Method for locating partial discharge defects of power equipment in ultra-high frequency online monitoring blind area

Abstract

The application discloses a method for positioning partial discharge defects of power equipment in a blind area of ultra-high frequency online monitoring, and relates to the technical field of partial discharge detection of power equipment. The method combines and detects positioning and comprehensively analyzes the joint detection of built-in ultra-high frequency sensors and external ultra-high frequency sensors at different positions and external ultrasonic sensors, diagnoses the position of partial discharge defects in the blind area of ultra-high frequency online monitoring such as the end outgoing line area, and detects the position of the external ultra-high frequency sensor, so that the effectiveness of diagnosis and positioning and the safety of live detection are fully considered, and the method has field implementability and operability.

Description

Technical Field

[0001] This invention relates to the field of partial discharge detection technology for power equipment, specifically to a method for locating partial discharge defects in power equipment in the blind zone of ultra-high frequency online monitoring. Background Technology

[0002] To promptly detect internal partial discharge defects and prevent insulation failures, an increasing number of power transformers, gas-insulated switchgear (GIS), and other equipment are being equipped with built-in UHF partial discharge online monitoring systems. According to standard requirements and operational needs, the system typically consists of built-in UHF sensors, local processing units, station-end centralized control units, and centralized monitoring units. The built-in UHF sensors are often pre-installed inside the equipment during manufacturing. Their installation locations aim to cover critical components such as windings, circuit breakers, and disconnectors, while avoiding internal field distortion and insulation level reduction during operation. They are often installed at locations such as drain valves, manholes, and tank ends. During operation, multiple built-in UHF sensors inside the equipment detect abnormal UHF signals generated by partial discharge. Through signal characteristic analysis, precise location, and trend tracking, the system understands the partial discharge defects and their development, providing a basis for targeted maintenance and repair, and preventing insulation failures.

[0003] The localization of partial discharge defects in power equipment using an integrated UHF partial discharge online monitoring system primarily relies on multi-sensor channel signal amplitude comparison or signal time delay localization. Multi-channel signal time delay localization offers higher accuracy and is currently the dominant method. However, due to limitations in the number and location of the integrated UHF sensors, discharge sources outside the end-effectors in various directions cannot be located by the system, and it may even be impossible to confirm whether the discharge source is located inside the equipment. This results in many abnormal UHF signals going undiagnosed, severely impacting equipment defect diagnosis and condition assessment.

[0004] Therefore, there is an urgent need to design a partial discharge defect location scheme for power equipment in the blind zone of ultra-high frequency online monitoring, so as to conduct blind-spot-free diagnosis and analysis and accurate location of partial discharge defects in power equipment. Summary of the Invention

[0005] To address the problem that existing built-in UHF partial discharge online monitoring systems have blind spots in the detection and location of partial discharge defects in some terminal outgoing areas of power equipment, potentially leading to missed or misjudged defects, this invention provides a method for locating partial discharge defects in power equipment within UHF online monitoring blind spots. This method utilizes a combination of built-in UHF sensors, external UHF sensors at different locations, and external ultrasonic sensors for joint detection, location, and comprehensive analysis to accurately diagnose the location of partial discharge defects in UHF online monitoring blind spots such as terminal outgoing areas. The detection location of the external UHF sensors in this invention fully considers the effectiveness of diagnostic location and the safety of live detection, making it feasible and operable in the field.

[0006] This invention is achieved through the following technical solution:

[0007] A method for locating partial discharge defects in power equipment in ultra-high frequency online monitoring blind zones includes:

[0008] When the defect location triggering condition is met, the signal collected by the first UHF sensor placed on the joint between the outgoing bushing and the power equipment tank and the signal collected by the pre-built UHF sensor at the far end are subjected to homology analysis to obtain the signal homology analysis results.

[0009] Based on the signal homology analysis results, and combined with the signals collected by the ultrasonic sensor placed on the outer surface of the equipment, the discharge defect is located, and the partial discharge defect location results of the power equipment are obtained.

[0010] The signal collected by the second UHF sensor externally placed on the outgoing frame above the bushing is used to optimize the partial discharge defect location results of the power equipment, and the final partial discharge defect location results of the power equipment are obtained.

[0011] In one possible implementation, the defect location triggering condition includes: when the power equipment UHF online monitoring system detects an abnormal UHF signal, and the discharge power source is located outside the end of the built-in UHF sensor in the outgoing line direction.

[0012] In one possible implementation, when the defect location triggering condition is met, a source-origination analysis is performed on the signal collected by the first UHF sensor located at the junction of the outgoing bushing and the power equipment tank, and the signal collected by the pre-built UHF sensor at the far end, to obtain the signal source-origination analysis results, including:

[0013] When the defect location triggering condition is met, a first UHF sensor externally mounted on the joint between the outgoing bushing and the power equipment tank is used to collect a signal and obtain a first UHF signal acquisition result; the first UHF signal acquisition result includes whether the initial UHF signal was acquired or not.

[0014] When the first UHF signal acquisition result is that an initial UHF signal has been acquired, the initial UHF signal is acquired by the pre-built UHF sensor at the far end, and the initial UHF signal acquired by the built-in UHF sensor is jointly analyzed with the initial UHF signal acquired by the first UHF sensor to obtain the signal homology analysis result; the signal homology analysis result is either homologous or dissimilar.

[0015] In one possible implementation, the initial UHF signal acquired by the terminal built-in UHF sensor is jointly analyzed with the initial UHF signal acquired by the first UHF sensor to obtain signal homology analysis results, including:

[0016] The discharge pulse situation of the two initial UHF signals collected simultaneously by the last built-in UHF sensor and the first UHF sensor is compared one by one within 5 power frequency cycles, i.e., 100ms time period. It is determined whether the discharge pulse of the two signals appears in each half cycle of each power frequency cycle or in the same half cycle of each power frequency cycle. If so, the pulse similarity is obtained; otherwise, the signal homology analysis result is determined to be different sources.

[0017] Obtain the pulse similarity ρ of the two sets of signals within a time interval of 5 power frequency cycles, i.e., 100ms. xy And determine the pulse similarity ρ xy If the signal origin is greater than a preset threshold, the signal origin analysis result is determined to be from the same source; otherwise, the signal origin analysis result is determined to be from different sources.

[0018] In one possible implementation, the pulse similarity ρ between the two sets of signals is obtained over a time period of 5 power frequency cycles, i.e., 100ms. xy for:

[0019]

[0020] Where, n represents the total number of signal windows divided on average over 5 power frequency cycles, x i y represents the initial UHF signal acquired by the built-in UHF sensor at the very end of the i-th window. i This represents the initial UHF signal acquired by the external first UHF sensor in the i-th window.

[0021] In one possible implementation, based on the signal homology analysis results, and combined with signals collected by an ultrasonic sensor externally placed on the outer surface of the equipment, the discharge defect is located to obtain the partial discharge defect location result of the power equipment, including:

[0022] When the first UHF signal acquisition result is that no initial UHF signal was acquired or the signal homology analysis result is that they are from different sources, the ultrasonic signal acquisition result is obtained by acquiring the signal through an ultrasonic sensor on the outer surface of the equipment between the UHF sensor at the end and the junction of the sleeve and the power equipment tank; the ultrasonic signal acquisition result includes whether an ultrasonic signal was acquired or not.

[0023] When the ultrasonic signal acquisition result is that no ultrasonic signal is acquired, the partial discharge defect location result of the power equipment is determined to be that the discharge source is located at the very end of the power equipment, between the built-in ultra-high frequency sensor and the junction of the bushing and the power equipment tank.

[0024] When the ultrasonic signal acquisition result is that an ultrasonic signal has been acquired, the position of the ultrasonic sensor is changed so that the arrival time delay between the initial UHF signal acquired by the built-in UHF sensor and the ultrasonic signal acquired by the ultrasonic sensor is minimized. Then, the location result of the partial discharge defect of the power equipment is determined to be the location of the ultrasonic sensor.

[0025] When the signal homology analysis result is homology, the shortest path along the power equipment between the last built-in UHF sensor and the first UHF sensor is obtained. Based on the signal arrival delay between the last built-in UHF sensor and the first UHF sensor and the shortest path, the partial discharge defect location result of the power equipment is obtained as being located between the last built-in UHF sensor and the junction of the bushing and the power equipment tank, or located outside the junction of the bushing and the power equipment tank in the outgoing direction.

[0026] In one possible implementation, based on the signal arrival delay between the last built-in UHF sensor and the first UHF sensor and the shortest path, the partial discharge defect location result of the power equipment is obtained as being located between the last built-in UHF sensor and the junction of the bushing and the power equipment tank, or located outside the junction of the bushing and the power equipment tank in the outgoing direction, including:

[0027] Based on the signal arrival delay between the last built-in UHF sensor and the first UHF sensor, and the shortest path, the distance x between the discharge power source and the last built-in UHF sensor is calculated.

[0028] If the calculation result is 0≤x<L, the location result of the partial discharge defect of the power equipment is determined to be between the end of the built-in UHF sensor and the junction of the bushing and the power equipment tank, and the distance from the end of the built-in UHF sensor is x.

[0029] If the calculation result x = L, the location result of the partial discharge defect in the power equipment is determined to be located outside the junction of the bushing and the power equipment tank in the direction of the outgoing line.

[0030] In one possible implementation, the distance x is:

[0031] |L-2x|=c×Δt

[0032] Where Δt represents the time delay for the abnormal UHF signal to reach the end-end built-in UHF sensor and the first UHF sensor, c represents the propagation speed of the partial discharge UHF electromagnetic wave, and L represents the shortest path between the end-end built-in UHF sensor and the external first UHF sensor.

[0033] In one possible implementation, the partial discharge defect location results of the power equipment are optimized using a second UHF sensor externally positioned on the outgoing line frame above the bushing to obtain the final partial discharge defect location results, including:

[0034] When the partial discharge defect location result of the power equipment is outside the junction of the bushing and the power equipment tank in the direction of the outgoing line, the signal is collected by the second UHF sensor placed on the outgoing line frame above the bushing, and the second UHF signal acquisition result is obtained; the second UHF signal acquisition result is either an abnormal UHF signal is collected or no abnormal UHF signal is collected;

[0035] When the second UHF signal acquisition result is that an abnormal UHF signal is acquired, the last built-in UHF sensor and the external second UHF sensor are connected along the power equipment and outgoing line in the shortest path. Based on the arrival time delay of the abnormal UHF signal, the location of the discharge source is obtained, and the partial discharge defect location result of the power equipment is obtained.

[0036] When the second UHF signal acquisition result is that no abnormal UHF signal is acquired, the result of the partial discharge defect location of the power equipment is determined to be that the discharge source is located inside the bushing.

[0037] In one possible implementation, the second UHF sensor wirelessly transmits the collected UHF signals.

[0038] This invention provides a method for locating partial discharge defects in power equipment within the blind zone of UHF online monitoring. It overcomes the shortcomings of existing built-in UHF online partial discharge monitoring systems that have blind zones for partial discharge detection and location in some terminal outgoing areas of power equipment. This method effectively reduces the possibility of missed or misjudged partial discharge defects within the equipment, improving the comprehensive detection and diagnosis capabilities for partial discharge defects in power equipment. It can effectively diagnose abnormal UHF signals detected by the built-in UHF sensor at the very end of the equipment using a relatively safe and simple operation process, calculation process, and low-cost hardware device. It determines whether partial discharge defects exist within the UHF online monitoring blind zone of the power equipment. Under suitable conditions, it can accurately locate the partial discharge defect and accurately assess the partial discharge status and health condition of the power equipment. Attached Figure Description

[0039] 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:

[0040] Figure 1 This is a flowchart of a method for locating partial discharge defects in power equipment in the blind zone of ultra-high frequency online monitoring, as described in this invention.

[0041] Figure 2(a) is a schematic diagram of the arrangement of the built-in UHF sensor and the external first UHF sensor at the end of the 500kV GIS provided in the embodiment of the present invention.

[0042] Figure 2(b) is a schematic diagram of the simultaneous acquisition of 500kV GIS UHF signals by the end-most built-in UHF sensor and the external first UHF sensor provided in the embodiment of the present invention.

[0043] Figure 3(a) is a schematic diagram of the arrangement of the built-in UHF sensor and the external second UHF sensor at the end of the 500kV GIS provided in the embodiment of the present invention.

[0044] Figure 3(b) is a schematic diagram of the simultaneous acquisition of 500kV GIS UHF signals by the built-in UHF sensor and the external second UHF sensor at the far end provided in the embodiment of the present invention.

[0045] Figure 4 The 500kV GIS outgoing line corona discharge power supply obtained by precise positioning is provided in the embodiments of the present invention. Detailed Implementation

[0046] 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.

[0047] like Figure 1 As shown, this embodiment of the invention provides a method for locating partial discharge defects in power equipment in the blind zone of ultra-high frequency online monitoring, including:

[0048] S1. If the UHF online monitoring system for power equipment detects an abnormal UHF signal and the discharge source is located outside the end of the built-in UHF sensor in the direction of the outgoing line, fix the external first UHF sensor at the junction of the outgoing bushing and the power equipment tank to collect the initial UHF signal. If an abnormal UHF signal is collected, proceed to S2. Otherwise, determine that the discharge source is located inside the power equipment between the end of the built-in UHF sensor and the junction of the bushing and the power equipment tank, and proceed to S3.

[0049] In S1, the external first UHF sensor is fixed at the junction of the outgoing bushing and the power equipment tank to collect the initial UHF signal. This ensures that the UHF electromagnetic waves excited by partial discharge are not shielded by the metal tank of the power equipment and are radiated from the bottom of the bushing so that they can be detected by the sensor. However, considering the safety distance, the external first UHF sensor cannot be arranged along the bushing towards the top of the bushing.

[0050] Outgoing bushings are components in electrical equipment that allow high-voltage conductors to be led out and insulate the external high-voltage conductors from the equipment tank. Common types of outgoing bushings include transformer bushings and GIS bushings.

[0051] Built-in UHF sensors are often attached to the tank of power equipment and installed inside the equipment. The last built-in UHF sensor along a certain direction outward from the equipment tank is called the "last external UHF sensor". It is usually arranged inside the equipment tank next to the outgoing bushing.

[0052] A power equipment tank is a grounded metal tank that completely encloses the high-voltage and insulation parts inside the equipment. Common examples include transformer metal tanks, GIS metal tanks, etc. However, it should be noted that this is only an example and not a specific equipment limitation. S2: Compare the initial UHF signal collected by the built-in UHF sensor at the far end with the initial UHF signal collected by the external first UHF sensor to determine whether the initial UHF signal collected by the built-in UHF sensor at the far end and the initial UHF signal collected by the external first UHF sensor are from the same source. If yes, proceed to S5; otherwise, determine that the discharge source is located between the built-in UHF sensor at the far end inside the power equipment and the junction of the bushing and the power equipment tank, and proceed to S3.

[0053] The specific steps are as follows:

[0054] S2.1 Compare the discharge pulse situation one by one within 5 power frequency cycles, i.e., 100ms time period, using the two initial UHF signals simultaneously collected by the built-in UHF sensor at the far end and the external first UHF sensor.

[0055] S2.2 If the discharge pulses of the two sets of signals appear in each half-cycle of each power frequency cycle or in the same half-cycle of each power frequency cycle, it is determined that the frequency correlation of the two sets of initial UHF signals is the same, and the process jumps to S2.3; otherwise, it is determined that the two sets of initial UHF signals are not from the same source.

[0056] S2.3 Calculate the pulse similarity ρ of the two sets of signals within a time interval of 5 power frequency cycles, i.e., 100ms. xy .

[0057] The pulse similarity

[0058] Among them, the average total number of signal windows divided over 5 power frequency cycles is n = 100000, x i The initial UHF signal, y, is collected by the UHF sensor built into the very end of the i-th window. i The initial UHF signal collected by the external first UHF sensor in the i-th window is set to "1" for all discharge pulse amplitudes to avoid interference from the propagation attenuation of abnormal UHF signals, based on the actual situation.

[0059] S2.4, Pulse similarity ρ between the two sets of signals xy If the calculation result exceeds 0.8, the two initial UHF signals are determined to be from the same source; otherwise, the two initial UHF signals are determined to be from different sources.

[0060] S3. Place the ultrasonic sensor detection surface close to the outer surface of the equipment between the end-end built-in UHF sensor and the junction of the sleeve and the power equipment tank to collect abnormal ultrasonic signals. If no abnormal ultrasonic signal can be collected, it is determined that the discharge power source is located inside the power equipment between the end-end built-in UHF sensor and the junction of the sleeve and the power equipment tank, and cannot be accurately located. If an abnormal ultrasonic signal is collected, proceed to S4.

[0061] The interior of electrical equipment refers to the inside of the electrical equipment tank, where the inaccessible parts of the equipment tank can be accessed without interrupting power.

[0062] Not all types of partial discharge can generate abnormal ultrasonic signals while simultaneously generating abnormal ultra-high frequency electromagnetic waves. Therefore, there are two possible outcomes for the implementation of S3.

[0063] S4. The initial UHF signal collected by the built-in UHF sensor at the far end is used to trigger the abnormal ultrasonic signal to obtain the arrival time delay of the abnormal UHF signal and the abnormal ultrasonic signal. The position of the ultrasonic sensor is continuously moved. When the arrival time delay of the abnormal UHF signal and the abnormal ultrasonic signal is minimized or even zero, the position of the ultrasonic sensor is the position of the discharge power supply, thus completing the precise positioning of the discharge power supply.

[0064] S5. Connect the last built-in UHF sensor and the first external UHF sensor along the shortest path along the power equipment. Calculate the discharge position based on the arrival delay of the abnormal UHF signal. If the calculated discharge position is located between the last built-in UHF sensor and the junction of the bushing and the power equipment tank, complete the precise positioning of the discharge. If the calculated discharge position is located outside the junction of the bushing and the power equipment tank in the outgoing direction, proceed to S6.

[0065] The specific steps are as follows:

[0066] S5.1 Use the initial UHF signal collected by the built-in UHF sensor at the far end to trigger the initial UHF signal collected by the external first UHF sensor, and read the arrival delay of the two sets of signals.

[0067] S5.2 Calculate the distance x between the discharge source and the built-in ultra-high frequency sensor at the far end, satisfying the following relationship:

[0068] |L-2x|=c×Δt

[0069] Where Δt is the time delay for the abnormal UHF signal to reach the terminal built-in UHF sensor and the external first UHF sensor, and c is the propagation speed of the partial discharge UHF electromagnetic wave (3×10⁻⁶). 8 m / s, where L is the distance between the built-in UHF sensor at the far end and the external first UHF sensor.

[0070] S5.3 If the calculation result 0≤x<L, determine that the distance between the discharge source and the end-end built-in UHF sensor inside the power equipment, between the bushing and the tank of the power equipment, is x.

[0071] S5.4 If the calculation result x = L, determine that the discharge source is located at the junction of the bushing and the power equipment tank or outside in the direction of the outgoing line.

[0072] The outgoing direction indicates that the exposed high-voltage conductor, i.e., the outlet line, extends outward from the bushing. Since the previous positioning has determined that the partial discharge source is located between the end of the bushing and the junction of the built-in UHF sensor and the power equipment tank, meaning this invention is situated in an online monitoring blind zone, x will not be less than zero and is therefore not considered.

[0073] As shown in Figures 2(a) and 2(b), the signal acquisition time delay of the built-in UHF sensor at the very end of the 500kV GIS outgoing branch pipe and the external first UHF sensor fixed at the junction of the outgoing bushing and the GIS tank is approximately 7ns. The signal arrives at the external first UHF sensor first. The shortest distance between the two sensors along the GIS tank is approximately 2.1 meters. It is calculated that the discharge power source is located at or outside the junction of the outgoing bushing and the GIS tank in the outgoing direction.

[0074] S6. Use a drone to fix the external second UHF sensor on the cable outlet frame above the bushing. If an abnormal UHF signal is collected, jump to S7. Otherwise, determine that the power supply is located inside the bushing and cannot be accurately located.

[0075] The external second UHF sensor wirelessly transmits the collected UHF signals.

[0076] The external second UHF sensor is fixed on the outgoing line frame above the bushing that is isolated from the outgoing line by the insulator string, so it will not cause discharge or breakdown. At the same time, in order to avoid the signal cable being too close to the high voltage conductor or even in contact, causing discharge or breakdown, the external second UHF sensor transmits the collected UHF signal to the outside wirelessly.

[0077] S7. Connect the built-in UHF sensor and the external second UHF sensor at the end along the shortest path along the power equipment and outgoing line. Calculate the location of the discharge source based on the arrival delay of the abnormal UHF signal. It can be determined whether the discharge source comes from inside the bushing or from the outgoing line corona discharge, thus obtaining the precise location of the discharge source.

[0078] As shown in Figures 3(a) and 3(b), the signal delay when simultaneously collected by the built-in UHF sensor at the very end of the 500kV GIS outgoing branch busbar and the external UHF sensor fixed above the bushing on the outgoing frame is approximately 9ns. The signal arrives at the external UHF sensor first. The straight-line distance between the two sensors along the outgoing line and the 500kV GIS tank is approximately 23.5 meters, of which the distance from the top of the outgoing bushing to the built-in UHF sensor at the very end is 8.5 meters. Calculations show that the distance from the discharge source to the built-in UHF sensor at the very end is approximately 13.1 meters. Figure 4 As shown, the power supply is located on the 500kV GIS outgoing line, not inside the GIS bushing.

[0079] 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 locating partial discharge defects in power equipment in blind zones of ultra-high frequency online monitoring, characterized in that, include: When the defect location triggering condition is met, the signals collected by the first UHF sensor placed on the joint between the outgoing bushing and the power equipment tank and the signals collected by the pre-built UHF sensor at the far end are subjected to homology analysis to obtain the signal homology analysis results; where the power equipment is GIS equipment; Based on the signal homology analysis results, and combined with the signals collected by the ultrasonic sensor placed on the outer surface of the power equipment, the discharge defect is located, and the partial discharge defect location result of the power equipment is obtained. The signal collected by the second ultra-high frequency sensor placed on the outgoing frame above the bushing is used to optimize the partial discharge defect location result of the power equipment and obtain the final partial discharge defect location result of the power equipment. The process of locating discharge defects based on signal homology analysis results, combined with signals collected by an ultrasonic sensor externally placed on the equipment's surface, yields the partial discharge defect location results for the power equipment, including: When the first UHF signal acquisition result is that no initial UHF signal was acquired or the signal homology analysis result is that they are from different sources, an ultrasonic sensor is used to acquire signals from the outer surface of the equipment between the sleeve and the junction of the sleeve and the power equipment tank, which is externally placed at the end of the built-in UHF sensor, to obtain the ultrasonic signal acquisition result; the ultrasonic signal acquisition result includes whether an ultrasonic signal was acquired or not. When the ultrasonic signal acquisition result is that no ultrasonic signal is acquired, the partial discharge defect location result of the power equipment is determined to be that the discharge source is located at the very end of the power equipment, between the built-in ultra-high frequency sensor and the junction of the bushing and the power equipment tank. When the ultrasonic signal acquisition result is that an ultrasonic signal has been acquired, the position of the ultrasonic sensor is changed so that the arrival time delay between the initial ultra-high frequency signal acquired by the built-in ultra-high frequency sensor at the far end and the ultrasonic signal acquired by the ultrasonic sensor is minimized. Then, the location result of the partial discharge defect of the power equipment is determined to be the location of the ultrasonic sensor. When the signal homology analysis result is homology, the shortest path along the power equipment between the last built-in UHF sensor and the first UHF sensor is obtained. Based on the signal arrival delay between the last built-in UHF sensor and the first UHF sensor and the shortest path, the partial discharge defect location result of the power equipment is obtained as being located between the last built-in UHF sensor and the junction of the bushing and the power equipment tank, or located outside the junction of the bushing and the power equipment tank in the outgoing direction.

2. The method for locating partial discharge defects in power equipment in the blind zone of UHF online monitoring according to claim 1, characterized in that, The defect location triggering conditions include: when the power equipment UHF online monitoring system detects an abnormal UHF signal, and the discharge power source is located outside the end of the built-in UHF sensor in the outgoing line direction.

3. The method for locating partial discharge defects in power equipment in the blind zone of UHF online monitoring according to claim 1, characterized in that, When the defect location triggering condition is met, a source-origination analysis is performed on the signal collected by the first UHF sensor located at the junction of the outgoing bushing and the power equipment tank, and the signal collected by the pre-built UHF sensor at the far end. The signal source-origination analysis results are obtained, including: When the defect location triggering condition is met, a first UHF sensor externally placed at the junction of the outgoing bushing and the power equipment tank collects a signal to obtain a first UHF signal acquisition result; the first UHF signal acquisition result includes whether the initial UHF signal was acquired or not. When the first UHF signal acquisition result is that an initial UHF signal has been acquired, the initial UHF signal is acquired by the pre-built UHF sensor at the far end, and the initial UHF signal acquired by the built-in UHF sensor is jointly analyzed with the initial UHF signal acquired by the first UHF sensor to obtain the signal homology analysis result; the signal homology analysis result is either homologous or dissimilar.

4. The method for locating partial discharge defects in power equipment in the blind zone of UHF online monitoring according to claim 3, characterized in that, The initial UHF signal acquired by the last built-in UHF sensor is jointly analyzed with the initial UHF signal acquired by the first UHF sensor to obtain the signal homology analysis results, including: The discharge pulse situation of the two initial UHF signals collected simultaneously by the last built-in UHF sensor and the first UHF sensor is compared one by one within 5 power frequency cycles, i.e., 100ms time period. It is determined whether the discharge pulse of the two signals appears in each half cycle of each power frequency cycle or in the same half cycle of each power frequency cycle. If so, the pulse similarity is obtained; otherwise, the signal homology analysis result is determined to be different sources. Obtain the pulse similarity ρ of the two sets of signals within a time interval of 5 power frequency cycles, i.e., 100ms. xy And determine the pulse similarity ρ xy If the signal origin is greater than a preset threshold, the signal origin analysis result is determined to be from the same source; otherwise, the signal origin analysis result is determined to be from different sources.

5. The method for locating partial discharge defects in power equipment in the blind zone of UHF online monitoring according to claim 4, characterized in that, Obtain the pulse similarity ρ of the two sets of signals within a time interval of 5 power frequency cycles, i.e., 100ms. xy for: ； Where n represents the total number of signal windows divided on average over 5 power frequency cycles. This represents the initial UHF signal acquired by the built-in UHF sensor at the very end of the i-th window. This represents the initial UHF signal acquired by the external first UHF sensor in the i-th window.

6. The method for locating partial discharge defects in power equipment in the blind zone of UHF online monitoring according to claim 3, characterized in that, Based on the signal arrival time delay between the last built-in UHF sensor and the first UHF sensor, and the shortest path, the partial discharge defect location result of the power equipment is obtained as being located between the last built-in UHF sensor and the junction of the bushing and the power equipment tank, or located outside the junction of the bushing and the power equipment tank in the outgoing direction, including: Based on the signal arrival delay between the last built-in UHF sensor and the first UHF sensor, and the shortest path, the distance x between the discharge power source and the last built-in UHF sensor is calculated. If the calculation result is 0≤x<L, the location result of the partial discharge defect in the power equipment is determined to be between the end-end built-in UHF sensor and the junction of the bushing and the power equipment tank, and the distance between the end-end built-in UHF sensor and the end-end built-in UHF sensor is x; where L represents the shortest path between the end-end built-in UHF sensor and the external first UHF sensor. If the calculation result x=L, the location result of the partial discharge defect in the power equipment is determined to be located outside the junction of the bushing and the power equipment tank in the direction of the outgoing line.

7. The method for locating partial discharge defects in power equipment in the blind zone of UHF online monitoring according to claim 6, characterized in that, The distance x is: ； Where Δt represents the time delay for the abnormal UHF signal to reach the end-end built-in UHF sensor and the first UHF sensor, c represents the propagation speed of the partial discharge UHF electromagnetic wave, and L represents the shortest path between the end-end built-in UHF sensor and the external first UHF sensor.

8. The method for locating partial discharge defects in power equipment in the blind zone of ultra-high frequency online monitoring according to claim 3, characterized in that, The partial discharge defect location results of the power equipment are optimized by using a second UHF sensor externally placed on the outgoing frame above the bushing to obtain the final partial discharge defect location results, including: When the partial discharge defect location result of the power equipment is outside the junction of the bushing and the power equipment tank in the direction of the outgoing line, the signal is collected by the second UHF sensor placed on the outgoing line frame above the bushing, and the second UHF signal acquisition result is obtained; the second UHF signal acquisition result is either an abnormal UHF signal is collected or no abnormal UHF signal is collected; When the second UHF signal acquisition result is that an abnormal UHF signal is acquired, the last built-in UHF sensor and the external second UHF sensor are connected along the power equipment and outgoing line in the shortest path. Based on the arrival time delay of the abnormal UHF signal, the location of the discharge source is obtained, and the partial discharge defect location result of the power equipment is obtained. When the second UHF signal acquisition result is that no abnormal UHF signal is acquired, the result of the partial discharge defect location of the power equipment is determined to be that the discharge source is located inside the bushing.

9. The method for locating partial discharge defects in power equipment in the blind zone of UHF online monitoring according to claim 8, characterized in that, The second UHF sensor transmits the collected UHF signals wirelessly.

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