Cable partial discharge point position detection method and system
By deploying clock-synchronized electromagnetic signal sensors on the cable and monitoring changes in signal sequence, combined with ultrasonic detection, the problem of accurately locating partial discharge points in cables was solved, achieving efficient and accurate geographic location of partial discharge points.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-04
- Publication Date
- 2026-03-31
AI Technical Summary
In existing technologies, it is difficult to quickly and accurately locate the partial discharge point of a cable. Time-difference positioning methods suffer from discrepancies between electrical and geographical locations, while single-sensor line-following methods are affected by electromagnetic interference and noise, resulting in insufficient positioning accuracy.
Two electromagnetic signal sensors are arranged along the cable extension direction, maintaining a distance D and clock synchronization. The signal reception sequence is detected and the sequence change is monitored during synchronous movement. The discharge point is determined to be located between the two endpoints by reversing the signal sequence. Ultrasonic detection is then used for refined detection.
It significantly improves the accuracy of determining the geographical range of partial discharge points, reduces the probability of false positives and false negatives, and achieves rapid and accurate geographical location of partial discharge points, adapting to real-time detection in complex environments.
Smart Images
Figure CN121763007A_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to the power industry, further to the field of cable testing, and particularly to a method and system for detecting the location of partial discharge points in cables. Background Technology
[0002] Partial discharge is a key indicator of cable insulation degradation. If not detected and located promptly, it can lead to serious faults such as insulation breakdown. Traditional methods for partial discharge detection generally include the following two approaches: 1. Time-difference positioning using partial discharge signals at both ends of the cable. The "electrical location" of the discharge point is calculated by placing acquisition devices at both ends of the cable and detecting the time difference between the arrival of the partial discharge signal at both ends. However, due to the complexity of actual cable laying, which may include multiple connections, bends, and different burial depths, there is often a deviation between the "electrical location" and the actual geographical location. This makes it difficult for on-site maintenance personnel to accurately locate the fault point underground directly using this result.
[0003] 2. Line following method using a single sensor In some situations, to more accurately locate the geographical location of partial discharge points, maintenance personnel will conduct manual line inspections above the area where partial discharge occurs, relying on a single sensor to judge changes in the intensity or characteristics of the discharge signal. Because partial discharge signals are affected by electromagnetic interference, environmental noise, and other factors, and the detection range is relatively large, line inspections require a considerable amount of time, and positioning accuracy is difficult to guarantee.
[0004] In the methods described above, time-of-flight positioning can roughly determine the range of partial discharge points. However, due to the lack of effective identification of the specific orientation and burial conditions around the discharge point, the actual detection of key locations remains insufficient. Furthermore, when the local discharge signal is weak or external interference is strong, the accuracy of conventional line-tracking methods is significantly affected, making it difficult to determine the precise geographical coordinates of the partial discharge point in a timely manner. In conclusion, how to quickly and accurately narrow the search range of partial discharge points and achieve precise geographical positioning based on existing time-of-flight positioning results has become an urgent problem to be solved in the field of cable partial discharge detection. Summary of the Invention
[0005] This disclosure provides a method and system for detecting the location of partial discharge points in cables, solving the technical problem of the difficulty in accurately determining the location of partial discharge points in cables.
[0006] According to a first aspect of this disclosure, a method for detecting the location of partial discharge points in a cable is provided. The method includes: Obtain the estimated location range of partial discharge points in the cable; Two sensors with a spacing D are arranged along the direction of cable extension in the estimated location range. Both sensors are electromagnetic signal sensors and are kept clock synchronized through a communication connection. The first time sequence of the electromagnetic signals received by the two sensors due to partial discharge is detected, and the two sensors are moved synchronously along the direction of the sensor that received the signal first, until the time sequence of the electromagnetic signals received by the two sensors is reversed to a second time sequence. At this point, it is determined that the partial discharge point of the cable is located between the first end and the second end, wherein: The first endpoint is located at the end of the first time sequence, at the sensor location where the electromagnetic signal is received last; The second endpoint is located at the initial moment of the second time sequence, at the sensor location where the electromagnetic signal is received later.
[0007] In a preferred embodiment, the method further includes: The region between the first and second endpoints is further examined using ultrasonic detection equipment to determine the geographical location of the partial discharge point.
[0008] In a preferred embodiment, the two sensors maintain a constant distance during synchronous movement, and the location of the partial discharge point of the cable is estimated to be exactly midway between the first end and the second end.
[0009] In a preferred embodiment, the distance D between the two sensors satisfies the following requirements: c△t<D<L Where c is the speed of light, Δt is the time resolution of the electromagnetic signal sensor, and L is the length of the estimated position interval.
[0010] In a preferred embodiment, the method for obtaining the estimated location interval is the time difference positioning method, which includes the following steps: Time-synchronized signal acquisition devices are installed at both ends of the cable; The signal acquisition device is used to monitor the time it takes for the partial discharge signal to propagate to both ends of the cable, and the timestamp of the arrival time is recorded. The location of the partial discharge point is calculated based on the time difference between the arrival times of the signals at both ends and the speed at which the partial discharge signal propagates in the cable. Based on the electrical location of the partial discharge point, the estimated location range of the discharge point is determined.
[0011] According to a second aspect of this disclosure, a cable partial discharge point location detection system is provided. It includes: The time difference positioning module is used to obtain the estimated location range of partial discharge points in the cable; Two sensors for detecting electromagnetic signals are set and spaced apart by a distance D along the direction of cable extension in the estimated position range, and the two sensors are kept synchronized by a communication connection. The signal detection module is used to detect the first time sequence in which the two sensors receive electromagnetic signals caused by partial discharge. The synchronous movement control module is used to synchronously move two sensors along the direction of the sensor that receives the signal first, until the time order in which the two sensors receive the electromagnetic signals is reversed to a second time order. The position determination module is used to determine, when the second time sequence occurs, that the partial discharge point of the cable is located between the first endpoint and the second endpoint, wherein the first endpoint is located at the sensor position where the electromagnetic signal is received later at the end of the first time sequence, and the second endpoint is located at the sensor position where the electromagnetic signal is received later at the beginning of the second time sequence.
[0012] In a preferred embodiment, the system further includes an ultrasonic detection device for further detection of the area between the first endpoint and the second endpoint to determine the geographical location of the partial discharge point.
[0013] In a preferred embodiment, the two sensors maintain a constant distance D during synchronous movement, and the location of the partial discharge point of the cable is estimated to be exactly midway between the first end point and the second end point.
[0014] In the preferred embodiment, the distance D between the two sensors meets the following requirements: c△t < D < L Where c is the speed of light, Δt is the time resolution of the electromagnetic signal sensor, and L is the length of the estimated position interval.
[0015] In a preferred embodiment, the time difference positioning module includes: Two signal acquisition units are used to be placed at both ends of the cable and maintain time synchronization; The time recording unit is used to monitor the arrival time of the partial discharge signal at both ends of the cable and record the timestamp. The location calculation unit is used to calculate the location of the partial discharge point based on the time difference between the arrival times of the two ends and the speed at which the partial discharge signal propagates in the cable. The interval determination unit is used to determine the estimated location interval of the discharge point based on the location of the partial discharge point.
[0016] This invention employs a dynamically switching positioning method using a "first time sequence" and a "second time sequence," which significantly improves the accuracy of determining the geographical range of partial discharge points. Compared to schemes that determine the location of partial discharge points solely based on "two sensors simultaneously receiving signals," the core advantage of this invention lies in: By continuously monitoring the sequence of signal reception during the synchronous movement of the sensor, this invention eliminates the need for instantaneous "simultaneity" determination, avoiding the accumulation of errors caused by limitations in the time resolution of signal acquisition equipment, external environmental noise interference, and subtle differences in signal propagation speed. As long as the order of the sensed signals is "reversed," it can be determined that the discharge point is sandwiched between the two endpoints, thus accurately defining the range between the first and second endpoints. In some embodiments, setting the partial discharge point precisely in the middle between the first and second endpoints provides even greater accuracy.
[0017] Furthermore, the present invention identifies the transition points in the time sequence through dynamic comparison at different times, significantly reducing the probability of misjudgment and missed judgment. Since it no longer relies on measurement results at a single moment but combines observation data from multiple time periods, any incidental interference is unlikely to simultaneously affect the entire time sequence change process, thus making the measurement results more stable and robust.
[0018] After determining a small interval, more sophisticated detection methods, such as ultrasonic detection, can be used to finally determine the geographical coordinates of the partial discharge point. This multi-verification mode inherits the efficiency of long-distance positioning using electromagnetic signals and integrates the high precision of acoustic detection, enabling rapid and accurate location of partial discharge faults in underground cables. By precisely dividing the detection interval based on the verifiable event of "time sequence reversal," this invention effectively improves the operability, real-time performance, and anti-interference capability of the technical solution.
[0019] It should be understood that the description in the Summary of the Invention is not intended to limit the key or essential features of the embodiments of this disclosure, nor is it intended to restrict the scope of this disclosure. Other features of this disclosure will become readily apparent from the following description. Attached Figure Description
[0020] The above and other features, advantages, and aspects of the embodiments of this disclosure will become more apparent from the accompanying drawings and the following detailed description. The drawings are provided for a better understanding of the invention and are not intended to limit the scope of this disclosure. In the drawings, the same or similar reference numerals denote the same or similar elements, wherein: Figure 1 This diagram illustrates the initial detection process in an embodiment of this disclosure. Figure 2 This diagram illustrates the end time of the first time sequence in an embodiment of this disclosure. Figure 3 This diagram illustrates the initial moment of the second time sequence in an embodiment of this disclosure. Figure 4 A schematic diagram of the overall method of this disclosure is shown. Detailed Implementation
[0021] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.
[0022] Furthermore, the term "and / or" in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.
[0023] This invention employs two sensors to determine the more precise location of partial discharge points. To better understand the solution, consider the following embodiment, and note that some parameters in this embodiment are merely exemplary: In a 500-meter-long high-voltage cable, it is assumed that the partial discharge point is located in the estimated range of approximately 200 to 300 meters from the cable's starting point, calculated using the time-difference positioning method. Based on this result, sensors A and B are placed at 200 meters and 210 meters respectively on the cable surface. The two sensors are synchronized via wireless communication, and the sensor spacing D is 10 meters.
[0024] like Figure 1 As shown, when a partial discharge occurs at point K, sensor A will definitely receive the electromagnetic signal first, followed by sensor B. The time sequence at this point is recorded as the first time sequence (i.e., A first, then B). Therefore, it can be determined that the partial discharge point is closer to sensor A.
[0025] Subsequently, sensors A and B were moved synchronously along the direction of the cable towards the end closer to sensor A (to the right in the figure), ensuring that the distance between them remained constant at 10 meters throughout the movement. As the moving distance gradually increased, the timing of the electromagnetic signals received by the two sensors was monitored and recorded multiple times.
[0026] Until a certain moment, such as Figure 2 At the position shown, it will be difficult to distinguish which sensor, A or B, received the signal first. This moment is the end of the first time sequence. The position of the sensor that received the signal later at this moment, i.e., sensor B, is recorded as the first endpoint.
[0027] Continue moving until you reach a position like... Figure 3At the position shown, it was found that the order of signal reception was reversed, that is, sensor B received the signal first, and sensor A received the signal later. This time sequence is marked as the second time sequence. The position of the sensor that received the signal later, that is, sensor A, is recorded as the second endpoint.
[0028] Therefore, it can be determined that the partial discharge point K falls within the interval between the first endpoint and the second endpoint.
[0029] In a further embodiment, the partial discharge point K can be initially set to fall exactly midway between the first endpoint and the second endpoint. To obtain more accurate geographical coordinates, an ultrasonic detection device can be introduced within the locked interval to further inspect the cable in that interval (inspection can start from the exact midway point), and the specific geographical location of the partial discharge point can be determined based on the intensity and phase characteristics of the acoustic signal.
[0030] It should be noted that ultrasonic detection of partial discharge points is an existing technology widely used in the detection of partial discharge in equipment such as cables, transformers, and switchgear. Partial discharge is accompanied by the generation of high-frequency sound waves. Ultrasonic detection determines the location of the discharge point by capturing these sound wave signals and analyzing their intensity and propagation characteristics. A common ultrasonic detection method involves placing an ultrasonic sensor (such as a piezoelectric sensor or air-coupled sensor) on or near the cable surface. The signal received by the sensor is amplified and filtered, and then combined with techniques such as time difference measurement, signal strength comparison, or phase analysis to pinpoint the exact location of the discharge point. For complex environments, three-dimensional positioning can be achieved through a multi-sensor setup, further improving detection accuracy. Ultrasonic detection is characterized by its non-contact nature, high accuracy, and strong anti-interference capabilities, making it one of the commonly used methods for partial discharge detection.
[0031] From the above embodiments, the overall technical solution can be summarized as follows: Figure 4 As shown, it can be specifically summarized as follows: Two sensors with a spacing D are arranged along the direction of cable extension in the estimated location range. Both sensors are electromagnetic signal sensors and are kept clock synchronized through a communication connection. The first time sequence of the electromagnetic signals received by the two sensors due to partial discharge is detected, and the two sensors are moved synchronously along the direction of the sensor that received the signal first, until the time sequence of the electromagnetic signals received by the two sensors is reversed to a second time sequence. At this point, it is determined that the partial discharge point of the cable is located between the first end and the second end, wherein: The first endpoint is located at the end of the first time sequence, at the sensor location where the electromagnetic signal is received last; The second endpoint is located at the initial moment of the second time sequence, at the sensor location where the electromagnetic signal is received later.
[0032] In this invention, the types of electromagnetic signal sensors can include high-frequency electromagnetic sensors (HFCT), ultra-high-frequency sensors (UHF), electromagnetic induction coil sensors, and surface potential sensors. High-frequency electromagnetic sensors detect partial discharge activity by sensing high-frequency current signals outside the cable, and can capture high-frequency signals in the range of tens to hundreds of MHz, making them one of the most widely used non-contact sensors for partial discharge detection. Ultra-high-frequency sensors detect partial discharge by sensing ultra-high-frequency electromagnetic waves (300MHz~3GHz) generated by partial discharge, exhibiting strong anti-interference capabilities and being particularly suitable for partial discharge detection in complex electromagnetic environments. Electromagnetic induction coil sensors, based on the principle of electromagnetic induction, can capture high-frequency signals near the cable. Due to their simple structure and ease of placement, they are often used to monitor signals over a wide frequency band. Surface potential sensors measure potential fluctuations on the cable surface by sensing transient electric field changes caused by partial discharge, exhibiting high sensitivity and being particularly suitable for detecting weak signals.
[0033] The detection method of this invention is non-contact, and the electromagnetic signal sensor does not need to be directly connected to the cable. This method monitors the discharge point by inducing the transient high-frequency electromagnetic signal generated by partial discharge. The sensor is usually placed on or near the cable surface (thus enabling detection of underground cables), without damaging the cable insulation or interfering with the normal operation of the cable. Non-contact detection can monitor partial discharge signals of operating cables online, adapting to the real-time detection needs in complex environments. Simultaneously, it maintains clock synchronization between sensors through wireless or wired communication, making it more suitable for dynamic line inspection scenarios. Through flexible deployment and a highly sensitive non-contact detection method, this invention effectively improves the efficiency and accuracy of partial discharge point location while enhancing safety.
[0034] In the above embodiments, preferably, the distance D between the two sensors satisfies the following requirements: c△t<D<L Where c is the speed of light, Δt is the time resolution of the electromagnetic signal sensor, and L is the length of the estimated position interval.
[0035] The lower limit ensures that the sensor can distinguish the order of signals; that is, the propagation time difference Δt1 between electromagnetic signals must be greater than the sensor's time resolution Δt. If D is too small, such that Δt1 < Δt, the sensor will not be able to accurately determine the order of the signals.
[0036] The upper limit restricts the sensor spacing D from exceeding the estimated location interval of the partial discharge point; otherwise, further sensor positioning would be meaningless.
[0037] Alternatively, the method for obtaining the estimated location range can be the time difference positioning method, which is an existing technology and includes the following steps: Time-synchronized signal acquisition devices are installed at both ends of the cable; The signal acquisition device is used to monitor the time it takes for the partial discharge signal to propagate to both ends of the cable, and the timestamp of the arrival time is recorded. The location of the partial discharge point is calculated based on the time difference between the arrival times of the signals at both ends and the speed at which the partial discharge signal propagates in the cable. Based on the electrical location of the partial discharge point, the estimated location range of the discharge point is determined.
[0038] Therefore, the present invention also discloses a system corresponding to the above method, comprising: The time difference positioning module is used to obtain the estimated location range of partial discharge points in the cable; Two sensors for detecting electromagnetic signals are set and spaced apart by a distance D along the direction of cable extension in the estimated position range, and the two sensors are kept synchronized by a communication connection. The signal detection module is used to detect the first time sequence in which the two sensors receive electromagnetic signals caused by partial discharge. The synchronous movement control module is used to synchronously move two sensors along the direction of the sensor that receives the signal first, until the time order in which the two sensors receive the electromagnetic signals is reversed to a second time order. The position determination module is used to determine, when the second time sequence occurs, that the partial discharge point of the cable is located between the first endpoint and the second endpoint, wherein the first endpoint is located at the sensor position where the electromagnetic signal is received later at the end of the first time sequence, and the second endpoint is located at the sensor position where the electromagnetic signal is received later at the beginning of the second time sequence.
[0039] In a preferred embodiment, the system further includes an ultrasonic detection device for further detection of the area between the first endpoint and the second endpoint to determine the geographical location of the partial discharge point.
[0040] In a preferred embodiment, the two sensors maintain a constant distance D during synchronous movement, and the location of the partial discharge point of the cable is estimated to be exactly midway between the first end point and the second end point.
[0041] In the preferred embodiment, the distance D between the two sensors meets the following requirements: c△t < D < L Where c is the speed of light, Δt is the time resolution of the electromagnetic signal sensor, and L is the length of the estimated position interval.
[0042] In a preferred embodiment, the time difference positioning module includes: Two signal acquisition units are used to be placed at both ends of the cable and maintain time synchronization; The time recording unit is used to monitor the arrival time of the partial discharge signal at both ends of the cable and record the timestamp. The location calculation unit is used to calculate the location of the partial discharge point based on the time difference between the arrival times of the two ends and the speed at which the partial discharge signal propagates in the cable. The interval determination unit is used to determine the estimated location interval of the discharge point based on the location of the partial discharge point.
[0043] The specific embodiments described above do not constitute a limitation on the scope of protection of this disclosure. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this disclosure should be included within the scope of protection of this disclosure.
Claims
1. A method for detecting a partial discharge point position of a cable, characterized by, The method comprises the following steps: obtaining an estimated position interval of a cable partial discharge point; arranging two sensors with a distance D along the direction of cable extension in the estimated position interval, both of the sensors being electromagnetic signal sensors and being kept clock-synchronized through communication connection; detecting a first time sequence of electromagnetic signals caused by partial discharge received by the two sensors, and synchronously moving the two sensors along the direction of the sensor that first receives the signal until the time sequence of electromagnetic signals received by the two sensors is reversed to a second time sequence, at which time it is determined that the cable partial discharge point is located between a first end point and a second end point, wherein the first end point is located at the position of the sensor that receives the electromagnetic signal later at the end of the first time sequence, and the second end point is located at the position of the sensor that receives the electromagnetic signal later at the beginning of the second time sequence. The method further comprises:
2. The method of claim 1, wherein, further detecting the area between the first end point and the second end point by an ultrasonic detection device to determine the geographical position of the partial discharge point. The distance between the two sensors remains unchanged during the synchronous movement, and the position of the cable partial discharge point is estimated to be in the middle of the first end point and the second end point.
3. The method of claim 1, wherein, The distance D between the two sensors satisfies the following requirement:
4. The method according to claim 1 or 3, characterized in that, c△t<D<L wherein c is the speed of light, △t is the time resolution of the electromagnetic signal sensor, and L is the length of the estimated position interval. The method for obtaining the estimated position interval is a time difference positioning method, which comprises the following steps:
5. The method of claim 1, wherein, arranging time-synchronized signal acquisition devices at both ends of the cable; monitoring the time of partial discharge signals propagating to both ends of the cable by using the signal acquisition devices, and recording the time stamp of the arrival time; calculating the position of the partial discharge point according to the time difference of the signal arrival time at both ends and the speed of the partial discharge signal propagating in the cable; determining the estimated position interval of the discharge point according to the electrical position of the partial discharge point. It comprises:
6. A partial discharge point location detection system for a cable, characterized by a time difference positioning module for obtaining an estimated position interval of a cable partial discharge point; two sensors for detecting electromagnetic signals, arranged with a distance D along the direction of cable extension in the estimated position interval, and kept clock-synchronized through communication connection; a signal detection module for detecting a first time sequence of electromagnetic signals caused by partial discharge received by the two sensors; a synchronous movement control module for synchronously moving the two sensors along the direction of the sensor that first receives the signal until the time sequence of electromagnetic signals received by the two sensors is reversed to a second time sequence; a position determination module for determining that the cable partial discharge point is located between a first end point and a second end point when the second time sequence appears, wherein the first end point is located at the position of the sensor that receives the electromagnetic signal later at the end of the first time sequence, and the second end point is located at the position of the sensor that receives the electromagnetic signal later at the beginning of the second time sequence. The system further comprises an ultrasonic detection device for further detecting the area between the first end point and the second end point to determine the geographical position of the partial discharge point.
7. The system of claim 6, wherein, 8. The system of claim 6, wherein, The two sensors keep the distance D unchanged during the synchronous movement, and the position of the cable partial discharge point is estimated in the middle of the first endpoint and the second endpoint.
9. The system of claim 6 or 8, wherein, The distance D of the two sensors satisfies the following requirements: c△t < D < L Wherein c is the speed of light, △t is the time resolution of the electromagnetic signal sensor, and L is the length of the estimated position interval.
10. The system of claim 6, wherein, The time difference positioning module comprises: Two end signal acquisition units arranged at both ends of the cable and kept time synchronization; A time recording unit for monitoring the arrival time of the partial discharge signal propagating to both ends of the cable and recording the time stamp; A position calculation unit for calculating the position of the partial discharge point according to the time difference of the arrival time at both ends and the speed of the partial discharge signal propagating in the cable; An interval determination unit for determining the estimated position interval of the discharge point according to the position of the partial discharge point.