Insulator leakage current collecting and measuring device and method

Abstract

The invention relates to the technical field of power equipment detection and monitoring, provides an insulator leakage current collection and measurement device and method, can monitor insulator surface layer leakage current, temperature and humidity information on line and reflect the insulator surface pollution degree in real time, and designs a spectrum entropy-based adaptive generalized S transformation time-frequency filter. Interference signals in leakage current are effectively eliminated, and the accuracy of insulator pollution monitoring results is improved; dividing the pollution discharge development process into a safe area, a forecast area and a danger area according to the leakage current effective value, and immediately giving an alarm when the pollution discharge development process is in the forecast area and the danger area; when the insulator is in a safe area, in order to comprehensively consider the influence of multiple factors on the surface contamination of the insulator, a comprehensive network comprising multiple input parameters such as the mean value of effective values of leakage current, the maximum value of effective values, the temperature and the humidity is established, the contamination state of the insulator is predicted based on TOPSIS, the monitoring accuracy is improved, and the application scene is expanded.

Description

Technical Field

[0001] The invention relates to the technical field of power equipment detection and monitoring, and in particular to an insulator leakage current collection and measurement device and method. Background Art

[0002] The function of insulators is to ensure the insulation between the conductor and the pole tower. They play a vital role in the distribution line, and their performance directly affects the safe operation of the distribution line. Insulators need to be used outdoors for a long time, so a large amount of solid particles and other substances will accumulate on their surface. Under severe weather conditions such as rain, fog and snow, these dirt attached to the surface of the insulator will increase the conductivity, thereby reducing the insulation performance and causing pollution flashover accidents.

[0003] In order to reduce the occurrence of pollution flashover accidents, the power department regularly inspects and repairs to supervise and maintain power equipment, and regularly cleans and adjusts the creepage distance of insulators. However, this method consumes a lot of manpower, material and financial resources, and is highly blind and has low maintenance efficiency. Therefore, online monitoring technology came into being. Online monitoring technology monitors the surface condition of insulators in real time through current collection and measurement devices installed on the surface of insulators to achieve online monitoring.

[0004] The current online monitoring mainly monitors the leakage current of insulators. By detecting the leakage current, the comprehensive condition of the insulator surface can be grasped. The main problem of the current leakage current monitoring device is that the detection signal is low in accuracy and is greatly affected by external interference. The most widely used monitoring methods are the equivalent salt density method, the pollution layer conductivity method, and the insulator pollution flashover gradient method.

[0005] The equivalent salt density method can be directly observed, is simple to understand and easy to operate, but the operation time is long, and this method is not suitable for online monitoring; the pollution layer conductivity method requires the removal of the insulator, the method is cumbersome, and cannot be applied to online monitoring; the insulator pollution gradient method can determine the actual pollution degree and quality grade of the insulator string, but the test cost is high, the cycle is long, and it is restricted by the area, making maintenance and protection inconvenient.

[0006] In summary, the current detection accuracy of insulator leakage current is not high, and it is necessary to propose an insulator leakage current collection and measurement device and method with high accuracy. Summary of the invention

[0007] The purpose of the present invention is to solve the deficiencies of the prior art and to provide an insulator leakage current collection and measurement device and method to monitor the insulator surface leakage current, temperature and humidity information online and reflect the degree of insulator surface contamination in real time.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] A method for collecting and measuring insulator leakage current comprises the following steps:

[0010] Step (1), collecting leakage current, collecting leakage current flowing from the steel cap to the bottom of the insulator;

[0011] Step (2), leakage current transmission, inputting the current collected in step (1) into a leakage current denoising module;

[0012] Step (3), leakage current denoising, using spectral entropy-based adaptive generalized S transform time-frequency filtering to denoise the current input in step (2);

[0013] Step (3.1), perform generalized S-transform on the leakage current to generate a time-frequency spectrum;

[0014] Step (3.2), dividing the frequency interval of the time-frequency spectrum into multiple small intervals, and calculating the energy of each small interval;

[0015] Step (3.3), calculate the spectral entropy at each time point and determine the filtering threshold;

[0016] Step (3.4), compare the spectral entropy of each point in the time-frequency spectrum with the filtering threshold, select to retain or filter out the signal point, and obtain the time-frequency spectrum after filtering out the noise;

[0017] Step (3.5), after inverse transformation of the filtered time-frequency spectrum, the leakage current signal is obtained;

[0018] Step (4), predicting the insulator contamination state, predicting the insulator contamination state of the current obtained in step (3) in combination with the ambient temperature and humidity;

[0019] Step (4.1), respectively calculate the mean effective value and the maximum effective value of the leakage current;

[0020] Step (4.2), dividing the development process of contaminated discharge into safe zone, forecast zone and danger zone according to the effective value;

[0021] Step (4.3), when in the forecast area and the danger area, an alarm signal is issued. When in the safe area, the insulator contamination probability is predicted based on the TOPSIS method, and a contamination probability signal is output;

[0022] Step (5), transmission of prediction results, transmitting the alarm signal and contamination probability signal in step (4) to the monitoring center.

[0023] Preferably, the generalized s-transformation formula in step (3.1) is:

[0024]

[0025] t=t1,t2,…,t n ; f=f1,f2,…,f m ;

[0026] Where x(t) is the leakage current signal with noise, τ represents the time shift parameter, f is the frequency, λ and p are parameters introduced based on the standard s-transformation; t = t1, t2, …, t n , represents the time domain sampling point; f =

[0027] f1,f2,…,f m , represents the frequency domain sampling points; the time-frequency spectrum forms an n×m matrix, where n and m are the number of sampling points in the time domain and frequency domain respectively.

[0028] Preferably, the specific formula for calculating the energy of each cell in step (3.2) is:

[0029]

[0030] Where N is the number of intervals, represents the energy of the frequency falling on the kth subinterval at the i-th time point, f l k represents the lth frequency value whose frequency falls on the kth subinterval; l represents the lth frequency value whose frequency falls within the kth subinterval, and k is the index of the interval; Gst(t i ,f l k ) is the time point t i and frequency f l k The generalized S transform value at .

[0031] The specific formula for calculating the spectral entropy at each time point and determining the filtering threshold in step (3.3) is:

[0032] E(i,j)=|Gst(t,f)| 2 ;

[0033] i=1,2,…,n; j=1,2,…,m;

[0034]

[0035] k=1,2,…,N;

[0036] Where E(I,j) is the instantaneous energy at the jth frequency point at the i-th time point, p(I,j) is the relative probability of the signal energy at the jth frequency point at the i-th time point under the total energy at the i-th time point, is the spectral entropy of the jth point in the kth subinterval at the i-th time, is the maximum value of the spectral entropy in the kth subinterval at the i-th time, is the mean of the maximum spectral entropy of each subinterval at the i-th moment, and is the filtering threshold at the i-th moment;

[0037] In the step (3.4), the spectral entropy of each point of the GST time-frequency spectrum within the i-th time point is compared with the filtering threshold at that moment. If the value of the point is greater than the threshold, the time-frequency filtering factor is set to 0, otherwise it is set to 1, and steps (3.1-3.3) are repeated until all sampling times are calculated to obtain the time-frequency spectrum with noise filtered out.

[0038] Preferably, in step (3.5), the generalized inverse transformation formula of the filtered time-frequency spectrum is:

[0039]

[0040] Preferably, in the step (4.1), the formula for calculating the mean effective value and the maximum effective value of the leakage current is:

[0041]

[0042] I max =max(I i );

[0043] i=1,2,…,M;

[0044] in, is the mean effective value of leakage current, I max is the maximum effective value of leakage current, M is the number of sampling points, I i is the effective value of the leakage current at the i-th sampling point;

[0045] In the step (4.2), if the effective value of the leakage current is less than 50 mA, it is divided into a safe area; if the effective value of the leakage current is between 50 and 150 mA, it is divided into a warning area; if the effective value of the leakage current is greater than 150 mA, it is divided into a dangerous area.

[0046] Preferably, in step (4.3), the TOPSIS method is used to predict the probability of insulator contamination, comprising the following steps:

[0047] Step (4.3.1), obtaining four characteristic parameters including the leakage current effective value mean value X1, effective value maximum value X2, temperature X3, and relative humidity X4;

[0048] Step (4.3.2), perform positive processing on the characteristic parameters obtained in step (4.3.1);

[0049] Step (4.3.3), normalizing the forward matrix obtained in step (4.3.2) to generate a standardized matrix;

[0050] Step (4.3.4), calculate the insulator contamination probability, and obtain the contamination probability value after normalization.

[0051] Preferably, the forward transformation formula in step (4.3.1) is:

[0052]

[0053] in, It is the positive result of the mean effective value of leakage current, the maximum effective value, temperature and relative humidity; X 1,max , X 2,max , X 4,max They are the mean effective value of the maximum leakage current, the maximum effective value, and the relative humidity in the safe zone; A=max{a-x3,x3-b}, [a,b] is the ideal temperature range.

[0054] Preferably, the standardization formula in step (4.3.2) is:

[0055]

[0056] Step (4.3.3), the standardized matrix is:

[0057]

[0058] Among them, z ij It represents the result after the jth characteristic parameter of the i-th insulator is standardized.

[0059] Preferably, the calculation and normalization formula for the contamination probability of the insulator in the step (4.3.4) is:

[0060]

[0061] Among them, ω j is the weight of the feature parameter, represents the minimum value of the jth characteristic parameter among all insulators; represents the maximum value of the jth characteristic parameter among all insulators; S i is the original contamination probability of the i-th insulator; is the normalized contamination probability of the i-th insulator.

[0062] Another object of the present invention is to provide an insulator leakage current collection and measurement device, comprising:

[0063] The leakage current collection device comprises a collector ring and a shielded conductor; the collector ring is composed of two copper metal half rings, and the collector ring is fixed to the surface of the first insulator piece connecting the insulator string and the tower;

[0064] The control and measurement device comprises a leakage current denoising module, an insulator contamination state prediction module, a power module, a wireless communication module, a temperature and humidity measurement module, and a microprocessor; the leakage current denoising module is used for filtering and denoising; the insulator contamination state prediction module is used for predicting the insulator contamination state; the power module is used for power supply; the wireless communication module is used for sending the contamination state signal to a monitoring center; the temperature and humidity measurement module obtains the ambient temperature and relative humidity data and provides them to the microprocessor; the microprocessor stores the ambient temperature and relative humidity information and assists in determining the probability of insulator contamination in a safe zone.

[0065] The present invention discloses an insulator leakage current collection and measurement device and method having the following beneficial effects.

[0066] Firstly, the present invention can monitor the leakage current, temperature and humidity information of the insulator surface online, reflect the degree of insulator surface pollution in real time, and prevent the occurrence of power system pollution flashover accidents. The present invention utilizes the unique advantages of generalized S transform in non-stationary signal processing and designs an adaptive generalized S transform time-frequency filter based on spectral entropy, which effectively eliminates interference signals in the leakage current and improves the accuracy of insulator pollution monitoring results.

[0067] Secondly, the present invention divides the development process of contamination discharge into three sections: safe zone, forecast zone and danger zone according to the effective value of leakage current. When in the forecast zone and danger zone, an alarm is immediately issued; when in the safe zone, in order to comprehensively consider the influence of various factors on the contamination of the insulator surface, the present invention establishes a comprehensive network including the mean effective value of leakage current, the maximum effective value, and multiple input parameters such as temperature and humidity, and predicts the contamination state of the insulator based on the superior and inferior solution distance method TOPSIS, which improves the accuracy of monitoring and expands the application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 The present invention is a flow chart of the insulator leakage current collection and measurement method.

[0069] Figure 2 It is a schematic diagram of the insulator leakage current collection and measurement device of the present invention.

[0070] Figure 3 This is a flowchart of the generalized s-transform denoising process based on spectral entropy of the present invention.

[0071] Figure 4 This is a flow chart for predicting the contamination state of insulators according to the present invention.

[0072] Figure 5 The figure is a schematic diagram of the installation of the insulator leakage current collection and measurement device of the present invention.

[0073] In the attached figure: 1. leakage current collection device; 11. collector ring; 12. shielded conductor; 2. control and measurement device; 3. insulator; 4. monitoring center; 5. pole tower. DETAILED DESCRIPTION

[0074] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0075] In the description of the present invention, it is necessary to understand that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0076] Example 1

[0077] The present invention discloses an insulator leakage current collection and measurement device, which is used for collecting and measuring the leakage current of an online insulator 3.

[0078] Please refer to Figure 2 and Figure 5 , an insulator leakage current collection and measurement device, comprising:

[0079] The leakage current collection device 1 comprises a collector ring 11 and a shielded conductor 12; specifically, the collector ring 11 is composed of two copper metal half rings, and during installation, the two half rings are fixed to the surface of the first insulator 3 connected to the tower 5 by bolts, and are attached to the surface of the insulator 3 to collect the surface leakage current of the insulator 3, and conductive glue is applied at the contact point between the collector ring 11 and the surface of the insulator 3 to improve the current collection effect; the shielded conductor 12 is a double-layer shielded wire, and the shielding layer of the shielded cable of the shielded conductor 12 is mainly made of non-magnetic materials such as copper and aluminum to shield external interference and improve the overall anti-interference ability of the collection and measurement device;

[0080] The control and measurement device 2 includes a leakage current denoising module, an insulator 3 contamination state prediction module, a power module, a wireless communication module, a temperature and humidity measurement module, and a microprocessor; the leakage current denoising module is used for filtering and denoising; the insulator 3 contamination state prediction module is used for predicting the contamination state of the insulator 3; the power module is used for power supply; the wireless communication module is used for sending the contamination state signal to the monitoring center 4; the temperature and humidity measurement module obtains the ambient temperature and relative humidity data and provides them to the microprocessor; the microprocessor stores the ambient temperature and relative humidity information and assists in determining the contamination probability of the insulator 3 in the safe zone. The microprocessor specifically uses an STM32 or ESP32 single-chip microcomputer, and the leakage current denoising module, the insulator 3 contamination state prediction module, the power module, the wireless communication module, the temperature and humidity measurement module, and the microprocessor in the control and measurement device 2 are installed in a shell. The shell of the device is made of stainless steel, and bolt holes are opened on the shell, and it is fixedly installed on the pole tower 5 with fixing bolts. The power module includes a solar panel and a battery. The solar panel is adhered to the outer wall of the device shell. The solar panel and the battery together supply energy to the device. The wireless communication module specifically adopts RS-485 communication mode, and uses RS-485 serial communication to support bus structure, which can achieve longer transmission distance, support long-distance communication, up to 1200 meters, higher data transmission rate, the data transmission rate can reach up to 10Mbps, with higher security and data transmission rate.

[0081] Example 2

[0082] The present invention discloses a method for collecting and measuring an insulator leakage current, and uses the device in Example 1 to perform online insulator leakage current collection and measurement.

[0083] Please refer to Figure 1 , a method for collecting and measuring insulator leakage current, comprising the following steps:

[0084] Step (1), leakage current collection, collecting the leakage current flowing from the steel cap to the bottom of the insulator 3 by means of the collector ring 11;

[0085] Step (2), leakage current transmission, inputting the current collected in step (1) into a leakage current denoising module;

[0086] Step (3), such as Figure 3 As shown, the leakage current denoising uses adaptive generalized S transform time-frequency filtering based on spectral entropy to denoise the current input in step (2);

[0087] Step (3.1), perform generalized S-transform on the leakage current to generate a time-frequency spectrum;

[0088] The leakage current signal x(t) collected from the collector ring 11 is subjected to a generalized s-transform to obtain the time-frequency spectrum, that is,

[0089] T=t1,t2,…,t n ; f=f1,f2,…,f m ;

[0090] The time-frequency spectrum is an nxm matrix, where n and m are the number of sampling points in the time domain and frequency domain, respectively; τ represents the time shift parameter, f is the frequency, λ and p are parameters introduced based on the standard s transform; λ and p are selected according to the specific leakage current signal; t = t1, t2, …, t n , represents the time domain sampling point; f =

[0091] f1,f2,…,f m , represents the frequency domain sampling point.

[0092] Step (3.2), divide the frequency interval of the time spectrum into multiple small intervals, and calculate the energy of each small interval; divide the frequency interval of the time spectrum into N small intervals, and calculate the energy of the kth sub-interval as in, represents the energy of the frequency falling on the kth subinterval at the i-th time point, f l k represents the lth frequency value whose frequency falls on the kth subinterval, l represents the lth frequency value whose frequency falls within the kth subinterval, and k is the index of the interval; Gst(t i ,f l k ) is the time point t i and frequency f l k The generalized S transform value at .

[0093] Step (3.3), calculate the spectral entropy at each time point and determine the filtering threshold; calculate the spectral entropy of each subinterval at the i-th time point. Define the instantaneous energy at the j-th frequency point at the i-th time point as, E(i,j)=|Gst(t,f)| 2 ,i=1,2,…,n;j=1,2,…,m, then the probability of the signal energy at the jth frequency point at the ith time point under the total energy at the ith time point is, Then the spectral entropy of the jth point in the kth subinterval at the i-th time is And find the point with the largest spectral entropy in the kth subinterval at the i-th time, recorded as Then, calculate the mean of the maximum spectral entropy of each subinterval at the i-th moment k=1,2,…,N, That is the filtering threshold at the i-th moment.

[0094] Step (3.4), compare the spectral entropy of each point in the time spectrum with the filtering threshold, select to retain or filter out the signal point, and obtain the time spectrum with noise filtered out; compare the spectral entropy of each point of the GST time spectrum in the i-th time point with the filtering threshold at that moment, if the value of the point is greater than the threshold, the time-frequency filtering factor is set to 0, otherwise it is set to 1. Repeat steps (3.1-3.3) until all sampling times are calculated to obtain the time spectrum with noise filtered out.

[0095] Step (3.5), after the filtered time-frequency spectrum is generalized s inversely transformed, the leakage current signal is obtained; the generalized s inverse transformation formula is:

[0096]

[0097] Step (4), such as Figure 4 As shown, the insulator contamination state prediction is performed by combining the ambient temperature and humidity with the current obtained in step (3) to predict the insulator contamination state;

[0098] Step (4.1), respectively calculate the mean effective value and the maximum effective value of the leakage current; the formula for calculating the mean effective value and the maximum effective value of the leakage current is:

[0099] in, is the mean effective value of leakage current, I max is the maximum effective value of leakage current, M is the number of sampling points, I i is the effective value of the leakage current at the i-th sampling point.

[0100] Step (4.2), the development process of the contaminated discharge is divided into a safe zone, a warning zone and a dangerous zone according to the effective value; if the effective value of the leakage current is <50mA, it is divided into a safe zone, if the effective value of the leakage current is between 50 and 150mA, it is divided into a warning zone, and if the effective value of the leakage current is >150mA, it is divided into a dangerous zone.

[0101] Step (4.3), when in the forecast area and the danger area, an alarm signal is issued, and when in the safe area, the probability of insulator contamination is predicted based on the TOPSIS method, and a contamination probability signal is output; the prediction of the probability of insulator contamination using the TOPSIS method includes the following steps:

[0102] Step (4.3.1), there are n insulator leakage currents in the safe zone, including the leakage current effective value mean X1, effective value maximum X2, and four characteristic parameters including temperature X3 and relative humidity X4. Obtaining the four characteristic parameters including the leakage current effective value mean X1, effective value maximum X2, and temperature X3 and relative humidity X4 belongs to the extremely small index;

[0103] Step (4.3.2) performs forward processing on the characteristic parameters obtained in step (4.3.1); the forward processing formula is:

[0104]

[0105] in, It is the positive result of the mean effective value of leakage current, the maximum effective value, temperature and relative humidity; X 1,max , X 2,max , X 4,max They are the mean effective value of the maximum leakage current in the safety zone, the maximum effective value, and the relative humidity; A=max{a-x3,x3-b}, [a,b] is the ideal temperature range

[0106] Step (4.3.3), normalize the forward matrix obtained in step (4.3.2) to generate a normalized matrix; the normalization formula is:

[0107]

[0108] The standardized matrix is ​​obtained as:

[0109]

[0110] Among them, z ij It represents the result after the jth characteristic parameter of the i-th insulator is standardized.

[0111] Step (4.3.4), calculate the insulator contamination probability, and obtain the contamination probability value after normalization. The formula for calculating and normalizing the insulator contamination probability is:

[0112]

[0113] Among them, ω j is the weight of the feature parameter, represents the minimum value of the jth characteristic parameter among all insulators; represents the maximum value of the jth characteristic parameter among all insulators; S i is the original contamination probability of the i-th insulator; is the normalized contamination probability of the i-th insulator.

[0114] Step (5), transmission of prediction results, transmitting the alarm signal and contamination probability signal in step (4) to the monitoring center 4.

[0115] The above are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. The substitution may be a substitution of a part of the structure, device, method step, or a complete technical solution. The equivalent replacement or change according to the technical solution and the inventive concept of the present invention shall be covered within the protection scope of the present invention.

Claims

1. A method for collecting and measuring insulator leakage current, characterized in that: The steps include: Step (1), collecting leakage current, collecting leakage current flowing from the steel cap to the bottom of the insulator; Step (2), leakage current transmission, inputting the current collected in step (1) into a leakage current denoising module; Step (3), leakage current denoising, using spectral entropy-based adaptive generalized S transform time-frequency filtering to denoise the current input in step (2); Step (3.1), perform generalized S-transform on the leakage current to generate a time-frequency spectrum; Step (3.2), dividing the frequency interval of the time-frequency spectrum into multiple small intervals, and calculating the energy of each small interval; Step (3.3), calculate the spectral entropy at each time point and determine the filtering threshold; Step (3.4), compare the spectral entropy of each point in the time-frequency spectrum with the filtering threshold, select to retain or filter out the signal point, and obtain the time-frequency spectrum after filtering out the noise; Step (3.5), after inverse transformation of the filtered time-frequency spectrum, the leakage current signal is obtained; Step (4), predicting the insulator contamination state, predicting the insulator contamination state of the current obtained in step (3) in combination with the ambient temperature and humidity; Step (4.1), respectively calculate the mean effective value and the maximum effective value of the leakage current; Step (4.2), dividing the development process of contaminated discharge into safe zone, forecast zone and danger zone according to the effective value; Step (4.3), when in the forecast area and the danger area, an alarm signal is issued. When in the safe area, the insulator contamination probability is predicted based on the TOPSIS method, and a contamination probability signal is output; Step (5), transmission of prediction results, transmitting the alarm signal and contamination probability signal in step (4) to the monitoring center.

2. The insulator leakage current collection and measurement method according to claim 1, characterized in that: The generalized s-transformation formula in step (3.1) is: t=t1,t2,…,t n ;f=f1,f2,…,f m ; Where x(t) is the leakage current signal with noise, τ represents the time shift parameter, f is the frequency, λ and p are parameters introduced based on the standard s-transformation; t = t1, t2, …, t n , represents the time domain sampling point; f=f1,f2,…,f m , represents the frequency domain sampling points; the time-frequency spectrum forms an n×m matrix, where n and m are the number of sampling points in the time domain and frequency domain respectively.

3. The insulator leakage current collection and measurement method according to claim 1, characterized in that: The specific formula for calculating the energy of each small interval in step (3.2) is: Where N is the number of intervals, represents the energy of the frequency falling on the kth subinterval at the i-th time point, f l k represents the lth frequency value whose frequency falls on the kth subinterval; l represents the lth frequency value whose frequency falls within the kth subinterval, and k is the index of the interval; is the time point t i and frequency f l k The generalized S transform value at . The specific formula for calculating the spectral entropy at each time point and determining the filtering threshold in step (3.3) is: E(i,j)=|Gst(t,f)| 2 ; i=1,2,…,n; j=1,2,…,m; k=1,2,…,N; Where E(I,j) is the instantaneous energy at the jth frequency point at the i-th time point, p(I,j) is the relative probability of the signal energy at the jth frequency point at the i-th time point under the total energy at the i-th time point, is the spectral entropy of the jth point in the kth subinterval at the i-th time, is the maximum value of the spectral entropy in the kth subinterval at the i-th time, is the mean of the maximum spectral entropy of each subinterval at the i-th moment, and is the filtering threshold at the i-th moment; In the step (3.4), the spectral entropy of each point of the GST time-frequency spectrum within the i-th time point is compared with the filtering threshold at that moment. If the value of the point is greater than the threshold, the time-frequency filtering factor is set to 0, otherwise it is set to 1, and steps (3.1-3.3) are repeated until all sampling times are calculated to obtain the time-frequency spectrum with noise filtered out.

4. The insulator leakage current collection and measurement method according to claim 1, characterized in that: In step (3.5), the generalized inverse transformation formula of the filtered time-frequency spectrum path s is:

5. The insulator leakage current collection and measurement method according to claim 1, characterized in that: In the step (4.1), the formula for calculating the mean effective value and the maximum effective value of the leakage current is: I max =max(I i ); i=1,2,…,M; in, is the mean effective value of leakage current, I max is the maximum effective value of leakage current, M is the number of sampling points, I i is the effective value of the leakage current at the i-th sampling point; In the step (4.2), if the effective value of the leakage current is less than 50 mA, it is divided into a safe area; if the effective value of the leakage current is between 50 and 150 mA, it is divided into a warning area; if the effective value of the leakage current is greater than 150 mA, it is divided into a dangerous area.

6. The insulator leakage current collection and measurement method according to claim 1, characterized in that: In the step (4.3), the TOPSIS method is used to predict the probability of insulator contamination, including the following steps: Step (4.3.1), obtaining four characteristic parameters including the leakage current effective value mean value X1, effective value maximum value X2, temperature X3, and relative humidity X4; Step (4.3.2), perform positive processing on the characteristic parameters obtained in step (4.3.1); Step (4.3.3), normalizing the forward matrix obtained in step (4.3.2) to generate a standardized matrix; Step (4.3.4), calculate the insulator contamination probability, and obtain the contamination probability value after normalization.

7. The insulator leakage current collection and measurement method according to claim 1, characterized in that: The forward conversion formula in step (4.3.1) is: in, It is the positive result of the mean effective value of leakage current, the maximum effective value, temperature and relative humidity; X 1,max , X 2,max , X 4,max They are the mean effective value of the maximum leakage current, the maximum effective value, and the relative humidity in the safe zone; A=max{a-x3,x3-b}, [a,b] is the ideal temperature range.

8. The insulator leakage current collection and measurement method according to claim 1, characterized in that: The standardization formula in step (4.3.2) is: Step (4.3.3), the standardized matrix is: Among them, z ij It represents the result after the jth characteristic parameter of the i-th insulator is standardized.

9. The insulator leakage current collection and measurement method according to claim 1, characterized in that: The calculation and normalization formula of the insulator contamination probability in step (4.3.4) is: j＝1,2,…,4； Among them, ω j is the weight of the feature parameter, represents the minimum value of the jth characteristic parameter among all insulators; represents the maximum value of the jth characteristic parameter among all insulators; S i is the original contamination probability of the i-th insulator; is the normalized contamination probability of the i-th insulator.

10. An insulator leakage current collection and measurement device, characterized in that: include: The leakage current collection device comprises a collector ring and a shielded conductor; the collector ring is composed of two copper metal half rings, and the collector ring is fixed to the surface of the first insulator piece connecting the insulator string and the tower; The control and measurement device comprises a leakage current denoising module, an insulator contamination state prediction module, a power module, a wireless communication module, a temperature and humidity measurement module, and a microprocessor; the leakage current denoising module is used for filtering and denoising; the insulator contamination state prediction module is used for predicting the insulator contamination state; the power module is used for power supply; the wireless communication module is used for sending the contamination state signal to a monitoring center; the temperature and humidity measurement module obtains the ambient temperature and relative humidity data and provides them to the microprocessor; the microprocessor stores the ambient temperature and relative humidity information and assists in determining the probability of insulator contamination in a safe zone.

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