Three-dimensional visual substation equipment local abnormal discharge positioning method and system

Abstract

The invention discloses a three-dimensional visual transformer substation equipment local abnormal discharge positioning method and a three-dimensional visual transformer substation equipment local abnormal discharge positioning system, and relates to the technical field of discharge positioning. Performing Hanning window processing and discrete Fourier transform to obtain a power spectrum, defining a working band, calculating a power spectrum mean value and a cross-channel spectrum value to determine a free spectrum interval, and generating a comb line center set; calculating a parasitic leakage index, and dividing the broadband energy by the index to obtain equalized broadband energy; based on this, a partial discharge space coordinate is calculated by combining sensor installation parameters, and finally, a device three-dimensional model is associated to realize three-dimensional visualization of a positioning result; according to the scheme, the interference of parasitic resonance on positioning is eliminated, the comparability of amplitude and distance attenuation is recovered, the positioning accuracy is improved, three-dimensional visualization is convenient for operation and maintenance personnel to quickly identify a discharge part, and the safe operation of substation equipment is ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of discharge positioning, in particular to a three-dimensional visual substation equipment partial abnormal discharge positioning method and system. BACKGROUND

[0002] In a hybrid compartment composed of gas insulated switchgear and cable termination, the epoxy sleeve and stress cone of the cable termination form a special axisymmetric thick-walled dielectric body. The ultra-high frequency pulse signals generated by partial discharge need to be collected by multiple sensors to realize positioning. The existing technology often relies on the law that the amplitude or energy of the ultra-high frequency pulse attenuates with the propagation distance, and the position of the partial discharge source is inversely calculated by comparing the amplitude ratio of the signals collected by different sensors. However, when the ultra-high frequency pulse generated by the partial discharge propagates inside the axisymmetric thick-walled dielectric body composed of the epoxy sleeve and stress cone of the cable termination, it will cause unexpected parasitic resonance due to the interface reflection of the dielectric and metal parts and the matching relationship between the structure geometric size and the electromagnetic wave wavelength. The parasitic resonance will cause the energy of the ultra-high frequency pulse to present a series of equally spaced parasitic comb lines in the frequency domain, and the degree of influence of different ultra-high frequency sensor channels on parasitic resonance is different. The parasitic resonance selectively stores the energy of the ultra-high frequency pulse generated by the internal defect in a specific narrow band and leaks directionally through openings such as flange openings, resin holes or slits.

[0003] The parasitic echo will cause the equivalent channel gain of each sensor in the parasitic narrow band to be amplified by different amplitudes, and the amplification amplitude is closely related to the directivity of the opening, thereby destroying the positioning assumption that the attenuation of the signal amplitude or energy is only related to the propagation distance and path geometry. Based on the existing partial discharge positioning method, the amplitude-frequency consistency is destroyed by parasitic resonance and directional leakage. Even if the difference in signal arrival time is not considered, there will be systematic positioning deviation, which cannot accurately determine the actual position of the partial discharge source in the substation equipment space, seriously affecting the accuracy of equipment insulation state evaluation and fault repair. SUMMARY

[0004] In view of the shortcomings of the prior art, the present application provides a three-dimensional visual substation equipment partial abnormal discharge positioning method and system, which solves the problem that the actual position of the partial discharge source in the substation equipment space cannot be accurately determined.

[0005] To achieve the above purpose, the present application realizes the following technical solutions: The time-domain waveform of the same partial discharge event is collected by the ultra-high frequency sensor, the power spectrum is obtained by performing discrete Fourier transform on the time-domain waveform, the power spectrum includes the power values of the frequency points marked at different frequency positions in the sensor channel, the power spectrum mean value of the power spectrum is obtained, a preset test frequency interval, the cross-channel spectral value is calculated according to the product of the difference value of the power values of the two frequency points in the test frequency interval and the power spectrum mean value, the test frequency interval with the maximum cross-channel spectral value is marked as the free spectrum interval through traversal test, the comb line center frequency is generated in turn with the free spectrum interval as the step, and each comb line center frequency is mapped to the frequency point closest to the interval; The power values of the frequency points corresponding to all comb line center frequencies are accumulated and summed to obtain the comb spectrum energy, the center frequency obtained by adding one-half of the free spectrum interval to the comb line center frequency is marked as the anti-comb line center frequency, the anti-comb spectrum energy is calculated according to the anti-comb line center frequency, the value obtained by dividing the comb spectrum energy by the anti-comb spectrum energy is marked as the parasitic leakage index, the value obtained by accumulating and summing the power values of all frequency points in the power spectrum is marked as the wideband energy, the value obtained by dividing the wideband energy by the parasitic leakage index is marked as the equalized wideband energy, and the partial abnormal discharge is located based on the equalized wideband energy.

[0006] Further, the time-domain waveform corresponding to each sensor channel is windowed by a Hanning window before being subjected to discrete Fourier transform, the power spectrum of the sensor channel is obtained by taking the modulus of the result of the discrete Fourier transform and squaring it; An effective analysis frequency range determined by the ultra-high frequency radiation characteristics of the substation equipment and the sampling system bandwidth is defined, and the effective analysis frequency range is marked as the working band, the power values of all frequency points in the power spectrum of each sensor channel are accumulated and summed in the working band, and then the summation result is divided by the number of frequency points in the working band to obtain the average value of each sensor channel power spectrum in the working band, and the average value is marked as the power spectrum mean value; The number of frequency points is the ratio of the difference between the upper limit of the frequency in the working band and the lower limit of the frequency to the frequency resolution, wherein the frequency resolution is the frequency interval of adjacent frequency points in the discrete Fourier transform.

[0007] Further, a preset test frequency interval is preset, and the test frequency interval is a frequency difference between 0 and the upper limit of the frequency of the working band. For the same sensor channel, the number of frequency points n in the working band is spaced at the interval of the frequency interval to be measured, the difference value obtained by subtracting the power spectrum average from the power value of the i-th frequency point is multiplied by the difference value obtained by subtracting the power spectrum average from the power value of the frequency point at the interval of the frequency to be measured, and then the product of n-1 frequency point pairs is obtained, and the sum of the products of n-1 frequency point pairs is accumulated and summed up, and the sum value obtained by summing up the sum values of all sensor channels is accumulated to obtain a cross-channel spectrum value, and the cross-channel spectrum value is a measure of the similarity of the power spectrum at the interval of the frequency to be measured. The result of traversing the cross-channel spectrum value obtained by inputting the above calculation process to each frequency interval to be measured will mark the frequency interval to be measured with the maximum cross-channel spectrum value as the free spectrum interval, and the free spectrum interval is the frequency difference between the adjacent two lines of the parasitic comb spectrum.

[0008] Further, from the lower limit frequency of the working band to the upper limit frequency of the working band, the comb line center frequency is generated in turn with the free spectrum interval as the step size, and the comb line center frequency = the lower limit frequency of the working band + n x the free spectrum interval, n is the order of generating the comb line center frequency. Then map each comb line center frequency to the frequency point closest to the frequency interval, and combine all the mapped frequency points into a comb line center set, and the comb line center set is a set of comb line center frequencies aligned with the frequency points.

[0009] Further, for the m-th sensor channel, the power values of the frequency points corresponding to all the comb line center frequencies in the comb line center set in the power spectrum are accumulated and summed up to obtain the comb spectrum energy of the m-th sensor channel, and the comb spectrum energy is the total energy of the frequency points corresponding to the parasitic comb spectrum.

[0010] Further, for the m-th sensor channel, all the comb line center frequencies in the comb line center set are traversed in turn to calculate the anti-comb line center frequency, and the specific calculation method is: The center frequency obtained by adding one-half of the free spectrum interval to each comb line center frequency in the comb line center set is marked as the anti-comb line center frequency, and the anti-comb line center frequency is a reference position without parasitic comb spectrum energy. For the anti-comb line center frequency, map each anti-comb line center frequency to the frequency point closest to the frequency interval, and accumulate and sum up the power values of the frequency points corresponding to all the anti-comb line center frequencies in the power spectrum to obtain the anti-comb spectrum energy of the m-th sensor channel, and the anti-comb spectrum energy is the total energy of the non-comb spectrum reference position.

[0011] Further, the comb spectrum energy of the m-th sensor channel is divided by the anti-comb spectrum energy to obtain a value marked as a parasitic leakage index, and the parasitic leakage index is a dimensionless parasitic leakage index of the m-th sensor channel. For the mth sensor channel, the value obtained by accumulating and summing the power values of all frequency points in the power spectrum within the working band is marked as the broadband energy of the mth sensor channel, and the broadband energy is the total energy of the mth channel within the working band; For the mth sensor channel, the value obtained by dividing the broadband energy of the mth sensor channel by the parasitic leakage index of the mth sensor channel is marked as the equalized broadband energy, and the equalized broadband energy is the corrected broadband energy of the mth sensor channel.

[0012] Further, a three-dimensional space model is constructed based on the coordinate system in the substation, sensor three-dimensional coordinates of each ultra-high frequency sensor in the coordinate system in the substation are obtained, the sensor three-dimensional coordinates are calibrated when the equipment is installed, a device three-dimensional allowable domain is obtained, the device three-dimensional allowable domain is a three-dimensional space range where a partial discharge source can exist, three-dimensional coordinate points in the device three-dimensional allowable domain are traversed, and the three-dimensional coordinate points in the device three-dimensional allowable domain are marked as candidate source points, the sensor three-dimensional coordinates and the device three-dimensional allowable domain are imported into the three-dimensional space model; The straight-line distance of each candidate source point to each ultra-high frequency sensor in the three-dimensional space is calculated, and the straight-line distance is marked as the equivalent distance, the equivalent distance is the spatial distance from the candidate source point to the mth sensor, and reflects the propagation path length of the signal from the partial discharge source to the sensor; For any two sensor channels, a logarithmic amplitude ratio is generated based on the equalized broadband energy of the sensor channels, specifically as follows: The ratio of the equalized broadband energy of the i th sensor channel to the equalized broadband energy of the j th sensor channel is taken as a natural logarithm to obtain a logarithmic amplitude ratio, and the logarithmic amplitude ratio reflects the logarithmic difference in energy attenuation after equalization of the two sensor channels; For any two sensor channels, a logarithmic distance ratio is generated based on the equivalent distance of the candidate source point to the sensor channel, specifically as follows: The ratio of the equivalent distance of the n th candidate source point to the i th sensor channel to the equivalent distance of the n th candidate source point to the j th sensor channel is taken as a natural logarithm to obtain a logarithmic distance ratio, and the logarithmic distance ratio reflects the logarithmic difference in distance from the candidate source point to the two sensors.

[0013] Further, the result of multiplying the logarithmic amplitude ratio and the logarithmic distance ratio of each pair of sensor channels corresponding to the same candidate source point is accumulated, and then divided by the sum of the squares of all logarithmic distance ratios corresponding to the same candidate source point to obtain a geometric attenuation proportionality coefficient, and the geometric attenuation proportionality coefficient reflects the proportional relationship between amplitude attenuation and distance attenuation; for each pair of sensors corresponding to the same candidate source point, square the difference between the logarithmic amplitude ratio corresponding to each pair of sensors and the product of the geometric attenuation proportional coefficient and the logarithmic distance ratio, and then accumulate and sum the square results of each pair of sensors corresponding to the same candidate source point to obtain a total residual error; Within the domain allowed by the device geometry, all candidate source points are traversed to obtain a candidate source point that minimizes the total residual error value, and the candidate source point is marked as a partial discharge positioning result; The partial discharge positioning result is output to a three-dimensional visualization interface.

[0014] Further, a substation device partial discharge positioning system for three-dimensional visualization is proposed, which is used to implement the partial discharge positioning method of any one of the above, comprising: The comb line center generation module obtains the time domain waveform of the same partial discharge event collected by the ultra-high frequency sensor, performs discrete Fourier transform on the time domain waveform after Hanning window processing to obtain the power spectrum, defines the working band, calculates the power spectrum mean value and cross-channel spectrum value of each sensor channel, determines the free spectrum interval, generates the comb line center frequency from the lower limit frequency of the working band with the free spectrum interval as the step, and maps it to the frequency point to form a comb line center set; The parasitic index calculation module accumulates the power spectrum power values of the frequency points corresponding to the comb line center set to obtain the comb spectrum energy, calculates the anti-comb line center frequency, and accumulates the power values after mapping the frequency points to obtain the anti-comb spectrum energy. The comb spectrum energy is divided by the anti-comb spectrum energy to obtain the parasitic leakage index reflecting the strength of the influence of the circumferential parasitic resonance echo on the channel; The wideband energy equalization module accumulates the power spectrum power values of all frequency points in the working band to obtain the wideband energy, and divides the wideband energy by the parasitic leakage index to obtain the equalized wideband energy. The narrowband amplification interference caused by parasitic resonance is eliminated, the comparability of amplitude and distance attenuation is restored, and it is ensured that the equalized wideband energy is only determined by the distance and propagation path from the partial discharge source to the sensor; The discharge positioning calculation module calculates the three-dimensional spatial coordinates of the partial discharge source based on the equalized wideband energy of each sensor channel, combines the installation position parameters of the sensor, and determines the specific position of the partial discharge according to the physical law of amplitude attenuation with distance; The three-dimensional visualization module associates the positioning result of the partial discharge source with the three-dimensional space model, displays the spatial position of the discharge point in the device through visualization technology, realizes the three-dimensional visualization of the partial discharge positioning result, and facilitates the accurate identification of the discharge part by the operation and maintenance personnel.

[0015] Compared with the prior art, the following beneficial effects are achieved: The method and system for locating partial discharge of substation equipment in three-dimensional visualization provided by the scheme, by acquiring time-domain waveforms collected by an ultra-high frequency sensor in a mixed interval formed by a gas insulated switchgear and a cable terminal, performing discrete Fourier transform on the waveforms after Hanning window processing to obtain a power spectrum, defining a working band and calculating the mean value of the power spectrum, and then determining a free spectrum interval that maximizes the value through cross-channel spectrum values, and further generating comb line center frequencies with the free spectrum interval as the step size from the lower limit frequency of the working band and composing a comb line center set, the parasitic resonance related frequency points are accurately locked; The scheme realizes quantitative comparison of parasitic interference of each sensor channel through a parasitic leakage index, obtains comb spectrum energy by accumulating power of the corresponding frequency points of the comb line center set, calculates anti-comb line center frequencies and accumulates power of the corresponding frequency points to obtain anti-comb spectrum energy, and the ratio of the two is the parasitic leakage index, which is a dimensionless value and can accurately reflect the strength of the influence of the circumferential parasitic resonance echo on each channel, and at the same time eliminates the interference of the difference in the overall energy level of different channels on the interference judgment, solving the problem that the prior art cannot quantify the degree of channel interference and is difficult to unify the analysis standard; The scheme completely solves the core problem of positioning distortion caused by parasitic resonance by equalizing the wideband energy, and the wideband energy obtained by accumulating the power of all frequency points in the working band of the sensor channel is divided by the parasitic leakage index to obtain the equalized wideband energy. In this process, the abnormal amplification of parasitic resonance on narrowband energy is regarded as equivalent multiplicative gain and removed, so that the equalized wideband energy is only determined by the distance and propagation path of the partial discharge source to the sensor, the physical law of amplitude decay with distance is restored, the distance judgment deviation caused by the destruction of amplitude-frequency consistency in the prior art is avoided, and the positioning accuracy is greatly improved; The scheme improves the operation and maintenance practicability in combination with three-dimensional visualization, calculates the discharge space coordinates according to the amplitude decay law based on the equalized wideband energy and sensor installation parameters, associates the positioning results with the three-dimensional model of the equipment, and intuitively displays the specific position of the discharge point in the mixed interval, solving the problem that the operation and maintenance personnel cannot quickly locate the maintenance position, and significantly improving the fault troubleshooting efficiency and the operation safety of the substation equipment. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 It is a method flowchart of the present application; Figure 2 It is a system framework schematic diagram of the present application; DETAILED DESCRIPTION

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] First Embodiment

[0019] This application provides a three-dimensional visualization method for locating local abnormal discharges in substation equipment; The method specifically includes the following steps: The time-domain waveform of the same partial discharge event is acquired by an ultra-high frequency sensor. The power spectrum is obtained by performing a discrete Fourier transform on the time-domain waveform. The power spectrum includes the power values ​​of frequency points marked at different frequency positions in the sensor channel. The power spectrum mean is obtained. The frequency interval to be tested is preset. The cross-channel spectrum value is calculated based on the product of the difference between the power values ​​of the two frequency points of the frequency interval to be tested and the power spectrum mean. The frequency interval to be tested with the largest cross-channel spectrum value is marked as the free spectrum interval by traversal test. The comb center frequency is generated sequentially with the free spectrum interval as the step size. Each comb center frequency is mapped to the frequency point with the closest interval. The comb spectrum energy is obtained by summing the power values ​​of all frequency points corresponding to the center frequencies of the comb lines. The center frequency obtained by adding half of the free spectrum interval to the center frequency of the comb lines is marked as the center frequency of the anti-comb line. The anti-comb spectrum energy is calculated based on the center frequency of the anti-comb line. The value obtained by dividing the comb spectrum energy by the anti-comb spectrum energy is marked as the parasitic leakage index. The value obtained by summing the power values ​​of all frequency points in the power spectrum is marked as the broadband energy. The value obtained by dividing the broadband energy by the parasitic leakage index is marked as the equalized broadband energy. Local abnormal discharges are located based on the equalized broadband energy.

[0020] Second Embodiment

[0021] Please see Figure 1 As a second embodiment of this application, this embodiment is implemented based on the first embodiment, and the method provided in this embodiment includes the following steps: Step 1: Obtain the time-domain waveform of the same partial discharge event collected in the mixed interval formed by the gas-insulated switchgear and the cable terminal. For example, install four or more UHF sensors at the cable terminal flange or the detection port of the gas-insulated switchgear housing to collect the time-domain signal of the same partial discharge event, and convert the time-domain signal into a time-domain waveform. The time-domain waveform corresponding to each sensor channel obtained is windowed by a Hanning window and then subjected to discrete Fourier transform, the result of the discrete Fourier transform is squared after being taken modulo to obtain the power spectrum of the sensor channel, the power spectrum can reflect the power values of different frequency points of the sensor channel, the frequency point is a discrete point in the frequency domain used to mark different frequency positions obtained by multiplying the frequency resolution determining the discrete Fourier transform and the frequency point sequence number, the specific frequency value corresponding to the frequency component in the frequency domain, the frequency resolution is equal to the ratio of the sampling rate of the sensor and the set length of the sample point number used to analyze the time-domain waveform, that is, the frequency interval of adjacent frequency points in the discrete Fourier transform; An effective analysis frequency range determined by the ultra-high frequency radiation characteristics of the substation equipment and the bandwidth of the sampling system is defined, for example, the range is [300MHz, 1.5GHz], and the effective analysis frequency range is marked as the working band, the power values of all frequency points in the power spectrum of each sensor channel are summed in the working band, and then the sum is divided by the number of frequency points in the working band to obtain the average value of each sensor channel power spectrum in the working band, and the average value is marked as the power spectrum average value, the power spectrum average value is used to eliminate the interference of the overall energy level difference of the channel on the subsequent analysis, specifically, the number of frequency points = the difference between the upper limit of the frequency in the working band and the lower limit of the frequency divided by the frequency resolution; For the same sensor channel, the number of frequency points with a frequency interval of a to-be-measured frequency interval in the working band is n, the difference between the power value of the i th frequency point and the power spectrum average value is multiplied by the difference between the power value of the i+ to-be-measured frequency interval frequency point and the power spectrum average value to obtain n-1 frequency point pair products, and then the n-1 frequency point pair products are summed to obtain the sum value, and then the sum value of all sensor channels is summed to obtain the cross-channel spectrum value, specifically, assuming that the number of frequency points of the same sensor channel in the working band is 10, and the number of frequency points with a to-be-measured frequency interval is 5, then there are 4 frequency point pairs, for example, the 1 st frequency point and the 2 nd frequency point are a frequency point pair, the 2 nd and the 3 rd frequency points are a frequency point pair, and the 5 th frequency point is only with the 4 th frequency point, that is, a frequency point pair, then 4 products will be obtained, and the sum of the 4 products is summed to obtain the sum value in a single sensor channel, and then the sum value of all sensor channels is summed to obtain the cross-channel spectrum value; Specifically, the to-be-measured frequency interval is a series of frequency differences in the preset value range of 0 to the upper limit of the working band, which is used to find the interval that makes the cross-channel spectrum value maximum, and the cross-channel spectrum value is used to measure the similarity of the power spectrum at the to-be-measured frequency interval, if the power spectrum exists equidistant comb spectrum lines, when the to-be-measured frequency interval is equal to the comb spectrum line interval, the cross-channel spectrum value will reach the maximum value; The result of traversing each test frequency interval input into the above calculation process to obtain the cross-channel spectrum value will mark the test frequency interval with the maximum cross-channel spectrum value as the free spectrum interval, and the free spectrum interval is the frequency difference between the adjacent two spectrum lines of the parasitic comb spectrum line, which is one of the core representations of the parasitic resonance, and provides interval basis for subsequent generation of the comb line center set; Specifically, in a hybrid interval formed by a gas-insulated switchgear and a cable terminal, the epoxy sleeve and stress cone of the cable terminal form an axisymmetric thick-walled medium. When the ultra-high frequency pulse generated by partial discharge propagates in this structure, due to factors such as the interface between the medium and the metal part and the structure geometry, an unexpected electromagnetic wave resonance phenomenon will be triggered. This resonance, which is not actively designed by the device but is generated by the structure, is a parasitic resonance. When the parasitic resonance occurs, the energy of the ultra-high frequency pulse will repeatedly oscillate at a specific frequency and store energy. After converting the signal from the time domain to the frequency domain, the energy distribution will show a series of equally spaced frequency peaks. These peaks arranged like the teeth of a comb are parasitic comb spectrum lines. The free spectrum interval refers to the frequency difference between the adjacent two spectrum lines in the parasitic comb spectrum line, which is determined by the thickness and geometry of the medium structure that generates the parasitic resonance, such as the epoxy part, and can reflect the resonance characteristics of the structure. If equally spaced comb peaks appear in the frequency domain, the existence of parasitic resonance can be determined by measuring the frequency difference between adjacent peaks, i.e., the free spectrum interval. At the same time, when extracting the energy of the parasitic comb spectrum line, the center frequency position of these spectrum lines needs to be determined first. The free spectrum interval provides the step size. Starting from an initial frequency, the center frequencies of all parasitic comb spectrum lines can be accurately determined by recursively incrementing the free spectrum interval, which lays the foundation for subsequent energy extraction, leakage quantification, etc. From the lower limit frequency of the working band to the upper limit frequency of the working band, generate comb line center frequencies in turn with the free spectrum interval as the step size. Comb line center frequency = lower limit frequency of working band + n x free spectrum interval, n = 0, 1, 2, etc. Then map each comb line center frequency to the frequency point closest to the interval, and combine all the mapped frequency points into a comb line center set. The comb line center set is a set of center frequencies of all parasitic comb spectrum lines aligned with the frequency points. Specifically, assuming that the free spectrum interval of the adjacent spectrum lines of the parasitic comb spectrum is 50 MHz, the cross-channel spectrum value will have a significant peak at the free spectrum interval = 50 MHz. Starting from the lower limit frequency of the working band, for example, 300 MHz, generate comb line center frequencies such as 300 MHz, 350 MHz, 400 MHz, etc. and map the comb line center frequencies to the frequency point closest to the frequency interval to obtain the comb line center set.

[0022] Step two: for the mth sensor channel, the power values of the frequency points corresponding to all comb line center frequencies in the comb line center set in the power spectrum are summed to obtain the comb spectrum energy of the mth sensor channel, the comb spectrum energy is the total energy of the frequency points corresponding to the parasitic comb spectrum lines, reflecting the comb spectrum energy leaked by the parasitic resonance of the sensor channel; For the mth sensor channel, all comb line center frequencies in the comb line center set are sequentially traversed to calculate the anti-comb line center frequency, the calculation method of the anti-comb line center frequency is to add one-half of the free spectral interval to each comb line center frequency in the comb line center set, and the anti-comb line center frequency is a reference position without parasitic comb spectrum energy; For the anti-comb line center frequency, each anti-comb line center frequency is mapped to the frequency point closest to the interval, and the power values of the frequency points corresponding to all anti-comb line center frequencies in the power spectrum are summed to obtain the anti-comb spectrum energy of the mth sensor channel, the anti-comb spectrum energy is the total energy of the non-comb spectrum reference position, reflecting the background energy level of the non-parasitic comb spectrum reference position of the channel; The comb spectrum energy of the mth sensor channel is divided by the anti-comb spectrum energy to obtain a value marked as a parasitic leakage index, the parasitic leakage index is a dimensionless parasitic leakage index of the mth sensor channel, reflecting the strength of the circumferential parasitic resonance echo affecting the sensor channel, the larger the parasitic leakage index, the more energy leaked by the parasitic resonance relative to the background energy, and the stronger the influence; Specifically, by the ratio of the comb spectrum energy and the anti-comb spectrum energy, the parasitic resonance leakage of each sensor channel relative to the background energy is quantified, eliminating the interference of the overall energy level difference of different channels on the judgment of the parasitic leakage degree, so that the leakage degree of each channel has the characteristic of dimensionless and comparable.

[0023] Step three: for the mth sensor channel, the power values of all frequency points in the power spectrum are summed to obtain the value marked as the broadband energy of the mth sensor channel, the broadband energy is the total energy of the mth channel in the working band, and the existence of parasitic resonance causes the amplification degree of different channels in the parasitic narrow band to be different due to the amplitude-frequency consistency destruction; For the mth sensor channel, the broadband energy of the mth sensor channel is divided by the parasitic leakage index of the mth sensor channel to obtain the value marked as the equalized broadband energy, the equalized broadband energy is the corrected broadband energy of the mth sensor channel, eliminating the narrow-band amplification caused by parasitic resonance and restoring the comparability of amplitude and distance attenuation, that is, the equalized broadband energy of different channels is only determined by the distance and propagation path from the partial discharge source to the sensor; Specifically, assuming that the broadband energy of the i-th sensor channel = 1000, the parasitic leakage index of the i-th sensor channel = 2.32, then the equalized broadband energy of the i-th sensor channel ≈ 431, assuming that the broadband energy of the j-th sensor channel = 900, the parasitic leakage index of the j-th sensor channel = 1.8, then the equalized broadband energy of the j-th sensor channel = 500, at this time the equalized broadband energy difference between the i-th sensor channel and the j-th sensor channel is only determined by the distance and path from the partial discharge source to the two sensors, and is no longer disturbed by the parasitic resonance amplification, through the equalized broadband energy, the abnormal amplification of the parasitic resonance on the narrowband energy is regarded as an equivalent multiplicative gain and removed, so that the broadband energy of each channel re-meets the rule that the amplitude decays with the distance, solving the core problem of positioning distortion caused by the destruction of amplitude-frequency consistency, and ensuring the positioning accuracy of subsequent partial abnormal discharge.

[0024] Step four: based on the substation internal coordinate system, a three-dimensional space model is constructed, the sensor three-dimensional coordinates of each sensor in the substation internal coordinate system are obtained, the sensor three-dimensional coordinates are calibrated when the equipment is installed, the value range is the actual installation space of the sensor, the device geometric allowable domain is obtained, the device geometric allowable domain is the three-dimensional space range where the partial discharge source may exist, which is determined by the structure size and insulation range of gas insulated switchgear, cable terminal and other equipment, the three-dimensional coordinate points in the device three-dimensional allowable domain are traversed, and the three-dimensional coordinate points in the device three-dimensional allowable domain are marked as candidate source points, the sensor three-dimensional coordinates, the device three-dimensional allowable domain are imported into the three-dimensional space model, and the boundary of the three-dimensional space, the sensor distribution and the area where the partial discharge source may exist are determined; The straight-line distance of each candidate source point to each sensor in the three-dimensional space is calculated, and the straight-line distance is marked as the equivalent distance, which is the spatial distance from the candidate source point to the m-th sensor, reflecting the propagation path length of the signal from the partial discharge source to the sensor; For any two sensor channels, the logarithmic amplitude ratio is generated based on the equalized broadband energy of the sensor channel, specifically: the ratio of the equalized broadband energy of the i-th sensor channel to the equalized broadband energy of the j-th sensor channel is taken as the natural logarithm to obtain the logarithmic amplitude ratio, the logarithmic amplitude ratio reflects the logarithmic difference of the energy attenuation of the two sensor channels after equalization, because the energy attenuation with distance usually presents an exponential relationship, the logarithmic amplitude ratio obtained after taking the natural logarithm can be converted to a linear relationship; For any two sensor channels, the logarithmic distance ratio is generated based on the equivalent distance from the candidate source point to the sensor channel, specifically: the ratio of the equivalent distance from the n-th candidate source point to the i-th sensor channel to the equivalent distance from the n-th candidate source point to the j-th sensor channel is taken as the natural logarithm to obtain the logarithmic distance ratio, the logarithmic distance ratio reflects the logarithmic difference of the distance from the candidate source point to the two sensors, and forms a linear corresponding relationship with the logarithmic amplitude ratio; Specifically, the amplitude ratio and the distance ratio are converted to the logarithmic domain, the linear relationship of the two is more obvious, a linear model basis is provided for subsequent least squares fitting, the fitting difficulty is reduced, and the fitting efficiency is improved; The logarithmic amplitude ratio and the logarithmic distance ratio of a pair of sensor channels corresponding to the same candidate source point are multiplied, the results of multiplying the logarithmic amplitude ratio and the logarithmic distance ratio of each pair of sensor channels corresponding to the same candidate source point are accumulated, and then the value obtained by dividing the sum of the squares of all the logarithmic distance ratios corresponding to the same candidate source point is marked as a geometric attenuation proportionality coefficient. The geometric attenuation proportionality coefficient reflects the proportional relationship between the amplitude attenuation and the distance attenuation. Specifically, assuming that a total of four ultra-high frequency sensors are installed, there will be six pairs of sensor channel combinations, that is, for the same candidate source point, there will be six logarithmic amplitude ratios and logarithmic distance ratios. The geometric attenuation proportionality coefficient is obtained by multiplying the logarithmic amplitude ratio and the logarithmic distance ratio of each pair of sensors corresponding to the same candidate source point, and then accumulating and summing the results. The result obtained by dividing the sum of the six logarithmic amplitude squares is obtained. For each pair of sensors corresponding to the same candidate source point, the square of the difference between the logarithmic amplitude ratio corresponding to each pair of sensors and the product of the geometric attenuation proportionality coefficient and the logarithmic distance ratio is taken. The total residual is obtained by accumulating and summing the square results of each pair of sensors corresponding to the same candidate source point. The smaller the total residual, the more consistent the distance relationship of the candidate source point with the energy relationship of the actual partial discharge source. Specifically, by least squares fitting, the global matching degree of the amplitude ratio and the distance ratio is quantified, and the total residual obtained can objectively measure the reasonableness of the candidate point, thereby improving the reliability of the partial abnormal discharge positioning. Within the device geometry allowed domain, all candidate source points are traversed to obtain the candidate source point that minimizes the total residual value, and the candidate source point is marked as the partial abnormal discharge positioning result. The partial abnormal discharge positioning result is the candidate source point that minimizes the total residual, and its distance relationship is most consistent with the energy relationship of the actual partial discharge source. Specifically, by global traversal and residual minimization, the position of the partial discharge source that best matches the consistency of the amplitude ratio and the distance ratio is determined, ensuring the accuracy and objectivity of the partial discharge positioning, achieving precise positioning of the partial discharge source, and solving the positioning distortion problem caused by the destruction of the amplitude-frequency consistency due to parasitic resonance.

[0025] Step five: In the three-dimensional visualization platform, load the three-dimensional space model, mark the sensor three-dimensional coordinates with different colors, and display the device three-dimensional allowed domain as a transparent block; Color mapping visualization of the candidate source points according to the total residual of the candidate source points, for example, the smaller the total residual of the candidate source points, the closer the color to red, and the larger, the closer to blue, directly presenting the spatial distribution of the total residual; In the three-dimensional space model, highlight the partial abnormal discharge positioning result with special markers, such as flashing red dots, and mark its coordinate values; output a three-dimensional visualization interface, the three-dimensional visualization interface including substation equipment spatial coordinates, sensor three-dimensional coordinates, candidate source point three-dimensional coordinates, and partial discharge positioning results; Specifically, the numerical calculation results are converted into intuitive three-dimensional visualization space images, which facilitates operators to quickly and intuitively find the spatial position of the partial discharge source of the substation equipment, and provides direct guidance for equipment maintenance.

[0026] Third embodiment

[0027] Referring to Figure 2 As shown in the drawings, a three-dimensional visualization substation equipment partial discharge positioning system is proposed, which is used to implement a three-dimensional visualization substation equipment partial discharge positioning method, and includes: The comb line center generation module obtains the time domain waveform of the same partial discharge event collected by the ultra-high frequency sensor, performs discrete Fourier transform on the time domain waveform after Hanning window processing, obtains the power spectrum, defines the working band, calculates the power spectrum mean value and cross-channel spectrum value of each sensor channel, determines the free spectrum interval, generates the comb line center frequency from the lower limit frequency of the working band with the free spectrum interval as the step, and maps it to the frequency points to form a comb line center set; The parasitic index calculation module accumulates the power spectrum power value of the frequency points corresponding to the comb line center set to obtain the comb spectrum energy, calculates the anti-comb line center frequency, and accumulates the power value after mapping the anti-comb line center frequency to the frequency points to obtain the anti-comb spectrum energy. Divide the comb spectrum energy by the anti-comb spectrum energy to obtain the parasitic leakage index reflecting the strength of the influence of the circumferential parasitic resonance echo on the channel.

[0028] The wideband energy equalization module accumulates the power spectrum power value of all frequency points in the working band to obtain the wideband energy, divides the wideband energy by the parasitic leakage index to obtain the equalized wideband energy, eliminates the narrowband amplification interference caused by parasitic resonance, restores the comparability of amplitude and distance attenuation, and ensures that the equalized wideband energy is only determined by the distance and propagation path from the partial discharge source to the sensor; The discharge positioning calculation module calculates the three-dimensional spatial coordinates of the partial discharge source based on the equalized wideband energy of each sensor channel, combines the installation position parameters of the sensor, and calculates the three-dimensional spatial coordinates of the partial discharge source according to the physical law of amplitude attenuation with distance, to determine the specific position of the partial discharge. The three-dimensional visualization module associates the positioning result of the partial discharge source with the three-dimensional space model, displays the spatial position of the discharge point in the equipment through the visualization technology, realizes the three-dimensional visualization presentation of the partial discharge positioning result, and facilitates the accurate identification of the discharge part by the operation and maintenance personnel.

[0029] The above examples are only used to illustrate the technical method of the present application but not limit the present application. Although the present application is described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical method of the present application can be modified or equivalently replaced without departing from the spirit and scope of the technical method of the present application.

Claims

1. A three-dimensional visualization method for locating partial abnormal discharges in substation equipment, characterized in that, include: The time-domain waveform of the same partial discharge event is acquired by an ultra-high frequency sensor. The power spectrum is obtained by performing a discrete Fourier transform on the time-domain waveform. The power spectrum includes the power values ​​of frequency points marked at different frequency positions in the sensor channel. The power spectrum mean is obtained. The frequency interval to be tested is preset. The cross-channel spectrum value is calculated based on the product of the difference between the power values ​​of the two frequency points of the frequency interval to be tested and the power spectrum mean. The frequency interval to be tested with the largest cross-channel spectrum value is marked as the free spectrum interval by traversal test. The comb center frequency is generated sequentially with the free spectrum interval as the step size. Each comb center frequency is mapped to the frequency point with the closest interval. The comb spectrum energy is obtained by summing the power values ​​of all frequency points corresponding to the center frequencies of the comb lines. The center frequency obtained by adding half of the free spectrum interval to the center frequency of the comb lines is marked as the center frequency of the anti-comb line. The anti-comb spectrum energy is calculated based on the center frequency of the anti-comb line. The value obtained by dividing the comb spectrum energy by the anti-comb spectrum energy is marked as the parasitic leakage index. The value obtained by summing the power values ​​of all frequency points in the power spectrum is marked as the broadband energy. The value obtained by dividing the broadband energy by the parasitic leakage index is marked as the equalized broadband energy. Local abnormal discharges are located based on the equalized broadband energy.

2. The method for locating partial abnormal discharge in substation equipment using three-dimensional visualization according to claim 1, characterized in that, Methods for obtaining the power spectrum mean include: The time-domain waveforms corresponding to each sensor channel are windowed using a Hanning window and then subjected to a Discrete Fourier Transform. The power spectrum of the sensor channel is obtained by taking the modulus of the Discrete Fourier Transform result and squaring it. Define the effective analysis frequency range determined by the ultra-high frequency radiation characteristics of substation equipment and the bandwidth of the sampling system, and mark the effective analysis frequency range as the working band. Within the working band, sum the power values ​​of all frequency points on the power spectrum of each sensor channel, and then divide the sum by the number of frequency points in the working band to obtain the average value of the power spectrum of each sensor channel within the working band, and mark this average value as the power spectrum mean. The number of frequency points is the ratio of the difference between the upper and lower frequency limits within the working band to the frequency resolution, where the frequency resolution is the frequency interval between adjacent frequency points in the discrete Fourier transform.

3. The method for locating partial abnormal discharge in substation equipment using three-dimensional visualization according to claim 1, characterized in that, The calculation methods for cross-channel spectrum values ​​include: The preset test frequency interval is the frequency difference between 0 and the upper limit of the working band. For the same sensor channel, the number of frequency points n within the working band that are spaced at the frequency interval to be measured is calculated by multiplying the difference between the power value of the i-th frequency point and the power spectrum mean by the power value of the frequency point at the (i+)-th frequency interval to be measured by ... The cross-channel spectral values ​​obtained after traversing and testing each frequency interval to be tested and inputting the above calculation process are used to mark the frequency interval to be tested with the largest cross-channel spectral value as the free spectrum interval. The free spectrum interval reflects the frequency difference between two adjacent spectral lines of the parasitic comb spectral line.

4. The method for locating partial abnormal discharge in substation equipment using three-dimensional visualization according to claim 1, characterized in that, The center frequency of the comb includes: Starting from the lower limit frequency of the working band to the upper limit frequency of the working band, the comb center frequency is generated sequentially with the free spectrum interval as the step size. The comb center frequency = the lower limit frequency of the working band + n × free spectrum interval, where n is the order in which the comb center frequencies are generated. Next, each comb center frequency is mapped to the frequency point with the closest frequency interval, and all mapped frequency points are combined into a comb center set, which includes all comb center frequencies aligned with the frequency points.

5. The three-dimensional visualization method for locating partial abnormal discharge in substation equipment according to claim 4, characterized in that, Spectral energy, including: For the m-th sensor channel, the comb spectrum energy of the m-th sensor channel is obtained by summing the power values ​​of the frequency points corresponding to the frequencies of all comb center frequencies in the comb center set. The comb spectrum energy is the total energy of the frequency points corresponding to the parasitic comb spectral lines.

6. The method for locating partial abnormal discharge in substation equipment using three-dimensional visualization according to claim 5, characterized in that, Methods for calculating the energy of an anticomb spectrum include: For the m-th sensor channel, iterate through all the comb center frequencies in the comb center set and calculate the reverse comb center frequency. The specific calculation method is as follows: The center frequency of each comb center in the comb center set, after adding half of the free spectrum interval, is marked as the anti-comb center frequency. The anti-comb center frequency is the reference position of the energy of the parasitic comb spectrum. For the center frequency of the anti-comb line, each anti-comb line center frequency is mapped to the frequency point with the closest frequency interval. The power values ​​of the corresponding frequency points of all anti-comb line center frequencies in the power spectrum are summed to obtain the anti-comb spectrum energy of the m-th sensor channel. The anti-comb spectrum energy is the total energy of the non-comb spectrum reference position.

7. The method for locating partial abnormal discharge in substation equipment using three-dimensional visualization according to claim 6, characterized in that, The calculation methods for equalized broadband energy include: The value obtained by dividing the comb energy of the m-th sensor channel by the anti-comb energy is denoted as the parasitic leakage index. The parasitic leakage index is a dimensionless parasitic leakage index of the m-th sensor channel. For the m-th sensor channel, the summation of the power values ​​at all frequency points within the power spectrum within the working band is marked as the broadband energy of the m-th sensor channel, which is the total energy of the m-th channel within the working band. For the m-th sensor channel, the value obtained by dividing the broadband energy of the m-th sensor channel by the parasitic leakage index of the m-th sensor channel is marked as the equalized broadband energy. The equalized broadband energy is the corrected broadband energy of the m-th sensor channel.

8. The method for locating partial abnormal discharge in substation equipment using three-dimensional visualization according to claim 7, characterized in that, Methods for locating localized anomalous discharges based on equalized broadband energy include: A three-dimensional spatial model is constructed based on the coordinate system within the substation. The three-dimensional coordinates of each UHF sensor in the coordinate system within the substation are obtained. The three-dimensional coordinates of the sensor are calibrated during equipment installation. The geometric allowable domain of the equipment is obtained. The geometric allowable domain of the equipment is the three-dimensional spatial range in which the local discharge power source may exist. The three-dimensional coordinate points within the three-dimensional allowable domain of the equipment are traversed, and the three-dimensional coordinate points within the three-dimensional allowable domain of the equipment are marked as candidate source points. The three-dimensional coordinates of the sensor and the three-dimensional allowable domain of the equipment are imported into the three-dimensional spatial model. Calculate the straight-line distance from each candidate source point to each UHF sensor in three-dimensional space, and mark this straight-line distance as the equivalent distance. The equivalent distance is the spatial distance from the candidate source point to the m-th sensor, which reflects the propagation path length of the signal from the local discharge source to the sensor. For any two sensor channels, the ratio of the equalized broadband energy generation logarithmic amplitudes based on the sensor channels is as follows: The logarithmic amplitude ratio is obtained by taking the natural logarithm of the ratio of the equalized broadband energy of the i-th sensor channel to the equalized broadband energy of the j-th sensor channel. The logarithmic amplitude ratio reflects the logarithmic difference in energy attenuation between the two sensor channels after equalization. For any two sensor channels, a logarithmic distance ratio is generated based on the equivalent distance from the candidate source point to the sensor channel, as follows: The logarithmic distance ratio is obtained by taking the natural logarithm of the ratio of the equivalent distance from the nth candidate source point to the i-th sensor channel to the equivalent distance from the nth candidate source point to the j-th sensor channel. The logarithmic distance ratio reflects the logarithmic difference between the distances from the candidate source point to the two sensors.

9. A three-dimensional visualization method for locating partial abnormal discharges in substation equipment according to claim 8, characterized in that, include: The result of multiplying the logarithmic amplitude ratio and logarithmic distance ratio of each pair of sensor channels corresponding to the same candidate source point, summing them up, and then dividing by the sum of the squares of all the logarithmic distance ratios corresponding to the same candidate source point, is marked as the geometric attenuation ratio coefficient. The geometric attenuation ratio coefficient reflects the proportional relationship between amplitude attenuation and distance attenuation. For each pair of sensors corresponding to the same candidate source point, the square of the difference between the logarithmic amplitude ratio of each pair of sensors and the product of the geometric attenuation ratio coefficient and the logarithmic distance ratio is taken, and the squares of the results of each pair of sensors corresponding to the same candidate source point are summed to obtain the total residual. Within the geometrically permissible domain of the device, all candidate source points are traversed to obtain the candidate source point that minimizes the total residual value, and this candidate source point is marked as the local abnormal discharge location result. The results of locating local abnormal discharges are output to a 3D visualization interface.

10. A three-dimensional visualization substation equipment partial abnormal discharge location system, used to implement the partial abnormal discharge location method as described in any one of claims 1-9, characterized in that, include: The comb center generation module acquires the time-domain waveform of the same partial discharge event collected by the UHF sensor. After processing the time-domain waveform through the Hanning window, it performs a discrete Fourier transform to obtain the power spectrum, defines the working band, calculates the mean power spectrum of each sensor channel and the cross-channel spectrum value, determines the free spectrum interval, generates the comb center frequency from the lower limit frequency of the working band with the free spectrum interval as the step size, and maps it to the frequency points to form a comb center set. The parasitic index calculation module accumulates the power spectrum power value of the comb center set corresponding to the comb energy, calculates the center frequency of the anti-comb, maps it to the frequency point, accumulates its power value to obtain the anti-comb energy, divides the comb energy by the anti-comb energy to obtain the parasitic leakage index, which reflects the strength of the channel affected by the circumferential parasitic resonance echo. The broadband energy equalization module accumulates the power spectrum power values ​​of all frequency points within the working band to obtain the broadband energy. The broadband energy is then divided by its parasitic leakage index to obtain the equalized broadband energy. This eliminates narrowband amplification interference caused by parasitic resonance, restores the comparability of amplitude and distance attenuation, and ensures that the equalized broadband energy is determined only by the distance from the partial discharge source to the sensor and the propagation path. The discharge location calculation module, based on the equalized broadband energy of each sensor channel and combined with the sensor installation position parameters, calculates the three-dimensional spatial coordinates of the local discharge source according to the physical law of amplitude attenuation with distance, and determines the specific location of the local abnormal discharge. The 3D visualization module associates the location results of localized discharge with the 3D spatial model, and uses visualization technology to display the spatial location of the discharge point in the equipment, realizing the 3D visualization of the localized abnormal discharge location results, which facilitates the operation and maintenance personnel to accurately identify the discharge location.

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