshold. If the waveform similarity of the two current abnormal signals is greater than the first threshold, the phase distribution similarity is greater than the second threshold, and the test voltage dependence similarity is greater than the third threshold, then the two current abnormal signals are determined to be signals from the same source. S34, repeat S32-S33 to obtain multiple groups of signals from the same source.

5. The partial discharge diagnosis method during the multi-aging stage withstand voltage test of GIS according to claim 4, characterized in that, The method for determining the valid abnormal signal includes: T31, Scenario 1 is defined as a single monitoring point having an abnormal signal, while adjacent similar monitoring points do not have abnormal signals; Scenario 2 is at least Two adjacent monitoring points of the same type have abnormal signals; For scenario one: If there are similar monitoring points on both sides of the current monitoring point, then it is determined that the abnormal signal at the current monitoring point originates from the subject. Internal GIS; For scenario two: if only monitoring point a is classified as a signal group A from the same source, and there are similar monitoring points on both sides of monitoring point a, then the judgment is... The abnormal signal at monitoring point a originates from within the subject's GIS; if at least two monitoring points are classified as signal group A, then dual-channel signal delay positioning is performed on the monitoring points classified as signal group A. T32: Among all the anomalous signals located inside the subject's GIS, the anomalous signals belonging to Case 1 are extracted as valid signals, and the anomalous signals with the largest amplitude belonging to Case 2 are extracted as valid signals.

6. The partial discharge diagnosis method during the multi-aging stage withstand voltage test of GIS according to claim 5, characterized in that, The dual-channel signal delay positioning method includes: Perform dual-channel signal delay calculations for any two monitoring points belonging to Case 2 and the same source signal group A: ； Where L represents the distance between monitoring point a and monitoring point b; v represents the signal propagation speed; Δt represents the time difference between the abnormal signal propagating to monitoring point a and monitoring point b; and m represents the distance between the abnormal signal source and monitoring point a or monitoring point b. If m < L, the abnormal signal is determined to originate from within the subject's GIS; otherwise, if monitoring point a or monitoring point b has adjacent monitoring points, the abnormal signal is determined to originate from within the subject's GIS.

7. The method for partial discharge diagnosis during the multi-aging stage withstand voltage test of GIS according to claim 1, characterized in that, Methods for plotting the phase spectrum of valid anomalous signals include: Based on the GIS withstand pressure test frequency, each pressurization or depressurization process is divided into a pressurization stage or a depressurization stage, and the holding process after each pressurization or depressurization is divided into a holding stage. Phase diagrams of each effective abnormal signal were plotted according to the time periods of the boost and hold phases.

8. The method for partial discharge diagnosis during the multi-aging stage withstand voltage test of GIS according to claim 7, characterized in that, The methods for assessing the severity of the defect include: Defect features are extracted based on the phase spectrum of each valid anomaly signal; Set up multi-dimensional evaluation indicators; the multi-dimensional evaluation indicators include at least: defect type, signal type, excitation voltage, extinction voltage, discharge pulse number, phase distribution, and defect location; The multidimensional evaluation index is calculated based on the defect characteristics, and the severity of the defect is classified according to the calculation results of the multidimensional evaluation index.

9. A partial discharge diagnostic system during the multi-aging stage withstand voltage test of GIS, characterized in that, For implementing the partial discharge diagnosis method during multi-aging stage withstand voltage test of GIS as described in any one of claims 1-8, the system comprises: The acquisition module is used to deploy multiple measuring points on the tested GIS and synchronously acquire monitoring signals from each measuring point during the AC withstand voltage test of the tested GIS; the measuring points include monitoring points and background points; the monitoring points include UHF measuring points and ultrasonic measuring points; the background points include UHF background points and ultrasonic background points; The preprocessing module is used to preprocess the monitoring signals: plotting the monitoring signals on the same time axis and performing adaptive filtering to filter out abnormal signals from the monitoring signals and record the basic information of each abnormal signal; the basic information includes: monitoring time, test voltage amplitude and test voltage phase at the monitoring time; The analysis and localization module is used to perform source analysis on all abnormal signals and, in combination with the source analysis results, locate each abnormal signal to determine the valid abnormal signal. The plotting module is used to divide the AC withstand voltage test into multiple voltage holding stages according to the test frequency, and plot the phase spectrum of the effective abnormal signal according to each voltage holding stage. An evaluation module is used to perform partial discharge diagnosis based on the phase spectrum and to assess the severity of defects in the tested GIS. The application module is used to guide the operation and maintenance process of the tested GIS based on the assessment results of defect severity.

10. A computer-readable medium having a computer program stored thereon, characterized in that, The computer program, executed by a processor, can implement the partial discharge diagnosis method during the multi-aging stage withstand voltage test of GIS as described in any one of claims 1-8.

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