Discharge phase determination method and device and storage medium

Abstract

The invention discloses a discharge phase determination method and device and a storage medium, and relates to the technical field of power dispatching. The method comprises the steps that three-phase current signals are obtained, and the three-phase current signals at least comprise phase current signals of three phases; identifying a time-frequency index, a polarity index and an energy index of the three-phase current signal, the time-frequency index being used for indicating a frequency spectrum energy density corresponding to the phase current signal, the polarity index being used for indicating a positive polarity ratio and a negative polarity ratio corresponding to the phase current signal, and the energy index being used for indicating an energy contribution corresponding to the phase current signal; based on the time-frequency index, the polarity index and the energy index, determining a comprehensive discrimination index corresponding to the phase current signal; and determining a target discharge phase based on the comprehensive discrimination index. According to the invention, the technical problem of low discharge phase identification precision is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of power system fault detection, and in particular to a method, device and storage medium for determining discharge phases. Background Art

[0002] At present, partial discharge is a common manifestation of insulation defects in power equipment. Detecting and identifying partial discharge signals is of great significance for the safe operation of power systems. In switch cabinets, the occurrence of partial discharge may lead to the degradation of insulation materials and even cause serious power failures. Therefore, accurately identifying the source phase of the partial discharge signal (i.e. determining whether the partial discharge signal comes from phase A, phase B or phase C) is crucial for taking timely maintenance measures and preventing accidents.

[0003] In the related technologies, many partial discharge phase identification methods rely on offline data processing, which makes it difficult to achieve real-time monitoring and identification, affecting the real-time maintenance and management of the power system. There is a large amount of electromagnetic interference in the power system, and the existing methods are still insufficient in anti-interference ability and are easily affected by noise, resulting in unreliable identification results. Therefore, there is a technical problem of low accuracy of discharge phase identification.

[0004] With respect to the above-mentioned technical problem of low accuracy in identifying discharge phases, no effective solution has been proposed so far. Summary of the invention

[0005] Embodiments of the present invention provide a method, device and storage medium for determining a discharge phase, so as to at least solve the technical problem of low accuracy in identifying a discharge phase.

[0006] According to one aspect of an embodiment of the present invention, a method for determining a discharge phase is provided. The method may include: obtaining a three-phase current signal, wherein the three-phase current signal includes at least three phases of phase current signals; identifying the time-frequency index, polarity index and energy index of the three-phase current signal, wherein the time-frequency index is used to indicate the spectral energy density corresponding to the phase current signal, the polarity index is used to indicate the positive polarity proportion and the negative polarity proportion corresponding to the phase current signal, and the energy index is used to indicate the energy contribution corresponding to the phase current signal; based on the time-frequency index, polarity index and energy index, determine the comprehensive discrimination index corresponding to the phase current signal; based on the comprehensive discrimination index, determine the target discharge phase.

[0007] Optionally, identifying the time-frequency index of the three-phase current signal includes: extracting the time-frequency characteristics of the three-phase current signal; and determining the time-frequency index of the three-phase current signal based on the time-frequency characteristics.

[0008] Optionally, identifying the energy index of the three-phase current signal includes: performing enhancement processing on phase-specific current signals in the three-phase current signal to obtain the energy index of the three-phase current signal.

[0009] Optionally, based on the time-frequency index, polarity index and energy index, a comprehensive discrimination index corresponding to the phase-differentiated current signal is determined, including: performing weighted operations on the time-frequency index, polarity index and energy index to determine the comprehensive discrimination index corresponding to the phase-differentiated current signal.

[0010] Optionally, based on the comprehensive discrimination index, the target discharge phase is determined, including: comparing the comprehensive discrimination indexes respectively to obtain comparison results; based on the comparison results, determining the maximum comprehensive discrimination index among the comprehensive discrimination indexes; determining the phase discrimination current signal corresponding to the maximum comprehensive discrimination index; and determining the discharge phase corresponding to the phase discrimination current signal as the target discharge phase.

[0011] Optionally, before identifying the time-frequency index, polarity index and energy index of the three-phase current signal, the discharge phase determination method further includes: preprocessing the three-phase current signal.

[0012] According to another aspect of an embodiment of the present invention, a discharge phase determination device is also provided. The device may include: an acquisition unit, used to acquire a three-phase current signal, wherein the three-phase current signal includes at least three phases of phase current signals; an identification unit, used to identify the time-frequency index, polarity index and energy index of the three-phase current signal, wherein the time-frequency index is used to indicate the spectral energy density corresponding to the phase current signal, the polarity index is used to indicate the positive polarity ratio and the negative polarity ratio corresponding to the phase current signal, and the energy index is used to indicate the energy contribution corresponding to the phase current signal; a first determination unit, used to determine the comprehensive discrimination index corresponding to the phase current signal based on the time-frequency index, the polarity index and the energy index; a second determination unit, used to determine the target discharge phase based on the comprehensive discrimination index.

[0013] According to another aspect of an embodiment of the present invention, a computer-readable storage medium is also provided, the computer-readable storage medium including a stored program, wherein when the program is executed by a processor, the device where the storage medium is located is controlled to execute the discharge phase determination method in an embodiment of the present invention.

[0014] According to another aspect of the embodiment of the present invention, a processor is further provided. The processor is used to run a program, wherein the method for determining the discharge phase in the embodiment of the present invention is executed when the program is run.

[0015] According to another aspect of the embodiment of the present invention, a computer program product is also provided, wherein the program product includes computer instructions, and when the computer instructions are executed by a processor, the method for determining the discharge phase in the embodiment of the present invention is implemented.

[0016] In an embodiment of the present invention, a three-phase current signal is obtained, wherein the three-phase current signal includes at least three phases of phase-by-phase current signals; the time-frequency index, polarity index and energy index of the three-phase current signal are identified, wherein the time-frequency index is used to indicate the spectral energy density corresponding to the phase-by-phase current signal, the polarity index is used to indicate the positive polarity ratio and the negative polarity ratio corresponding to the phase-by-phase current signal, and the energy index is used to indicate the energy contribution corresponding to the phase-by-phase current signal; based on the time-frequency index, polarity index and energy index, the comprehensive discrimination index corresponding to the phase-by-phase current signal is determined; based on the comprehensive discrimination index, the target discharge phase is determined. That is to say, the present invention identifies the time-frequency index, polarity index and energy index of the three-phase current signal, thereby determining the comprehensive discrimination index of each phase-by-phase current signal according to the time-frequency index, polarity index and energy index, and then determining the discharge phase according to the comprehensive discrimination index, thereby solving the technical problem of low discharge phase recognition accuracy and achieving the technical effect of improving the discharge phase recognition accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0018] Figure 1 is a flow chart of a method for determining a discharge phase according to an embodiment of the present invention;

[0019] Figure 2 is a flow chart of a phase identification method for partial discharge (PD) signals of a switch cabinet according to an embodiment of the present invention;

[0020] Figure 3 is a schematic diagram of a discharge phase determination device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0021] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described 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, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0022] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, functional component or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, functional components or devices.

[0023] According to an embodiment of the present invention, an embodiment of a method for determining a discharge phase is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0024] Figure 1 is a flow chart of a method for determining a discharge phase according to an embodiment of the present invention. Figure 1 As shown, the method may include the following steps:

[0025] Step S101, acquiring three-phase current signals.

[0026] In the technical solution provided in the above step S101 of the present invention, the three-phase current signal includes at least three phase current signals, and the three-phase current signal can also be called a three-phase high-frequency current signal.

[0027] In this embodiment, a three-phase current signal is obtained. For example, high-frequency current sensors are respectively installed on the three-phase circuits (phase A, phase B, and phase C) of the switch cabinet to collect the three-phase high-frequency current signals in real time. This is only an illustrative example and does not limit the specific method of obtaining the three-phase current signal.

[0028] Step S102, identifying the time-frequency index, polarity index and energy index of the three-phase current signal.

[0029] In the technical solution provided in the above step S102 of the present invention, the time-frequency index is used to indicate the spectral energy density corresponding to the phase-by-phase current signal, the polarity index is used to indicate the positive polarity ratio and the negative polarity ratio corresponding to the phase-by-phase current signal, and the energy index is used to indicate the energy contribution corresponding to the phase-by-phase current signal. The time-frequency index may also be a time-frequency analysis result, which includes the spectral energy density, the polarity index may also be a signal polarity analysis result, and the energy index may also be a signal addition and subtraction operation result.

[0030] In this embodiment, after the three-phase current signal is acquired in step S101, the time-frequency index, polarity index and energy index of the three-phase current signal are identified.

[0031] Optionally, for identifying the time-frequency index, the time-frequency characteristics of the three-phase current signal are extracted; and the time-frequency index of the three-phase current signal is determined based on the time-frequency characteristics.

[0032] For example, a short-time Fourier transform (STFT) is performed on the three-phase current signal to extract the time-frequency characteristics of the three-phase current signal. STFT applies a sliding window to the three-phase current signal and performs Fourier transform on the three-phase current signal in each window, thereby obtaining the frequency spectrum distribution of the three-phase current signal in different time periods. The calculation formula of STFT is shown in the following formula (1):

[0033]

[0034] Among them, X(t,f) represents the result of short-time Fourier transform, that is, the complex value of signal x(τ) at time t and frequency f, which represents the spectral characteristics of the signal at time t and frequency f. t is the time variable, which represents the current time point, and f is the frequency variable, which represents the frequency. x(τ) is the original time signal, which represents the signal value at time τ, and τ is the integral variable, which represents time. w(τ-t) is the window function, which determines the signal segment for Fourier transform at time t. j is the imaginary unit, which satisfies j 2 =-1, e is the base of the natural logarithm, approximately equal to 2.71828, and π is a constant used to convert the frequency f into angular frequency (radians per second). The spectrum energy density of the three-phase current signal after STFT transformation is calculated to quantify the energy distribution of the three-phase current signal at different frequencies. The calculation formula of the spectrum energy density is shown in the following formula (2):

[0035] E i (f) = ∑ t |X i (t,f)| 2 (2)

[0036] Among them, E i (f) is the spectral energy density of the i-th phase (phase A, phase B or phase C) at frequency f. Spectral energy density indicates the energy of the signal at each frequency and can help identify the characteristic frequency and energy distribution of the partial discharge signal. By analyzing the spectral energy density, the spectral characteristics of the partial discharge signal can be identified.

[0037] For another example, the ratio of positive and negative polarity of each phase signal is calculated based on the polarity index to characterize the polarity characteristics of the signal. The calculation formulas for the ratio of positive and negative polarity are shown in the following formulas (3) and (4):

[0038]

[0039] Where N is the number of signal samples, and [·] is the indicator function. The positive polarity ratio indicates the proportion of the positive part of the signal in the entire sampling period, and the negative polarity ratio indicates the proportion of the negative part of the signal. Through polarity analysis, the polarity distribution characteristics of the signal can be determined to assist in determining the source of the signal.

[0040] Optionally, in order to identify the energy index, the phase-specific current signals in the three-phase current signal are enhanced to obtain the energy index of the three-phase current signal.

[0041] For example, three-phase signals are added and subtracted to enhance signal characteristics and highlight signal differences. By adding, the common characteristics of the signal can be enhanced, that is, the signals of the same partial discharge source on different phases will be more obvious after the addition operation. The addition operation method is shown in the following formulas (5) to (7):

[0042] S AB =x A +x B (5)

[0043] S AC =x A +x C (6)

[0044] S BC =x B +x C (7)

[0045] Through subtraction operations, the differences of signals can be highlighted, common mode interference can be weakened or eliminated, and the identifiability of signals can be improved. The subtraction operation method is shown in the following formulas (8) to (10):

[0046] D AB =x A -x B (8)

[0047] D AC =x A -x C (9)

[0048] D BC =x B -x C (10)

[0049] The total energy of the signal after addition and subtraction operations is calculated to quantify the energy distribution of the signal. The calculation formula for the total energy is shown in the following formulas (11) to (16):

[0050]

[0051] Among them, S AB , S AC , S BC and D AB , D AC , D BC They represent the signal values ​​after addition and subtraction respectively. By calculating the total energy of the signal after addition and subtraction, the energy distribution characteristics of the signal can be further analyzed to determine the source of the partial discharge signal.

[0052] Step S103, determining a comprehensive discrimination index corresponding to the phase-specific current signal based on the time-frequency index, the polarity index and the energy index.

[0053] In the technical solution provided in step S103 of the present invention, the comprehensive discrimination index can be recorded as I i .

[0054] In this embodiment, after the time-frequency index, polarity index and energy index of the three-phase current signal are identified in step S102, the comprehensive discrimination index corresponding to the phase current signal is determined according to the time-frequency index, polarity index and energy index.

[0055] Optionally, a time-frequency index, a polarity index and an energy index are weighted to determine a comprehensive discrimination index corresponding to the phase-differentiated current signal.

[0056] For example, firstly, the positive and negative polarity ratios of each phase signal are calculated to characterize the polarity characteristics of the signal, as shown in the following formulas (14) and (15):

[0057]

[0058] Among them, P pos,i and P neg,i are the positive and negative polarity proportions of the i-th phase respectively. Through addition and subtraction operations, the energy contribution of each phase after addition and subtraction operations is calculated. The specific method is to calculate the average energy of each phase in all addition and subtraction operations. As shown in the following formula (16) and formula (21):

[0059]

[0060] This ensures that the energy contribution of each phase in the addition and subtraction operations is considered independently without affecting other phases. Set a weight coefficient for each analysis result. The coefficient w of the spectrum energy tf , the coefficient w of signal polarity pol , polarity of addition operation w sum , polarity of subtraction operation w diff , and calculate the comprehensive discrimination index I iTo determine the main source of the partial discharge signal. The comprehensive discrimination index is shown in the following formula (22):

[0061] I i =w tf ·E i +w pol ·P pos,i +w pol ·P neg,i +w sum ·E sum,i +w diff ·E diff,i (twenty two)

[0062] Among them, i represents phase A, phase B or phase C, E i is the spectrum energy density obtained by time-frequency analysis, P pos,i and P neg,i is the ratio of positive and negative polarity obtained by polarity analysis, E sum,i and E diff,i is the total energy after addition and subtraction operations.

[0063] Step S104: determining a target discharge phase based on the comprehensive discrimination index.

[0064] In the technical solution provided in the above step S104 of the present invention, the target discharge phase difference may also be referred to as the main source phase difference of the partial discharge signal.

[0065] In this embodiment, after the comprehensive discrimination index is determined in step S103, the target discharge phase is determined according to the comprehensive discrimination index.

[0066] Optionally, the comprehensive discrimination indexes are compared respectively to determine the maximum comprehensive discrimination index among the comprehensive discrimination indexes; a phase discrimination current signal corresponding to the maximum comprehensive discrimination index is determined; and a discharge phase corresponding to the phase discrimination current signal is determined as a target discharge phase.

[0067] For example, comparing the comprehensive discrimination index I of the three-phase signal A ,I B and I C , the phase with the largest comprehensive discrimination index is the main source phase of the partial discharge signal, as shown in the following formula (23):

[0068] I source =max(I A ,I B ,I C ) (twenty three)

[0069] Optionally, the method of the present invention can more accurately determine the source phase of the partial discharge signal. The method comprehensively considers the time-frequency characteristics, polarity characteristics and energy characteristics after addition and subtraction operations, thereby improving the accuracy and reliability of identification.

[0070] It should be noted that the above embodiment can be implemented by a discharge phase determination device.

[0071] In the above steps S101 to S104 of the present invention, a three-phase current signal is obtained, wherein the three-phase current signal includes at least three phases of phase-by-phase current signals; the time-frequency index, polarity index and energy index of the three-phase current signal are identified, wherein the time-frequency index is used to indicate the spectral energy density corresponding to the phase-by-phase current signal, the polarity index is used to indicate the positive polarity ratio and the negative polarity ratio corresponding to the phase-by-phase current signal, and the energy index is used to indicate the energy contribution corresponding to the phase-by-phase current signal; based on the time-frequency index, polarity index and energy index, the comprehensive discrimination index corresponding to the phase-by-phase current signal is determined; based on the comprehensive discrimination index, the target discharge phase is determined. In other words, the present invention identifies the time-frequency index, polarity index and energy index of the three-phase current signal, thereby determining the comprehensive discrimination index of each phase-by-phase current signal according to the time-frequency index, polarity index and energy index, and then determining the discharge phase according to the comprehensive discrimination index, thereby solving the technical problem of low discharge phase recognition accuracy and achieving the technical effect of improving the discharge phase recognition accuracy.

[0072] The above method of this embodiment is further introduced below.

[0073] As an optional implementation manner, identifying the time-frequency index of the three-phase current signal includes: extracting the time-frequency characteristics of the three-phase current signal; and determining the time-frequency index of the three-phase current signal based on the time-frequency characteristics.

[0074] In this embodiment, the time-frequency characteristics of the three-phase current signal are extracted; and the time-frequency index of the three-phase current signal is determined according to the time-frequency characteristics.

[0075] Optionally, a short-time Fourier transform (STFT) is performed on the three-phase current signal to extract the time-frequency characteristics of the three-phase current signal. The specific extraction method is shown in the above formula (1) and formula (2), which will not be repeated here.

[0076] Optionally, by determining the spectrum energy density, it can help identify the characteristic frequency and energy distribution of the partial discharge signal. By analyzing the spectrum energy density, the spectrum characteristics of the partial discharge signal can be identified.

[0077] As an optional implementation manner, identifying the energy index of the three-phase current signal includes: enhancing the phase current signals in the three-phase current signal to obtain the energy index of the three-phase current signal.

[0078] In this embodiment, the phase current signals in the three-phase current signal are enhanced to obtain the energy index of the three-phase current signal.

[0079] Optionally, the three-phase signals are added and subtracted to enhance the signal characteristics and highlight the signal differences. By adding, the common characteristics of the signals can be enhanced, that is, the signals of the same partial discharge source on different phases will be more obvious after the addition operation. The specific enhancement method is shown in the above formula (5) to formula (16), which will not be repeated here.

[0080] As an optional implementation method, based on the time-frequency index, polarity index and energy index, the comprehensive discrimination index corresponding to the phase-differentiated current signal is determined, including: performing weighted operations on the time-frequency index, polarity index and energy index to determine the comprehensive discrimination index corresponding to the phase-differentiated current signal.

[0081] In this embodiment, a weighted operation is performed on the time-frequency index, the polarity index and the energy index to determine a comprehensive discrimination index corresponding to the phase-specific current signal.

[0082] Optionally, a weight coefficient is set for each analysis result, the coefficient w of the spectrum energy tf , the coefficient w of signal polarity pol , polarity of addition operation w sum , polarity of subtraction operation w diff , and calculate the comprehensive discrimination index I i To determine the main source of the partial discharge signal. The comprehensive discrimination index is shown in the above formula (22), which will not be repeated here.

[0083] As an optional implementation method, based on the comprehensive discrimination index, the target discharge phase is determined, including: comparing the comprehensive discrimination indexes respectively to obtain comparison results; based on the comparison results, determining the maximum comprehensive discrimination index among the comprehensive discrimination indexes; determining the phase discrimination current signal corresponding to the maximum comprehensive discrimination index; and determining the discharge phase corresponding to the phase discrimination current signal as the target discharge phase.

[0084] In this embodiment, the comprehensive discrimination indexes are compared respectively to determine the maximum comprehensive discrimination index among the comprehensive discrimination indexes; the phase discrimination current signal corresponding to the maximum comprehensive discrimination index is determined; and the discharge phase corresponding to the phase discrimination current signal is determined as the target discharge phase.

[0085] Optionally, the comprehensive discrimination index I of the three-phase signal is compared A ,I B and I C , the phase with the largest comprehensive discrimination index is the main source phase of the partial discharge signal, as shown in the above formula (23), which will not be repeated here.

[0086] As an optional implementation manner, before identifying the time-frequency index, polarity index and energy index of the three-phase current signal, the discharge phase determination method further includes: preprocessing the three-phase current signal.

[0087] In this embodiment, before identifying the time-frequency index, polarity index and energy index of the three-phase current signal, the three-phase current signal needs to be preprocessed.

[0088] For example, the collected three-phase current signal is filtered and denoised to improve the signal quality and signal-to-noise ratio. The Butterworth high-pass filter is used to remove the low-frequency noise component. The filtered signal is normalized to standardize the amplitude range of the signal. The normalization formula is shown in the following formula (24):

[0089]

[0090] Among them, x(t) is the original signal, μ is the signal mean, and σ is the signal standard deviation.

[0091] Optionally, normalization processing can eliminate differences in signal amplitudes, unify signal feature scales, and improve the accuracy of subsequent feature extraction.

[0092] It should be noted that the above embodiment can be implemented by a discharge phase determination device.

[0093] In this embodiment, a three-phase current signal is obtained, wherein the three-phase current signal includes at least three phases of phase-by-phase current signals; the time-frequency index, polarity index and energy index of the three-phase current signal are identified, wherein the time-frequency index is used to indicate the spectral energy density corresponding to the phase-by-phase current signal, the polarity index is used to indicate the positive polarity ratio and the negative polarity ratio corresponding to the phase-by-phase current signal, and the energy index is used to indicate the energy contribution corresponding to the phase-by-phase current signal; based on the time-frequency index, polarity index and energy index, the comprehensive discrimination index corresponding to the phase-by-phase current signal is determined; based on the comprehensive discrimination index, the target discharge phase is determined. That is to say, the present invention identifies the time-frequency index, polarity index and energy index of the three-phase current signal, thereby determining the comprehensive discrimination index of each phase-by-phase current signal according to the time-frequency index, polarity index and energy index, and then determining the discharge phase according to the comprehensive discrimination index, thereby solving the technical problem of low discharge phase recognition accuracy and achieving the technical effect of improving the discharge phase recognition accuracy.

[0094] The technical solution of the embodiment of the present invention is illustrated below in conjunction with preferred implementation modes.

[0095] At present, partial discharge is a common manifestation of insulation defects in power equipment. Detecting and identifying partial discharge signals is of great significance for the safe operation of power systems. In switch cabinets, the occurrence of partial discharge may lead to the degradation of insulation materials and even cause serious power failures. Therefore, accurately identifying the source phase of the partial discharge signal (i.e. determining whether the partial discharge signal comes from phase A, phase B or phase C) is crucial for taking timely maintenance measures and preventing accidents.

[0096] In the related art, many partial discharge phase identification methods rely on offline data processing, which makes it difficult to achieve real-time monitoring and identification, affecting the real-time maintenance and management of the power system. There is a large amount of electromagnetic interference in the power system, and the existing methods are still insufficient in anti-interference ability and are easily affected by noise, resulting in unreliable identification results. Therefore, there is a technical problem of low discharge phase identification accuracy. In view of the above-mentioned technical problem of low discharge phase identification accuracy, no effective solution has been proposed.

[0097] However, an embodiment of the present invention proposes a phase identification method for partial discharge (PD) signals of a switch cabinet, which collects three-phase high-frequency current signals in real time by installing high-frequency current sensors on the three-phase circuits of the switch cabinet, and filters, denoises and normalizes the signals. The preprocessed signal is subjected to a short-time Fourier transform (STFT), the time-frequency characteristics of the signal are extracted and the spectrum energy density is calculated. The polarity characteristics of the signal are characterized by analyzing the proportion of positive and negative polarity of each phase signal. In addition, the three-phase signals are added and subtracted, and the total energy of the signals after addition and subtraction is calculated to enhance the common characteristics of the signals and highlight the difference characteristics of the signals. Finally, the source phase of the PD signal is determined by combining the results of time-frequency analysis, signal polarity and signal addition and subtraction analysis. The method utilizes the multidimensional characteristics of the signal to improve the accuracy and reliability of identification, is suitable for online monitoring and fault diagnosis of power systems, and effectively improves the safety and reliability of power system operation. Thereby solving the technical problem of low accuracy of discharge phase identification and achieving the technical effect of improving the accuracy of discharge phase identification.

[0098] The embodiments of the present invention are further described below.

[0099] Figure 2 The present invention is a flowchart of a phase identification method for a partial discharge (PD) signal of a switch cabinet according to an embodiment of the present invention. The analysis method comprises the following steps:

[0100] Step S201: signal acquisition and preprocessing.

[0101] In this embodiment, the signal is collected and pre-processed.

[0102] Optionally, high-frequency current sensors are installed on the three-phase circuits (phase A, phase B, and phase C) of the switch cabinet to collect three-phase high-frequency current signals in real time. These sensors can detect high-frequency current pulse signals generated by partial discharge, and each phase of the high-frequency current sensor will independently record the current signal of the corresponding phase to form three independent time series data.

[0103] Optionally, the collected three-phase current signal is filtered and denoised to improve signal quality and signal-to-noise ratio. A Butterworth high-pass filter is used to remove low-frequency noise components. The filtered signal is normalized to standardize the amplitude range of the signal. The normalization formula is shown in the above formula (24) and will not be repeated here. Normalization can eliminate the difference in signal amplitude, unify the signal feature scale, and improve the accuracy of subsequent feature extraction.

[0104] Step S202, analyzing time and frequency.

[0105] In this embodiment, time-frequency analysis is performed on the signal pre-processed in step S201.

[0106] Optionally, short-time Fourier transform (STFT): Short-time Fourier transform (STFT) is performed on the preprocessed signal to extract the time-frequency characteristics of the signal. STFT applies a sliding window to the signal and performs Fourier transform on the signal in each window, thereby obtaining the spectrum distribution of the signal in different time periods. The calculation formula of STFT is shown in the above formula (1), which will not be repeated here.

[0107] Optionally, spectrum energy density calculation: Calculate the spectrum energy density of the signal after STFT transformation to quantify the energy distribution of the signal at different frequencies. The calculation formula of spectrum energy density is shown in the above formula (2), which will not be repeated here.

[0108] Optionally, the spectrum energy density indicates the energy of the signal at each frequency, which can help identify the characteristic frequency and energy distribution of the partial discharge signal. By analyzing the spectrum energy density, the spectrum characteristics of the partial discharge signal can be identified.

[0109] Step S203: analyzing the signal polarity.

[0110] In this embodiment, the positive and negative polarity ratios of each phase signal are calculated to characterize the polarity characteristics of the signal. The calculation formulas for the positive and negative polarity ratios are shown in the above formulas (3) and (4), which will not be repeated here.

[0111] Optionally, the positive polarity ratio indicates the ratio of the positive value part of the signal in the entire sampling period, and the negative polarity ratio indicates the ratio of the negative value part of the signal. Through polarity analysis, the polarity distribution characteristics of the signal can be determined to assist in determining the source of the signal.

[0112] Step S204, three-phase signal addition and subtraction.

[0113] In this embodiment, the three-phase signals are subjected to addition and subtraction operations to enhance the signal characteristics and highlight the signal differences. By adding operations, the common characteristics of the signals can be enhanced, that is, the signals of the same partial discharge source at different phases will be more obvious after the addition operation. The addition operation method is shown in the above formulas (5) to (7), which will not be repeated here.

[0114] Optionally, through subtraction operation, the difference of the signal can be highlighted, the common mode interference can be weakened or eliminated, and the identifiability of the signal can be improved. The subtraction operation method is shown in the above formula (8) to formula (10), which will not be repeated here. The total energy of the signal after the addition and subtraction operation is calculated to quantify the energy distribution of the signal. The calculation formula of the total energy is shown in the above formula (11) to formula (16), which will not be repeated here.

[0115] Optionally, by calculating the total energy of the signal after addition and subtraction operations, the energy distribution characteristics of the signal can be further analyzed to determine the source of the partial discharge signal.

[0116] Optionally, by performing addition and subtraction operations on the three-phase signals and calculating the total energy of the signals after addition and subtraction, this method can effectively enhance the common characteristics of the signals and highlight the difference characteristics of the signals of different phases. This processing method helps to identify the signal source more clearly, especially in the case of large signal interference, it can still maintain a high resolution.

[0117] Step S205, identifying the source of the partial discharge signal.

[0118] In this embodiment, an innovative comprehensive method is designed by integrating the results of time-frequency analysis, signal polarity analysis and signal addition and subtraction analysis to determine the source phase of the partial discharge signal.

[0119] Optionally, the time-frequency analysis result: extract the time-frequency characteristics of each phase signal through STFT transformation, and calculate the spectrum energy density. Set the spectrum energy threshold E th , to determine whether each phase signal has significant spectrum energy. As shown in the above formula (2), it will not be repeated here.

[0120] Optionally, the signal polarity analysis result: calculate the positive and negative polarity ratio of each phase signal to characterize the polarity characteristics of the signal. Set the polarity ratio threshold P th , as shown in the previous formula (14) and formula (15), which will not be repeated here.

[0121] Optionally, the result of signal addition and subtraction operation: by addition and subtraction operation, the energy contribution of each phase after the addition and subtraction operation is calculated. The specific method is to calculate the average energy of each phase in all addition and subtraction operations. As shown in the above formula (16) and formula (21), it will not be repeated here.

[0122] Optionally, calculate the comprehensive discrimination index: set a weight coefficient for each analysis result, the coefficient w of the spectrum energy tf , the coefficient w of signal polarity pol , polarity of addition operation w sum , polarity of subtraction operation w diff , and calculate the comprehensive discrimination index I i To determine the main source of the partial discharge signal. The formula of the comprehensive discrimination index is shown in the above formula (22), which will not be repeated here.

[0123] Optionally, determine the source phase of the partial discharge signal: compare the comprehensive discrimination index I of the three-phase signal A ,I B and I C , the phase with the largest comprehensive discrimination index is the main source phase of the partial discharge signal. As shown in the above formula (23), it will not be repeated here.

[0124] Optionally, by comprehensively analyzing the time-frequency characteristics, signal polarity, and energy characteristics after signal addition and subtraction, and making full use of the multi-dimensional characteristic information of the signal, the source phase of the partial discharge signal can be more accurately and reliably identified. This greatly improves the fault detection effect in a complex power system environment and reduces the possibility of misjudgment.

[0125] In this embodiment, the present invention can perform online monitoring during the operation of the power system by real-time acquisition and analysis of three-phase high-frequency current signals, and timely discover and diagnose partial discharge faults. This not only improves the operational safety and reliability of the power system, but also provides strong technical support for the maintenance and management of power equipment, and reduces the risk of power outages caused by faults.

[0126] In this embodiment, high-frequency current sensors are respectively installed on the three-phase circuits of the switch cabinet to collect three-phase high-frequency current signals in real time, and the signals are filtered, denoised and normalized. The pre-processed signal is subjected to short-time Fourier transform (STFT), the time-frequency characteristics of the signal are extracted and the spectrum energy density is calculated. The polarity characteristics of the signal are characterized by analyzing the proportion of positive and negative polarity of each phase signal. In addition, the three-phase signal is added and subtracted, and the total energy of the signal after addition and subtraction is calculated to enhance the common characteristics of the signal and highlight the difference characteristics of the signal. Finally, the source phase of the partial discharge signal is determined by combining the results of time-frequency analysis, signal polarity and signal addition and subtraction analysis. This method utilizes the multidimensional characteristics of the signal to improve the accuracy and reliability of recognition, is suitable for online monitoring and fault diagnosis of power systems, and effectively improves the safety and reliability of power system operation, thereby solving the technical problem of low accuracy of discharge phase recognition and achieving the technical effect of improving the accuracy of discharge phase recognition.

[0127] According to an embodiment of the present invention, a discharge phase determination device is also provided. It should be noted that the discharge phase determination device can be used to execute the discharge phase determination method in the method embodiment.

[0128] Figure 3 Schematic diagram of a discharge phase determination device according to an embodiment of the present invention. Figure 3 As shown, the discharge phase determination device 300 may include: an acquisition unit 301 , an identification unit 302 , a first determination unit 303 , and a second determination unit 304 .

[0129] The acquisition unit 301 is used to acquire a three-phase current signal, wherein the three-phase current signal includes at least three phase current signals.

[0130] The identification unit 302 is used to identify the time-frequency index, polarity index and energy index of the three-phase current signal, wherein the time-frequency index is used to indicate the spectral energy density corresponding to the phase-by-phase current signal, the polarity index is used to indicate the positive polarity proportion and the negative polarity proportion corresponding to the phase-by-phase current signal, and the energy index is used to indicate the energy contribution corresponding to the phase-by-phase current signal.

[0131] The first determination unit 303 is used to determine the comprehensive discrimination index corresponding to the phase-specific current signal based on the time-frequency index, the polarity index and the energy index.

[0132] The second determination unit 304 is configured to determine a target discharge phase based on the comprehensive discrimination index.

[0133] Optionally, the identification unit 302 may include: an extraction module, configured to extract the time-frequency characteristics of the three-phase current signal; and a first determination module, configured to determine the time-frequency index of the three-phase current signal based on the time-frequency characteristics.

[0134] Optionally, the identification unit 302 may further include: an enhancement module, configured to perform enhancement processing on the phase-specific current signals in the three-phase current signal to obtain an energy index of the three-phase current signal.

[0135] Optionally, the first determination unit 303 may include: a weighting module, configured to perform a weighted operation on the time-frequency index, the polarity index and the energy index to determine a comprehensive discrimination index corresponding to the phase-specific current signal.

[0136] Optionally, the second determination unit 304 may include: a comparison module, used to compare the comprehensive discrimination indexes respectively to obtain a comparison result; a second determination module, used to determine the maximum comprehensive discrimination index among the comprehensive discrimination indexes based on the comparison result; a third determination module, used to determine the phase difference current signal corresponding to the maximum comprehensive discrimination index; and a fourth determination module, used to determine the discharge phase corresponding to the phase difference current signal as the target discharge phase.

[0137] Optionally, the discharge phase determination device 300 may further include: a preprocessing unit, configured to preprocess the three-phase current signal.

[0138] In this embodiment, a three-phase current signal is obtained, wherein the three-phase current signal includes at least three phases of phase-by-phase current signals; the time-frequency index, polarity index and energy index of the three-phase current signal are identified, wherein the time-frequency index is used to indicate the spectral energy density corresponding to the phase-by-phase current signal, the polarity index is used to indicate the positive polarity ratio and the negative polarity ratio corresponding to the phase-by-phase current signal, and the energy index is used to indicate the energy contribution corresponding to the phase-by-phase current signal; based on the time-frequency index, polarity index and energy index, the comprehensive discrimination index corresponding to the phase-by-phase current signal is determined; based on the comprehensive discrimination index, the target discharge phase is determined. That is to say, the present invention identifies the time-frequency index, polarity index and energy index of the three-phase current signal, thereby determining the comprehensive discrimination index of each phase-by-phase current signal according to the time-frequency index, polarity index and energy index, and then determining the discharge phase according to the comprehensive discrimination index, thereby solving the technical problem of low discharge phase recognition accuracy and achieving the technical effect of improving the discharge phase recognition accuracy.

[0139] According to an embodiment of the present invention, a computer-readable storage medium is further provided. The storage medium includes a stored program, wherein the program executes the discharge phase determination method in the method embodiment.

[0140] According to an embodiment of the present invention, a processor is further provided. The processor is used to run a program. When the program is run, the discharge phase determination method in the method embodiment is executed.

[0141] According to an embodiment of the present invention, a computer program product is further provided. The computer program product includes computer instructions. When the computer instructions are executed by a processor, the discharge phase determination method in the method embodiment is implemented.

[0142] The serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0143] In the above embodiments of the present invention, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0144] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. Among them, the device embodiments described above are only schematic. For example, the division of units can be a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of units or modules, which can be electrical or other forms.

[0145] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed over multiple units. Some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0146] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0147] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent functional component, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software functional component, which is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, server or network device, etc.) to perform all or part of the steps of the methods of each embodiment of the present invention. The aforementioned storage medium includes: U disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), mobile hard disk, disk or optical disk, etc., which can store program codes.

[0148] The above are only preferred embodiments of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for determining a discharge phase, characterized in that: include: Acquire a three-phase current signal, wherein the three-phase current signal includes at least three phase-specific current signals; Identify the time-frequency index, polarity index and energy index of the three-phase current signal, wherein the time-frequency index is used to indicate the spectral energy density corresponding to the phase-by-phase current signal, the polarity index is used to indicate the positive polarity proportion and the negative polarity proportion corresponding to the phase-by-phase current signal, and the energy index is used to indicate the energy contribution corresponding to the phase-by-phase current signal; Determining a comprehensive discrimination index corresponding to the phase-specific current signal based on the time-frequency index, the polarity index and the energy index; Based on the comprehensive discrimination index, a target discharge phase is determined.

2. The method according to claim 1, characterized in that Identifying the time-frequency index of the three-phase current signal includes: Extracting time-frequency characteristics of the three-phase current signal; Based on the time-frequency characteristics, the time-frequency index of the three-phase current signal is determined.

3. The method according to claim 1, characterized in that Identifying the energy index of the three-phase current signal includes: The phase-specific current signals in the three-phase current signal are enhanced to obtain the energy index of the three-phase current signal.

4. The method according to claim 1, characterized in that: Determining a comprehensive discrimination index corresponding to the phase-specific current signal based on the time-frequency index, the polarity index, and the energy index includes: A weighted operation is performed on the time-frequency index, the polarity index and the energy index to determine the comprehensive discrimination index corresponding to the phase-specific current signal.

5. The method according to claim 1, characterized in that Based on the comprehensive discrimination index, determining a target discharge phase includes: Comparing the comprehensive discrimination indexes respectively to obtain comparison results; Based on the comparison result, determining the maximum comprehensive discrimination index among the comprehensive discrimination indexes; Determine the phase current signal corresponding to the maximum comprehensive discrimination index; The discharge phase corresponding to the phase current signal is determined as the target discharge phase.

6. The method according to any one of claims 1 to 5, characterized in that: Before identifying the time-frequency index, polarity index and energy index of the three-phase current signal, the method further includes: The three-phase current signal is preprocessed.

7. A device for determining a discharge phase, characterized in that: include: An acquisition unit, configured to acquire a three-phase current signal, wherein the three-phase current signal includes at least three phase-specific current signals; An identification unit, used to identify the time-frequency index, polarity index and energy index of the three-phase current signal, wherein the time-frequency index is used to indicate the spectral energy density corresponding to the phase-by-phase current signal, the polarity index is used to indicate the positive polarity proportion and the negative polarity proportion corresponding to the phase-by-phase current signal, and the energy index is used to indicate the energy contribution corresponding to the phase-by-phase current signal; A first determination unit, configured to determine a comprehensive discrimination index corresponding to the phase-specific current signal based on the time-frequency index, the polarity index and the energy index; The second determination unit is used to determine a target discharge phase based on the comprehensive discrimination index.

8. A computer-readable storage medium, characterized in that: The computer-readable storage medium includes a stored program, wherein when the program is executed by a processor, the device where the storage medium is located is controlled to execute the method according to any one of claims 1 to 6.

9. A processor, characterized in that: The processor is used to run a program, wherein the program executes the method according to any one of claims 1 to 6 when running.

10. A computer program product, characterized in that The computer program product comprises computer instructions, which implement the method according to any one of claims 1 to 6 when executed by a processor.

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