A method and device for identifying and testing characteristic current based on Fourier transform algorithm

Abstract

The present invention discloses a characteristic current identification and verification method and device based on Fourier transform algorithm. The technical scheme adopted by the method of the present invention is: first, the current data is recorded by a recording board and uploaded through a network cable, and the analysis module converts the received data; then, the converted current data is Fourier transformed to obtain a frequency domain curve, and the starting point of the signal is obtained according to the frequency domain curve, and the current data is segmented and sliced ​​according to the current characteristic code bits sent by the carrier module; finally, the sliced ​​current data is subjected to signal quality analysis and power quality analysis to obtain signal quality and power quality results. The present invention combines the characteristic current identification function, simulates the operation of the on-site substation, and realizes the substation topology identification function.

Description

Technical Field

[0001] The invention belongs to the field of transformer area topology identification, and in particular to a characteristic current identification and verification method and device based on Fourier transform algorithm. Background Art

[0002] At present, there is no complete and accurate device in China to verify the substation topology identification function. There is confusion in the substations and errors in substation identification on site, which leads to chaotic management of the substations on site, affecting the operation monitoring of electricity meters, fault location and early warning, etc.

[0003] The existing power frequency voltage distortion technology realizes the substation topology identification by sending power frequency voltage signals that do not interfere with carrier communication. This technology is greatly affected by line distance, power supply quality and equipment on the line, resulting in low accuracy of identification effect. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the defects of the above-mentioned prior art and provide a characteristic current identification and verification method and device based on Fourier transform algorithm to simulate the on-site substation operation conditions and realize substation topology identification.

[0005] To this end, a technical solution adopted by the present invention is: a characteristic current identification and verification method based on Fourier transform algorithm, the steps of which are as follows:

[0006] First, the current data is recorded using a wave recording board and uploaded via a network cable. The analysis module converts the received data.

[0007] Then, the converted current data is subjected to Fourier transform to obtain a frequency domain curve, the starting point of the signal is obtained according to the frequency domain curve, and the current data is segmented and sliced ​​according to the current characteristic code bits sent by the carrier module;

[0008] Finally, the signal quality analysis and power quality analysis are performed on the sliced ​​current data to obtain the signal quality and power quality results.

[0009] Further, the process of signal quality analysis is as follows:

[0010] First, determine whether the current is greater than the set threshold. If it is less than or equal to the set threshold, it is considered to be a low level and there is no signal, and the next point is determined. If the signal is greater than the set threshold, the number of points greater than the set threshold, n1, is recorded, and then the low level is found, the number of low level points is recorded, and the number of low level points is recorded as n2. The signal quality parameters are calculated based on the number of high level points and low level points.

[0011] Furthermore, the power quality analysis refers to: analyzing the harmonic voltage content rate, the voltage total harmonic distortion rate, the 0-800Hz interharmonic voltage content rate and the maximum allowable harmonic current based on Fourier transform.

[0012] Furthermore, the spectrum information of the characteristic current signal is obtained by using discrete Fourier transform on the converted current data. The calculation formula is:

[0013]

[0014]

[0015] Among them, a k represents the real part of the kth harmonic, b k Represents the imaginary part of the kth harmonic, N represents the number of data points of the power frequency cycle, k represents the harmonic number; T0 represents the signal period of 100ms; T represents the signal sending time;

[0016] The cross-correlation function is used to quantify the amplitude of the sinusoidal signal and calculate the attenuation state of the signal amplitude. The calculation process is:

[0017] x(t i )=s(t i )+G(t i ), i = 1, 2, ..., N, where x(t i ) is the observed signal, s(t i ) is a sinusoidal signal, G(t i ) represents additive Gaussian white noise with variance σ, and the simulation parameters are as follows:

[0018] Frequency f0 = 10 Hz, initial phase Amplitude a=1;

[0019] Furthermore, the line status monitoring circuit of the recording board uses a 14-bit high-speed AD sampling chip to collect characteristic current signals, uses FPGA XC7Z020 as a data processing unit, and uses the carrier channel as an uplink channel to realize the collection and reporting of the transmitted current signal.

[0020] The present invention also provides another technical solution: a characteristic current identification and verification device based on Fourier transform algorithm, which includes a concentrator, a modular terminal, a fusion terminal, a circuit breaker, a type II concentrator, an electric energy meter and a carrier module;

[0021] When the carrier module sends a characteristic current signal, the corresponding characteristic current signal is transmitted through the electric energy meter to the circuit breaker or type II concentrator. The circuit breaker or type II concentrator is connected to the recording board. The recording board analyzes and quantifies the characteristic current through high-speed AD sampling, and compares the analysis result with the normal value obtained by the carrier module during normal communication. The data is analyzed based on the time domain and frequency domain through the Fourier transform algorithm, and the characteristic current information is sent to the concentrator, modular terminal or fusion terminal. The concentrator, modular terminal or fusion terminal sorts it out and reports the result to the main station to realize the substation topology identification function.

[0022] The present invention combines the characteristic current identification function, simulates the on-site substation operation situation, and realizes the substation topology identification function. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a flow chart of the characteristic current identification and verification method of the present invention;

[0024] Figure 2 A flow chart of signal quality analysis of the present invention;

[0025] Figure 3 This is a structural diagram of the characteristic current identification and verification device of the present invention. DETAILED DESCRIPTION

[0026] The technical solution of the present invention is described more clearly and completely below in conjunction with the embodiments and the accompanying drawings.

[0027] Example 1

[0028] This embodiment provides a characteristic current identification and verification method based on Fourier transform algorithm, such as Figure 1 As shown, the steps are as follows:

[0029] First, the characteristic current identification and verification method based on Fourier transform algorithm has the following steps:

[0030] First, the current data is recorded using a wave recording board and uploaded via a network cable. The analysis module converts the received data.

[0031] Then, the converted current data is subjected to Fourier transform to obtain a frequency domain curve, the starting point of the signal is obtained according to the frequency domain curve, and the current data is segmented and sliced ​​according to the current characteristic code bits sent by the carrier module;

[0032] Finally, the signal quality analysis and power quality analysis are performed on the sliced ​​current data to obtain the signal quality and power quality results.

[0033] Specifically, the process of signal quality analysis is as follows:

[0034] First, determine whether the current is greater than the set threshold. If it is less than or equal to the set threshold, it is considered to be a low level and there is no signal, and the next point is determined. If the signal is greater than the set threshold, the number of points greater than the set threshold, n1, is recorded, and then the low level is found, the number of low level points is recorded, and the number of low level points is recorded as n2. The signal quality parameters are calculated based on the number of high level points and low level points.

[0035] Specifically, power quality analysis refers to: analyzing the harmonic voltage content rate, the voltage total harmonic distortion rate, the 0-800Hz interharmonic voltage content rate and the maximum allowable harmonic current based on Fourier transform.

[0036] Specifically, the frequency spectrum information of the characteristic current signal is obtained by using discrete Fourier transform on the converted current data. The calculation formula is:

[0037]

[0038]

[0039] Among them, a k represents the real part of the kth harmonic, b k Represents the imaginary part of the kth harmonic, N represents the number of data points of the power frequency cycle, k represents the harmonic number; T0 represents the signal period of 100ms; T represents the signal sending time;

[0040] The cross-correlation function is used to quantify the amplitude of the sinusoidal signal and calculate the attenuation state of the signal amplitude. The calculation process is:

[0041] x(t i )=s(t i )+G(t i ), i = 1, 2, ..., N, where x(t i ) is the observed signal, s(t i ) is a sinusoidal signal, G(t i ) represents additive Gaussian white noise with variance σ, and the simulation parameters are as follows:

[0042] Frequency f0 = 10 Hz, initial phase Amplitude a=1;

[0043] Specifically, the line status monitoring circuit of the recording board uses a 14-bit high-speed AD sampling chip to collect characteristic current signals, uses FPGA XC7Z020 as a data processing unit, and uses a carrier channel as an uplink channel to realize the collection and reporting of the transmitted current signal.

[0044] Example 2

[0045] This embodiment provides a characteristic current identification and verification device based on Fourier transform algorithm, such as Figure 3 As shown, it includes a concentrator, a modular terminal, a fusion terminal, a circuit breaker, a type II concentrator, an electric energy meter and a carrier module.

[0046] When the carrier module sends a characteristic current signal, the corresponding characteristic current signal is transmitted through the electric energy meter to the circuit breaker or type II concentrator. The circuit breaker or type II concentrator is connected to the recording board. The recording board analyzes and quantifies the characteristic current through high-speed AD sampling, and compares the analysis result with the normal value obtained by the carrier module during normal communication. The data is analyzed based on the time domain and frequency domain through the Fourier transform algorithm, and the characteristic current information is sent to the concentrator, modular terminal or fusion terminal. The concentrator, modular terminal or fusion terminal sorts it out and reports the result to the main station to realize the substation topology identification function.

[0047] The line state monitoring circuit of the wave recording board uses a 14-bit high-speed AD sampling chip to collect characteristic current signals, uses FPGA XC7Z020 as a data processing unit, and uses a carrier channel as an uplink channel to realize the collection and reporting of the transmitted current signal.

[0048] The above embodiments are only preferred embodiments of the present invention. Any simple modification, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention fall within the protection scope of the present invention.

Claims

1. A characteristic current identification and verification method based on Fourier transform algorithm, characterized in that: First, the current data is recorded using a wave recording board and uploaded via a network cable. The analysis module converts the received data. Then, the converted current data is subjected to Fourier transform to obtain a frequency domain curve, the starting point of the signal is obtained according to the frequency domain curve, and the current data is segmented and sliced ​​according to the current characteristic code bits sent by the carrier module; Finally, the signal quality analysis and power quality analysis are performed on the sliced ​​current data to obtain the signal quality and power quality results; The frequency spectrum information of the characteristic current signal is obtained by using discrete Fourier transform on the converted current data. The calculation formula is: Among them, a k represents the real part of the kth harmonic, b k Represents the imaginary part of the kth harmonic, N represents the number of data points of the power frequency cycle, k represents the harmonic number; T0 represents the signal period of 100ms; T represents the signal sending time; The cross-correlation function is used to quantify the amplitude of the sinusoidal signal and calculate the attenuation state of the signal amplitude. The calculation process is: x(t i )=s(t i )+G(t i ), i = 1, 2, ..., N, where x(t i ) is the observed signal, s(t i ) is a sinusoidal signal, G(t i ) represents additive Gaussian white noise with variance σ, and the simulation parameters are as follows: Frequency f0 = 10 Hz, initial phase Amplitude a=1.

2. The characteristic current identification and verification method based on Fourier transform algorithm according to claim 1 is characterized in that: The signal quality analysis process is as follows: First, determine whether the current is greater than the set threshold. If it is less than or equal to the set threshold, it is considered to be a low level and there is no signal, and the next point is determined. If the signal is greater than the set threshold, the number of points greater than the set threshold, n1, is recorded, and then the low level is found, the number of low level points is recorded, and the number of low level points is recorded as n2. The signal quality parameters are calculated based on the number of high level points and low level points.

3. The characteristic current identification and verification method based on Fourier transform algorithm according to claim 1 is characterized in that: Power quality analysis refers to: analyzing the harmonic voltage content rate, voltage total harmonic distortion rate, 0-800Hz interharmonic voltage content rate and maximum allowable harmonic current based on Fourier transform.

4. The characteristic current identification and verification method based on Fourier transform algorithm according to claim 1 is characterized in that: The line state monitoring circuit of the wave recording board uses a 14-bit high-speed AD sampling chip to collect characteristic current signals, uses FPGA XC7Z020 as a data processing unit, and uses a carrier channel as an uplink channel to realize the collection and reporting of the transmitted current signal.

5. A characteristic current identification and verification device based on Fourier transform algorithm, used to implement the characteristic current identification and verification method according to any one of claims 1 to 4, characterized in that: Including concentrator, modular terminal, fusion terminal, circuit breaker, type II concentrator, energy meter and carrier module; When the carrier module sends a characteristic current signal, the corresponding characteristic current signal is transmitted through the electric energy meter to the circuit breaker or type II concentrator. The circuit breaker or type II concentrator is connected to the recording board. The recording board analyzes and quantifies the characteristic current through high-speed AD sampling, and compares the analysis result with the normal value obtained by the carrier module during normal communication. The data is analyzed based on the time domain and frequency domain through the Fourier transform algorithm, and the characteristic current information is sent to the concentrator, modular terminal or fusion terminal. The concentrator, modular terminal or fusion terminal sorts it out and reports the result to the main station to realize the substation topology identification function.

6. The characteristic current identification and verification device based on Fourier transform algorithm according to claim 5 is characterized in that: The line state monitoring circuit of the wave recording board uses a 14-bit high-speed AD sampling chip to collect characteristic current signals, uses FPGA XC7Z020 as a data processing unit, and uses a carrier channel as an uplink channel to realize the collection and reporting of the transmitted current signal.

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