Detection system and method for live detection of degraded insulators of power transmission line by unmanned aerial vehicle

Abstract

The invention provides a detection system and method for live detection of a degraded insulator of a power transmission line by an unmanned aerial vehicle. The detection system comprises the unmanned aerial vehicle, an image acquisition unit, an airborne processing unit, a multidirectional adjusting mechanism, a measuring device and a handheld controller, the controller is in communication connection with the unmanned aerial vehicle, controls the multidirectional adjusting mechanism to adjust the attitude of the measuring device, and triggers the measuring device to collect voltage; based on the image analysis result and the voltage distribution data, whether each insulator has an apparent defect and whether the insulator is a low-value or zero-value insulator is judged, if any insulator has an apparent defect or belongs to at least one of the low-value or zero-value insulator, the insulator is judged as a deteriorated insulator, the specific position of the insulator in the to-be-detected insulator string is determined, and the to-be-detected insulator string is detected. And warning information containing the position identification is generated. The whole detection process is remotely controlled by a ground controller, manual tower climbing operation is not needed, the safety of operators in a high-pressure environment is effectively guaranteed, and meanwhile, the inspection efficiency is greatly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power transmission equipment operation and maintenance, in particular to a detection system and method for detecting deteriorated insulators of power transmission lines by unmanned aerial vehicle (UAV) under electric power. BACKGROUND

[0002] With the increase of the operation life of the power transmission line, if there is a deteriorated insulator in the insulator string of the power transmission line, once there is an overvoltage, the internal breakdown of the insulator will occur, the porcelain will completely lose the insulation capability, and thus a low-zero-value insulator will be generated. The instantaneous short-circuit current generated by lightning stroke and pollution flashover may cause overheat explosion of the low-zero-value insulator, and thus a string falling accident will occur, which poses a great threat to the safe operation of the power transmission line. In order to master the operation state of the insulator of the power transmission line, the insulator deterioration sampling inspection is performed every 3-5 years after the power transmission line is put into operation, and a part of the insulators are sampled and inspected, which is difficult to comprehensively master the operation state of the insulators.

[0003] For the porcelain insulator low-zero-value monitoring, in the traditional detection method, one is the spark gap method, which determines whether there is a low-zero-value insulator by whether the spark gap discharges or not, which belongs to qualitative detection and cannot quantitatively detect the voltage value of each insulator, and the power operation and maintenance personnel need to climb the tower and walk along the insulator string to detect each insulator, which has low operation efficiency and great safety risks such as high-altitude falling.

[0004] Another method is to build a circuit model for insulator detection according to the calculated capacitance matrix parameters in the electrostatic field and the measured loop parameters, to calculate the voltage distribution characteristics of the insulator string under different working conditions by changing the simulated low and zero-value insulators with different insulator resistances, and to compare the measured value with the simulation value to determine whether there is a low or zero-value insulator. Although this method can identify the low or zero-value insulator to some extent, the theoretical calculation value is greatly affected by different line arrangement structures, wire-to-ground capacitance, field environment, measurement probe and calculation model, and it is difficult to guarantee the measurement accuracy. SUMMARY

[0005] In view of this, the present application provides a detection system and method for detecting deteriorated insulators of power transmission lines by unmanned aerial vehicle (UAV) under electric power, aiming at solving the technical problem of low detection precision in the prior art when detecting the state of the insulator string in the power transmission line.

[0006] In one aspect, the present application provides a detection system for detecting deteriorated insulators of power transmission lines by unmanned aerial vehicle (UAV) under electric power, comprising: an unmanned aerial vehicle, an image acquisition unit, an airborne processing unit, a multi-direction adjusting mechanism, a measuring device and a handheld controller; wherein,

[0007] The image acquisition unit is arranged on the unmanned aerial vehicle and is used to acquire the appearance image of the to-be-detected insulator string and shoot a detection video;

[0008] The on-board processing unit is arranged on the unmanned aerial vehicle and connected with the image acquisition unit, for receiving and analyzing the appearance image, and identifying the appearance defects of the to-be-tested insulator string;

[0009] The measuring device is connected with the unmanned aerial vehicle through the multi-direction adjusting mechanism, for contacting with both ends of each insulator in the to-be-tested insulator string, measuring the voltage of both ends, and obtaining the voltage distribution data of the entire to-be-tested insulator string;

[0010] The controller is in communication connection with the unmanned aerial vehicle, for controlling the multi-direction adjusting mechanism to adjust the posture of the measuring device, triggering the measuring device to collect the voltage, receiving the image analysis result from the on-board processing unit and the voltage distribution data from the measuring device, judging whether each insulator has appearance defects based on the image analysis result, judging whether each insulator is a low-value or zero-value insulator based on the voltage distribution data, and determining the insulator as a deteriorated insulator if at least one of the appearance defects and the low-value or zero-value insulator exists in any insulator, determining the specific position of the insulator in the to-be-tested insulator string, and generating warning information containing the position identifier.

[0011] Further, in the detection system for detecting deteriorated insulators of power transmission lines by the unmanned aerial vehicle, the measuring circuit of the measuring device comprises a high-voltage voltage divider, a signal conditioning circuit, an A / D sampling module and a wireless transmission module; wherein,

[0012] The high-voltage voltage divider comprises a high-voltage arm resistor and a low-voltage arm resistor connected in series, for proportionally reducing the voltage of the insulator;

[0013] The signal conditioning circuit is connected with the output end of the high-voltage voltage divider, for filtering and amplifying the signal after voltage division;

[0014] The A / D sampling module is connected with the output end of the signal conditioning circuit, for converting the processed analog signal into a digital signal;

[0015] The wireless transmission module is connected with the output end of the A / D sampling module, for sending the digital signal to the controller.

[0016] Further, in the detection system for detecting deteriorated insulators of power transmission lines by the unmanned aerial vehicle, the measuring device comprises a shell, a high-voltage end measuring probe and a low-voltage end measuring probe; wherein,

[0017] The shell is provided with a first compartment and a second compartment which are isolated from each other, and the electrical wiring is realized through the threading hole between the two compartments;

[0018] The high-voltage arm resistor is arranged inside the first bin body, and is integrally packaged with an epoxy resin structure;

[0019] The low-voltage arm resistor, the A / D sampling module, the signal conditioning circuit and the wireless transmission module are arranged inside the second bin body, and the inner wall of the second bin body is provided with a metal shielding sleeve;

[0020] One end of the high-voltage end measurement probe is electrically connected to the input end of the high-voltage arm resistor, and the other end extends to the outside of the shell for contacting the high-voltage side fitting of the insulator string to be measured;

[0021] One end of the low-voltage end measurement probe is electrically connected to the low-voltage arm resistor, and the other end extends to the outside of the shell for contacting the low-voltage side fitting of the insulator string to be measured.

[0022] Further, in the above unmanned aerial vehicle detection system for detecting deteriorated insulators of power transmission lines, a plurality of high-voltage measurement probes are arranged circumferentially at the end of the first bin body, and a plurality of low-voltage measurement probes are arranged circumferentially at the end of the second bin body.

[0023] Further, in the above unmanned aerial vehicle detection system for detecting deteriorated insulators of power transmission lines, the on-board processing unit is an embedded AI computing module, which is in communication connection with the image acquisition unit, is used to acquire the appearance image collected by the image acquisition unit, identify the appearance defects of the insulator string to be measured, and send the image analysis result to the controller.

[0024] Further, in the above unmanned aerial vehicle detection system for detecting deteriorated insulators of power transmission lines, the multi-directional adjusting mechanism comprises a vertical telescopic rod, a horizontal telescopic rod and a rotating mechanism connected in series, wherein,

[0025] The vertical telescopic rod is connected to the bottom of the load-bearing platform of the unmanned aerial vehicle, the horizontal telescopic rod is connected to the bottom of the vertical telescopic rod in the horizontal direction, and the other end of the horizontal telescopic rod is connected to one end of the rotating mechanism; the other end of the rotating mechanism is connected to the measuring device for driving the measuring device to rotate in the horizontal plane to adjust the relative position of the probe of the measuring device and the fitting of the insulator string to be measured.

[0026] Further, in the above unmanned aerial vehicle detection system for detecting deteriorated insulators of power transmission lines, the controller comprises a main control unit, a data analysis unit and a wireless communication unit, wherein,

[0027] The main control unit is connected to the wireless communication unit for generating measurement control instructions;

[0028] The wireless communication unit establishes a wireless communication connection with the unmanned aerial vehicle, for sending measurement control instructions to the unmanned aerial vehicle, and receiving distributed voltage data and image analysis results from the unmanned aerial vehicle;

[0029] The data analysis unit is connected with the wireless communication unit for pre-processing the received distributed voltage data, and combining the image analysis results, to determine the specific position of the insulator with low value or zero value in the insulator string to be measured, and generate warning information containing position identification.

[0030] The detection system for detecting deteriorated insulators of power transmission lines by the unmanned aerial vehicle in the application realizes stable contact voltage measurement of the fittings at both ends of the insulator by integrating a multidirectional adjusting mechanism and a measuring device on the unmanned aerial vehicle, and overcomes the problems of low detection accuracy and easy electromagnetic interference of the traditional non-contact detection; the multidirectional adjusting mechanism can flexibly adjust the position and angle of the measuring device, ensure reliable contact with insulators of different specifications, and further ensure the reliability of the measurement data; the on-board processing unit is used to analyze the collected appearance images in real time, and accurately identify the appearance defects of the insulator; the controller accurately determines the specific position of the insulator with low value or zero value in the insulator string to be measured based on the distributed voltage data, and generates warning information with position identification; the entire detection process is remotely controlled by the ground controller, without the need for manual tower climbing operation, effectively ensuring the safety of the operating personnel in the high-voltage environment, and greatly reducing the need for re-measurement due to high measurement accuracy and strong data reliability, thereby greatly improving the inspection efficiency.

[0031] On the other hand, the application also provides a detection method for detecting deteriorated insulators of power transmission lines by an unmanned aerial vehicle, comprising:

[0032] Controlling the unmanned aerial vehicle to fly to the vicinity of the insulator string to be measured and hover;

[0033] For each insulator in the insulator string to be measured, obtaining its appearance image and voltage at both ends;

[0034] Analyzing the appearance image of each insulator by the on-board processing unit to identify whether it has appearance defects, and judging whether each insulator is a low value or zero value insulator based on the voltage at both ends;

[0035] If any insulator is determined to have at least one of the appearance defects or belong to the low value or zero value insulator, the insulator is determined to be a deteriorated insulator, the specific position of the insulator in the insulator string is determined, and warning information containing position identification is generated.

[0036] Furthermore, in the above-mentioned method for detecting deteriorated insulators of transmission lines by unmanned aerial vehicles (UAVs), if the voltage at both ends of the insulator located at the high-voltage end and the low-voltage end of the insulator string to be tested is significantly lower than that of the adjacent insulators, the insulator is determined to be a zero-value or low-value insulator.

[0037] Furthermore, in the above-mentioned method for detecting deteriorated insulators in transmission lines using live-line testing by drones, for insulators located in the middle of the insulator string to be tested, the adjacent ratio method is used to determine whether they are low-value or zero-value insulators. The criteria are as follows:

[0038]

[0039] Among them, U n U is the effective value of the distributed voltage of the nth insulator; n±1 R is the smaller of the effective values ​​of the distributed voltage of the preceding and following insulators adjacent to the nth insulator; R is the ratio of the effective values ​​of the distributed voltage of the insulator to the adjacent insulators; when R≤K%, K is 50, and the insulator is determined to be a low-value or zero-value insulator.

[0040] This invention provides a method for detecting deteriorated insulators on power transmission lines using a drone. By integrating a voltage measurement device, an image acquisition unit, and an onboard processing unit onto the drone, it achieves simultaneous detection of distributed voltage and visual defects in the insulator string. Ground operators remotely control the drone using a handheld controller, ensuring reliable contact between the measurement device and both ends of the insulator to acquire voltage data. This avoids measurement errors caused by electric field distortion or environmental interference in non-contact methods, significantly improving voltage acquisition accuracy and stability. Simultaneously, the onboard image acquisition unit acquires visual images, and the onboard processing unit accurately identifies visual defects on the drone. The controller determines the specific location of low-value or zero-value insulators within the insulator string based on the distributed voltage data and generates visual warning information. The entire process eliminates the need for tower climbing, ensuring personnel safety. Furthermore, the high measurement accuracy and data reliability significantly reduce the need for retesting, thereby greatly improving inspection efficiency. Attached Figure Description

[0041] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0042] Figure 1 This is a schematic diagram of the structure of the UAV-based live-line detection system for detecting deteriorated insulators in power transmission lines, provided in an embodiment of the present invention.

[0043] Figure 2This is a structural block diagram of the measuring device in the live-line detection system for deteriorated insulators of power transmission lines provided in an embodiment of the present invention;

[0044] Figure 3 This is a schematic diagram of the measuring device in the live-line detection system for deteriorated insulators of power transmission lines provided in an embodiment of the present invention;

[0045] Figure 4 This is a schematic diagram of the probe structure in the UAV live-line inspection system for detecting deteriorated insulators of power transmission lines provided in an embodiment of the present invention;

[0046] Figure 5 This is a structural block diagram of the controller in the live-line detection system for deteriorated insulators of power transmission lines provided in an embodiment of the present invention;

[0047] Figure 6 The flowchart of the controller in the live-line detection system for deteriorated insulators of power transmission lines provided in an embodiment of the present invention is shown below.

[0048] Figure 7 The voltage distribution curves of a 220kV insulator at different zero positions are shown in the live-line inspection method for deteriorated insulators of transmission lines provided in this embodiment of the invention.

[0049] Figure 8 This is a distributed voltage curve measured on-site in a specific embodiment of the method for detecting deteriorated insulators of power transmission lines using a drone in an embodiment of the present invention. Detailed Implementation

[0050] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0051] In practical applications, besides detection accuracy, the ease of on-site deployment, simplicity of operation, and equipment reliability are also crucial factors affecting detection efficiency. Traditional detection equipment often requires manual climbing of towers for complex installation and disassembly, increasing operational risks and costs. Furthermore, while UAV-assisted detection technology improves operational flexibility, it suffers from high operational difficulty in practical use, and the equipment's practicality and reliability are limited. Therefore, this invention proposes a UAV-based live-line detection system for deteriorated insulators in transmission lines. This system improves detection accuracy while enhancing on-site deployment convenience, simplifying operational procedures, and strengthening equipment reliability. A detailed implementation of this system is described below.

[0052] System Implementation Example:

[0053] See Figure 1 The UAV-based live-line inspection system for deteriorated insulators of transmission lines according to an embodiment of the present invention includes: a UAV 1, an image acquisition unit 2, an airborne processing unit 3, a multi-directional adjustment mechanism 4, a measuring device 5, and a controller 6. The image acquisition unit 2 is mounted on the UAV 1 and is used to acquire images of the appearance of the insulator string under test and to capture inspection videos. The airborne processing unit 3 is mounted on the UAV 1 and connected to the image acquisition unit 2, and is used to receive and analyze the appearance images to identify appearance defects in the insulator string under test. The measuring device 5 is connected to the UAV 1 via the multi-directional adjustment mechanism 4 and is used to contact both ends of each insulator in the insulator string under test to measure the voltage across its ends, thereby obtaining the overall voltage of the entire insulator string. The controller is connected to the UAV 1 and controls the multi-directional adjustment mechanism 4 to adjust the attitude of the measuring device 5. It also triggers the measuring device 5 to collect voltage data and receives image analysis results from the airborne processing unit 3 and distributed voltage data from the measuring device 5. Based on the image analysis results, it determines whether each insulator has appearance defects. Based on the voltage distribution data, it determines whether each insulator is a low-value or zero-value insulator. If any insulator is determined to have appearance defects or is a low-value or zero-value insulator, then the insulator is determined to be a deteriorated insulator, its specific position in the insulator string is determined, and a warning message containing the position identifier is generated.

[0054] Specifically, the UAV 1 includes the UAV body and the support platform mounted below it. The support platform is used to install the image acquisition unit 2, the airborne processing unit 3, and the measuring device 5, and achieves precise positioning and contact measurement through the multi-directional adjustment mechanism 4.

[0055] In this embodiment, a lightweight multi-rotor UAV with an effective payload of ≥2.5kg and a flight time of ≥25min is selected. The UAV is connected to the vertical telescopic rod 41 of the multi-directional adjustment mechanism 4. The image acquisition unit 2 is fixed to the support platform below the UAV via a three-axis stabilized gimbal. Its main function is to acquire images of the insulator's appearance and to capture and transmit inspection videos to the ground in real time, providing visual reference for the controller so that the probe can accurately locate the insulator. The image acquisition unit 2 can be a visible light camera.

[0056] The airborne processing unit 3 is an embedded AI computing module that is communicatively connected to the image acquisition unit 2. It is used to acquire the appearance image acquired by the image acquisition unit 2, identify the appearance defects of the insulator string under test, and send the image analysis results to the controller.

[0057] The embedded AI computing module uses NVIDIA's embedded Jetson Xavier NX hardware module, which supports a 6-core ARMv8 64-bit core and a GPU, including 384 NVIDIA Volta GPU cores and 48 Tensor Cores, achieving an AI computing power of up to 21 TOPS. This AI computing power of up to 21 TOPS supports efficient execution of deep learning models at the edge.

[0058] The computing module runs on a customized embedded Linux operating system. Its software architecture, from bottom to top, includes the Linux driver and kernel layer, application layer, platform management interface layer, and data transmission layer. The system acquires appearance images captured by a visible light camera uploaded by UAV 1 via an SDK data connection. After decoding the image data, it calls the locally deployed lightweight target detection algorithm YOLOU 7 to identify appearance defects in the insulator string under test in real time. After identification, the generated image analysis results are sent by the onboard processing unit 3 to the controller for visualization. To ensure communication security, the system integrates encryption, authentication, and access control mechanisms during data transmission to ensure the security and privacy of image data and identification results.

[0059] See Figure 2In this embodiment, the measurement circuit of the measuring device 5 includes: a high-voltage divider, a signal conditioning circuit, an A / D sampling module, and a wireless transmission module; wherein, the high-voltage divider includes a high-voltage arm resistor 513 and a low-voltage arm resistor 514 connected in series, used to proportionally reduce the voltage across the insulator; the signal conditioning circuit is connected to the output terminal of the high-voltage divider, used to filter and amplify the divided signal; the A / D sampling module is connected to the output terminal of the signal conditioning circuit, used to convert the processed analog signal into a digital signal; the wireless transmission module is connected to the output terminal of the A / D sampling module, used to send the digital signal to the controller.

[0060] For further details, please refer to [link / reference]. Figure 3 and Figure 4 The measuring device 5 includes: a housing 51, a high-voltage end measuring probe 52, and a low-voltage end measuring probe 53; wherein, the housing 51 has a first compartment 511 and a second compartment 512 that are isolated from each other, and the two are electrically connected through a wire hole; the first compartment 511 houses the high-voltage arm resistor 513 and is encapsulated by an epoxy resin structure 515; the second compartment 512 houses the low-voltage arm resistor 514, the signal conditioning circuit, and the wireless transmission module, and the inner wall of the second compartment 512 is provided with a metal shielding sleeve 510; one end of the high-voltage end measuring probe 52 is electrically connected to the input end of the high-voltage arm resistor 513, and the other end extends to the outside of the housing 51 for contacting the high-voltage side fittings of the insulator string to be tested; one end of the low-voltage end measuring probe 53 is electrically connected to the low-voltage arm resistor 514, and the other end extends to the outside of the housing 51 for contacting the low-voltage side fittings of the insulator string to be tested.

[0061] Specifically, the housing 51 has an arc-shaped or handle-shaped structure and is made of an insulating material, such as polytetrafluoroethylene. This material has a high insulation level and a long surface creepage distance, which can effectively prevent surface discharge and avoid the reduction of the equivalent resistance of the high-voltage arm resistor 513 or the introduction of additional capacitive current due to material leakage or parallel capacitance.

[0062] The housing 51 has a first compartment 511 and a second compartment 512 distributed along its length. The two are isolated from each other and are electrically connected through a wire hole provided in the housing 51.

[0063] The first compartment 511 is used to house the high-voltage arm resistor 513. The structural design of the measuring device 5 has a key impact on the insulation performance and voltage division accuracy of the equipment. In order to meet the high-voltage insulation requirements, the high-voltage end adopts an epoxy resin integral potting process to completely seal the high-voltage arm resistor 513, which not only achieves high-voltage isolation, but also provides good mechanical protection and moisture resistance. Since the high-voltage end has been epoxy encapsulated, there is no need to install a metal shielding sleeve.

[0064] The second chamber 512 is used to install the low-voltage arm resistor 514, the signal conditioning circuit motherboard, and the wireless data transmission module. Its inner wall is equipped with a metal shielding sleeve and reliably grounded, providing electromagnetic shielding. The two chambers are connected by electrical wiring through a 4mm diameter through-hole, ensuring that the insulation distance between the high-voltage and low-voltage areas meets safety requirements. The entire measuring device 5 forms a complete voltage sampling circuit by having the high-voltage end measuring probe 52 and the low-voltage end measuring probe 53 contact the fittings at both ends of the insulator string under test, enabling online detection of distributed voltage.

[0065] In this embodiment, the high voltage divider in the measuring device 5 adopts a resistive voltage divider method. Both the high voltage arm and the low voltage arm are made of resistors. In order to ensure the linearity and stability of the voltage divider under different temperature environments, the high voltage arm resistor 513 and the low voltage arm resistor 514 are specially made high voltage precision resistors with the same temperature coefficient to reduce the measurement error caused by temperature drift.

[0066] Under favorable weather conditions, the equivalent capacitance of the insulator is approximately 30–60 pF, and its equivalent capacitive reactance at power frequency is 106.1 MΩ–53.05 MΩ. To ensure that the leakage current of the voltage divider is controlled below microamps to avoid affecting the system under test, while also considering measurement sensitivity and safety, the resistance value of the high-voltage arm resistor 513 is selected to be between 1 GΩ and 3 GΩ, and the low-voltage arm resistor 514 is between 20 kΩ and 30 kΩ. The resulting voltage division ratio N = (R1 + R2) / R2 can meet the requirements for wide-range voltage detection.

[0067] The signal acquired by the measuring probe, after passing through a voltage divider, is primarily a power frequency voltage signal, but it is accompanied by high-frequency electromagnetic interference. Therefore, a low-pass filter is set at the signal output to filter out high-frequency noise. To further improve the measurement accuracy of small voltage signals, a gain 10-fold amplifier circuit is connected after the low-pass filter to enhance the weak signal. To balance the measurement accuracy of both large and small voltages, a dual-range measurement strategy is adopted: first, the voltage output after the low-pass filter is directly read; when the effective value of this voltage is detected to be lower than a certain set threshold (i.e., the minimum identifiable voltage of the non-saturated waveform), the system automatically switches to the channel with the 10-fold amplification for voltage signal sampling. In this way, the measuring instrument can achieve the required measurement accuracy when measuring both large and small voltages.

[0068] The multi-directional adjustment mechanism 4 is located between the UAV 1 and the measuring device 5, and is used to adjust the spatial position and attitude of the measuring device 5. This mechanism has vertical extension, lateral extension and rotation functions, and can flexibly adjust the extension direction and alignment angle of the measuring probe to ensure reliable electrical contact with the fittings at both ends of insulator strings of different diameters and installation attitudes.

[0069] In this embodiment, the appearance images, defect identification results, and distributed voltage data generated by the image acquisition unit 2, the airborne processing unit 3, and the measuring device 5, along with the UAV's flight status information, are transmitted in real time to the ground controller via a wireless communication link. The wireless communication link includes a dedicated UAV image transmission system, Wi-Fi, a data radio, or a 4G / 5G network, supporting the synchronous transmission of multiple types of data to ensure that operators can monitor the entire inspection process in real time.

[0070] See Figure 5 The controller 6 includes a main control unit, a data analysis unit, and a wireless communication unit. The main control unit is connected to the wireless communication unit and is used to generate measurement control commands. The wireless communication unit establishes a wireless communication connection with the UAV 1 and is used to send measurement control commands to the UAV 1 and receive distributed voltage data and image analysis results from the UAV 1. The data analysis unit is connected to the wireless communication unit and is used to preprocess the received distributed voltage data and, in conjunction with the image analysis results, determine the specific location of the insulator with low or zero values ​​in the insulator string to be tested, and generate warning information containing location identifiers.

[0071] Specifically, the controller's main function is to control the actions of the measuring device 5 and related subsequent information processing.

[0072] The controller can activate the measuring device 5, receive the insulator distribution voltage information, and display and store the voltage in real time. It can also display and store the insulator appearance defect information and analyze the location of insulators with low zero values.

[0073] The controller 6 can be a handheld remote control, tablet computer, smartphone, laptop computer, or remote control terminal integrated into a cloud platform; preferably, to facilitate flexible operation by on-site personnel, the controller is an industrial-grade handheld remote control.

[0074] In this embodiment, insulator appearance defects include surface damage, porcelain cracks, corrosion of steel feet and caps, arc burning, and missing locking devices. Degraded insulators include two main categories: appearance defects and the presence of zero or low voltage values. If either category is detected, the insulator is considered degraded, and the controller will generate a warning message. In this embodiment, based on the voltage distribution curve plotted from the voltage across each insulator, insulators with abnormal voltage are identified. Combined with their number in the insulator string, the specific location of the low-value or zero-value insulator in the string under test is determined.

[0075] In one specific embodiment of the present invention, electrical contact between the measuring device and the two ends of the insulator means that the measuring device is electrically connected to the fittings of each insulator.

[0076] Specifically, the fitting includes a steel cap on the high-voltage side and a steel foot on the low-voltage side. The probes of the measuring device contact the steel cap and the steel foot respectively, forming a conductive path, thereby measuring the voltage difference across the insulator. Since the insulator string is arranged sequentially from the high-voltage side to the low-voltage side, the voltage distribution data of the entire string can be obtained by measuring the voltage between the steel cap and the steel foot piece by piece.

[0077] In practice, the system starts numbering the insulators from the high-voltage end of the string (number 1 being the first insulator). The measuring device on the UAV sequentially contacts each insulator to measure its voltage. When a low or zero voltage value is identified based on the voltage distribution curve, its specific location within the string can be determined by combining the measurement sequence and its number. Simultaneously with each voltage measurement, the system triggers a synchronization signal for voltage acquisition, controlling the image acquisition unit to capture images of the currently measured insulator. Based on the acquisition timing and numbering, the images are matched one-to-one with the voltage data. The onboard processing unit analyzes the images to identify any external defects such as cracks, damage, or dirt. The controller interface displays the voltage data, distribution curve, and the number and location of the low or zero voltage insulators in real time, and generates visual warning information.

[0078] In this embodiment, the controller software module is written in embedded C language. The main control unit is the core of the program, responsible for controlling the MCU to execute the system control logic, realizing communication with other units, monitoring external interrupts and internal interrupts, and determining whether to start the data acquisition process according to the set parameters, and performing conversion and filtering processing on the acquired data.

[0079] The data analysis unit utilizes the functions of the dedicated measurement chip to acquire and analyze the data collected by the five probes of the measurement device. The wireless communication module is responsible for communication with the LoRa hardware module, receiving and parsing control commands, and packaging and transmitting measurement data while verifying its integrity.

[0080] See Figure 6In practice, after the controller starts up, it first performs a power-on self-test to ensure that all hardware and software modules are working properly. After the self-test is completed, it establishes a communication link with UAV 1 through the wireless communication module. The main control module waits for and receives the measurement setting parameters from the host computer, and after receiving the start measurement command, it determines whether to start the data acquisition process based on preset conditions.

[0081] Once the startup conditions are met, the main control unit will enter the measurement mode selection phase, selecting either automatic or manual measurement mode based on user settings or default settings. In automatic measurement mode, the main control unit automatically triggers data acquisition according to preset conditions; while in manual measurement mode, the operator manually triggers the data acquisition process through the human-machine interface unit.

[0082] During the measurement process, the measuring device 5 acquires voltage distribution data in real time and transmits this data to the data analysis unit for further processing. The data analysis unit filters and normalizes the received distributed voltage data to generate voltage distribution curves for the insulator strings. Combining this with image analysis results, it determines the presence of low-value or zero-value insulators based on abrupt changes in the voltage distribution curves or the adjacent ratio method. Once a degraded insulator is identified, the data analysis unit generates a detection result containing warning information, which can be uploaded to the backend system via the wireless communication unit.

[0083] Studies have shown that radio interference levels on or near power transmission towers gradually decrease with increasing frequency; when the frequency is between 49.75 and 222.75 MHz and above, interference caused by corona discharge is negligible. To ensure communication stability in the complex electromagnetic environment near high-voltage transmission line towers, the controller in this embodiment uses a low-power RF transceiver chip with an adjustable carrier frequency in the ISM band. The selected chip has a supply voltage of <5V and a maximum transmit power consumption of ≤200mW.

[0084] The controller may also include a human-machine interface unit for displaying insulator distribution voltage curves, images of visual defects, and detection results on a screen in real time, and providing an operating interface for ground personnel to initiate measurements, view historical data, or confirm alarm information. This unit supports touch or button input, improving ease of operation.

[0085] In this embodiment, ground personnel control the measuring device 5 mounted on the UAV via a controller, using a probe to perform contact voltage measurements on the hardware at both ends of the insulator. The entire detection process is initiated, and after the data is transmitted back, the data analysis unit completes the judgment, forming a closed-loop detection mechanism, which realizes efficient and accurate identification of deteriorated insulators in transmission lines.

[0086] It is evident from the above that the UAV-based live-line inspection system for deteriorated insulators of transmission lines provided in this embodiment, by integrating a multi-directional adjustment mechanism 4 and a measuring device 5 on the UAV 1, achieves stable contact voltage measurement of the fittings at both ends of the insulator, overcoming the problems of low accuracy and susceptibility to electromagnetic interference in traditional non-contact inspections. The multi-directional adjustment mechanism 4 can flexibly adjust the position and angle of the measuring device to ensure reliable contact with insulators of different specifications, further guaranteeing the reliability of the measurement data. The onboard processing unit performs real-time analysis of the collected appearance images to accurately identify insulator appearance defects. Based on distributed voltage data, the controller accurately determines the specific location of low-value or zero-value insulators in the string of insulators to be tested and generates warning information with location markers. The entire inspection process is remotely controlled by the ground controller, eliminating the need for manual tower climbing, effectively ensuring the safety of operators in high-voltage environments. At the same time, due to the high measurement accuracy and strong data reliability, the need for retesting is greatly reduced, thereby significantly improving inspection efficiency.

[0087] In the above embodiment, multiple high-voltage measuring probes are arranged circumferentially at the end of the first chamber 511, and multiple low-voltage measuring probes are arranged circumferentially at the end of the second chamber 512, to ensure that at least one probe at each end forms a stable electrical connection with the fittings on the corresponding side of the insulator string to be tested when the flight attitude of the UAV 1 changes.

[0088] Specifically, the measuring probes extending from the high-voltage and low-voltage measuring ends are made of steel wire with a certain degree of toughness to ensure good contact with the insulator fittings. To facilitate drone operation and ensure good contact with the insulator, preferably, three probes are used at each end, and the angle between two adjacent probes is 90° to 180°; more preferably, it is 120°. When the drone approaches the insulator string, even with deviations in flight attitude, at least one probe can still ensure good contact with the fittings, significantly improving the detection success rate.

[0089] Furthermore, the gap between any adjacent measuring probes at the high-voltage and low-voltage ends is adjustable to accommodate different types and diameters of insulators, such as bell-shaped insulators and double-umbrella insulators. More specifically, the probes can be slidably connected to their bottom supports via sliders to change the spacing between them.

[0090] In the above embodiment, the multi-directional adjustment mechanism 4 includes: a vertical telescopic rod 41, a horizontal telescopic rod 42, and a rotating mechanism 43 connected together; wherein, the vertical telescopic rod 41 is connected to the bottom of the carrying platform of the UAV 1, the horizontal telescopic rod 42 is connected to the bottom of the vertical telescopic rod 41 in a horizontal direction, and the other end of the horizontal telescopic rod 42 is connected to one end of the rotating mechanism 43; the other end of the rotating mechanism 43 is connected to the measuring device 5, and is used to drive the measuring device 5 to rotate in the horizontal plane to adjust the relative position of the probe of the measuring device 5 and the insulator string fitting to be tested.

[0091] Specifically, the tail of the vertical telescopic rod 41 is fixed to the lower part of the drone via the drone foot bracket connector. The telescopic range is 400mm-1000mm. Its main function is to provide lifting and lowering movement for the probe of the measuring device 5, so as to facilitate accurate positioning of the insulator string and to maintain a certain safe working distance between the drone and the high-voltage end of the insulator to prevent damage such as corona discharge of the drone.

[0092] The tail of the horizontal telescopic rod 42 is fixed to the end of the vertical telescopic rod 41 through an "L"-shaped connector. The telescopic range is adjustable according to the voltage level of the insulator, with an adjustment range of 500mm-1500mm. Its main function is to provide lateral telescopic support for the probe of the measuring device 5, so as to facilitate accurate positioning of the insulator. It also provides a certain safe operating distance between the drone and the insulator, reducing electromagnetic interference.

[0093] One end of the transverse telescopic rod 42 is connected to a rotating structure, and the other end of the rotating structure is connected to the housing 51 of the measuring device 5. The rotating structure includes a bidirectional rotary motor, a reducer, and a rotary output shaft. The bidirectional rotary motor drives the rotary output shaft to rotate through the reducer. The rotary output shaft is connected to the measuring device 5 and is used to drive the measuring device 5 to rotate around the horizontal axis within a range of ±90°.

[0094] It can be seen that by setting up the rotating structure, the spatial orientation of the probe plane of the measuring device can be adjusted to adapt to insulator strings with different arrangements, thereby realizing voltage detection of various types of insulators such as tension horizontal strings, suspension strings, and V-string insulators, significantly improving the applicability of the detection system.

[0095] Method Implementation Examples:

[0096] This invention also provides a method for detecting deteriorated insulators in power transmission lines using a live UAV, comprising:

[0097] Step S1: Control the drone to fly to the vicinity of the insulator string to be tested and hover.

[0098] Specifically, for tension insulator strings, the test insulator is suspended at a safe position above the insulator string; for suspension insulator strings, the test insulator is suspended outside the conductor and at the same height as the string to be tested.

[0099] Step S2: For each insulator in the insulator string to be tested, obtain its appearance image and the voltage at both ends.

[0100] In practice, when the drone hovers, the camera's field of view is adjusted to fill the frame as much as possible to obtain an image of the current insulator string under test, ensuring that the image is clear and complete, and the test video is captured simultaneously.

[0101] Subsequently, the multi-directional adjustment mechanism is adjusted to bring the measuring device into contact with the fittings at both ends of the insulator under test, and the voltage across its ends is obtained:

[0102] More specifically, the rotating mechanism in the multi-directional adjustment mechanism is adjusted so that the probe plane of the measuring device is parallel to the plane of the insulator to be tested. Combined with real-time images provided by the UAV vision system for auxiliary observation, the vertical telescopic rod and the horizontal telescopic rod are controlled by the controller so that the high-voltage end measuring probe and the low-voltage end measuring probe form stable electrical contact with the steel foot and steel cap of the insulator to be tested, respectively, and the voltage at both ends of the insulator is obtained.

[0103] In one specific embodiment of this example, after data acquisition of a single insulator is completed, the image capturing and voltage measurement operations are repeated in a sequence proceeding from the low-voltage side (near the tower) to the high-voltage side (near the conductor) of the insulator string until all insulators in the entire string have been inspected. In step S3, if any insulator is determined to have an appearance defect or is at least one of a low-value or zero-value insulator, then that insulator is classified as a degraded insulator, its specific location within the insulator string is determined, and a warning message containing the location identifier is generated.

[0104] Specifically, the appearance image of each insulator obtained in step S2 is transmitted in real time to the airborne processing unit, which receives and analyzes the appearance image to identify appearance defects of the insulator string under test; and transmits the image analysis results and distributed voltage data to the ground controller.

[0105] In the controller, by combining the distributed voltage data of the entire string of insulators with the image analysis results, the specific location of the insulator with low or zero values ​​in the insulator string is determined, and a warning message with location identification is generated.

[0106] More specifically, after acquiring the voltage of the entire string of insulators, the controller receives distributed voltage data from various points on the measuring device. These data are arranged sequentially according to the physical position of the insulators in the string (numbered 1→n), forming an ordered voltage sequence. To further analyze the voltage distribution pattern, the system can plot this voltage sequence as a voltage distribution curve.

[0107] In a transmission line insulator string, the voltage is normally distributed non-linearly along the string length. The insulators at the high-voltage and low-voltage ends bear higher voltages, while the voltage in the middle section is lower and the distribution is more gradual. In other words, the voltage distribution of the insulator string follows a "U"-shaped curve (high at both ends and low in the middle).

[0108] When an insulator located at the high-voltage or low-voltage side of the insulator string experiences zero or low-value degradation, the voltage shared by that insulator will decrease significantly, manifesting as a noticeable voltage abrupt drop on the overall voltage distribution curve, forming a steep "step-like" characteristic. Therefore, for insulators located at the high-voltage and low-voltage ends of the insulator string under test, if the voltage at both ends of the insulator shows a significant abrupt decrease compared to adjacent insulators, the insulator is determined to be a zero-value or low-value insulator.

[0109] For insulators located in the middle of the insulator string under test, to eliminate the influence of external factors such as voltage level, number of insulator discs in the string, and environment, the adjacent ratio method is used to determine whether it is a low-value or zero-value insulator. The adjacent ratio method only analyzes the distributed voltage of three adjacent insulators. Let the effective value of the distributed voltage of the nth insulator be Un, and the distributed voltage of the insulator immediately before and after it be U. n±1 If we take the smaller of the two adjacent pieces, then the ratio of adjacent pieces is:

[0110]

[0111] Among them, U n U is the effective value of the distributed voltage of the nth insulator; n-1 U is the effective value of the distributed voltage of the insulator preceding the nth insulator; n+1 U represents the effective value of the distributed voltage of the insulator adjacent to the nth insulator; n±1 R is the smaller of the effective values ​​of the distributed voltage of the preceding and following insulators adjacent to the nth insulator; R is the ratio of the effective values ​​of the distributed voltage of the insulator to the adjacent values; when R≤K%, K is taken as 50, and the insulator is determined to be a low zero value insulator.

[0112] The present invention will be described in detail below with a specific embodiment:

[0113] A 220kV insulator voltage testing environment was set up in the high-voltage test hall. Voltage (peak voltage 179kV) was applied by the power frequency step-up insulators, and commands were sent to the measuring device using a handheld controller. The insulators from the high-voltage end to the low-voltage end were named 1-13 sequentially. Simulated zero-voltage insulators were located at 1 (high-voltage end), 7 (middle), and 13 (low-voltage end). Based on the test data, the voltage distribution curve of the insulator string was plotted. Figure 7 (The horizontal axis represents the position of the insulator disc (e.g., disc 1 to disc 13), and the vertical axis represents the corresponding effective voltage value).

[0114] from Figure 7 The voltage distribution curve shows that the test results conform to a U-shaped voltage distribution curve. Compared with the normal insulator distribution curve, when zero values ​​are found in insulator No. 1 at the high-voltage end and insulator No. 13 at the low-voltage end, the voltage is significantly reduced, which can be directly judged from the voltage distribution curve. When zero values ​​are found in insulator No. 7 in the middle string, the adjacent ratio R = U7 / min(U6, U8)*100% = 0.11% < 50%, indicating the presence of zero-value insulators, verifying the accuracy of the adjacent ratio method for judgment.

[0115] To test the effectiveness of the entire equipment on actual power transmission line towers, a live-line insulator testing system using a drone was configured. This system included a multi-rotor drone flight platform, a visible light camera and onboard computing module, one vertical telescopic rod, one horizontal telescopic rod, a rotating structure, a measuring device, and a handheld controller. Tests were conducted on insulators of a 220kV power line belonging to a certain power company. The insulators were in double strings of 18 pieces per string. The testing procedures are as follows:

[0116] (1) Install and fix the measuring device on the UAV flight platform and check that it is normal.

[0117] (2) Take off with the drone carrying the detection device, fly to the outside of the conductor and hover at the same height as the insulator string to be tested, adjust the visible light camera so that the insulator string to be tested fills the camera's field of view as much as possible, and ensure that the image is clear and complete.

[0118] (3) Adjust the rotation mechanism to make the detection probe plane of the measuring device parallel to the insulator;

[0119] (4) Ground operators use the UAV's vision assistance to control the vertical and horizontal telescopic rods to move so that the probes at either end contact the insulator's steel foot and steel cap respectively, and record the test data at this time. At the same time, the airborne computing module is used to identify the captured images in real time and detect appearance defects such as insulator damage, cracks, and burns.

[0120] (5) Start testing from the low-voltage side of the insulator string (close to the tower) and continue testing to the high-voltage side (close to the conductor) piece by piece. Record and check the test data on the ground.

[0121] The single-phase 18-piece insulator test was completed in 22 minutes, and the 220kV single-phase measurement results are as follows: Figure 8 As shown (measurement starts from the end of the conductor).

[0122] from Figure 8 The results show that the measurement conforms to the "U"-shaped voltage distribution curve, and the total voltage deviates from the standard voltage division sum by less than 0.3%, meeting the measurement requirements. However, since the standard distributed voltage is not a precise value for the voltage division of a single insulator, it cannot be used as a standard value for judging the accuracy of the voltage of a single insulator.

[0123] For the determination of low zero-value insulators, numerical simulation measurement was used for testing, which meets the requirements of the adjacent ratio method criterion. This set of testing inclines meets the requirements of the on-site testing procedures and does not require manual tower climbing for testing. The measurement method is flexible and easy to operate, greatly saving the manpower and material resources consumed by tower climbing testing.

[0124] The relevant parts of the method embodiments and the system embodiments described above can be referred to each other, and will not be repeated here.

[0125] In summary, the method for live-line inspection of deteriorated insulators on transmission lines provided by this invention achieves simultaneous detection of insulator distributed voltage and appearance defects by integrating a voltage measurement device, an image acquisition unit, and an onboard processing unit onto the drone. Ground operators remotely control the drone using a handheld controller, ensuring reliable contact between the measurement device and both ends of the insulator to acquire voltage data. Simultaneously, the onboard image acquisition unit acquires appearance images, and the onboard processing unit identifies appearance defects on the drone, only transmitting the identification results back to the controller, reducing communication load. The controller determines the specific location of low-value or zero-value insulators within the insulator string based on the distributed voltage data and generates visual warning information. The entire process requires no tower climbing, is applicable to insulators of different specifications, and significantly improves inspection safety, accuracy, and efficiency.

[0126] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A detection system for degraded insulators of power transmission lines using a drone, characterized in that, include: The drone, image acquisition unit, airborne processing unit, multi-directional adjustment mechanism, measuring device, and controller; among them, The image acquisition unit is mounted on the drone and is used to acquire images of the appearance of the insulator string under test and to capture inspection videos. The airborne processing unit is mounted on the UAV and connected to the image acquisition unit. It is used to receive and analyze the appearance image and identify appearance defects of the insulator string under test. The measuring device is connected to the UAV through the multi-directional adjustment mechanism and is used to contact the two ends of each insulator in the insulator string to be tested, measure the voltage at both ends, and obtain the distributed voltage data of the entire insulator string to be tested. The controller is communicatively connected to the UAV and is used to control the multi-directional adjustment mechanism to adjust the attitude of the measuring device and trigger the measuring device to perform voltage acquisition. It receives image analysis results from the airborne processing unit and distributed voltage data from the measuring device. Based on the image analysis results, it determines whether each insulator has appearance defects. Based on the voltage distribution data, it determines whether each insulator is a low-value or zero-value insulator. If any insulator is determined to have appearance defects or is a low-value or zero-value insulator, then the insulator is determined to be a deteriorated insulator, its specific position in the string of insulators to be tested is determined, and a warning message containing the position identifier is generated.

2. The detection system for detecting deteriorated insulators of power transmission lines using a drone under live-line testing as described in claim 1, characterized in that, The measurement circuit of the measuring device includes: a high-voltage divider, a signal conditioning circuit, an A / D sampling module, and a wireless transmission module; wherein... The high-voltage divider includes a high-voltage arm resistor and a low-voltage arm resistor connected in series, which are used to proportionally reduce the voltage across the insulator. The signal conditioning circuit is connected to the output terminal of the high voltage divider and is used to filter and amplify the divided signal. The A / D sampling module is connected to the output of the signal conditioning circuit and is used to convert the processed analog signal into a digital signal. The wireless transmission module is connected to the output of the A / D sampling module to send the digital signal to the controller.

3. The UAV-based detection system for detecting deteriorated insulators in power transmission lines under live-line conditions, as described in claim 2, is characterized in that... The measuring device includes: a housing, a high-voltage end measuring probe, and a low-voltage end measuring probe; wherein... The housing contains a first compartment and a second compartment that are isolated from each other, and electrical wiring is achieved between the two through a wire hole; The high-voltage arm resistor is installed inside the first chamber and is encapsulated in an integral manner using an epoxy resin structure; The second compartment is equipped with the low-voltage arm resistor, the A / D sampling module, the signal conditioning circuit, and the wireless transmission module, and the inner wall of the second compartment is provided with a metal shielding sleeve. One end of the high-voltage end measuring probe is electrically connected to the input end of the high-voltage arm resistor, and the other end extends to the outside of the housing for contact with the high-voltage side fittings of the insulator string to be tested. One end of the low-voltage end measuring probe is electrically connected to the low-voltage arm resistor, and the other end extends to the outside of the housing for contact with the low-voltage side fittings of the insulator string to be tested.

4. The UAV-based detection system for detecting deteriorated insulators in power transmission lines under live-line conditions, as described in claim 3, is characterized in that... Multiple high-pressure measuring probes are arranged circumferentially at the end of the first chamber, and multiple low-pressure measuring probes are arranged circumferentially at the end of the second chamber.

5. The UAV-based detection system for detecting deteriorated insulators in power transmission lines under live-line conditions, as described in claim 1, is characterized in that... The airborne processing unit is an embedded AI computing module that is communicatively connected to the image acquisition unit. It is used to acquire the appearance image acquired by the image acquisition unit, identify the appearance defects of the insulator string under test, and send the image analysis results to the controller.

6. The detection system for detecting deteriorated insulators of power transmission lines using a drone as described in claim 1, characterized in that, The multi-directional adjustment mechanism includes: a vertical telescopic rod, a horizontal telescopic rod, and a rotating mechanism connected together; wherein, The vertical telescopic rod is connected to the bottom of the UAV's carrying platform, and the horizontal telescopic rod is connected to the bottom of the vertical telescopic rod in a horizontal direction. The other end of the horizontal telescopic rod is connected to one end of the rotating mechanism. The other end of the rotating mechanism is connected to the measuring device, which is used to drive the measuring device to rotate in the horizontal plane to adjust the relative position of the probe of the measuring device and the insulator string fitting to be tested.

7. The detection system for detecting deteriorated insulators of power transmission lines using a drone under live-line testing as described in claim 1, characterized in that, The controller includes: a main control unit, a data analysis unit, and a wireless communication unit; wherein... The main control unit is connected to the wireless communication unit and is used to generate measurement control commands; The wireless communication unit establishes a wireless communication connection with the UAV, and is used to send measurement and control commands to the UAV and receive distributed voltage data and image analysis results from the UAV. The data analysis unit is connected to the wireless communication unit to preprocess the received distributed voltage data, and in combination with the image analysis results, determine the specific location of the insulator with low or zero values ​​in the insulator string under test, and generate a warning message containing the location identifier.

8. A method for detecting deteriorated insulators in power transmission lines using a live-line inspection system using an unmanned aerial vehicle (UAV), characterized in that, include: Control the drone to fly near the insulator string to be tested and hover it; For each insulator in the insulator string to be tested, obtain its appearance image and the voltage across its terminals; The airborne processing unit analyzes the appearance images of each insulator to identify whether there are appearance defects, and determines whether each insulator is a low-value or zero-value insulator based on the voltage at both ends. If any insulator is found to have an appearance defect or is a low-value or zero-value insulator, then the insulator is identified as a deteriorated insulator, its specific position in the insulator string is determined, and a warning message containing the position identifier is generated.

9. The method for detecting deteriorated insulators of transmission lines by unmanned aerial vehicles (UAVs) under live-line testing according to claim 8, characterized in that, For insulators located at the high-voltage end and low-voltage end of the insulator string to be tested, if the voltage at both ends of the insulator is significantly lower than that of the adjacent insulators, the insulator is determined to be a zero-value or low-value insulator.

10. The method for detecting deteriorated insulators according to claim 8, characterized in that, For insulators located in the middle of the insulator string to be tested, the adjacent ratio method is used to determine whether they are low-value or zero-value insulators. The criteria are as follows: Among them, U n U is the effective value of the distributed voltage of the nth insulator; n±1 R is the smaller of the effective values ​​of the distributed voltage of the preceding and following insulators adjacent to the nth insulator; R is the ratio of the effective values ​​of the distributed voltage of the insulator to the adjacent insulators; when R≤K%, K is 50, and the insulator is determined to be a low-value or zero-value insulator.

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