Method and device for monitoring partial discharge of high-voltage transmission cable

Abstract

The invention provides a high-voltage power transmission cable partial discharge monitoring method and device, and the method comprises the steps: collecting an abnormal current analog waveform signal of a cable at the end connection part of a power transmission cable when abnormal discharge is monitored, and converting the abnormal current analog waveform signal into an abnormal current digital waveform signal after processing; the photoelectric sensor receives an ultraviolet light signal emitted by a discharge arc of a cable at the terminating position of the power transmission cable and converts the received ultraviolet light signal into a discharge arc current analog waveform signal, and the discharge arc current analog signal is converted into a discharge arc voltage digital waveform signal after being processed. And cross-correlation operation processing is carried out on the abnormal current digital waveform signal and the discharge arc voltage digital waveform signal, and if the two waveforms have high positive correlation in frequency spectrum distribution and energy intensity, it is judged that a partial discharge event occurs. According to the method, the abnormal current data and the arc data are fused, cross-correlation operation is carried out, and the abnormal discharge phenomenon at the cable terminating position can be accurately judged.

Description

Technical Field

[0001] The present invention relates to the field of power transmission cable status detection, and in particular to a method and device for monitoring partial discharge of high-voltage power transmission cables. Background Art

[0002] In order to ensure the stability and safety of electricity use, the stability requirements of transmission cables have received more and more attention. Many power-related units have launched research on the status detection of transmission cables. The termination points of transmission cables, such as the middle joints of transmission cables, the connection points between transmission cables and insulators, and the connection points between transmission cables and transformers, are key locations for carrying load currents and are also the weakest insulation links in cable transmission systems. Monitoring abnormal discharge phenomena at the termination points of transmission cables helps to determine the insulation performance of the termination points of transmission cables, so as to achieve early detection and early prevention, and prevent further degradation of insulation performance at the cable termination points, thereby causing serious faults such as arcing and burning cables.

[0003] There are two existing methods for monitoring partial discharge at transmission cable joints: One is to use a high-frequency current monitoring coil to monitor abnormal high-frequency current during discharge. This method has a single monitoring dimension and is easily affected by high-order harmonics of power frequency current, short-circuit current, surge current, and grid-hanging equipment, resulting in a high false alarm rate and inaccurate discharge location positioning.

[0004] Another method is to monitor the local temperature at the joint of the transmission cable. When the joint is discharged, the temperature of the joint will rise. However, this method is easily affected by line load, ambient temperature, outdoor weather, etc.

[0005] Therefore, it is necessary to provide a method or device that can accurately judge abnormal discharge phenomena at the cable termination without being affected by interference signals on the cable. Summary of the invention

[0006] The purpose of the present invention is to improve the prediction effect of the transition period, and to provide a method and device for monitoring partial discharge of a high-voltage transmission cable.

[0007] In a first aspect, the present invention provides a method for monitoring partial discharge of a high-voltage transmission cable, comprising the following steps: When abnormal discharge is detected, the abnormal current analog waveform signal of the cable at the power transmission cable termination is collected and converted into an abnormal current digital waveform signal after processing; When abnormal discharge is detected, the photoelectric sensor receives the ultraviolet light signal emitted by the discharge arc at the power transmission cable termination point during cable discharge, and converts the received ultraviolet light signal into a discharge arc current analog waveform signal, which is converted into a discharge arc voltage digital waveform signal after processing; The abnormal current digital waveform signal and the discharge arc voltage digital waveform signal are cross-correlated and processed. If the two waveforms are highly positively correlated in terms of frequency spectrum distribution and energy intensity, it is determined that a partial discharge event has occurred.

[0008] Based on the above, the abnormal current simulation waveform signal and the discharge arc current simulation waveform signal at the power transmission cable termination are recorded in real time, and the trigger threshold S of the abnormal current simulation waveform signal and the discharge arc current simulation waveform signal is set; When the amplitude of the abnormal current analog waveform signal or the discharge arc current analog waveform signal exceeds the trigger threshold S, there is abnormal discharge, and this moment is recorded as t 1 ; Continuously record and store abnormal current analog waveform signals and discharge arc current analog waveform signals, and the end time of recording is recorded as t 2 ; t 1 The abnormal current simulation waveform signal and the discharge arc current simulation waveform signal T milliseconds before the moment t 2 -t 1 The abnormal current simulation waveform signal and the discharge arc current simulation waveform signal during the period are used as the collected simulation signals; After the collected analog signal is converted into a discrete digital signal, the continuous analog signal will be converted into a discrete digital signal. The stored abnormal current digital waveform signal is recorded as C, and the discharge arc voltage digital waveform signal is recorded as L. C={c 1 、c 2 、c 3、 …、c m}; L={l 1 , l 2 , l 3、 …、l m}; Where m=(t 2 -t 0 ) / F sample ; F sample is the sampling rate of analog-to-digital conversion, and C(n) is {c 1 、c 2 、c 3 ……c m}The nth data in the sequence, L(n) is {l 1 , l 2 , l 3 …… m}The nth data in the sequence.

[0009] Based on the above, the method for performing cross-correlation operation on the abnormal current digital waveform signal C and the discharge arc voltage digital waveform signal L is: (1) Formula (1) is understood as the result of multiplying and summing sequence C after sequence L is shifted left by d time units without changing sequence C. The translation process satisfies the principle of left addition and right subtraction, n represents time, and d represents the translation amount. Calculation formula (1) gives the following equations at different times {1, 2, 3, …, d max}The cross-correlation sequence R under translation cl ={r 1 、r 2 、r 3、 …、d max}; define R(n) as {r 1 、r 2 、r 3、 …、r m}The nth data in the sequence; For the cross-correlation sequence R cl Normalize and get the sequence R nom , then the sequence R nom The data value range in is between [0, 1], and then the sequence R is retrieved nom The maximum value R nom_max , and record the maximum value R at this time nom_max In sequence R nom The position Loc in R nom (loc) = R nom_max ; If R nom_max <=TRIGER_LEVEL, indicating that the correlation between the abnormal current digital waveform signal and the discharge arc voltage digital waveform signal is not large, and the monitoring result is discarded; If R nom_max >=TRIGER_LEVEL, indicating that the abnormal current digital waveform signal and the discharge arc voltage digital waveform signal have a large correlation, and it is judged that the monitoring result is a cable discharge phenomenon, that is, a partial discharge event occurs; Among them, TRIGER_LEVEL is a configurable user parameter with a value range of (0, 1). The smaller the value, the more sensitive the device response.

[0010] Based on the above, when it is determined that a partial discharge event occurs, the abnormal current digital waveform signal C, the discharge arc voltage digital waveform signal L, and the cross-correlation sequence R cl , the maximum value R in the cross-correlation sequence nom_max , and R nom_max In sequence R nom The location Loc in the image is uploaded to the cloud server.

[0011] Based on the above, when performing cross-correlation operation on the abnormal current digital waveform signal C and the discharge arc voltage digital waveform signal L, it is necessary to calculate the cross-correlation value within a shift time to avoid the inconsistency of the arrival time of the abnormal current signal and the abnormal arc signal caused by different acquisition paths; among which, the maximum time shift is d max =1ms / F sample .

[0012] In a second aspect, the present invention provides a high-voltage transmission cable partial discharge monitoring device, comprising: A high-frequency current sensor is provided at the termination of the power transmission cable and is used to collect an abnormal current analog waveform signal of the cable at the termination of the power transmission cable when abnormal discharge is detected; A filter module is provided at the termination of the power transmission cable, comprising a Fresnel lens for focusing light emitted by the discharge arc when the cable is discharged at the termination of the power transmission cable, and an ultraviolet transmission filter for filtering non-ultraviolet components in the light emitted by the discharge arc; A photoelectric sensor is arranged behind the filter module, and is used to receive the ultraviolet light signal emitted by the discharge arc of the cable at the termination of the power transmission cable when abnormal discharge is detected, and convert the received ultraviolet light signal into a discharge arc current analog waveform signal; A current signal amplification and filtering module, connected to the high-frequency current sensor, for amplifying and filtering the collected abnormal current analog waveform signal; A photoelectric signal conversion and filtering module is connected to the photoelectric sensor and is used for filtering and processing the collected discharge arc current analog waveform signal and converting it into a discharge arc voltage analog waveform signal; an analog-to-digital conversion module, used for converting the abnormal current analog waveform signal into an abnormal current digital waveform signal, and converting the discharge arc voltage analog signal into a discharge arc voltage digital waveform signal; A data processing module, used for performing cross-correlation operation on the received abnormal current digital waveform signal and the discharge arc voltage digital waveform signal; The data processing module is connected to the analog-to-digital conversion module, and the analog-to-digital conversion module is respectively connected to the current signal amplification and filtering module and the photoelectric signal conversion and filtering module, so as to implement the local discharge monitoring method of the high-voltage transmission cable.

[0013] Based on the above, the local discharge monitoring device for high-voltage transmission cables further includes: a voltage transformer module for collecting power frequency voltage analog signals on the cable; The power frequency voltage analog signal is converted into a power frequency voltage digital signal after being processed by the analog-to-digital conversion module and transmitted to the data processing module.

[0014] Based on the above, the analog-to-digital conversion module adopts a three-channel synchronous high-speed sampling analog-to-digital converter, and the sampling rate of the analog-to-digital converter is twice the frequency band of the discharge arc voltage analog waveform signal.

[0015] Based on the above, the local discharge monitoring device for high-voltage transmission cables further includes: a GPS positioning module for obtaining timing information and location information, and transmitting the information to the data processing module; When a partial discharge event is determined to have occurred, the data from the discharge monitoring is uploaded to the cloud server together with the location information and time information.

[0016] Based on the above, the local discharge monitoring device for high-voltage transmission cables also includes: a CT energy acquisition module, which is used to sense AC voltage from the high-voltage bus and output DC voltage after processing; a solar energy acquisition module, which is used to convert solar energy into electrical energy; an energy storage module, including a charging circuit, a battery and a voltage conversion circuit; The charging circuit is used to store the electricity collected by the CT energy acquisition module and the solar energy acquisition module in the battery, and the voltage conversion circuit is used to convert the battery voltage into other suitable voltages for use by other subsequent modules.

[0017] Compared with the prior art, the present invention has outstanding substantive features and significant progress. Specifically, the present invention greatly eliminates interference signals on the cable by fusing two types of data, abnormal high-frequency current and discharge arc, and performing cross-correlation operations on the two types of data, and can accurately determine abnormal discharge phenomena at the termination of the power transmission cable. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a flowchart of the method of Example 1 of the present invention.

[0019] Figure 2 This is a principle block diagram of the device of embodiment 3 of the present invention.

[0020] Figure 3 This is a principle block diagram of the device of embodiment 4 of the present invention.

[0021] Figure 4 This is a schematic diagram of the installation structure of the device of Example 5 of the present invention.

[0022] Figure 5 It is a side schematic diagram of the shell structure of the device of Example 5 of the present invention. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0024] Example 1 The degradation of insulation performance at the termination of power transmission cables will cause the transmission cables to discharge between phases or to the ground. During the discharge process, there will not only be abnormal high-frequency current, but also weak arcs. Since the arc can be detected by photoelectric sensors, and there is a strong correlation between the spectrum distribution and energy intensity of the abnormal high-frequency current and the discharge arc; therefore, the abnormal high-frequency current waveform and arc waveform at the termination of the power transmission cable are monitored at the same time, and the correlation between the two waveforms is calculated. When the two waveforms are highly positively correlated, it can be determined as cable discharge behavior, and other interference on the transmission cable is eliminated.

[0025] This embodiment provides a method for monitoring partial discharge of a high-voltage transmission cable, comprising the following steps: When abnormal discharge is detected, the abnormal current analog waveform signal of the cable at the power transmission cable termination is collected and converted into an abnormal current digital waveform signal after processing; When abnormal discharge is detected, the photoelectric sensor receives the ultraviolet light signal emitted by the discharge arc of the cable at the termination of the power transmission cable, and converts the received ultraviolet light signal into a discharge arc current analog waveform signal, and the discharge arc current analog signal is converted into a discharge arc voltage digital waveform signal after processing; The abnormal current digital waveform signal and the discharge arc voltage digital waveform signal are cross-correlated and processed. If the two waveforms are highly positively correlated in terms of frequency spectrum distribution and energy intensity, it is determined that a partial discharge event has occurred.

[0026] like Figure 1 As shown, the specific method for monitoring partial discharge of high-voltage transmission cables includes the following steps: Record the abnormal current simulation waveform signal and the discharge arc current simulation waveform signal at the power transmission cable termination in real time, and set the trigger threshold S of the abnormal current simulation waveform signal and the discharge arc current simulation waveform signal; When the amplitude of the abnormal current analog waveform signal or the discharge arc current analog waveform signal exceeds the trigger threshold S, there is abnormal discharge, and this moment is recorded as t 1 ; Continuously record and store abnormal current analog waveform signals and discharge arc current analog waveform signals, and the end time of recording is recorded as t 2 ; t 1 The abnormal current simulation waveform signal and the discharge arc current simulation waveform signal T milliseconds before the moment t 2 -t 1 The abnormal current simulation waveform signal and the discharge arc current simulation waveform signal during the period are used as the collected simulation signals; specifically, T=5, t 2-t 1 It is 25ms, that is, a total of 30ms of waveform data is collected; After the collected analog signal is converted into a discrete digital signal, the continuous analog signal will be converted into a discrete digital signal. The stored abnormal current digital waveform signal is recorded as C, and the discharge arc voltage digital waveform signal is recorded as L. C={c 1 、c 2 、c 3、 …、c m}; L={l 1 , l 2 , l 3、 …、l m}; Where m=(t 2 -t 0 ) / F sample ; F sample is the sampling rate of analog-to-digital conversion, and C(n) is {c 1 、c 2 、c 3 ……c m}The nth data in the sequence, L(n) is {l 1 , l 2 , l 3 …… m}The nth data in the sequence, for example, C(1)=c 1 , L(1)=l 1 .

[0027] The abnormal current digital waveform signal C and the discharge arc voltage digital waveform signal L are cross-correlated by: (1) Formula (1) is understood as the result of multiplying and summing sequence C after sequence L is shifted left by d time units, where the translation process satisfies the principle of left addition and right subtraction, n represents time, and d represents the translation amount.

[0028] Although the abnormal current and the discharge arc basically occur at the same time during abnormal discharge, the abnormal current signal and the discharge arc signal arrive at different times due to different acquisition paths. Therefore, when performing cross-correlation calculation on the abnormal current digital waveform signal C and the discharge arc voltage digital waveform signal L, it is necessary to calculate the cross-correlation value within a shift time to avoid the inconsistency of the abnormal current signal and the abnormal arc signal arriving at different times due to different acquisition paths; the maximum time shift is d max =1ms / F sample .

[0029] Calculation formula (1) gives the following equations at different times {1, 2, 3, …, dmax}The cross-correlation sequence R under translation cl ={r 1 、r 2 、r 3、 …、d max}; define R(n) as {r 1 、r 2 、r 3、 …、r m The nth data in the sequence, for example, R cl (1) = r 1 ; For the cross-correlation sequence R cl Normalize and get the sequence R nom , then the sequence R nom The data value range in is between [0, 1], and then the sequence R is retrieved nom The maximum value R nom_max , and record the maximum value R at this time nom_max In sequence R nom The position Loc in R nom (loc) = R nom_max .

[0030] If R nom_max <=TRIGER_LEVEL, indicating that the correlation between the abnormal current digital waveform signal and the discharge arc voltage digital waveform signal is not large, so the monitoring result is discarded and the next monitoring is started; If R nom_max >=TRIGER_LEVEL, indicating that the abnormal current digital waveform signal and the discharge arc voltage digital waveform signal have a large correlation, and it is judged that the monitoring result is a cable discharge phenomenon, that is, a partial discharge event occurs; Among them, TRIGER_LEVEL is a configurable user parameter with a value range of (0, 1). The smaller the value, the more sensitive the device response.

[0031] When a partial discharge event is determined, the next monitoring is started and the abnormal current digital waveform signal C, the discharge arc voltage digital waveform signal L, and the cross-correlation sequence R are recorded. cl , the maximum value R in the cross-correlation sequence nom_max , and R nom_max In sequence R nom The location Loc in the image is uploaded to the cloud server.

[0032] Example 2 The difference between this embodiment and embodiment 1 is that the method for monitoring partial discharge of high-voltage transmission cables further includes: real-time recording of the power frequency voltage analog signal on the cable, after analog-to-digital conversion, the continuous power frequency voltage analog signal will be converted into a discrete power frequency voltage digital signal, and transmitted to the data processing module for storage, and the stored power frequency voltage digital signal is recorded as V, where V={v 1 、v 2 、v 3、 …、v m When a partial discharge event occurs, the power frequency voltage digital signal V (the specific voltage of the cable during discharge) and the abnormal current digital waveform signal C (the magnitude of the discharge current) are uploaded to the cloud server together, which helps the operation and maintenance personnel to understand the basic situation of cable discharge and troubleshoot the problem line in time, greatly saving manpower and material resources.

[0033] Example 3 This embodiment provides a partial discharge monitoring device for high-voltage transmission cables, such as Figure 2 As shown, including: CT energy acquisition module, used to sense AC voltage from the high-voltage bus and output DC voltage after processing; A solar energy harvesting module is used to convert solar energy into electrical energy; The energy storage module includes a charging circuit, a battery and a voltage conversion circuit; the charging circuit is used to store the electricity collected by the CT energy acquisition module and the solar energy acquisition module in the battery, and the voltage conversion circuit is used to convert the battery voltage into other suitable voltages for use by other modules at the subsequent stage; A high-frequency current sensor is provided at the termination of the power transmission cable and is used to collect an abnormal current analog waveform signal of the cable at the termination of the power transmission cable when abnormal discharge is detected; A filter module is provided at the termination of the power transmission cable, comprising a Fresnel lens for focusing the light emitted by the discharge arc when the cable is discharged at the termination of the power transmission cable, and an ultraviolet transmission filter for filtering non-ultraviolet components in the light emitted by the discharge arc; A photoelectric sensor is arranged behind the filter module, and is used to receive the ultraviolet light signal emitted by the discharge arc of the cable at the termination of the power transmission cable when abnormal discharge is detected, and convert the received ultraviolet light signal into a discharge arc current analog waveform signal; A current signal amplification and filtering module, connected to the high-frequency current sensor, for amplifying and filtering the collected abnormal current analog waveform signal; A photoelectric signal conversion and filtering module is connected to the photoelectric sensor and is used for filtering and processing the collected discharge arc current analog waveform signal and converting it into a discharge arc voltage analog waveform signal; an analog-to-digital conversion module, used for converting the abnormal current analog waveform signal into an abnormal current digital waveform signal, and converting the discharge arc voltage analog signal into a discharge arc voltage digital waveform signal; A data processing module, used for performing cross-correlation operation on the received abnormal current digital waveform signal and the discharge arc voltage digital waveform signal; The data processing module is connected to the analog-to-digital conversion module, and the analog-to-digital conversion module is respectively connected to the current signal amplification and filtering module and the photoelectric signal conversion and filtering module, so as to implement the high-voltage transmission cable partial discharge monitoring method described in Example 1.

[0034] Furthermore, the high-voltage transmission cable partial discharge monitoring device further comprises: a GPS positioning module, which is used to obtain timing information and location information, and transmit them to the data processing module; When a partial discharge event is determined to have occurred, the data from the discharge monitoring is uploaded to the cloud server together with the location information and time information.

[0035] In this embodiment, the data processing module can communicate with the cloud server through wireless data transmission modules such as IoT modules and 5G modules to upload data.

[0036] Example 4 The difference between this embodiment and embodiment 3 is that: like Figure 3 As shown, the local discharge monitoring device for high-voltage transmission cables also includes: a voltage transformer module, which is used to collect the power frequency voltage analog signal on the cable; the power frequency voltage analog signal is converted into a power frequency voltage digital signal after being processed by the analog-to-digital conversion module, and transmitted to the data processing module.

[0037] The high-voltage transmission cable partial discharge monitoring device of this embodiment is used to implement the high-voltage transmission cable partial discharge monitoring method described in Example 2.

[0038] In this embodiment, the analog-to-digital conversion module adopts a three-channel synchronous high-speed sampling analog-to-digital converter, and the sampling rate of the analog-to-digital converter is twice the frequency band of the discharge arc voltage analog waveform signal.

[0039] Example 5 This embodiment provides a housing structure of a partial discharge monitoring device for high-voltage transmission cables, such as Figure 4 and Figure 5 As shown, a through hole 2 for passing a power transmission cable 4 is provided in the middle of the shell structure 1, and a lens opening 3 for installing a Fresnel lens is provided on the side of the shell structure 1 near the terminal 5 of the power transmission cable 4.

[0040] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for monitoring partial discharge of high voltage transmission cables, It is characterized in that The following steps are involved: When abnormal discharge is detected, the abnormal current analog waveform signal of the cable at the power transmission cable termination is collected and converted into an abnormal current digital waveform signal after processing; When abnormal discharge is detected, the photoelectric sensor receives the ultraviolet light signal emitted by the discharge arc at the power transmission cable termination point during cable discharge, and converts the received ultraviolet light signal into a discharge arc current analog waveform signal, which is converted into a discharge arc voltage digital waveform signal after processing; The abnormal current digital waveform signal and the discharge arc voltage digital waveform signal are cross-correlated and processed. If the two waveforms are highly positively correlated in terms of frequency spectrum distribution and energy intensity, it is determined that a partial discharge event has occurred.

2. The method for monitoring partial discharge of high-voltage transmission cables according to claim 1, Features: Record the abnormal current simulation waveform signal and the discharge arc current simulation waveform signal at the power transmission cable termination in real time, and set the trigger threshold S of the abnormal current simulation waveform signal and the discharge arc current simulation waveform signal; When the amplitude of the abnormal current analog waveform signal or the discharge arc current analog waveform signal exceeds the trigger threshold S, there is abnormal discharge, and this moment is recorded as t 1 ; Continuously record and store abnormal current analog waveform signals and discharge arc current analog waveform signals, and the end time of recording is recorded as t 2 ; t 1 The abnormal current simulation waveform signal and the discharge arc current simulation waveform signal T milliseconds before the moment t 2 -t 1 The abnormal current simulation waveform signal and the discharge arc current simulation waveform signal during the period are used as the collected simulation signals; After the collected analog signal is converted into a discrete digital signal, the continuous analog signal will be converted into a discrete digital signal. The stored abnormal current digital waveform signal is recorded as C, and the discharge arc voltage digital waveform signal is recorded as L. C={c 1 、c 2 、c 3、 …、c m }; L={l 1 、l 2 、l 3、 …、l m}； Where m=(t 2 -t 0 ) / F sample ; F sample is the sampling rate of analog-to-digital conversion, and C(n) is {c 1 、c 2 、c 3 ……c m }The nth data in the sequence, L(n) is {l 1 , l 2 , l 3 …… m }The nth data in the sequence.

3. The method for monitoring partial discharge of high-voltage transmission cables according to claim 2, Features: The method for performing cross-correlation operation on the abnormal current digital waveform signal C and the discharge arc voltage digital waveform signal L is: （1） Formula (1) is understood as the result of multiplying and summing sequence C after sequence L is shifted left by d time units without changing sequence C. The translation process satisfies the principle of left addition and right subtraction, n represents time, and d represents the translation amount. Calculation formula (1) gives the following equations at different times {1, 2, 3, …, d max }The cross-correlation sequence R under translation cl ={r 1 、r 2 、r 3、 …、d max }; define R(n) as {r 1 、r 2 、r 3 、 …、r m }The nth data in the sequence; For the cross-correlation sequence R cl Normalize and get the sequence R nom , then the sequence R nom The data value range in is between [0, 1], and then the sequence R is retrieved nom The maximum value R nom_max , and record the maximum value R at this time nom_max In sequence R nom The position Loc in R nom (loc) = R nom_max ; If R nom_max <=TRIGER_LEVEL, indicating that the correlation between the abnormal current digital waveform signal and the discharge arc voltage digital waveform signal is not large, and the monitoring result is discarded; If R nom_max >=TRIGER_LEVEL, indicating that the abnormal current digital waveform signal and the discharge arc voltage digital waveform signal have a large correlation, and it is judged that the monitoring result is a cable discharge phenomenon, that is, a partial discharge event occurs; Among them, TRIGER_LEVEL is a configurable user parameter with a value range of (0, 1). The smaller the value, the more sensitive the device response.

4. The method for monitoring partial discharge of high-voltage transmission cables according to claim 3, Features: When it is determined that a partial discharge event has occurred, the abnormal current digital waveform signal C, the discharge arc voltage digital waveform signal L, and the cross-correlation sequence R cl , the maximum value R in the cross-correlation sequence nom_max , and R nom_max In sequence R nom The location Loc in the image is uploaded to the cloud server.

5. The method for monitoring partial discharge of a high-voltage transmission cable according to claim 4, Features: When performing cross-correlation calculation on the abnormal current digital waveform signal C and the discharge arc voltage digital waveform signal L, it is necessary to calculate the cross-correlation value within a shift time to avoid the inconsistency of the arrival time of the abnormal current signal and the abnormal arc signal caused by different acquisition paths; among which, the maximum time shift is d max =1ms / F sample .

6. A partial discharge monitoring device for high voltage transmission cables, It is characterized in that include: A high-frequency current sensor is provided at the termination of the power transmission cable and is used to collect an abnormal current analog waveform signal of the cable at the termination of the power transmission cable when abnormal discharge is detected; A filter module is provided at the termination of the power transmission cable, comprising a Fresnel lens for focusing the light emitted by the discharge arc when the cable is discharged at the termination of the power transmission cable, and an ultraviolet transmission filter for filtering non-ultraviolet components in the light emitted by the discharge arc; A photoelectric sensor is arranged behind the filter module, and is used to receive the ultraviolet light signal emitted by the discharge arc of the cable at the termination of the power transmission cable when abnormal discharge is detected, and convert the received ultraviolet light signal into a discharge arc current analog waveform signal; A current signal amplification and filtering module, connected to the high-frequency current sensor, for amplifying and filtering the collected abnormal current analog waveform signal; A photoelectric signal conversion and filtering module is connected to the photoelectric sensor and is used for filtering and processing the collected discharge arc current analog waveform signal and converting it into a discharge arc voltage analog waveform signal; an analog-to-digital conversion module, used for converting the abnormal current analog waveform signal into an abnormal current digital waveform signal, and converting the discharge arc voltage analog signal into a discharge arc voltage digital waveform signal; A data processing module, used for performing cross-correlation operation on the received abnormal current digital waveform signal and the discharge arc voltage digital waveform signal; The data processing module is connected to the analog-to-digital conversion module, and the analog-to-digital conversion module is respectively connected to the current signal amplification and filtering module and the photoelectric signal conversion and filtering module, so as to implement the local discharge monitoring method of high-voltage transmission cables as described in any one of claims 1-5.

7. The partial discharge monitoring device for high-voltage transmission cables according to claim 6, It is characterized in that The local discharge monitoring device for high-voltage power transmission cables also includes: a voltage transformer module for collecting power frequency voltage analog signals on the cable; The power frequency voltage analog signal is converted into a power frequency voltage digital signal after being processed by the analog-to-digital conversion module and transmitted to the data processing module.

8. The partial discharge monitoring device for high-voltage transmission cables according to claim 7, Features: The analog-to-digital conversion module adopts a three-channel synchronous high-speed sampling analog-to-digital converter, and the sampling rate of the analog-to-digital converter is twice the frequency band of the discharge arc voltage analog waveform signal.

9. The partial discharge monitoring device for high-voltage transmission cables according to claim 6, It is characterized in that The high-voltage transmission cable partial discharge monitoring device also includes: a GPS positioning module, which is used to obtain timing information and location information, and transmit them to the data processing module; When a partial discharge event is determined to have occurred, the data from the discharge monitoring is uploaded to the cloud server together with the location information and time information.

10. The partial discharge monitoring device for high-voltage transmission cables according to any one of claims 6 to 9, It is characterized in that The local discharge monitoring device for high-voltage transmission cables also includes: a CT energy acquisition module, which is used to sense AC voltage from the high-voltage bus and output DC voltage after processing; a solar energy acquisition module, which is used to convert solar energy into electrical energy; an energy storage module, including a charging circuit, a battery and a voltage conversion circuit; The charging circuit is used to store the electricity collected by the CT energy acquisition module and the solar energy acquisition module in the battery, and the voltage conversion circuit is used to convert the battery voltage into other suitable voltages for use by other subsequent modules.

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