A power distribution equipment defect multi-physics parameter cross-modal feature extraction method

Abstract

The present application relates to the technical field of electrical performance detection of power distribution equipment, and discloses a kind of power distribution equipment defect multi-physical parameter cross-modal feature extraction method.The present application divides the power distribution equipment to be tested into multiple detection units, and determines the transient ground voltage detection point, reference detection point, ultrasonic detection direction, infrared temperature measurement area and calibration pulse coupling position for each detection unit;In the calibration phase, the transient ground voltage calibration response, ultrasonic calibration delay range and infrared background fluctuation range of each detection unit are obtained;In the operation phase, the transient ground voltage pulse is collected, and the suspected abnormal detection unit is determined according to the amplitude ratio relationship between the transient ground voltage detection point and the reference detection point, then the corresponding ultrasonic pulse is collected with the transient ground voltage pulse as the trigger reference, and the suspected defect unit is determined according to the electroacoustic arrival delay;Finally, the defect state is output in combination with the infrared temperature measurement result.The present application can correspond multiple detection parameters to the same detection site, and improve the accuracy of defect judgment.

Description

Technical Field

[0001] This invention relates to the field of electrical performance testing technology for power distribution equipment, and in particular to a method for extracting multi-physical parameter cross-modal features of defects in power distribution equipment. Background Technology

[0002] During long-term operation, power distribution equipment such as switchgear and ring main units are prone to defects such as partial discharge and contact heating due to factors such as insulation aging, moisture, dirt, loose connections, or contact oxidation. Existing power distribution equipment condition monitoring typically employs methods such as transient ground voltage detection, ultrasonic testing, and infrared thermography for routine inspections or online monitoring. Transient ground voltage detection is used to sense transient voltage pulses caused by partial discharge, ultrasonic testing is used to sense acoustic pulses generated by discharge, and infrared thermography is used to obtain equipment surface temperature rise, neighborhood temperature difference, and areas of thermal anomaly. These detection methods can reflect the operating status of power distribution equipment from different perspectives.

[0003] However, existing transient ground voltage, ultrasonic, and infrared temperature measurement methods typically use fixed thresholds or separate judgments, failing to establish on-site benchmark correspondences for specific cabinet compartment structures, grounding states, sensor installation locations, and detection sites. This makes it difficult to accurately correlate the transient ground voltage response, ultrasonic arrival delay, and infrared temperature rise of the same defect under different cabinet types or detection locations. Consequently, external electromagnetic interference, common pulses between adjacent cabinets, or normal load temperature rises are easily misjudged as equipment defects. Furthermore, the inability to correlate electroacoustic responses with the same detection site can affect the accuracy of judging partial discharge, contact heating, and compound deterioration defects. Summary of the Invention

[0004] The technical problem to be solved by this invention is that the transient ground voltage, ultrasonic and infrared temperature measurement results in the existing power distribution equipment defect detection lack on-site reference correspondence for the same detection location, which makes it difficult to accurately distinguish between external interference, normal load temperature rise and real defects. To this end, we propose a method for extracting multi-physical parameter cross-modal features of power distribution equipment defects.

[0005] To achieve the above objectives, this application adopts the following technical solution: a method for extracting multi-physical parameter cross-modal features of defects in power distribution equipment, comprising the following steps: S1. Divide the power distribution equipment under test into multiple detection units, and determine the transient ground voltage detection point, reference detection point, ultrasonic detection direction, infrared temperature measurement area and verification pulse coupling position for each detection unit; S2. During the verification phase, each detection unit is verified on-site by verifying the pulse coupling position to obtain the on-site reference information corresponding to each detection unit. The on-site reference information includes transient ground voltage verification response, ultrasonic verification delay range and infrared background fluctuation range. S3. During the operation phase, the transient ground voltage pulse of the power distribution equipment under test is collected. Based on the amplitude ratio of the transient ground voltage pulse between the transient ground voltage detection point and the reference detection point, it is compared with the transient ground voltage verification response of each detection unit to determine the suspected abnormal detection unit. S4. Using the arrival time of the transient ground voltage pulse as the trigger reference, collect the running ultrasonic pulse in the ultrasonic detection direction corresponding to the suspected anomaly detection unit, and determine whether the arrival delay between the running ultrasonic pulse and the transient ground voltage pulse falls within the ultrasonic verification delay range of the suspected anomaly detection unit. S5. Based on the comparison results of the amplitude ratio relationship and the judgment results of the arrival delay, identify the suspected defective units; S6. Measure the temperature of the infrared temperature measurement area corresponding to the suspected defective unit, and output the defect status based on the relationship between the temperature measurement result and the infrared background fluctuation range.

[0006] Preferably, in step S1, the power distribution equipment under test is a switch cabinet, ring main unit, prefabricated substation, or cable branch box; the detection unit includes at least two of the following: cable terminal detection unit, busbar connection detection unit, circuit breaker contact detection unit, insulation support detection unit, and cabinet grounding detection unit; each detection unit corresponds to an electrical connection part, insulation support part, switch contact part, grounding connection part, or cable terminal part of the power distribution equipment under test.

[0007] Preferably, in step S1, the transient ground voltage detection point is located on the outer shell, door, outer wall of the partition, or grounding bar adjacent to the corresponding detection unit; the reference detection point is located on the grounding bar, the outer shell of the adjacent cabinet, or the cabinet location away from the corresponding detection unit; the ultrasonic detection direction is the detection direction of the ultrasonic sensor toward the corresponding detection unit; the infrared temperature measurement area is the temperature measurement area of ​​the corresponding detection unit on the cabinet surface, observation window, or exposed connection part; and the calibration pulse coupling position is located on the outer wall of the cabinet, the grounding coupling end, or the external coupling plate adjacent to the corresponding detection unit.

[0008] Preferably, in step S2, the on-site verification of each detection unit includes: applying an amplitude-limited electrical verification pulse to the corresponding detection unit through the verification pulse coupling position, and emitting a synchronous acoustic verification pulse to the corresponding detection unit through the acoustic verification transmitter; the electrical verification pulse and the synchronous acoustic verification pulse are controlled by the same trigger signal; the transient ground voltage verification response is obtained based on the response amplitude, response polarity, and attenuation relationship generated by the electrical verification pulse at the transient ground voltage detection point and the reference detection point; and the ultrasonic verification delay range is obtained based on the emission time of the synchronous acoustic verification pulse, the arrival time of the ultrasonic verification response, and the arrival time of the transient ground voltage verification response corresponding to the electrical verification pulse.

[0009] Preferably, in step S2, obtaining the infrared background fluctuation range includes: when the power distribution equipment under test is in a stable operating state or a calibration state, measuring the temperature of the infrared temperature measurement area corresponding to each detection unit to obtain the background temperature of the corresponding infrared temperature measurement area, the basic value of the temperature difference between adjacent areas, and the temperature fluctuation range; the infrared background fluctuation range is used to determine whether the temperature rise, neighboring temperature difference, or temperature gradient of the corresponding infrared temperature measurement area exceeds the normal fluctuation range during the operation phase.

[0010] Preferably, in step S3, the amplitude ratio of the transient ground voltage pulse between the transient ground voltage detection point and the reference detection point is determined by the pulse peak value collected at the transient ground voltage detection point and the pulse peak value collected at the reference detection point. When the amplitude ratio matches the transient ground voltage verification response of any detection unit, the matching detection unit is identified as a suspected abnormal detection unit. When the amplitude ratio does not match the transient ground voltage verification response of any detection unit, the suspected abnormal detection unit is not identified, and an external interference or retest prompt is output.

[0011] Preferably, in step S4, the running ultrasonic pulse is a pulse signal acquired within a preset acoustic response time window after the running transient ground voltage pulse; when the arrival delay between the arrival time of the running ultrasonic pulse and the arrival time of the running transient ground voltage pulse falls within the ultrasonic verification delay range of the suspected anomaly detection unit, it is determined that the suspected anomaly detection unit meets the electroacoustic correspondence condition; when no running ultrasonic pulse is acquired within the preset acoustic response time window, or the arrival delay does not fall within the ultrasonic verification delay range of the suspected anomaly detection unit, it is determined that the suspected anomaly detection unit does not meet the electroacoustic correspondence condition.

[0012] Preferably, in step S5, determining the suspected defective unit includes: judging the degree of deviation between the transient ground voltage verification response and the amplitude ratio relationship of each detection unit, and the degree of deviation between the ultrasonic verification delay range and the arrival delay of each detection unit; determining the detection unit that simultaneously meets the transient ground voltage response matching condition and the electroacoustic delay matching condition as a candidate detection unit; when there are multiple candidate detection units, determining the candidate detection unit with the smallest combined degree of transient ground voltage response deviation and electroacoustic delay deviation as the suspected defective unit; when there are no candidate detection units, outputting external interference, common pulse, or retest prompt.

[0013] Preferably, in step S6, measuring the temperature of the infrared temperature measurement area corresponding to the suspected defective unit includes: obtaining the current highest temperature, neighborhood temperature difference, and temperature gradient of the infrared temperature measurement area; comparing the current highest temperature with the corresponding background temperature obtained in step S2 to obtain the temperature rise result; when the temperature rise result, neighborhood temperature difference, or temperature gradient exceeds the infrared background fluctuation range, it is determined that the suspected defective unit has a thermal anomaly; when the temperature rise result, neighborhood temperature difference, and temperature gradient do not exceed the infrared background fluctuation range, it is determined that the suspected defective unit has not formed an obvious thermal anomaly.

[0014] Preferably, in step S6, the defect status includes early partial discharge, partial discharge accompanied by thermal degradation, contact heating, normal load temperature rise, external interference, and retest status. When a suspected defective unit meets the electroacoustic correspondence condition and does not form an obvious thermal anomaly, early partial discharge is output. When a suspected defective unit meets the electroacoustic correspondence condition and has a thermal anomaly, partial discharge accompanied by thermal degradation is output. When there is a thermal anomaly in the infrared temperature measurement area and the detection unit corresponding to the infrared temperature measurement area does not meet the electroacoustic correspondence condition, contact heating or normal load temperature rise is judged and output based on the operating current of the power distribution equipment under test. The operating current is obtained from the existing current transformer, measurement and control device, or external current acquisition device of the power distribution equipment under test. When no suspected defective unit is determined, external interference or retest status is output.

[0015] The technical effects and advantages of this invention are as follows: This invention first divides the power distribution equipment under test into multiple detection units, and determines the transient ground voltage detection point, reference detection point, ultrasonic detection direction, infrared temperature measurement area, and verification pulse coupling position for each detection unit. Then, during the verification stage, the transient ground voltage verification response, ultrasonic verification delay range, and infrared background fluctuation range corresponding to each detection unit are obtained. This allows subsequent operational testing to establish a field reference correspondence based on the specific cabinet's compartment structure, grounding status, sensor installation position, and detection location. This reduces the impact of different cabinet types, different installation states, and external electromagnetic interference on the transient ground voltage detection results, and improves the accuracy of determining the source of the operational transient ground voltage pulse.

[0016] Meanwhile, during the operation phase, this invention first determines suspected anomaly detection units based on the amplitude ratio between the transient ground voltage pulse at the transient ground voltage detection point and the reference detection point. Then, using the transient ground voltage pulse as the trigger reference, it acquires the ultrasonic pulse in the corresponding ultrasonic detection direction. Based on whether the arrival delay of the ultrasonic pulse falls within the corresponding ultrasonic verification delay range, it determines suspected defect units. Finally, it outputs the defect status by combining the temperature rise, neighborhood temperature difference, and temperature gradient of the infrared thermometry area corresponding to the suspected defect unit. Through the above electroacoustic correspondence confirmation and infrared thermal anomaly verification, the transient ground voltage, ultrasonic, and infrared thermometry results can be correlated to the same detection location, thereby more accurately distinguishing early partial discharge, partial discharge accompanied by thermal degradation, contact heating, normal load temperature rise, and external interference or retest status, reducing false alarms and missed alarms. Attached Figure Description

[0017] The disclosure of this invention is illustrated with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of this invention. In the drawings, the same reference numerals are used to refer to the same parts: Figure 1 This is a schematic flowchart of the method of the present invention; Figure 2 This is a timing diagram of the verification phase and the operation phase in this invention; Figure 3 This is a schematic diagram of the defect status determination logic based on on-site benchmark information in this invention. Detailed Implementation

[0018] It is readily understood that, based on the technical solution of this invention, those skilled in the art can propose various interchangeable structural methods and implementations without altering the essential spirit of the invention. Therefore, the following detailed embodiments and accompanying drawings are merely illustrative examples of the technical solution of this invention and should not be considered as the entirety of the invention or as limitations or restrictions on the technical solution of this invention.

[0019] Reference Figures 1-3 As shown, this invention provides a method for extracting cross-modal features of multiple physical parameters for defects in power distribution equipment, applicable to defect detection of power distribution equipment such as switchgear, ring main units, prefabricated substations, and cable branch boxes. The multiple physical parameters in the method include transient ground voltage parameters, ultrasonic parameters, and infrared temperature parameters. Cross-modal feature extraction refers to extracting on-site benchmarks for the transient ground voltage verification response, ultrasonic verification delay range, and infrared background fluctuation range under the same detection unit, and determining whether the operating transient ground voltage pulse, operating ultrasonic pulse, and infrared temperature measurement results correspond to the same detection unit based on the on-site benchmark information during the operation phase.

[0020] Example 1: This example provides a method for extracting multi-physical parameter cross-modal features of defects in power distribution equipment. The method includes the following steps.

[0021] S1 divides the power distribution equipment under test into multiple detection units, and determines the transient ground voltage detection point, reference detection point, ultrasonic detection direction, infrared temperature measurement area, and verification pulse coupling position for each detection unit.

[0022] The power distribution equipment under test can be a switchgear, ring main unit, prefabricated substation, or cable branch box. In this embodiment, a switchgear is used as an example. The switchgear includes a cabinet, cable compartment, busbar compartment, circuit breaker compartment, cabinet door, grounding busbar, busbar connection part, cable terminal, circuit breaker contacts, and insulating support components.

[0023] Based on the internal electrical structure and externally detectable locations of the switchgear, the switchgear is divided into multiple testing units. Each testing unit includes at least two of the following: cable termination testing unit, busbar connection testing unit, circuit breaker contact testing unit, insulation support testing unit, and cabinet grounding testing unit. Each testing unit corresponds to one of the following electrical connection points, insulation support points, switch contact points, grounding connection points, or cable termination points in the power distribution equipment under test.

[0024] Specifically, the cable terminal detection unit corresponds to the cable terminal head, stress cone, grounding position of the cable shield layer, or cable compartment area; the busbar connection detection unit corresponds to the busbar lap point, busbar bolt connection point, or busbar compartment area; the circuit breaker contact detection unit corresponds to the stationary contact, moving contact, clover contact, or contact box area of ​​the circuit breaker; the insulation support detection unit corresponds to the insulator, insulation partition, bushing, or supporting insulation component area; and the cabinet grounding detection unit corresponds to the cabinet door grounding wire, cabinet grounding busbar, grounding switch, or metal shell connection position.

[0025] For each detection unit, a transient ground voltage detection point, a reference detection point, an ultrasonic detection direction, an infrared temperature measurement area, and a calibration pulse coupling position are determined. The transient ground voltage detection point is located on the outer shell, door, outer wall of the partition, or grounding bar adjacent to the corresponding detection unit, and is used to collect transient ground voltage pulses related to the corresponding detection unit. The reference detection point is located on the grounding bar, the outer shell of an adjacent cabinet, or a cabinet location away from the corresponding detection unit, and is used to provide transient ground voltage pulse amplitude comparison and a common pulse reference.

[0026] The ultrasonic testing direction is the direction in which the ultrasonic sensor faces the corresponding testing unit. For example, when the ultrasonic sensor is attached to the outer wall of the cable cabinet and faces the cable terminal testing unit, this direction is the ultrasonic testing direction of the cable terminal testing unit; the infrared temperature measurement area is the temperature measurement area of ​​the corresponding testing unit on the cabinet surface, observation window, or exposed connection part; the calibration pulse coupling position is set on the outer wall of the cabinet adjacent to the corresponding testing unit, the grounding coupling terminal, or the position of the external coupling plate.

[0027] The above settings ensure that each detection unit has a clearly defined electrical detection location, acoustic detection direction, temperature detection area, and calibration coupling location, allowing different detection parameters to be mapped to the same detection unit during subsequent operation and testing.

[0028] S2. During the verification phase, each detection unit is verified on-site by verifying the pulse coupling position to obtain the corresponding on-site reference information for each detection unit. The on-site reference information includes transient ground voltage verification response, ultrasonic verification delay range, and infrared background fluctuation range.

[0029] In this step, a verification pulse coupler is first placed at the verification pulse coupling location. The verification pulse coupler can be an external coupling plate, a grounding coupling clamp, a capacitor coupling component on the cabinet surface, or a safety coupling terminal that can be connected during maintenance. The verification pulse coupler does not directly apply a high-energy signal to the primary high-voltage conductor; its function is to couple a limited-amplitude electrical verification pulse to the vicinity of the corresponding detection unit, enabling the detection system to obtain the transient ground voltage response of that detection unit under its on-site installation condition. The electrical verification pulse is used to obtain the detection link response; it is not used to simulate actual equipment faults, nor does it change the primary circuit operating state of the power distribution equipment under test.

[0030] When calibrating any detection unit, an amplitude-limited electrical calibration pulse is applied to the corresponding detection unit through the calibration pulse coupling position, and a synchronous acoustic calibration pulse is sent to the corresponding detection unit through the acoustic calibration transmitter; the electrical calibration pulse and the synchronous acoustic calibration pulse are controlled by the same trigger signal, so that the two have a unified time reference.

[0031] The transient ground voltage detection point and the reference detection point respectively collect the transient ground voltage verification response generated by the electrical verification pulse. The transient ground voltage verification response includes the response amplitude, response polarity, and attenuation relationship; the response amplitude can be the peak value of the pulse collected by the transient ground voltage detection point or the reference detection point; the response polarity is used to subsequently determine whether the polarity of the operating transient ground voltage pulse is consistent with the verification response; the attenuation relationship can be represented by the ratio of the response amplitudes between the transient ground voltage detection point and the reference detection point.

[0032] For example, when calibrating a cable terminal detection unit, an electrical calibration pulse is applied near the cable compartment shell through an external coupling plate. The transient ground voltage detection point at the cable compartment shell collects the first calibration response peak value, and the reference detection point at the grounding bar collects the second calibration response peak value. The ratio between the first calibration response peak value and the second calibration response peak value is taken as the amplitude ratio in the transient ground voltage calibration response of the cable terminal detection unit. This amplitude ratio reflects the field propagation attenuation relationship of the electrical calibration pulse under the current cabinet structure, grounding status, and detection point arrangement conditions.

[0033] The ultrasonic sensor in the ultrasonic detection direction acquires the ultrasonic verification response generated by the synchronous acoustic verification pulse; the ultrasonic verification delay range is obtained based on the emission time of the synchronous acoustic verification pulse, the arrival time of the ultrasonic verification response, and the arrival time of the transient ground voltage verification response corresponding to the electrical verification pulse; the ultrasonic verification delay range is used to characterize the electroacoustic response time relationship of the corresponding detection unit under the current cabinet compartment structure, sensor attachment state, and acoustic propagation path conditions.

[0034] In practice, multiple electrical verification pulses and synchronous acoustic verification pulses can be repeatedly applied to the same detection unit to obtain multiple sets of transient ground voltage verification responses and ultrasonic verification responses. Based on the results of multiple sets of responses, the stable transient ground voltage verification response and ultrasonic verification delay range can be determined. The ultrasonic verification delay range can be the stable time interval of the ultrasonic verification response relative to the transient ground voltage verification response in multiple verifications, or it can be the range formed by adding an allowable margin to the stable time interval.

[0035] The infrared background fluctuation range is obtained by measuring the temperature of the infrared temperature measurement area corresponding to each detection unit. Specifically, when the power distribution equipment under test is in a stable operating state or a calibration state, the infrared temperature measurement area corresponding to each detection unit is measured to obtain the background temperature of the corresponding infrared temperature measurement area, the basic value of the temperature difference between adjacent areas, and the temperature fluctuation range. The infrared background fluctuation range is used to determine whether the temperature rise, neighboring temperature difference, or temperature gradient of the corresponding infrared temperature measurement area exceeds the normal fluctuation range during the operation phase.

[0036] After completing the on-site verification of each testing unit, an on-site benchmark table can be generated. The on-site benchmark table should include at least the testing unit name, the corresponding location of the testing unit, the transient ground voltage detection point, the reference detection point, the ultrasonic testing direction, the infrared thermometry area, the calibration pulse coupling position, the transient ground voltage calibration response, the ultrasonic calibration delay range, and the infrared background fluctuation range. The on-site benchmark table can be stored in the testing device or used as an on-site testing record.

[0037] When the power distribution equipment under test has undergone maintenance, sensor location changes, cabinet grounding status changes, or detection unit structure changes, repeat this step and update the field reference table to ensure that the field reference information is consistent with the actual testing link.

[0038] S3, during the operation phase, collect the transient ground voltage pulse of the power distribution equipment under test, and compare it with the transient ground voltage verification response corresponding to each detection unit based on the amplitude ratio of the transient ground voltage pulse between the transient ground voltage detection point and the reference detection point to identify the suspected abnormal detection unit.

[0039] During operation, the transient ground voltage detection component continuously or periodically acquires the transient ground voltage signal of the power distribution equipment under test. When the transient ground voltage detection point acquires the operating transient ground voltage pulse, it records the pulse peak value, pulse polarity, duration, and arrival time of the operating transient ground voltage pulse, and simultaneously records the reference pulse peak value acquired by the reference detection point at the corresponding time.

[0040] The amplitude ratio of the transient ground voltage pulse between the transient ground voltage detection point and the reference detection point is determined by the pulse peak value collected by the transient ground voltage detection point and the pulse peak value collected by the reference detection point. When the reference detection point does not collect a valid reference pulse, the upper limit of the background noise of the reference detection point or the preset minimum reference amplitude can be used as the comparison basis to avoid judgment distortion due to the reference pulse being too low.

[0041] The amplitude ratio relationship obtained during the operation phase is compared with the transient ground voltage verification response of each detection unit in the field reference table. The comparison includes at least amplitude ratio relationship comparison, and may also include pulse polarity comparison and attenuation relationship comparison. When the amplitude ratio relationship matches the transient ground voltage verification response of any detection unit, the matching detection unit is identified as a suspected abnormal detection unit.

[0042] In this embodiment, matching can be understood as: the amplitude ratio relationship during the operation phase falls within the allowable range formed by the corresponding detection unit during the verification phase, and the polarity of the transient ground voltage pulse during operation is consistent with or conforms to the polarity of the transient ground voltage verification response of the corresponding detection unit; when multiple detection units meet the transient ground voltage response matching conditions, multiple detection units can be regarded as suspected abnormal detection units and enter the subsequent electroacoustic corresponding judgment.

[0043] When the amplitude ratio does not match the transient ground voltage verification response of each detection unit, the suspected abnormal detection unit is not identified, and an external interference or retest prompt is output. At this time, the transient ground voltage pulse may be external electromagnetic interference, common pulses of adjacent cabinets, coupling pulses of non-target equipment, or occasional noise at the detection point, and a defect alarm is not directly output.

[0044] S4. Using the arrival time of the transient ground voltage pulse as the trigger reference, the running ultrasonic pulse in the ultrasonic detection direction corresponding to the suspected anomaly detection unit is collected, and it is determined whether the arrival delay between the running ultrasonic pulse and the running transient ground voltage pulse falls within the ultrasonic verification delay range of the suspected anomaly detection unit.

[0045] After identifying the suspected anomaly detection unit, the arrival time of the transient ground voltage pulse is used as the trigger reference, and the ultrasonic signal in the corresponding ultrasonic detection direction is collected within the preset acoustic response time window after the transient ground voltage pulse. The preset acoustic response time window can be determined based on the ultrasonic verification delay range obtained by the suspected anomaly detection unit in the verification stage, or it can be determined by adding an allowable margin to the ultrasonic verification delay range.

[0046] When an ultrasonic pulse is acquired within the preset acoustic response time window, the arrival time, response amplitude, and duration of the ultrasonic pulse are recorded. The arrival time of the ultrasonic pulse is compared with the arrival time of the transient ground voltage pulse to obtain the arrival delay between the two.

[0047] When the arrival delay between the arrival time of the ultrasonic pulse and the arrival time of the transient ground voltage pulse falls within the ultrasonic verification delay range of the suspected anomaly detection unit, the suspected anomaly detection unit is determined to meet the electroacoustic correspondence condition. Meeting the electroacoustic correspondence condition means that the transient ground voltage pulse and the ultrasonic pulse correspond to the on-site verification result of the detection unit in terms of time relationship, and the two are more likely to originate from the partial discharge or related anomaly of the same detection unit.

[0048] If no ultrasonic pulse is collected within the preset acoustic response time window, or if the arrival delay does not fall within the ultrasonic verification delay range of the suspected anomaly detection unit, the suspected anomaly detection unit is determined to not meet the electroacoustic correspondence conditions. At this time, even if there is a transient ground voltage pulse during the operation phase, it is not directly judged as a partial discharge defect, but external interference, common pulse, or retest prompt can be output.

[0049] S5. Based on the comparison results of the amplitude ratio relationship and the judgment results of the arrival delay, identify the suspected defective units.

[0050] In this embodiment, the transient ground voltage response matching condition refers to the following: the amplitude ratio between the transient ground voltage detection point and the reference detection point obtained during the operation phase is close to the amplitude ratio in the transient ground voltage verification response obtained by a certain detection unit during the verification phase, and the polarity of the operating transient ground voltage pulse is consistent with or within the preset allowable relationship of the transient ground voltage verification response of the detection unit; wherein, being close can mean that the amplitude ratio falls within the preset response deviation range of the detection unit.

[0051] The electroacoustic delay matching condition refers to the following: after taking the arrival time of the transient ground voltage pulse as the trigger reference, the arrival delay between the acquired ultrasonic pulse and the transient ground voltage pulse falls within the ultrasonic verification delay range obtained by the corresponding detection unit during the verification phase; when the ultrasonic pulse is not acquired, or the arrival delay does not fall within the ultrasonic verification delay range, the detection unit is considered not to meet the electroacoustic delay matching condition.

[0052] The preset response deviation range can be determined based on the transient ground voltage verification response fluctuation range obtained from multiple on-site verifications by the same detection unit, or it can be set based on the on-site commissioning results of the power distribution equipment under test.

[0053] In this step, the deviation between the transient ground voltage verification response and the amplitude ratio of each detection unit is determined, as well as the deviation between the ultrasonic verification delay range and the arrival delay of each detection unit. Detection units that simultaneously meet the transient ground voltage response matching condition and the electroacoustic delay matching condition are identified as candidate detection units. When multiple candidate detection units exist, the candidate detection unit with the smallest combined deviation of transient ground voltage response and electroacoustic delay is identified as a suspected defect unit. When no candidate detection unit exists, an external interference, common pulse, or retest prompt is output.

[0054] For ease of implementation, the electroacoustic deviation value can be used in the implementation process of the instruction manual to represent the combined result of the deviation of transient ground voltage response and the deviation of electroacoustic delay.

[0055] Let the first The electroacoustic corresponding deviation value of each detection unit is The ratio of the transient ground voltage response obtained during the operation phase is , No. The transient ground voltage reference response ratio obtained by each detection unit during the calibration phase is: The arrival delay of the operating electroacoustic signal obtained during the operation phase is , No. The electroacoustic reference delay obtained by each detection unit during the calibration phase is: Then the first The electroacoustic deviation value of each detection unit can be calculated using the following formula: ; Among them, the ratio of transient ground voltage response. The ratio of the peak pulse value acquired at the transient ground voltage detection point to the peak pulse value acquired at the reference detection point during operation; transient ground voltage reference response ratio. For the verification phase The ratio of the peak value of the transient ground voltage response at the detection point corresponding to each detection unit to the peak value of the response at the reference detection point; the arrival delay of the operating electroacoustic signal. The time difference between the arrival time of the transient ground voltage pulse and the arrival time of the ultrasonic pulse during operation; electroacoustic reference delay. For the verification phase The time difference between the arrival time of the transient ground voltage verification response and the arrival time of the ultrasonic verification response for each detection unit.

[0056] The first term in the above formula This is used to indicate the degree of deviation between the transient ground voltage amplitude ratio during operation and the transient ground voltage reference response ratio during verification; the second item This indicates the degree of deviation between the electroacoustic arrival delay during operation and the electroacoustic reference delay during calibration. The smaller the corresponding electroacoustic deviation value, the closer the transient ground voltage pulse and ultrasonic pulse detected during operation are to the field reference information of the i-th detection unit.

[0057] When the electroacoustic deviation value of a certain detection unit is less than the preset deviation limit, and the electroacoustic deviation value is the minimum value among all detection units, the detection unit is identified as a suspected defective unit. The preset deviation limit can be determined based on the fluctuation range of the electroacoustic deviation value obtained from multiple on-site verifications of the same detection unit, or based on the historical test data or on-site debugging data of the power distribution equipment under test. When the electroacoustic deviation values ​​of all detection units are greater than the preset deviation limit, the suspected defective unit is not identified, and external interference, common pulse, or retest prompts are output.

[0058] The above formulas are only used to describe the degree of similarity between transient ground voltage measurement results and ultrasonic measurement results and field reference information, and do not involve model training, classification models, dimensionality reduction processing or general pattern recognition.

[0059] S6 measures the temperature of the infrared temperature measurement area corresponding to the suspected defective unit, and outputs the defect status based on the relationship between the temperature measurement result and the infrared background fluctuation range.

[0060] After identifying a suspected defective unit, the temperature of the corresponding infrared thermography area is measured. Temperature measurement can be performed immediately after the suspected defective unit is identified, or it can be performed after the same suspected defective unit has repeatedly met the electroacoustic conditions.

[0061] During temperature measurement, the current highest temperature, neighborhood temperature difference, and temperature gradient of the infrared temperature measurement area are obtained. The current highest temperature is compared with the corresponding background temperature obtained in step S2 to obtain the temperature rise result; the neighborhood temperature difference is used to represent the temperature difference between the infrared temperature measurement area and adjacent areas; the temperature gradient is used to represent the concentration of temperature changes within the infrared temperature measurement area.

[0062] When the temperature rise, neighborhood temperature difference, or temperature gradient exceeds the range of infrared background fluctuations, the suspected defective element is determined to have thermal anomalies; when the temperature rise, neighborhood temperature difference, and temperature gradient do not exceed the range of infrared background fluctuations, the suspected defective element is determined not to have formed obvious thermal anomalies.

[0063] Based on whether the suspected defective unit meets the corresponding electroacoustic conditions and whether there is thermal anomaly, the defect status is output; the defect status includes early partial discharge, partial discharge accompanied by thermal degradation, contact heating, normal load temperature rise, external interference, and retest status.

[0064] When a suspected defective unit meets the electroacoustic correspondence conditions and does not form an obvious thermal anomaly, it outputs an early partial discharge. This state indicates that the operating transient ground voltage pulse and the operating ultrasonic pulse both correspond to the field reference information of the same detection unit, but the detection unit has not yet shown an obvious temperature rise.

[0065] When a suspected defective unit meets the electroacoustic correspondence condition and has thermal anomalies, the output partial discharge is accompanied by thermal degradation. This state indicates that the same detection unit has both electroacoustic correspondence anomalies and temperature rise, expansion of neighborhood temperature difference, or concentration of temperature gradient, indicating that partial discharge may have caused thermal degradation.

[0066] When thermal anomalies are detected in the infrared temperature measurement area, and the corresponding detection unit does not meet the electroacoustic conditions, the system will determine and output either contact heating or normal load temperature rise based on the operating current of the equipment under test. Specifically, when the operating current is high and the temperature rise in the infrared temperature measurement area is consistent with the temperature rise level of similar parts, the system will output normal load temperature rise; when the operating current does not increase significantly but the temperature rise in the infrared temperature measurement area is significantly higher than that of adjacent areas, the system will output contact heating.

[0067] When no suspected defective unit is identified, the external interference or retest status is output. This status indicates that the transient ground voltage pulse has failed to establish a correspondence with the field reference information of any detection unit, or that no ultrasonic pulse corresponding to the transient ground voltage pulse has been detected, therefore no defect alarm is directly output.

[0068] Example 2: This example provides a specific application method of a cable terminal detection unit.

[0069] The equipment under test is a medium-voltage switchgear, and the object of testing is the cable termination area. The cable termination head, stress cone, grounding location of the cable shield, and the corresponding cable compartment area are divided into cable termination testing units.

[0070] A transient ground voltage detection point is set on the outer shell of the cable compartment, and a reference detection point is set near the grounding busbar of the switchgear; an ultrasonic sensor is attached to the outer wall of the cable compartment and the ultrasonic sensor is facing the cable terminal; the surface of the cabinet or the observation window area corresponding to the cable terminal is set as the infrared temperature measurement area; an external coupling plate is set on the outer shell of the cable compartment near the cable terminal as the verification pulse coupling position.

[0071] During the verification phase, an amplitude-limited electrical verification pulse is applied to the cable terminal detection unit through an external coupling plate, and a synchronous acoustic verification pulse is emitted towards the cable terminal through an acoustic verification transmitter; the electrical verification pulse and the synchronous acoustic verification pulse are controlled by the same trigger signal.

[0072] The transient ground voltage detection point collects the first response peak value generated by the electrical verification pulse, and the reference detection point collects the second response peak value generated by the electrical verification pulse. The transient ground voltage verification response of the cable terminal detection unit is obtained based on the first and second response peak values. The ultrasonic sensor collects the ultrasonic verification response corresponding to the synchronous acoustic verification pulse, and the ultrasonic verification delay range of the cable terminal detection unit is obtained based on the arrival time of the transient ground voltage verification response and the arrival time of the ultrasonic verification response. At the same time, the infrared temperature measurement area corresponding to the cable terminal is measured to obtain the background temperature, the basic value of the temperature difference between adjacent areas, and the temperature fluctuation range.

[0073] During operation, when a transient ground voltage pulse is detected at the transient ground voltage detection point on the cable compartment casing, the amplitude ratio between this transient ground voltage detection point and the grounding busbar reference detection point is compared with the transient ground voltage verification response of the cable terminal detection unit. If they match, the cable terminal detection unit is identified as a suspected abnormal detection unit.

[0074] Subsequently, using the arrival time of the transient ground voltage pulse as the trigger reference, the ultrasonic pulse in the direction of the cable terminal is acquired. If the arrival delay between the ultrasonic pulse and the transient ground voltage pulse falls within the ultrasonic verification delay range of the cable terminal detection unit, the cable terminal detection unit is determined to meet the electroacoustic correspondence condition and is identified as a suspected defective unit.

[0075] Next, the temperature of the infrared temperature measurement area corresponding to the cable terminal is measured. If the temperature rise, neighborhood temperature difference, and temperature gradient of the infrared temperature measurement area do not exceed the infrared background fluctuation range, early partial discharge is output; if the temperature rise, neighborhood temperature difference, or temperature gradient of the infrared temperature measurement area exceeds the infrared background fluctuation range, partial discharge accompanied by thermal degradation is output.

[0076] This embodiment avoids alarming the cable terminal area solely based on the transient ground voltage pulse amplitude, and simultaneously confirms whether the running ultrasonic pulse corresponds to the cable terminal detection unit by verifying the ultrasonic delay range, thereby improving the reliability of partial discharge detection at the cable terminal.

[0077] Example 3: This example provides a specific application method of a busbar connection detection unit.

[0078] The power distribution equipment under test is a switchgear, and the object of inspection is the busbar connection. The busbar lap joints, busbar bolt connection locations, and their corresponding busbar compartment areas are divided into busbar connection inspection units.

[0079] A transient ground voltage detection point is set on the outer shell of the busbar compartment, and a reference detection point is set on the grounding busbar or the cabinet location away from the busbar compartment; an ultrasonic sensor is set on the outer wall of the busbar compartment facing the busbar connection direction; the cabinet surface, infrared observation window or exposed connection part corresponding to the busbar connection part is set as an infrared temperature measurement area; a verification pulse coupling position is set on the outer wall of the busbar compartment near the busbar connection part.

[0080] During the verification phase, the transient ground voltage verification response, ultrasonic verification delay range, and infrared background fluctuation range of the busbar connection detection unit are obtained using the same method as in Example 1.

[0081] During operation, if the infrared temperature measurement component detects a temperature rise in the infrared temperature measurement area corresponding to the busbar connection, it will further determine whether there are transient ground voltage pulses and ultrasonic pulses corresponding to the busbar connection detection unit.

[0082] If the transient ground voltage pulse matches the transient ground voltage verification response of the busbar connection detection unit, and the arrival delay between the ultrasonic pulse and the transient ground voltage pulse falls within the ultrasonic verification delay range of the busbar connection detection unit, then the busbar connection detection unit is deemed to meet the electroacoustic correspondence condition. At this time, if there is a thermal anomaly in the infrared temperature measurement area, then partial discharge accompanied by thermal degradation will be output.

[0083] If there is a thermal anomaly in the infrared temperature measurement area, but the transient ground voltage pulse does not match the transient ground voltage verification response of the busbar connection detection unit, or no ultrasonic pulse falling within the ultrasonic verification delay range is collected, then it is not judged as partial discharge. In this case, the judgment is made in conjunction with the operating current of the power distribution equipment under test. If the operating current is high and the temperature rise of the busbar connection part is consistent with the temperature rise level of similar parts, then the normal load temperature rise is output. If the operating current does not increase significantly but the temperature rise of the busbar connection part is significantly higher than that of the adjacent area, then contact heating is output.

[0084] This embodiment can distinguish between simple contact heating, normal load temperature rise, and partial discharge accompanied by thermal degradation, thus avoiding the direct use of infrared hot spots as evidence of partial discharge defects.

[0085] Example 4: This example provides a specific application method for identifying external interference or common pulses.

[0086] The power distribution equipment under test consists of multiple switchgear units arranged in parallel. One switchgear unit is designated as the target unit, and the grounding busbars of adjacent switchgear units or the target unit serve as reference test objects. Multiple transient ground voltage detection points are set on the target unit, and reference test points are set at the locations of adjacent switchgear units or grounding busbars.

[0087] During the verification phase, each detection unit in the target cabinet is verified on-site to obtain the transient ground voltage verification response, ultrasonic verification delay range, and infrared background fluctuation range of each detection unit, and to form an on-site benchmark table.

[0088] During operation, if the transient ground voltage detection point of the target cabinet and the adjacent switch cabinet or reference detection point collect transient ground voltage pulses almost simultaneously, the transient ground voltage verification response of each detection unit in the field reference table is compared with the amplitude ratio between the transient ground voltage detection point of the target cabinet and the reference detection point.

[0089] If the amplitude ratio does not match the transient ground voltage verification response of each detection unit, and no ultrasonic pulse is collected within the ultrasonic verification delay range corresponding to each detection unit, then the transient ground voltage pulse is determined to be external electromagnetic interference, common pulse of adjacent cabinets, or signal from a non-target cabinet, and external interference or retest status is output.

[0090] If the amplitude ratio matches the transient ground voltage verification response of a certain detection unit, and an ultrasonic pulse is collected within the ultrasonic verification delay range corresponding to that detection unit, it will not be excluded as a common pulse, but will proceed to the steps of identifying suspected defective units and infrared temperature measurement verification.

[0091] This embodiment can avoid false alarms caused by electromagnetic pulses inside and outside the power distribution room, coupling pulses between adjacent cabinets, or common propagation pulses, thereby improving the reliability of transient ground voltage detection results.

[0092] Example 5: This example provides a specific application method for updating field reference information.

[0093] If any of the following situations occur during the operation and maintenance of the power distribution equipment under test, the verification phase will be re-executed and the field reference information will be updated: the installation position of the transient ground voltage sensor has changed; the attachment position or orientation of the ultrasonic sensor has changed; the infrared temperature measurement area has changed; the grounding status of the cabinet has changed; the cabinet door, partition plate, busbar connection or cable terminal structure has been repaired; or the corresponding part of the detection unit has been replaced or reinstalled.

[0094] During recalibration, amplitude-limited electrical calibration pulses and synchronous acoustic calibration pulses are applied again to each detection unit, and the transient ground voltage calibration response, ultrasonic calibration delay range, and infrared background fluctuation range are reacquired. The updated field reference information replaces the original field reference information and is used for comparison and judgment in subsequent operation phases.

[0095] This embodiment enables the invention to adapt to detection conditions after power distribution equipment maintenance, sensor reinstallation, and changes in grounding status, avoiding misjudgments caused by using failed historical reference information.

[0096] The technical scope of this invention is not limited to the content described above. Those skilled in the art can make various modifications and variations to the above embodiments without departing from the technical concept of this invention, and all such modifications and variations should fall within the protection scope of this invention.

Claims

1. A method for extracting multi-physical parameter cross-modal features of defects in power distribution equipment, characterized in that, Includes the following steps: S1. Divide the power distribution equipment under test into multiple detection units, and determine the transient ground voltage detection point, reference detection point, ultrasonic detection direction, infrared temperature measurement area and verification pulse coupling position for each detection unit; S2. During the verification phase, each detection unit is verified on-site through the verification pulse coupling position to obtain the on-site reference information corresponding to each detection unit. The on-site reference information includes transient ground voltage verification response, ultrasonic verification delay range, and infrared background fluctuation range. S3. During the operation phase, the transient ground voltage pulse of the power distribution equipment under test is collected. Based on the amplitude ratio of the transient ground voltage pulse between the transient ground voltage detection point and the reference detection point, it is compared with the transient ground voltage verification response corresponding to each detection unit to determine the suspected abnormal detection unit. S4. Using the arrival time of the transient ground voltage pulse as the trigger reference, collect the running ultrasonic pulse in the ultrasonic detection direction corresponding to the suspected anomaly detection unit, and determine whether the arrival delay between the running ultrasonic pulse and the transient ground voltage pulse falls within the ultrasonic verification delay range of the suspected anomaly detection unit. S5. Based on the comparison results of the amplitude ratio relationship and the judgment results of the arrival delay, identify the suspected defective unit; S6. Measure the temperature of the infrared temperature measurement area corresponding to the suspected defective unit, and output the defect status based on the relationship between the temperature measurement result and the infrared background fluctuation range.

2. The method for extracting multi-physical parameter cross-modal features of defects in power distribution equipment according to claim 1, characterized in that, In step S1, the power distribution equipment under test is a switch cabinet, ring main unit, prefabricated substation, or cable branch box; the detection unit includes at least two of the following: cable terminal detection unit, busbar connection detection unit, circuit breaker contact detection unit, insulation support detection unit, and cabinet grounding detection unit; each detection unit corresponds to an electrical connection part, insulation support part, switch contact part, grounding connection part, or cable terminal part of the power distribution equipment under test.

3. The method for extracting multi-physical parameter cross-modal features of defects in power distribution equipment according to claim 2, characterized in that, In step S1, the transient ground voltage detection point is located on the outer shell, door, outer wall of the partition, or grounding bar adjacent to the corresponding detection unit; the reference detection point is located on the grounding bar, the outer shell of the adjacent cabinet, or the cabinet away from the corresponding detection unit; the ultrasonic detection direction is the detection direction of the ultrasonic sensor toward the corresponding detection unit; the infrared temperature measurement area is the temperature measurement area of ​​the corresponding detection unit on the cabinet surface, observation window, or exposed connection part; the calibration pulse coupling position is located on the outer wall of the cabinet, the grounding coupling end, or the external coupling plate adjacent to the corresponding detection unit.

4. The method for extracting multi-physical parameter cross-modal features of defects in power distribution equipment according to claim 1, characterized in that, In step S2, the on-site verification of each detection unit includes: applying an amplitude-limited electrical verification pulse to the corresponding detection unit through the verification pulse coupling position, and emitting a synchronous acoustic verification pulse to the corresponding detection unit through an acoustic verification transmitter; the electrical verification pulse and the synchronous acoustic verification pulse are controlled by the same trigger signal; obtaining the transient ground voltage verification response based on the response amplitude, response polarity, and attenuation relationship generated by the electrical verification pulse at the transient ground voltage detection point and the reference detection point; and obtaining the ultrasonic verification delay range based on the emission time of the synchronous acoustic verification pulse, the arrival time of the ultrasonic verification response, and the arrival time of the transient ground voltage verification response corresponding to the electrical verification pulse.

5. The method for extracting multi-physical parameter cross-modal features of defects in power distribution equipment according to claim 4, characterized in that, In step S2, obtaining the infrared background fluctuation range includes: when the power distribution equipment under test is in a stable operating state or a calibration state, measuring the temperature of the infrared temperature measurement area corresponding to each detection unit to obtain the background temperature of the corresponding infrared temperature measurement area, the basic value of the temperature difference between adjacent areas, and the temperature fluctuation range; the infrared background fluctuation range is used to determine whether the temperature rise, neighboring temperature difference, or temperature gradient of the corresponding infrared temperature measurement area exceeds the normal fluctuation range during the operation phase.

6. The method for extracting multi-physical parameter cross-modal features of defects in power distribution equipment according to claim 1, characterized in that, In step S3, the amplitude ratio of the transient ground voltage pulse between the transient ground voltage detection point and the reference detection point is determined by the pulse peak value collected by the transient ground voltage detection point and the pulse peak value collected by the reference detection point. When the amplitude ratio matches the transient ground voltage verification response of any detection unit, the matching detection unit is identified as the suspected abnormal detection unit. When the amplitude ratio does not match the transient ground voltage verification response of any detection unit, the suspected abnormal detection unit is not identified, and an external interference or retest prompt is output.

7. The method for extracting multi-physical parameter cross-modal features of defects in power distribution equipment according to claim 1, characterized in that, In step S4, the running ultrasonic pulse is a pulse signal acquired within a preset acoustic response time window after the running transient ground voltage pulse; When the arrival delay between the arrival time of the running ultrasonic pulse and the arrival time of the running transient ground voltage pulse falls within the ultrasonic verification delay range of the suspected anomaly detection unit, the suspected anomaly detection unit is determined to meet the electroacoustic correspondence condition; when no running ultrasonic pulse is collected within the preset acoustic response time window, or when the arrival delay does not fall within the ultrasonic verification delay range of the suspected anomaly detection unit, the suspected anomaly detection unit is determined not to meet the electroacoustic correspondence condition.

8. The method for extracting multi-physical parameter cross-modal features of defects in power distribution equipment according to claim 1, characterized in that, In step S5, determining the suspected defective unit includes: judging the degree of deviation between the transient ground voltage verification response and the amplitude ratio relationship of each detection unit, and the degree of deviation between the ultrasonic verification delay range and the arrival delay of each detection unit; determining the detection unit that simultaneously meets the transient ground voltage response matching condition and the electroacoustic delay matching condition as a candidate detection unit; when there are multiple candidate detection units, determining the candidate detection unit with the smallest combined degree of deviation of transient ground voltage response and electroacoustic delay as the suspected defective unit; when there are no candidate detection units, outputting external interference, common pulse, or retest prompt.

9. The method for extracting multi-physical parameter cross-modal features of defects in power distribution equipment according to claim 1, characterized in that, In step S6, measuring the temperature of the infrared temperature measurement area corresponding to the suspected defective unit includes: obtaining the current highest temperature, neighborhood temperature difference, and temperature gradient of the infrared temperature measurement area; comparing the current highest temperature with the corresponding background temperature obtained in step S2 to obtain a temperature rise result; when the temperature rise result, the neighborhood temperature difference, or the temperature gradient exceeds the infrared background fluctuation range, it is determined that the suspected defective unit has a thermal anomaly; when the temperature rise result, the neighborhood temperature difference, and the temperature gradient do not exceed the infrared background fluctuation range, it is determined that the suspected defective unit has not formed an obvious thermal anomaly.

10. The method for extracting multi-physical parameter cross-modal features of defects in power distribution equipment according to claim 9, characterized in that, In step S6, the defect status includes early partial discharge, partial discharge accompanied by thermal degradation, contact heating, normal load temperature rise, external interference, and retest status. When the suspected defective unit meets the electroacoustic correspondence condition and does not form an obvious thermal anomaly, early partial discharge is output. When the suspected defective unit meets the electroacoustic correspondence condition and has a thermal anomaly, partial discharge accompanied by thermal degradation is output. When there is a thermal anomaly in the infrared temperature measurement area and the detection unit corresponding to the infrared temperature measurement area does not meet the electroacoustic correspondence condition, contact heating or normal load temperature rise is judged and output based on the operating current of the power distribution equipment under test. When the suspected defective unit is not determined, external interference or retest status is output.

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