Cable joint partial discharge positioning method and system based on flexible electromagnetic sensor array

Abstract

The application provides a cable joint partial discharge positioning method and system based on a flexible electromagnetic sensor array, and relates to the technical field of cable joint partial discharge. The technical points of the application include: collecting a plurality of signal strengths measured by a plurality of sensing units arranged on the surface of the cable joint in real time; processing the plurality of signal strengths to detect and position the partial discharge position of the cable joint, including: calculating a plurality of distances between the partial discharge position and the plurality of sensing units; establishing a plurality of three-dimensional geometric distance equations according to the plurality of distances, solving the plurality of three-dimensional geometric distance equations, and obtaining the three-dimensional coordinates of the partial discharge position; further adopting a unit calibration and error compensation mechanism to correct the distances and the position of the partial discharge position. The flexible electromagnetic sensor can be non-invasively installed, combined with the partial discharge positioning algorithm, to realize high-precision spatial positioning of the partial discharge position and effectively eliminate the detection blind area.

Description

Technical Field

[0001] This invention relates to the field of partial discharge technology for cable joints, and specifically to a method and system for locating partial discharge in cable joints based on a flexible electromagnetic sensor array. Background Technology

[0002] Power cables, as a crucial carrier of electrical energy transmission, play an indispensable role in modern power grids. Medium and high voltage cables, in particular, are widely used in key areas such as urban power grids, large industrial and mining enterprises, new energy power generation grid connection, and inter-regional interconnection. Compared with overhead transmission lines, cable lines have significant advantages such as smaller footprint, higher transmission reliability, and less susceptibility to natural environmental influences. In cable lines, cable joints, as key components connecting cable sections to power equipment, are often the weakest link in the entire cable system due to their complex structure and demanding on-site manufacturing requirements. Cable joints are prone to increased contact resistance and localized overheating due to poor installation techniques, material aging, and uneven interface pressure, leading to decreased insulation performance and even breakdown faults. These defects can easily induce partial discharge under long-term operating voltage. Partial discharge is not only a direct sign of insulation degradation, but its continued development also further accelerates the aging of insulation materials, seriously threatening the operational safety of cable joints.

[0003] Currently, methods for detecting partial discharge in power equipment are mainly classified into three categories: electrical parameter measurement, acoustic methods, and optical methods. Electrical parameter measurement mainly includes pulse current method, high-frequency current transformer, and ultra-high frequency detection; acoustic methods mainly include ultrasonic sensor array detection; and optical methods mainly include ultraviolet imaging and fluorescence fiber optic sensing. Monitoring the condition of cable joints largely relies on non-electrical parameter methods. While these non-electrical parameter methods can detect partial discharge to some extent, they are generally susceptible to electromagnetic interference, lack sensitivity, and are difficult to pinpoint precisely. Among electrical parameter measurement methods, detection methods such as pulse current method are easily interfered with in complex electromagnetic environments and are difficult to spatially locate the discharge source.

[0004] Ultra-high frequency (UHF) detection is a method for diagnosing insulation defects by capturing ultra-high frequency electromagnetic wave signals radiated during partial discharge. Its main principle is as follows: When a partial discharge occurs due to an internal defect in electrical insulation equipment, the physical process is essentially the development of a transient charge avalanche or stagnant current process, often accompanied by a pulse current with a rise time on the order of nanoseconds. According to Maxwell's equations, this current pulse excites spectral components and abundant electromagnetic wave radiation. At this time, the UHF sensor detects the emitted electromagnetic wave signal and interacts with its resonant structure, inducing a high-frequency voltage signal at the sensor port. This process follows electromagnetic field theory and the principle of electromagnetic radiation.

[0005] In summary, how to achieve partial discharge localization of cable joints based on flexible electromagnetic sensor arrays is worth studying. Summary of the Invention

[0006] Therefore, this invention proposes a method and system for locating partial discharge of cable joints based on a flexible electromagnetic sensor array, in an attempt to solve or alleviate one or more of the above-mentioned problems.

[0007] According to one aspect of the present invention, a method for locating partial discharge of cable joints based on a flexible electromagnetic sensor array is proposed, the method comprising:

[0008] The signal strengths of multiple sensors deployed on the surface of the cable joint are collected in real time.

[0009] Based on the aforementioned signal strengths, the following processing is performed to detect and locate the partial discharge site of the cable joint:

[0010] The distances between the partial discharge site and the multiple sensing units are calculated based on multiple signal strengths and the calibrated inherent coefficients of the sensing units.

[0011] Multiple three-dimensional geometric distance equations are established based on the multiple distances and the planar coordinates of the multiple sensing units. The three-dimensional coordinates of the partial discharge location are obtained by solving the multiple three-dimensional geometric distance equations simultaneously.

[0012] Furthermore, the multiple sensing units deployed on the surface of the cable connector are a flexible electromagnetic sensor array arranged in a regular grid, and the sensing part of each flexible electromagnetic sensor has a hollow structure.

[0013] Furthermore, based on multiple signal strengths and the calibrated inherent coefficients of the sensing units, multiple distances between the partial discharge site and the multiple sensing units are calculated, including:

[0014] The intrinsic coefficients of multiple sensing units are calibrated to ensure consistency among them; this includes calculating the intrinsic coefficients of each sensing unit based on multiple standard electromagnetic wave signal sources using the following formula:

[0015] ;

[0016] In the formula, This represents the inherent coefficient of the i-th sensing unit; This represents the distance between the nth standard electromagnetic wave signal source and the ith sensing unit. This represents the signal strength of the nth standard electromagnetic wave signal source measured by the i-th sensing unit;

[0017] The inherent coefficients of each sensing unit are determined based on interpolation. By performing a fitting process, the calibrated intrinsic coefficient K of the sensing unit is obtained;

[0018] Based on multiple signal strengths and the calibrated inherent coefficients of the sensing units, the distances between the partial discharge sites and the multiple sensing units are calculated using the following formula:

[0019] ;

[0020] In the formula, This represents the distance between the partial discharge site and the i-th sensing unit; This represents the signal strength measured by the i-th sensing unit.

[0021] Furthermore, the three-dimensional geometric distance equation is:

[0022] ;

[0023] In the formula, Represents the planar coordinates of the i-th sensing unit; Represents the three-dimensional coordinates of the partial discharge site.

[0024] Furthermore, the method further includes: after obtaining the three-dimensional coordinates of the partial discharge site, obtaining a linear correction coefficient based on the directional gain function corresponding to each sensing unit, and then correcting multiple distances between the partial discharge site and multiple sensing units based on the linear correction coefficient to obtain multiple corrected distances; substituting the multiple corrected distances into multiple three-dimensional geometric distance equations, and then solving them simultaneously to obtain the corrected three-dimensional coordinates of the partial discharge site.

[0025] Furthermore, the linear correction coefficients are obtained based on the directional gain function corresponding to each sensing unit, including: measuring the azimuth angle of each sensing unit in advance in a microwave anechoic chamber at different azimuth angles. The receiving gain below and the receiving gain of each sensing unit. A fitting process is performed to obtain the directional gain function corresponding to each sensing unit; for each sensing unit, the corresponding azimuth angle is calculated based on its planar coordinates and the three-dimensional coordinates of the partial discharge site. ; azimuth angle Substituting into the already determined directional gain function, we obtain the corresponding directional gain. The linear correction coefficient is then calculated using the following formula. : .

[0026] Furthermore, the distance of the i-th sensing unit after correction is expressed as: .

[0027] Furthermore, the method further includes: after obtaining the corrected multiple distances, using a trained deep learning-based partial discharge detection model to correct the three-dimensional coordinates of the partial discharge site; the input of the partial discharge detection model includes multiple signal intensities measured by multiple sensing units, the planar coordinates of multiple sensing units, the corrected multiple distances, multiple azimuth angles, and an SDP time-series image generated by polar coordinate mapping of multiple consecutive frames of signal intensity time-series signals; the output is the corrected three-dimensional coordinates of the partial discharge site.

[0028] Furthermore, each flexible electromagnetic sensor operates in the 0.06 GHz to 0.64 GHz frequency band and has directional radiation characteristics, with the maximum receiving sensitivity direction of each flexible electromagnetic sensor perpendicular to the substrate plane.

[0029] According to another aspect of the present invention, a partial discharge location system for cable joints based on a flexible electromagnetic sensor array is proposed. The system is implemented based on the aforementioned partial discharge location method for cable joints based on a flexible electromagnetic sensor array; the system includes:

[0030] The signal strength acquisition module is configured to acquire in real time multiple signal strengths measured by multiple sensing units deployed on the surface of the cable joint.

[0031] The detection and positioning module is configured to perform the following processing based on the multiple signal strengths to detect and locate the partial discharge location of the cable joint: calculate multiple distances between the partial discharge location and the multiple sensing units based on the multiple signal strengths and the calibrated inherent coefficients of the sensing units; establish multiple three-dimensional geometric distance equations based on the multiple distances and the planar coordinates of the multiple sensing units; and solve the multiple three-dimensional geometric distance equations simultaneously to obtain the three-dimensional coordinates of the partial discharge location.

[0032] The positioning correction module is configured to, after obtaining the three-dimensional coordinates of the partial discharge site, obtain a linear correction coefficient based on the directional gain function corresponding to each sensing unit, and then correct multiple distances between the partial discharge site and multiple sensing units based on the linear correction coefficients to obtain multiple corrected distances; substitute the multiple corrected distances into multiple three-dimensional geometric distance equations, and then solve them simultaneously to obtain the corrected three-dimensional coordinates of the partial discharge site.

[0033] The beneficial technical effects of this invention are:

[0034] This invention proposes a method and system for locating partial discharge in cable joints based on a flexible electromagnetic sensor array, which has the following advantages:

[0035] 1) The flexible electromagnetic sensor fits tightly to the surface of the irregular cable joint, enabling non-invasive installation and solving the problem of traditional sensors being bulky and difficult to deploy; the flexible electromagnetic sensor operates in the ultra-high frequency band and is directional, which can effectively couple partial discharge signals and suppress low frequency interference, significantly improving the signal-to-noise ratio and reliability.

[0036] 2) A high-density array of miniature flexible electromagnetic sensors is used, combined with a partial discharge localization algorithm, to achieve high-precision spatial positioning of the partial discharge location and effectively eliminate detection blind spots. The partial discharge localization algorithm uses a unit calibration and error compensation mechanism to correct the distance measurement value, thereby correcting the position of the partial discharge location, reducing the influence of multipath effect and field strength distortion, and improving positioning accuracy and robustness. Attached Figure Description

[0037] The present invention can be better understood by referring to the description given below in conjunction with the accompanying drawings, which together with the following detailed description are included in and form part of this specification, and are used to further illustrate preferred embodiments of the invention and explain the principles and advantages of the invention.

[0038] Figure 1 This is a flowchart of the partial discharge location method for cable joints based on a flexible electromagnetic sensor array, as described in an embodiment of the present invention.

[0039] Figure 2 This is a schematic diagram of the flexible electromagnetic sensor array structure in an embodiment of the present invention;

[0040] Figure 3 This is an example of the simulation results of the voltage standing wave ratio of the flexible electromagnetic sensor in this embodiment of the invention;

[0041] Figure 4 This is an example of the radiation pattern characteristics of the flexible electromagnetic sensor at a center frequency of 0.34 GHz in an embodiment of the present invention;

[0042] Figure 5 This is a schematic diagram of the partial discharge location system for cable joints based on a flexible electromagnetic sensor array, as described in an embodiment of the present invention. Detailed Implementation

[0043] To enable those skilled in the art to better understand the present invention, exemplary embodiments or examples of the present invention will be described below in conjunction with the accompanying drawings. Obviously, the described embodiments or examples are merely some, not all, of the embodiments or examples of the present invention. All other embodiments or examples obtained by those skilled in the art based on the embodiments or examples of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0044] This invention proposes a method and system for locating partial discharge in cable joints based on a flexible electromagnetic sensor array, which can be used to locate and detect partial discharge sources in cable joints.

[0045] This invention proposes a method for locating partial discharge of cable joints based on a flexible electromagnetic sensor array, such as... Figure 1 As shown, the method includes:

[0046] S1. Real-time acquisition of multiple signal strengths measured by multiple sensing units deployed on the surface of the cable joint;

[0047] S2. Based on the multiple signal strengths, the following processing is performed to detect and locate the partial discharge location of the cable joint:

[0048] S21. Calculate the distances between the partial discharge location and the multiple sensing units based on multiple signal strengths and the calibrated inherent coefficients of the sensing units.

[0049] S22. Based on the multiple distances and the planar coordinates of the multiple sensing units, establish multiple three-dimensional geometric distance equations, solve the multiple three-dimensional geometric distance equations simultaneously, and obtain the three-dimensional coordinates of the partial discharge location.

[0050] S3. After obtaining the three-dimensional coordinates of the partial discharge site, a linear correction coefficient is obtained based on the directional gain function corresponding to each sensing unit. Then, based on the linear correction coefficient, multiple distances between the partial discharge site and multiple sensing units are corrected to obtain multiple corrected distances. The multiple corrected distances are substituted into multiple three-dimensional geometric distance equations, and then the corrected three-dimensional coordinates of the partial discharge site are obtained by solving them simultaneously.

[0051] The method begins with S1, which collects in real time the signal strengths of multiple sensing units deployed on the surface of the cable connector.

[0052] According to an embodiment of the present invention, multiple sensing units (flexible electromagnetic sensors) are deployed in an array on the surface of a cable connector, wherein the multiple flexible electromagnetic sensors in the array are arranged in a regular grid. This sensor array can receive ultra-high frequency signals radiated by partial discharge. Figure 2This example illustrates a sensor array consisting of 10 sensing units, where the sensing portion of each flexible electromagnetic sensor is a hollow structure. Utilizing the geometric symmetry and uniform spatial structure of circular or square hollow areas, the measurement errors of signal strength caused by multipath effects and field strength distortion can be reduced. It can normalize the chaotic interference patterns of multipath signals into a regular state, weakening amplitude fluctuations after superposition. Simultaneously, it "smooths out" the distorted field strength in non-uniform propagation environments, making it approach the uniform attenuation characteristics of spherical waves, allowing the signal strength to more accurately reflect the discharge distance. Furthermore, it ensures that each sensing unit is in a consistent electromagnetic environment, avoiding measurement deviation differences and error accumulation caused by local field strength anomalies. Moreover, it filters out stray electromagnetic modes such as higher harmonics through resonance characteristics, resulting in a purer sensor signal. Ultimately, by optimizing the electromagnetic propagation environment, signal strength distortion is reduced, improving positioning accuracy.

[0053] In this embodiment, preferably, the sensor array operates in the 0.06 GHz to 0.64 GHz frequency band, has directional radiation characteristics, and its maximum receiving sensitivity direction is perpendicular to the substrate plane.

[0054] Specifically, using full-wave electromagnetic field simulation software, a detailed voltage standing wave ratio (VSWR) analysis was performed on the flexible electromagnetic sensor encapsulated in polyethylene dielectric. The corresponding simulation results are as follows: Figure 3 As shown in the figure. The analysis results show that when the sensing unit operates in a polyethylene dielectric environment, its effective operating frequency range covers 0.06 GHz to 0.64 GHz. This frequency band can fully cover the partial discharge electromagnetic wave signals excited by typical insulation defects in cable joints, confirming the applicability of the sensor design from the frequency domain characteristics. Figure 4 The radiation pattern characteristics of the flexible electromagnetic sensor at a center frequency of 0.34 GHz are demonstrated. In the E-plane (electric field plane), the sensor achieves a maximum gain of -46.05 dB in the polyethylene medium; while in the H-plane (magnetic field plane), its gain stabilizes at approximately -18 dB. A closer look at the E-plane radiation pattern reveals a classic figure-eight distribution, which closely matches theoretical expectations, reflecting the sensor's excellent directional radiation characteristics. Combined analysis of the E-plane and H-plane radiation patterns shows that the flexible electromagnetic sensor possesses significant directionality. Its maximum receiving sensitivity is concentrated in the front direction of the sensing unit, enabling efficient coupling of electromagnetic energy from potential discharge points in cable joints. This directional receiving mode effectively focuses on critical areas of the joint, improving the signal-to-noise ratio and accurately locating the discharge source, perfectly meeting the core requirements of sensor directionality and sensitivity for partial discharge detection in cable joints.

[0055] Then, S2 is executed, and the following processing is performed based on the multiple signal strengths to detect and locate the partial discharge part of the cable joint: S21, multiple distances between the partial discharge part and the multiple sensing units are calculated based on the multiple signal strengths and the calibrated sensing unit inherent coefficients; S22, multiple three-dimensional geometric distance equations are established based on the multiple distances and the planar coordinates of the multiple sensing units, and the multiple three-dimensional geometric distance equations are solved simultaneously to obtain the three-dimensional coordinates of the partial discharge part.

[0056] According to an embodiment of the present invention, firstly, the intrinsic coefficients of multiple sensing units are calibrated to make the intrinsic coefficients of each sensing unit tend to be consistent; this includes: calculating the intrinsic coefficients of each sensing unit according to the following formula based on multiple standard electromagnetic wave signal sources with different distances and known coordinates and signal strengths. :

[0057] ;

[0058] In the formula, The sensing element inherent coefficient of the i-th sensing element is determined by structural parameters such as substrate thickness h and conduction band spacing g. This represents the distance between the nth standard electromagnetic wave signal source and the ith sensing unit. This represents the signal strength of the nth standard electromagnetic wave signal source measured by the i-th sensing unit.

[0059] Then, the element intrinsic coefficients of each sensing unit are calculated based on the interpolation method. By performing a fitting process, the calibrated intrinsic coefficients K are obtained.

[0060] Then, when the local power supply radiates electromagnetic waves in space, the signal strength measured by each sensing unit is: By combining the inherent coefficient K obtained from calibration, the distance from the partial discharge source to the i-th sensing unit can be calculated. :

[0061] ;

[0062] Then, using the three-dimensional geometric distance formula, the three-dimensional geometric distance equations corresponding to each sensing unit are solved simultaneously, the z-term is eliminated, and the three-dimensional coordinates of the partial discharge source are obtained. For any two sensing units i and j, the three-dimensional geometric distance equation is expressed as:

[0063] ;

[0064] ;

[0065] In the formula, , Let represent the coordinates of the i-th sensing unit and the j-th sensing unit, respectively.

[0066] Then, S3 is executed. After obtaining the three-dimensional coordinates of the partial discharge site, a linear correction coefficient is obtained based on the directional gain function corresponding to each sensing unit. Then, based on the linear correction coefficient, multiple distances between the partial discharge site and multiple sensing units are corrected to obtain multiple corrected distances. The multiple corrected distances are substituted into multiple three-dimensional geometric distance equations, and then the corrected three-dimensional coordinates of the partial discharge site are obtained by solving them simultaneously.

[0067] According to an embodiment of the present invention, in order to improve positioning accuracy, an error compensation mechanism is further introduced. That is, by combining the directional gain characteristics of the elliptical radiating surface A2, the direction coefficient of the signal strength measurement values ​​at different azimuth angles is corrected to ensure distance accuracy. The calculations are more closely aligned with actual propagation scenarios. The specific steps are as follows:

[0068] First, the measurements of each sensor unit at different azimuth angles were taken in advance in a microwave anechoic chamber. The receiving gain below and the receiving gain of each sensor unit. By performing a fitting, the directional gain function corresponding to the sensor unit is obtained. ;

[0069] Then, calculate the real-time azimuth angle. For the i-th sensing unit (i≤10), based on its coordinates and the coordinates of the partial discharge power source The azimuth angle is obtained according to the following formula. :

[0070] ;

[0071] Then, the azimuth angle Substitute the already determined directional gain function In this process, the corresponding directional gain is obtained. The linear correction coefficient is obtained according to the following formula. : ;

[0072] Then, the signal strength measured by each sensing unit By inversely eliminating the influence of directional gain, we obtain Then, substituting into the distance formula, we obtain the corrected distance. : ;

[0073] Then, Substitute the three-dimensional geometric distance equations corresponding to each sensing unit into the equations, eliminate the z-term, and solve to obtain the corrected three-dimensional coordinates of the local discharge source.

[0074] Furthermore, to counteract the residual nonlinear field strength distortion, minor sensor deviations, and multipath low-frequency interference that still exist after traditional correction, S4 is included after S3. After obtaining multiple corrected distances, a deep learning-based partial discharge detection model is constructed and trained. The trained partial discharge detection model is used to correct the three-dimensional coordinates of the partial discharge location. The input of the partial discharge detection model includes multiple signal intensities measured by multiple sensing units, the planar coordinates of multiple sensing units, multiple corrected distances, multiple azimuth angles, and an SDP time-series image generated by polar coordinate mapping of multiple consecutive frames of signal intensity time-series signals. The output is the corrected three-dimensional coordinates of the partial discharge location.

[0075] According to an embodiment of the present invention, a lightweight deep learning model with multimodal feature fusion is used to construct a partial discharge detection model, so as to accurately correct the location of the partial discharge source using the trained partial discharge detection model.

[0076] The input layer of the partial discharge detection model is used to receive input numerical data and image data; the numerical data includes multiple signal intensities corresponding to the sensing unit after homogenization compensation by a square hollow area. Multiple correction distances after direction coefficient correction Multiple azimuth angles and multiple coordinate information of the sensing unit The image data is an SDP time-series image, which is composed of signal strength. The sequential signals of multiple consecutive frames are generated by polar coordinate mapping and used to capture the spatial texture patterns of multipath residues and field strength distortion.

[0077] The feature extraction layer of the partial discharge detection model is used to extract features from numerical and image data. This includes: using a 3-layer Deep Belief Network (DBN) to extract numerical features corresponding to the numerical data. This network has a 50-dimensional input layer and 64, 32, and 16 hidden layer nodes respectively. Nonlinear residual error correlation features are extracted using the ReLU activation function, adapting to application scenarios with limited field measurement sample sizes. A simplified version of MobileNetV2 lightweight convolutional neural network is used to extract image features from the image data. This network uses 3 layers of depthwise separable convolution, batch normalization, and ReLU activation processing, and outputs 32-dimensional quantized features through global average pooling to reduce computational load and meet the needs of real-time field monitoring.

[0078] The feature fusion layer of the partial discharge detection model uses a multi-head self-attention structure to concatenate 16-dimensional numerical features with 32-dimensional image features to obtain a 48-dimensional feature vector, and dynamically allocates cross-modal feature weights to adaptively increase the contribution ratio of image features in strong interference scenarios.

[0079] The output layer of the partial discharge detection model consists of two fully connected layers and a Dropout layer. It sequentially passes through 48→32-dimensional ReLU activation mapping, Dropout regularization to suppress overfitting, and 32→16-dimensional ReLU activation mapping. Finally, it outputs the corrected three-dimensional coordinates of the partial discharge source through 16→3-dimensional linear activation.

[0080] In this embodiment, the training dataset for the model training phase consists of 70% simulated samples and 30% measured samples. The simulated samples are generated by simulation software and cover different discharge source locations, interference intensities, and sensor deviation scenarios. The measured samples are partial discharge data of different defect types collected on-site. The diversity of samples can be expanded by adding Gaussian noise to numerical features and data enhancement by rotating and scaling image features. The model parameters are iteratively optimized using the mean square error (MSE) loss function to obtain a trained partial discharge detection model. The trained partial discharge detection model is then used to improve the accuracy of partial discharge location of cable joints.

[0081] This invention achieves sensor miniaturization and high integration, overcoming the shortcomings of bulky and difficult-to-install sensors, reducing sensor size and improving portability; it also increases sensor deployment density and spatial resolution, eliminates detection blind spots, and achieves precise localization of partial discharge signals. This invention is applicable to the detection and localization of partial discharge in cable joints, and its core applications include real-time status monitoring of key components such as urban power grid cable joints, power supply hubs in large industrial and mining enterprises, and grid connection points of new energy power plants. Leveraging its planar design and integrated widescreen response, this invention can be non-invasively installed on the surface of cable joints, achieving high-sensitivity sensing and spatial localization of ultra-high frequency electromagnetic wave signals radiated by partial discharge.

[0082] Another embodiment of the present invention proposes a partial discharge location system for cable joints based on a flexible electromagnetic sensor array. The system is implemented based on the partial discharge location method for cable joints based on a flexible electromagnetic sensor array described in the above embodiment. Figure 5 As shown, the system includes:

[0083] The signal strength acquisition module 510 is configured to acquire in real time multiple signal strengths measured by multiple sensing units deployed on the surface of the cable joint.

[0084] The detection and positioning module 520 is configured to perform the following processing based on multiple signal strengths to detect and locate the partial discharge part of the cable joint: calculate multiple distances between the partial discharge part and multiple sensing units based on multiple signal strengths and the calibrated inherent coefficients of the sensing units; establish multiple three-dimensional geometric distance equations based on the multiple distances and the planar coordinates of the multiple sensing units; and solve the multiple three-dimensional geometric distance equations simultaneously to obtain the three-dimensional coordinates of the partial discharge part.

[0085] The positioning correction module 530 is configured to, after obtaining the three-dimensional coordinates of the partial discharge site, obtain a linear correction coefficient based on the directional gain function corresponding to each sensing unit, and then correct multiple distances between the partial discharge site and multiple sensing units based on the linear correction coefficients to obtain multiple corrected distances; substitute the multiple corrected distances into multiple three-dimensional geometric distance equations, and then solve them simultaneously to obtain the corrected three-dimensional coordinates of the partial discharge site.

[0086] The function of the cable joint partial discharge location system based on a flexible electromagnetic sensor array described in this embodiment of the invention can be explained by the aforementioned cable joint partial discharge location method based on a flexible electromagnetic sensor array. Therefore, for the parts not described in detail in the system embodiment, please refer to the above method embodiment, and they will not be repeated here.

[0087] Although the invention has been described with respect to a limited number of embodiments, those skilled in the art will understand from the foregoing description that other embodiments are conceivable within the scope of the invention described herein. The disclosure of the invention is illustrative and not restrictive, and the scope of the invention is defined by the appended claims.

Claims

1. A method for locating partial discharge of cable joints based on a flexible electromagnetic sensor array, characterized in that, include: The signal strengths of multiple sensors deployed on the surface of the cable joint are collected in real time. Based on the aforementioned signal strengths, the following processing is performed to detect and locate the partial discharge site of the cable joint: The distances between the partial discharge site and the multiple sensing units are calculated based on multiple signal strengths and the calibrated inherent coefficients of the sensing units. Based on the multiple distances and the planar coordinates of the multiple sensing units, multiple three-dimensional geometric distance equations are established. The multiple three-dimensional geometric distance equations are solved simultaneously to obtain the three-dimensional coordinates of the partial discharge location. The linear correction coefficient is obtained based on the directional gain function corresponding to each sensing unit. Then, the multiple distances between the partial discharge part and multiple sensing units are corrected based on the linear correction coefficient to obtain the corrected multiple distances. Substituting the corrected distances into multiple three-dimensional geometric distance equations, and then solving them simultaneously, the corrected three-dimensional coordinates of the partial discharge location are obtained. The linear correction coefficients, derived from the directional gain function of each sensing unit, include: pre-measuring each sensing unit at different azimuth angles in a microwave anechoic chamber. The receiving gain below and the receiving gain of each sensing unit. A fitting process is performed to obtain the directional gain function corresponding to each sensing unit; for each sensing unit, the corresponding azimuth angle is calculated based on its planar coordinates and the three-dimensional coordinates of the partial discharge site. ; azimuth angle Substituting into the already determined directional gain function, we obtain the corresponding directional gain. The linear correction coefficient is then calculated using the following formula. : The distance to the i-th sensing unit after correction is expressed as: Where K represents the calibrated intrinsic coefficient of the sensing unit. This represents the signal strength measured by the i-th sensing unit.

2. The method for locating partial discharge of cable joints based on a flexible electromagnetic sensor array according to claim 1, characterized in that, The multiple sensing units deployed on the surface of the cable joint are a flexible electromagnetic sensor array arranged in a regular grid, and the sensing part of each flexible electromagnetic sensor has a hollow structure.

3. The method for locating partial discharge of cable joints based on a flexible electromagnetic sensor array according to claim 1, characterized in that, Based on multiple signal strengths and the calibrated inherent coefficients of the sensing units, multiple distances between the partial discharge site and the multiple sensing units are calculated, including: The intrinsic coefficients of multiple sensing units are calibrated to ensure consistency among them; this includes calculating the intrinsic coefficients of each sensing unit based on multiple standard electromagnetic wave signal sources using the following formula: ； In the formula, This represents the inherent coefficient of the i-th sensing unit; This represents the distance between the nth standard electromagnetic wave signal source and the ith sensing unit. This represents the signal strength of the nth standard electromagnetic wave signal source measured by the i-th sensing unit; The inherent coefficients of each sensing unit are determined based on interpolation. By performing a fitting process, the calibrated intrinsic coefficient K of the sensing unit is obtained; Based on multiple signal strengths and the calibrated inherent coefficients of the sensing units, the distances between the partial discharge sites and the multiple sensing units are calculated using the following formula: ； In the formula, This represents the distance between the partial discharge site and the i-th sensing unit; This represents the signal strength measured by the i-th sensing unit.

4. The method for locating partial discharge of cable joints based on a flexible electromagnetic sensor array according to claim 3, characterized in that, The three-dimensional geometric distance equation is: ； In the formula, Represents the planar coordinates of the i-th sensing unit; Represents the three-dimensional coordinates of the partial discharge site.

5. The method for locating partial discharge of cable joints based on a flexible electromagnetic sensor array according to claim 1, characterized in that, The method further includes: after obtaining the corrected distances, using a trained deep learning-based partial discharge detection model to correct the three-dimensional coordinates of the partial discharge site; the input of the partial discharge detection model includes multiple signal intensities measured by multiple sensing units, the planar coordinates of multiple sensing units, the corrected distances, multiple azimuth angles, and an SDP time-series image generated by polar coordinate mapping of multiple consecutive frames of signal intensity time-series signals; the output is the corrected three-dimensional coordinates of the partial discharge site.

6. The method for locating partial discharge of cable joints based on a flexible electromagnetic sensor array according to claim 2, characterized in that, Each flexible electromagnetic sensor operates in the 0.06 GHz to 0.64 GHz frequency band and has directional radiation characteristics. The maximum receiving sensitivity of each flexible electromagnetic sensor is perpendicular to the substrate plane.

7. A cable joint partial discharge location system based on a flexible electromagnetic sensor array, characterized in that, The system is implemented based on the cable joint partial discharge location method based on a flexible electromagnetic sensor array as described in any one of claims 1-6; the system includes: The signal strength acquisition module is configured to acquire in real time multiple signal strengths measured by multiple sensing units deployed on the surface of the cable joint. The detection and positioning module is configured to perform the following processing based on the multiple signal strengths to detect and locate the partial discharge location of the cable joint: calculate multiple distances between the partial discharge location and the multiple sensing units based on the multiple signal strengths and the calibrated inherent coefficients of the sensing units; establish multiple three-dimensional geometric distance equations based on the multiple distances and the planar coordinates of the multiple sensing units; and solve the multiple three-dimensional geometric distance equations simultaneously to obtain the three-dimensional coordinates of the partial discharge location. The positioning correction module is configured to, after obtaining the three-dimensional coordinates of the partial discharge site, obtain a linear correction coefficient based on the directional gain function corresponding to each sensing unit, and then correct multiple distances between the partial discharge site and multiple sensing units based on the linear correction coefficients to obtain multiple corrected distances; substitute the multiple corrected distances into multiple three-dimensional geometric distance equations, and then solve them simultaneously to obtain the corrected three-dimensional coordinates of the partial discharge site.

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