CN107831412B - Electrical equipment partial discharge positioning method and system, storage medium and terminal equipment - Google Patents
Electrical equipment partial discharge positioning method and system, storage medium and terminal equipment Download PDFInfo
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- CN107831412B CN107831412B CN201710942874.2A CN201710942874A CN107831412B CN 107831412 B CN107831412 B CN 107831412B CN 201710942874 A CN201710942874 A CN 201710942874A CN 107831412 B CN107831412 B CN 107831412B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
- G01R31/1209—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing using acoustic measurements
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/08—Locating faults in cables, transmission lines, or networks
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
- G01R31/1227—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials
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Abstract
The invention provides a method and a system for positioning partial discharge of electrical equipment, a storage medium and terminal equipment, wherein the method comprises the steps of obtaining the harmonic frequency cut-off frequency of the power frequency of a sound pressure signal of the electrical equipment; filtering a sound pressure signal of the electrical equipment by adopting a linear phase-shift multi-stopband comb filter to obtain a residual signal obtained after filtering harmonic frequency of power frequency; calculating the kurtosis of the residual signal, and setting a kurtosis threshold; if the kurtosis is larger than the kurtosis threshold, judging that partial discharge occurs in a time period corresponding to the kurtosis; generating a partial discharge signal including a phase characteristic based on the determined partial discharge time period and a partial discharge signal model; and realizing the positioning of the partial discharge according to the phase characteristics of the partial discharge signal. The method and the system for positioning the partial discharge of the electrical equipment, the storage medium and the terminal equipment can realize accurate and rapid positioning of the partial discharge of the transformer substation.
Description
Technical Field
The invention relates to the technical field of signal processing, in particular to a method and a system for positioning partial discharge of electrical equipment, a storage medium and terminal equipment.
Background
Due to dirt accumulation or corrosion generated by a manufacturing process or long-term operation, the transformer substation or the power transmission line can cause the change of electric field intensity to generate partial discharge. The partial discharge is accompanied by phenomena such as acousto-optic heat and chemical reaction, which cause loss of electric energy and accelerated aging of components, thereby affecting the stability of the operation of the power supply equipment. Therefore, partial discharge monitoring has become an important component of online monitoring of electrical equipment. However, because the partial discharge noise of the electrical equipment has instantaneity, and the partial discharge noise signal generated in the early stage of the fault is weak, and meanwhile, a large amount of harmonic noise and other interference exist in the test field, the accuracy of the noise source monitoring and the partial discharge positioning is seriously influenced.
The partial discharge can determine the orientation of the multi-channel sound pressure signal according to the phase characteristics of the multi-channel sound pressure signal. However, in the implementation process, the collected sound pressure signal is often interfered by harmonic noise of the transformer body, noise of the fan and the like, and the noise greatly exceeds the noise generated by discharge. Therefore, harmonic frequency noise is removed, discharge noise is quickly separated, and the fidelity of the phase is kept, so that the method has great significance for accurately positioning partial discharge based on phase characteristics. The traditional partial discharge signal processing method comprises an FFT threshold filtering method, a self-adaptive digital filtering method, an empirical mode decomposition method, a wavelet analysis method and the like. These methods have the disadvantages of difficult threshold selection, modal aliasing, slow convergence rate, large calculation amount and the like to different degrees. In recent years, an atomic function is constructed according to signal prior characteristics, and a partial discharge signal can be separated by adopting a sparse decomposition method, but the most outstanding problem is that the calculation amount is huge.
Disclosure of Invention
In view of the above drawbacks of the prior art, an object of the present invention is to provide a method and a system for positioning partial discharge of an electrical device, a storage medium, and a terminal device, wherein the method and the system are used for filtering harmonic noise by using a linear phase-shift multi-stopband comb filter through spectrum analysis of substation noise, determining a time period in which a suspected partial discharge occurs by calculating a kurtosis of a residual signal, and finally extracting a partial discharge noise signal through sparse decomposition, so as to accurately and quickly position the partial discharge of the substation.
In order to achieve the above and other related objects, the present invention provides a method for positioning partial discharge of electrical equipment based on phase characteristics, comprising the steps of: acquiring the harmonic frequency cut-off frequency of the power frequency of the sound pressure signal of the electrical equipment; filtering a sound pressure signal of the electrical equipment by adopting a linear phase-shift multi-stopband comb filter to obtain a residual signal obtained after filtering harmonic frequency of power frequency; the harmonic center frequencies of the stopbands of the multi-stopband comb filter include all harmonic frequencies with frequencies below the harmonic cut-off frequency and amplitudes above the cut-off threshold; calculating the kurtosis of the residual signal, and setting a kurtosis threshold; if the kurtosis is larger than the kurtosis threshold, judging that partial discharge occurs in a time period corresponding to the kurtosis; generating a partial discharge signal including a phase characteristic based on the determined partial discharge time period and a partial discharge signal model; and realizing the positioning of the partial discharge according to the phase characteristics of the partial discharge signal.
In an embodiment of the present invention, obtaining the harmonic cut-off frequency of the power frequency of the sound pressure signal of the electrical device includes the following steps:
carrying out FFT (fast Fourier transform) on a sound pressure signal of the electrical equipment to obtain a noise frequency spectrum characteristic;
determining the highest harmonic frequency amplitude according to the frequency spectrum characteristics of the harmonic frequencies of the power frequency in the noise frequency spectrum, and taking the highest harmonic frequency amplitude with preset percentage as a cut-off threshold;
and if the amplitudes of the harmonic frequencies which are more than or equal to a certain frequency are all smaller than the cut-off threshold value, setting the frequency as the harmonic frequency cut-off frequency.
In an embodiment of the present invention, the multi-stop-band comb filter is an FIR filter.
In an embodiment of the present invention, a kurtosis of the residual signal is calculated, and a kurtosis threshold is set; if the kurtosis is larger than the kurtosis threshold, judging that partial discharge occurs in a time period corresponding to the kurtosis comprises the following steps:
determining the length of a sliding window;
calculating a kurtosis of the residual signal
Where i denotes the number of kurtosis values, W is the length of the sliding window, SrRepresenting the residual signal, j representing the sequence number of the residual signal in the window;
and setting a kurtosis threshold, and if the kurtosis is larger than the kurtosis threshold, judging that partial discharge occurs in a time period corresponding to the kurtosis.
In an embodiment of the present invention, a value of rounding up to an even number of sampling points of the sound pressure signal in the power frequency period is used as the length of the sliding window.
In an embodiment of the present invention, the kurtosis threshold is
And σ represents a mean and a variance, respectively, of the kurtosis of the residual signal.
In an embodiment of the present invention, generating the partial discharge signal including the phase characteristic based on the determined partial discharge time period and the partial discharge signal model includes the following steps:
constructing a partial discharge signal modelNormalizing the local discharge noise; wherein gamma isjIs a set of discretized waveform parameters,
α denotes the bandwidth factor, τ denotes the time at which the partial discharge occurs, f0Which represents the center frequency of the partial discharge pulse,
representing an initial phase; a and f0Determining the value range of the partial discharge by the prior knowledge of the partial discharge, determining the value range of the tau according to the time period for judging the occurrence of the partial discharge,
is a numerical parameter which needs to be solved by optimization;
and aiming at parameter combinations of different partial discharge signal models, calculating an inner product of the partial discharge noise signal subjected to normalization processing and the residual signal, acquiring a partial discharge signal with the maximum inner product, and acquiring phase information of the partial discharge signal.
Correspondingly, the invention also provides a phase characteristic-based electrical equipment partial discharge positioning system, which comprises an acquisition module, a filtering module, a judgment module, a generation module and a positioning module;
the acquisition module is used for acquiring the harmonic frequency cut-off frequency of the power frequency of the sound pressure signal of the electrical equipment;
the filtering module is used for filtering a sound pressure signal of the electrical equipment by adopting a linear phase-shift multi-stopband comb filter so as to obtain a residual signal obtained after filtering harmonic frequency of power frequency; the harmonic center frequencies of the stopbands of the multi-stopband comb filter include all harmonic frequencies with frequencies below the harmonic cut-off frequency and amplitudes above the cut-off threshold;
the judging module is used for calculating the kurtosis of the residual signal and setting a kurtosis threshold; if the kurtosis is larger than the kurtosis threshold, judging that partial discharge occurs in a time period corresponding to the kurtosis;
the generation module is used for generating a partial discharge signal containing phase characteristics based on the determined partial discharge time period and the partial discharge signal model;
the positioning module is used for realizing the positioning of the partial discharge according to the phase characteristics of the partial discharge signal.
In addition, the invention also provides a computer readable storage medium, on which a computer program is stored, which when executed by a processor implements the above-mentioned method for positioning partial discharge of electrical equipment based on phase characteristics.
Finally, the present invention also provides a terminal device, comprising: a processor and a memory; the memory is used for storing computer programs, and the processor is used for executing the computer programs stored by the memory so as to enable the terminal equipment to execute the above-mentioned electric equipment partial discharge positioning system method based on the phase characteristics.
As described above, the electrical device partial discharge positioning method and system, the storage medium, and the terminal device according to the present invention have the following advantageous effects:
(1) by filtering harmonic noise, the signal-to-noise ratio of the partial discharge signal is improved, and the accuracy of judging whether partial discharge occurs is improved;
(2) by calculating the kurtosis of the residual signal, the period of time when the discharge is suspected to occur can be estimated quickly and accurately, and the calculation amount of a sparse decomposition algorithm is greatly reduced;
(3) filtering through a multi-stop-band comb filter with linear phase characteristics, maintaining the phase characteristics of partial discharge signals in residual signals, and realizing the positioning of a phase-based partial discharge noise source;
(4) compared with the prior art, the method has the advantages that the solving speed is high, and the characteristics of each channel phase can be kept unchanged, so that the discharging noise source based on the phase characteristics can be accurately positioned.
Drawings
FIG. 1 is a flow chart illustrating a method for locating partial discharge of electrical equipment based on phase signature according to an embodiment of the present invention;
FIG. 2 is a noise time domain diagram and a frequency spectrum diagram of an embodiment of the method for locating partial discharge of electrical equipment based on phase characteristics of the present invention;
FIG. 3 is a graph showing the amplitude-frequency and phase-frequency of a multi-stopband comb filter in an embodiment of the method for locating partial discharge of an electrical device based on phase characteristics of the present invention;
FIG. 4 is a graph of a sound pressure signal, residual noise, kurtosis, and partial discharge signal of an embodiment of a method for locating partial discharge in an electrical device based on phase signature of the present invention;
FIG. 5 is a schematic diagram of an embodiment of a phase-based electrical device partial discharge positioning system according to the present invention;
fig. 6 is a schematic structural diagram of a terminal device according to an embodiment of the present invention.
Description of the element reference numerals
51 acquisition module
52 filtering module
53 judging module
54 generating module
55 positioning module
6 terminal equipment
61 processor
62 memory
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It is to be noted that the features in the following embodiments and examples may be combined with each other without conflict.
It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present invention, and the components related to the present invention are only shown in the drawings rather than drawn according to the number, shape and size of the components in actual implementation, and the type, quantity and proportion of the components in actual implementation may be changed freely, and the layout of the components may be more complicated.
The electrical equipment partial discharge positioning method and system based on the phase characteristics, the storage medium and the terminal equipment of the invention are based on identifying and separating the partial discharge noise and carrying out multi-channel partial discharge noise linear phase shift, thereby greatly improving the solving speed, and maintaining the phase difference between the separated multi-channel signals unchanged, thereby realizing the accurate positioning of the discharge noise source based on the phase characteristics.
As shown in fig. 1, in an embodiment, the method for positioning partial discharge of electrical equipment based on phase characteristics of the present invention includes the following steps:
and step S1, obtaining the harmonic frequency cut-off frequency of the power frequency of the sound pressure signal of the electrical equipment.
Specifically, the spectral characteristics of noise are obtained by performing spectral analysis on the collected sound pressure signal of the electrical device, and then the harmonic cut-off frequency of the power frequency is determined. The power frequency refers to the rated frequency adopted by power generation, transmission, transformation and distribution equipment of a power system and industrial and civil electrical equipment, and is in Hz. For example, the power frequency used in China is 50Hz, and the power frequency used in some countries is 60 Hz.
Preferably, the electrical device comprises a transformer.
In one embodiment, the step of obtaining the harmonic cut-off frequency of the power frequency of the sound pressure signal of the electrical device comprises the following steps:
11) and carrying out FFT (fast Fourier transform) on the sound pressure signal of the electrical equipment to acquire the noise spectrum characteristic.
For transformers, the noise signals include transformer body harmonic noise, discharge noise, fan noise, and other noise. The harmonic frequency noise of the transformer body is concentrated on power frequency and harmonic frequency components taking the power frequency as fundamental frequency; the discharge noise is short-time pulse noise; the fan noise is low-frequency periodic noise; other noise includes background noise and random noise.
12) And determining the highest harmonic frequency amplitude according to the frequency spectrum characteristics of the harmonic frequencies of the power frequency in the noise frequency spectrum, and taking the highest harmonic frequency amplitude with preset percentage as a cut-off threshold.
Preferably, the preset percentage is 10%.
13) And if the amplitudes of the harmonic frequencies which are more than or equal to a certain frequency are all smaller than the cut-off threshold value, setting the frequency as the harmonic frequency cut-off frequency.
Step S2, filtering the sound pressure signal of the electrical equipment by adopting a linear phase-shift multi-stop-band comb filter to obtain a residual signal obtained after filtering harmonic frequency of power frequency; the harmonic center frequencies of the stopbands of the multi-stopband comb filter include all harmonic frequencies having frequencies below the harmonic cut-off frequency and amplitudes above the cut-off threshold.
In an embodiment of the present invention, the filtering the sound pressure signal of the electrical device by using the linear phase-shift multi-stop-band comb filter to obtain a residual signal obtained after filtering the harmonic frequency of the power frequency includes the following steps:
21) generating a multi-stopband comb filter having stopband center frequencies that include all harmonic frequencies having frequencies below the harmonic cut-off frequency and amplitudes above the cut-off threshold.
Specifically, according to a spectrogram of noise and harmonic cut-off frequencies, all harmonic frequencies with frequencies lower than the harmonic cut-off frequency and amplitudes exceeding the cut-off threshold are determined as stopband center frequencies of the multi-stopband comb filter. Preferably, the stopband center frequency of the multi-stopband comb filter is all harmonic frequencies from the power frequency to the harmonic cut-off frequency.
Preferably, the multi-stopband comb filter is an FIR filter. A FIR (Finite Impulse Response) filter, also called a non-recursive filter, is the most basic element in a digital signal processing system, and can have a strict linear phase-frequency characteristic while ensuring an arbitrary amplitude-frequency characteristic, and at the same time, the unit sampling Response of the filter is Finite, so that the filter is a stable system. Thus, the linear phase shift characteristic of the multi-stopband comb filter is ensured.
22) And filtering the sound pressure signal of the electrical equipment by adopting the multi-stop-band comb filter to obtain a residual signal obtained after filtering harmonic frequency of power frequency.
Step S3, calculating the kurtosis of the residual signal, and setting a kurtosis threshold; and if the kurtosis is larger than the kurtosis threshold, judging that partial discharge occurs in a time period corresponding to the kurtosis.
In an embodiment of the present invention, a kurtosis of the residual signal is calculated, and a kurtosis threshold is set; if the kurtosis is larger than the kurtosis threshold, judging that partial discharge occurs in a time period corresponding to the kurtosis comprises the following steps:
31) a slip window length is determined.
Specifically, the value of the sound pressure signal rounded up to an even number in the number of sampling points in the power frequency period is used as the length of the sliding window.
32) Calculating a kurtosis of the residual signal
Where i denotes the number of kurtosis values, W is the length of the sliding window, SrIndicating a disabilityThe difference signal, j, represents the sequence number of the residual signal within the window.
33) And setting a kurtosis threshold, and if the kurtosis is larger than the kurtosis threshold, judging that partial discharge occurs in a time period corresponding to the kurtosis.
Specifically, the kurtosis threshold is
And σ represents a mean and a variance, respectively, of the kurtosis of the residual signal.
Step S4 is to generate a partial discharge signal including a phase characteristic based on the determined partial discharge time period and the partial discharge signal model.
In an embodiment of the present invention, generating the partial discharge signal including the phase characteristic based on the determined partial discharge time period and the partial discharge signal model includes the following steps:
41) constructing a partial discharge signal model
Normalizing the local discharge noise; wherein gamma isjIs a set of discretized waveform parameters,
α denotes the bandwidth factor, τ denotes the time at which the partial discharge occurs, f0Which represents the center frequency of the partial discharge pulse,
indicating the initial phase.
In particular, τ ∈ { τ ∈ }i}，α∈{αk}，
A and f0The value range can be determined by the prior knowledge of partial discharge, the value range of tau is determined according to the time period for judging the occurrence of partial discharge,
is a numerical parameter that requires an optimization solution, preferably α is a positive constant.
42) And aiming at parameter combinations of different partial discharge signal models, calculating an inner product of the partial discharge noise signal subjected to normalization processing and the residual signal, acquiring a partial discharge signal with the maximum inner product, and acquiring phase information of the partial discharge signal.
And step S5, realizing the positioning of the partial discharge according to the phase characteristics of the partial discharge signal.
Specifically, for a multi-channel sound pressure signal, the time delay of each channel is estimated according to the phase characteristics of a partial discharge signal, and the spatial positioning of a partial discharge noise source is realized by combining with spatial coordinates.
The method for positioning partial discharge of electrical equipment based on phase characteristics according to the present invention is further illustrated by the following specific examples. In this embodiment, if the electrical device is a substation, the method for positioning partial discharge of the substation includes the following steps:
1) and obtaining the harmonic frequency cut-off frequency of the power frequency of the sound pressure signal of the transformer substation.
Specifically, FFT conversion is carried out on a multichannel sound pressure signal of a transformer substation to obtain a noise frequency spectrum characteristic; as shown in FIG. 2, 10% of the amplitude of the highest harmonic frequency with a frequency of 400Hz is used as the cutoff threshold; and if the amplitudes of the harmonic frequencies which are more than or equal to a certain frequency are all smaller than the cut-off threshold value, setting the frequency as the harmonic frequency cut-off frequency.
The transformer substation noise mainly comprises transformer body noise, partial discharge noise, fan noise and other noises. The body noise of the transformer or the reactor is concentrated on 50Hz and harmonic frequency components with 50Hz as fundamental frequency; the local discharge noise is short-time pulse noise, and the main frequency band is an audible band of 20 Hz-20 KHz; the fan noise is a low-frequency periodic signal, and other noises comprise white noise, background noise and the like.
2) Filtering a sound pressure signal of the electrical equipment by adopting a linear phase-shift multi-stopband comb filter to obtain a residual signal obtained after filtering harmonic frequency of power frequency; the harmonic center frequencies of the stopbands of the multi-stopband comb filter include all harmonic frequencies having frequencies below the harmonic cut-off frequency and amplitudes above the cut-off threshold.
As shown in fig. 3, the stop band center frequencies of the multi-stop band comb filter are determined to be [100, 250, 300, 350, 400, 450, 550] based on the determined harmonic cut-off frequencies and the determined spectral curves.
3) Calculating the kurtosis of the residual signal, and setting a kurtosis threshold; and if the kurtosis is larger than the kurtosis threshold, judging that partial discharge occurs in a time period corresponding to the kurtosis.
As shown in fig. 4, first, the width of the slip window at the time of kurtosis calculation is determined; calculating the kurtosis of the residual signal and drawing a kurtosis curve; and calculating the mean value and the variance of the kurtosis to obtain a kurtosis threshold, and finally finding a data segment with abnormal kurtosis at 0.2s, namely judging that the local discharge occurs at the data segment.
4) A partial discharge signal including a phase characteristic is generated based on the determined partial discharge time period and the partial discharge signal model.
And for the partial discharge signal with the maximum inner product, acquiring information such as time delay, phase, frequency, attenuation index and the like of the partial discharge signal.
5) And realizing the positioning of the partial discharge according to the phase characteristics of the partial discharge signal.
In particular, the spatial position of the partial discharge signal is determined by multi-channel phase information
As shown in fig. 5, in an embodiment, the system for locating partial discharge of electrical equipment based on phase characteristics of the present invention includes an obtaining module 51, a filtering module 52, a determining module 53, a generating module 54, and a locating module 55.
The obtaining module 51 is configured to obtain a harmonic cut-off frequency of a power frequency of the sound pressure signal of the electrical device.
Specifically, the spectral characteristics of noise are obtained by performing spectral analysis on the collected sound pressure signal of the electrical device, and then the harmonic cut-off frequency of the power frequency is determined. The power frequency refers to the rated frequency adopted by power generation, transmission, transformation and distribution equipment of a power system and industrial and civil electrical equipment, and is in Hz. For example, the power frequency used in China is 50Hz, and the power frequency used in some countries is 60 Hz.
Preferably, the electrical device comprises a transformer.
In an embodiment, the obtaining module 51 obtains the harmonic cut-off frequency of the power frequency of the sound pressure signal of the electrical device, and performs the following steps:
a) and carrying out FFT (fast Fourier transform) on the sound pressure signal of the electrical equipment to acquire the noise spectrum characteristic.
For transformers, the noise signals include transformer body harmonic noise, discharge noise, fan noise, and other noise. The harmonic frequency noise of the transformer body is concentrated on power frequency and harmonic frequency components taking the power frequency as fundamental frequency; the discharge noise is short-time pulse noise; the fan noise is low-frequency periodic noise; other noise includes background noise and random noise.
b) And determining the highest harmonic frequency amplitude according to the frequency spectrum characteristics of the harmonic frequencies of the power frequency in the noise frequency spectrum, and taking the highest harmonic frequency amplitude with preset percentage as a cut-off threshold.
Preferably, the preset percentage is 10%.
c) And if the amplitudes of the harmonic frequencies which are more than or equal to a certain frequency are all smaller than the cut-off threshold value, setting the frequency as the harmonic frequency cut-off frequency.
The filtering module 52 is connected to the obtaining module 51, and is configured to filter a sound pressure signal of the electrical device by using a linear phase-shift multi-stop-band comb filter, so as to obtain a residual signal obtained after filtering out a harmonic frequency of a power frequency; the harmonic center frequencies of the stopbands of the multi-stopband comb filter include all harmonic frequencies having frequencies below the harmonic cut-off frequency and amplitudes above the cut-off threshold.
In an embodiment of the present invention, the filtering module 52 filters the sound pressure signal of the electrical device by using a linear phase-shift multi-stop-band comb filter, so as to obtain a residual signal packet obtained after filtering the harmonic frequency of the power frequency, and performs the following steps:
a) generating a multi-stopband comb filter having stopband center frequencies that include all harmonic frequencies having frequencies below the harmonic cut-off frequency and amplitudes above the cut-off threshold.
Specifically, according to a spectrogram of noise and harmonic cut-off frequencies, all harmonic frequencies with frequencies lower than the harmonic cut-off frequency and amplitudes exceeding the cut-off threshold are determined as stopband center frequencies of the multi-stopband comb filter. Preferably, the stopband center frequency of the multi-stopband comb filter is all harmonic frequencies from the power frequency to the harmonic cut-off frequency.
Preferably, the multi-stopband comb filter is an FIR filter. A FIR (Finite Impulse Response) filter, also called a non-recursive filter, is the most basic element in a digital signal processing system, and can have a strict linear phase-frequency characteristic while ensuring an arbitrary amplitude-frequency characteristic, and at the same time, the unit sampling Response of the filter is Finite, so that the filter is a stable system. Thus, the linear phase shift characteristic of the multi-stopband comb filter is ensured.
b) And filtering the sound pressure signal of the electrical equipment by adopting the multi-stop-band comb filter to obtain a residual signal obtained after filtering harmonic frequency of power frequency.
The decision module 53 is connected to the filtering module 52, and configured to calculate a kurtosis of the residual signal and set a kurtosis threshold; and if the kurtosis is larger than the kurtosis threshold, judging that partial discharge occurs in a time period corresponding to the kurtosis.
In an embodiment of the present invention, the determining module 53 calculates a kurtosis of the residual signal, and sets a kurtosis threshold; if the kurtosis is larger than the kurtosis threshold, judging that partial discharge occurs in a time period corresponding to the kurtosis, and executing the following steps:
a) a slip window length is determined.
Specifically, the value of the sound pressure signal rounded up to an even number in the number of sampling points in the power frequency period is used as the length of the sliding window.
b) Calculating a kurtosis of the residual signal
Wherein i represents the order of kurtosis valuesNumber, W is the sliding window length, SrDenotes the residual signal, and j denotes the number of the residual signal within the window.
c) And setting a kurtosis threshold, and if the kurtosis is larger than the kurtosis threshold, judging that partial discharge occurs in a time period corresponding to the kurtosis.
Specifically, the kurtosis threshold is
And σ represents a mean and a variance, respectively, of the kurtosis of the residual signal.
The generating module 54 is connected to the determining module 53 and the filtering module 52, and is configured to generate a partial discharge signal including a phase characteristic based on the determined partial discharge time period and the partial discharge signal model.
In an embodiment of the present invention, the generating module 54 generates the partial discharge signal including the phase characteristic based on the determined partial discharge time period and the partial discharge signal model, and performs the following steps:
a) constructing a partial discharge signal model
Normalizing the local discharge noise; wherein gamma isjIs a set of discretized waveform parameters,
α denotes the bandwidth factor, τ denotes the time at which the partial discharge occurs, f0Which represents the center frequency of the partial discharge pulse,
indicating the initial phase.
In particular, τ ∈ { τ ∈ }i}，α∈{αk}，
A and f0Can be discharged by partial dischargeDetermining the value range by experimental knowledge, determining the value range by tau according to the time period for judging the occurrence of partial discharge,
is a numerical parameter that requires an optimization solution, preferably α is a positive constant.
b) And aiming at parameter combinations of different partial discharge signal models, calculating an inner product of the partial discharge noise signal subjected to normalization processing and the residual signal, acquiring a partial discharge signal with the maximum inner product, and acquiring phase information of the partial discharge signal.
The positioning module 55 is connected to the generating module 54 for positioning the partial discharge according to the phase characteristics of the partial discharge signal.
Specifically, for a multi-channel sound pressure signal, the time delay of each channel is estimated according to the phase characteristics of a partial discharge signal, and the spatial positioning of a partial discharge noise source is realized by combining with spatial coordinates.
It should be noted that the division of the modules of the above system is only a logical division, and the actual implementation may be wholly or partially integrated into one physical entity, or may be physically separated. And these modules can be realized in the form of software called by processing element; or may be implemented entirely in hardware; and part of the modules can be realized in the form of calling software by the processing element, and part of the modules can be realized in the form of hardware. For example, the x module may be a processing element that is set up separately, or may be implemented by being integrated in a chip of the apparatus, or may be stored in a memory of the apparatus in the form of program code, and the function of the x module may be called and executed by a processing element of the apparatus. Other modules are implemented similarly. In addition, all or part of the modules can be integrated together or can be independently realized. The processing element described herein may be an integrated circuit having signal processing capabilities. In implementation, each step of the above method or each module above may be implemented by an integrated logic circuit of hardware in a processor element or an instruction in the form of software.
For example, the above modules may be one or more integrated circuits configured to implement the above methods, such as: one or more Application Specific Integrated Circuits (ASICs), or one or more microprocessors (DSPs), or one or more Field Programmable Gate Arrays (FPGAs), etc. For another example, when one of the above modules is implemented in the form of a processing element scheduler code, the processing element may be a general-purpose processor, such as a Central Processing Unit (CPU) or other processor capable of calling program code. For another example, these modules may be integrated together and implemented in the form of a system-on-a-chip (SOC).
The storage medium of the present invention stores thereon a computer program that, when executed by a processor, implements the above-described method for locating partial discharge of an electrical device based on phase characteristics. Those of ordinary skill in the art will understand that: all or part of the steps for implementing the above method embodiments may be performed by hardware associated with a computer program. The aforementioned computer program may be stored in a computer readable storage medium. When executed, the program performs steps comprising the method embodiments described above; and the aforementioned storage medium includes: various media that can store program codes, such as ROM, RAM, magnetic or optical disks.
As shown in fig. 6, in an embodiment, the terminal device 6 of the present invention includes a processor 61 and a memory 62.
The memory 62 is configured to store a computer program, and the processor 61 is configured to execute the computer program stored in the memory 62, so as to enable the terminal device to execute the above-mentioned electrical device partial discharge positioning method based on the phase characteristics.
Preferably, the processor 61 may be a general-purpose processor, including a Central Processing Unit (CPU), a Network Processor (NP), and the like; the integrated circuit may also be a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic device, or discrete hardware components.
In summary, the electrical device partial discharge positioning method and system, the storage medium and the terminal device of the present invention improve the signal-to-noise ratio of the partial discharge signal by filtering harmonic noise, and improve the accuracy of determining whether partial discharge occurs; by calculating the kurtosis of the residual signal, the period of time when the discharge is suspected to occur can be estimated quickly and accurately, and the calculation amount of a sparse decomposition algorithm is greatly reduced; filtering through a multi-stop-band comb filter with linear phase characteristics, maintaining the phase characteristics of partial discharge signals in residual signals, and realizing the positioning of a phase-based partial discharge noise source; compared with the prior art, the method has the advantages that the solving speed is high, and the characteristics of each channel phase can be kept unchanged, so that the discharging noise source based on the phase characteristics can be accurately positioned. Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.
The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.
Claims (8)
1. A method for positioning partial discharge of electrical equipment based on phase characteristics is characterized in that: comprises the following steps
Acquiring the harmonic frequency cut-off frequency of the power frequency of the sound pressure signal of the electrical equipment; the method for acquiring the harmonic cut-off frequency of the power frequency of the sound pressure signal of the electrical equipment comprises the following steps: carrying out FFT (fast Fourier transform) on a sound pressure signal of the electrical equipment to obtain a noise frequency spectrum characteristic; determining the highest harmonic frequency amplitude according to harmonic frequency spectrum characteristics of power frequency in the noise spectrum, and taking the highest harmonic frequency amplitude with preset percentage as a cut-off threshold; if the amplitudes of the harmonic frequencies which are more than or equal to a certain frequency are all smaller than a cut-off threshold value, setting the frequency as a harmonic frequency cut-off frequency;
filtering a sound pressure signal of the electrical equipment by adopting a linear phase-shift multi-stopband comb filter to obtain a residual signal obtained after filtering harmonic frequency of power frequency; the harmonic center frequencies of the stopbands of the multi-stopband comb filter include all harmonic frequencies with frequencies below the harmonic cut-off frequency and amplitudes above the cut-off threshold;
calculating the kurtosis of the residual signal, and setting a kurtosis threshold; if the kurtosis is larger than the kurtosis threshold, judging that partial discharge occurs in a time period corresponding to the kurtosis;
generating a partial discharge signal including a phase characteristic based on the determined partial discharge time period and a partial discharge signal model;
realizing the positioning of the partial discharge according to the phase characteristics of the partial discharge signals;
generating a partial discharge signal including a phase characteristic based on the determined partial discharge time period and the partial discharge signal model includes the steps of:
constructing a partial discharge signal model
Normalizing the local discharge noise; wherein gamma isjIs a set of discretized waveform parameters,α denotes the bandwidth factor, τ denotes the time at which the partial discharge occurs, f0Which represents the center frequency of the partial discharge pulse,
indicating the initial phase α and f0Determining the value range of the partial discharge by the prior knowledge of the partial discharge, determining the value range of the tau according to the time period for judging the occurrence of the partial discharge,
is a numerical parameter needing optimization solution, and t represents time;
and aiming at parameter combinations of different partial discharge signal models, calculating an inner product of the partial discharge noise signal subjected to normalization processing and the residual signal, acquiring a partial discharge signal with the maximum inner product, and acquiring phase information of the partial discharge signal.
2. The phase signature-based electrical equipment partial discharge positioning method of claim 1, characterized in that: the multi-stopband comb filter is an FIR filter.
3. The phase signature-based electrical equipment partial discharge positioning method of claim 1, characterized in that: calculating the kurtosis of the residual signal, and setting a kurtosis threshold; if the kurtosis is larger than the kurtosis threshold, judging that partial discharge occurs in a time period corresponding to the kurtosis comprises the following steps:
determining the length of a sliding window;
calculating a kurtosis of the residual signal
Where i denotes the number of kurtosis values, W is the length of the sliding window, SrRepresenting the residual signal, j representing the sequence number of the residual signal in the window;
and setting a kurtosis threshold, and if the kurtosis is larger than the kurtosis threshold, judging that partial discharge occurs in a time period corresponding to the kurtosis.
4. The phase signature-based electrical device partial discharge location method of claim 3, wherein: and rounding up the sampling point number of the sound pressure signal in the power frequency period to an even number as the length of a sliding window.
5. The method for locating partial discharge of electrical equipment according to claim 3, wherein the method is based on the phase characteristicsCharacterized in that: the kurtosis threshold is
And σ represents a mean and a variance, respectively, of the kurtosis of the residual signal.
6. An electrical equipment partial discharge positioning system based on phase characteristics, characterized in that: the device comprises an acquisition module, a filtering module, a judgment module, a generation module and a positioning module;
the acquisition module is used for acquiring the harmonic frequency cut-off frequency of the power frequency of the sound pressure signal of the electrical equipment; the method for acquiring the harmonic cut-off frequency of the power frequency of the sound pressure signal of the electrical equipment comprises the following steps: carrying out FFT (fast Fourier transform) on a sound pressure signal of the electrical equipment to obtain a noise frequency spectrum characteristic; determining the highest harmonic frequency amplitude according to harmonic frequency spectrum characteristics of power frequency in the noise spectrum, and taking the highest harmonic frequency amplitude with preset percentage as a cut-off threshold; if the amplitudes of the harmonic frequencies which are more than or equal to a certain frequency are all smaller than a cut-off threshold value, setting the frequency as a harmonic frequency cut-off frequency;
the filtering module is used for filtering a sound pressure signal of the electrical equipment by adopting a linear phase-shift multi-stop-band comb filter so as to obtain a residual signal obtained after filtering harmonic frequency of power frequency; the harmonic center frequencies of the stopbands of the multi-stopband comb filter include all harmonic frequencies with frequencies below the harmonic cut-off frequency and amplitudes above the cut-off threshold;
the judging module is used for calculating the kurtosis of the residual signal and setting a kurtosis threshold; if the kurtosis is larger than the kurtosis threshold, judging that partial discharge occurs in a time period corresponding to the kurtosis;
the generation module is used for generating a partial discharge signal containing phase characteristics based on the determined partial discharge time period and the partial discharge signal model;
the positioning module is used for realizing the positioning of the partial discharge according to the phase characteristics of the partial discharge signal;
generating a partial discharge signal including a phase characteristic based on the determined partial discharge time period and the partial discharge signal model includes the steps of:
constructing a partial discharge signal modelNormalizing the local discharge noise; wherein gamma isjIs a set of discretized waveform parameters,
α denotes the bandwidth factor, τ denotes the time at which the partial discharge occurs, f0Which represents the center frequency of the partial discharge pulse,
indicating the initial phase α and f0Determining the value range of the partial discharge by the prior knowledge of the partial discharge, determining the value range of the tau according to the time period for judging the occurrence of the partial discharge,
is a numerical parameter needing optimization solution, and t represents time;
and aiming at parameter combinations of different partial discharge signal models, calculating an inner product of the partial discharge noise signal subjected to normalization processing and the residual signal, acquiring a partial discharge signal with the maximum inner product, and acquiring phase information of the partial discharge signal.
7. A computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, carries out a method for locating partial discharges in an electrical device based on phase signatures as set forth in any one of claims 1 to 5.
8. A terminal device, comprising: a processor and a memory;
the memory is used for storing computer programs, and the processor is used for executing the computer programs stored by the memory to enable the terminal device to execute the partial discharge positioning method of the electric device based on the phase characteristics according to any one of claims 1 to 5.
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