阅读说明：本技术 一种基于录波文件基准通道的二次设备时标对齐方法 (Secondary equipment time mark alignment method based on recording file reference channel ) 是由 陈军 孙仲民 赵子涵 庞晓艳 朱小红 向博 文继锋 吕航 叶翔 于 2019-12-06 设计创作，主要内容包括：本发明公开了一种基于录波文件基准通道的二次设备时标对齐方法,选取不同设备间的同电气节点处的录波通道,设定参考录波信号和待对齐信号,利用总谐波畸变率分布特点提取待对齐信号的特征信号波段,建立短时归一化相关系数模型,定义时间识别指标,计算并修正时标,最后完成不同二次设备录波波形及SOE时标对齐,准确还原电网事故关键事件状态序列,为事故回放、分析和处理提供参考依据。本发明所述方法不受不同设备录波极性影响,时间偏差计算准确度高,具有良好的抗噪声能力。(The invention discloses a secondary equipment time scale alignment method based on a wave recording file reference channel, which comprises the steps of selecting wave recording channels at the same electrical node among different equipment, setting reference wave recording signals and signals to be aligned, extracting characteristic signal wave bands of the signals to be aligned by utilizing the distribution characteristics of total harmonic distortion, establishing a short-time normalized correlation coefficient model, defining time identification indexes, calculating and correcting time scales, finally completing the alignment of wave recording waveforms of the different secondary equipment and SOE time scales, accurately reducing a power grid accident key event state sequence, and providing reference basis for accident playback, analysis and processing. The method is not influenced by the recording polarity of different equipment, has high time deviation calculation accuracy and has good anti-noise capability.)

1. A secondary device time mark alignment method based on a recording file reference channel is characterized by comprising the following steps:

the method comprises the following steps: designating a reference wave recording file as A, and selecting reference wave recording signals including A;

step 1.1: selecting a certain recording channel from the file A, wherein the signal of the certain recording channel is represented as:

wherein D istFor a sampling interval, Dt=1/f _s ，f _s Is the sampling frequency;n=0,1,2,…,N-1，Ncounting the number of sampling points;

step 1.2: will be provided withx[n]Defining as reference recording signal, and solving the relative time deviation of other recording signals to be aligned；

Step two: setting the recording file to be aligned as B, selecting the signal channel to be aligned in the B file, and defining the signal to be aligned asy[n]：

Step three: selecting a signal to be aligned;

step four: if the sampling frequencies of the two signals are not consistent, the two signals are respectivelyf _s1Andf _s2，f _s1≠f _s2then, the high frequency sampling signal needs to be resampled, and the resampling frequency is min: (f _s1,f _s2)；

Step five: extracting a signal to be alignedy[n]The characteristic signal band of (2);

step six: definition ofx[n]Andy _s [n]short-time normalized correlation coefficient of (2):

wherein the content of the first and second substances,lthe number of sampling points for the rectangular window movement, an

step seven: setting deviation time identification index

；

step eight: calculating the maximum position of the deviation time identification index:

wherein the content of the first and second substances,l _p the calculated deviation time is the maximum value position of the identification index;

step nine: the difference between the two sets of signal times is obtained as:

wherein the content of the first and second substances,kis the starting time of the characteristic signal interval;

step ten:y[n]the signal modification time scale is expressed as:

step eleven: setting upt _SWx Andt _SWy respectively calculating the recording waveform of different secondary equipment and the time scale alignment result of SOE according to the recording waveform of the secondary equipment and the time scale alignment result of SOE to which the reference signal and the signal to be aligned belong:

；

wherein the content of the first and second substances,the time after the correction of the recording waveform of the secondary equipment to which the signal to be aligned belongs and the SOE event.

2. The method according to claim 1, wherein the selection of the signal to be aligned in the third step comprises:

(1) channel signal selected by wave recording file By[n]Reference signal selected from recording file Ax[n]Both are voltage or current signals;

(2) and the signals are collected at the same electrical node of the power system.

3. The method according to claim 1, wherein the step five specifically includes:

step 5.1- △ near the start of recordingNThe total harmonic distortion rate is calculated over the range, expressed as:

wherein the content of the first and second substances,G _h is as followshThe effective value of the sub-harmonic component,G ₁is the effective value of the fundamental component, and the window length is calculated as the sampling pointnThe number of sampling points of the previous cycle,Hthe highest harmonic frequency needing to be calculated;

step 5.2: the total harmonic distortion maximum is calculated, expressed as:

step 5.3: sampling pointn _p The total harmonic distortion of (A) is the highest, and can be calculatedkComprises the following steps:

step 5.4: signal to be alignedy[n]The characteristic signal band of (a) may be expressed as:

wherein the content of the first and second substances,kfor the start time of the characteristic signal interval,h[n]a rectangular window, shown as:

wherein the content of the first and second substances,Mis the rectangular window length and is also the characteristic signal length.

Technical Field

The invention relates to the field of relay protection of power systems, in particular to a secondary equipment time scale alignment method based on a wave recording file reference channel.

Background

The coverage range of a modern power system is very wide, the operation of a power grid is changeable instantly, and a uniform time reference is needed among all systems of the power system for comprehensively, timely and accurately monitoring the operation state of the power system so as to analyze the process and the reason of accident development. When the external synchronous clock signal is interrupted or abnormal, the substation automation device only depends on the internal self-contained clock, the inherent error is difficult to avoid, and the error is accumulated along with the increase of the running time, so that the accurate time unification effect is lost. The event sequence and the development process of the power system are difficult to accurately describe, and an effective analysis basis cannot be provided for the power grid accident analysis. Therefore, unifying accurate time is an important measure for ensuring the safe operation of the power system and improving the operation level.

Once the external synchronous clock signal is abnormal or missing, the secondary equipment of the power system lacks a uniform time reference, the provided SOE recording and wave recording files inevitably have time sequence dislocation, and only manual comparison of time sequences is needed, so that time and labor are consumed, and the correction precision is low. Therefore, the time scale alignment function of the fault recording files of different devices is urgently needed to be realized, the calculated time error between the secondary equipment is used for correcting the relevant SOE time scale, the power grid accident key event state sequence is accurately restored, and a reference basis is provided for accident playback, analysis and processing, so that the secondary equipment time scale alignment method based on the recording file reference channel is provided.

Disclosure of Invention

The invention aims to solve the technical problem of providing a secondary equipment time scale alignment method based on a wave recording file reference channel, which utilizes a short-time normalized correlation coefficient model to accurately unify fault wave recording and SOE event time scales among different equipment.

In order to solve the technical problems, the invention adopts the technical scheme that: a secondary device time mark alignment method based on a recording file reference channel is characterized by comprising the following steps:

step 1: the waveform of each channel of the secondary equipment recording data of the transformer substation is considered to be a discrete signal with limited energy, and the time scale of the internal channel of each recording file is consistent. Designating a reference wave recording file as A, and selecting reference wave recording signals including A;

step 1.1: selecting a certain recording channel from the file A, wherein the signal can be represented as:

wherein D istFor a sampling interval, Dt=1/f _s ，f _s Is the sampling frequency;n=0,1,2,…,N-1，Ncounting the number of sampling points;

step 1.2: will be provided withx[n]Defining as reference recording signal, taking the sampling time of said signal as reference time, and solving the relative time deviation of other recording signals to be aligned

。

Step 2: setting the recording file to be aligned as B, selecting the signal channel to be aligned in the B file, and defining the signal to be aligned asy[n]It can be expressed as:

and step 3: the selection principle of the signal to be aligned comprises the following steps:

step 3.1: channel signal selected by wave recording file By[n]Reference signal selected from recording file Ax[n]Both are voltage or current signals;

step 3.2: the signals are collected at the same electrical node of the power system;

and 4, step 4: if the sampling frequencies of the two signals are not consistent, the two signals are respectivelyf _s1Andf _s2if, iff _s1≠f _s2Then, the high frequency sampling signal needs to be resampled, and the resampling frequency is min: (f _s1,f _s2)；

And 5: extracting a signal to be alignedy[n]Comprises:

step 5.1- △ near the start of recordingNThe total harmonic distortion rate is calculated over the range, expressed as:

wherein the content of the first and second substances,G _h is as followshThe effective value of the sub-harmonic component,G ₁is the effective value of the fundamental component, and the window length is calculated as the sampling pointnThe number of sampling points of the previous cycle,Hthe highest harmonic frequency needing to be calculated;

step 5.2: the total harmonic distortion maximum is calculated, expressed as:

step 5.3: sampling pointn _p The total harmonic distortion of (A) is the highest, and can be calculatedkComprises the following steps:

step 5.4: signal to be alignedy[n]The characteristic signal band of (a) may be expressed as:

wherein，kFor the start time of the characteristic signal interval,h[n]a rectangular window, shown as:

wherein the content of the first and second substances,Mthe window length is a rectangular window length and is also a characteristic signal length;

step 6: definition ofx[n]Andy _s [n]the short-time normalized correlation coefficient of (a) may be expressed as:

wherein the content of the first and second substances,lthe number of sampling points for the rectangular window movement, an

；

And 7: considering that recording polarities of different devices are possibly inconsistent, defining deviation time identification index

Expressed as:

and 8: calculating the position of the maximum value of the deviation time identification index, and expressing as:

wherein the content of the first and second substances,l _p the calculated deviation time is the maximum value position of the identification index;

and step 9: the difference between the two sets of signal times is obtained as:

step 10:y[n]the signal modification time scale is expressed as:

step 11: definition oft _SWx Andt _SWy respectively calculating the recording waveform of different secondary equipment and the time scale alignment result of SOE according to the recording waveform of the secondary equipment and the time scale alignment result of SOE to which the reference signal and the signal to be aligned belong:

wherein the content of the first and second substances,the time after the correction of the recording waveform of the secondary equipment to which the signal to be aligned belongs and the SOE event.

The invention has the beneficial effects that: by adopting the method, a signal selection principle is provided for fault recording files of different devices, the characteristic signal wave band of the signal to be aligned is extracted by utilizing the distribution characteristics of the total harmonic distortion rate, a short-time normalized correlation system model is established, the time scale correction of different recording files is realized, the calculation result has high accuracy, is not influenced by the CT polarity wiring mode, is less influenced by noise, has good anti-interference capability, and improves the accuracy of fault time sequence analysis under the same time coordinate.

Drawings

FIG. 1 illustrates a reference signal and a signal to be aligned according to an embodiment of the present invention;

FIG. 2 is a diagram illustrating a result of extracting a feature signal of a signal to be aligned according to an embodiment of the present invention;

FIG. 3 is a calculation result of the maximum position of the deviation time identification indicator according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the invention.

The invention is further described with reference to the following drawings and detailed description. The method comprises the following steps:

step 1: the waveform of each channel of the secondary equipment recording data of the transformer substation is considered to be a discrete signal with limited energy, and the time scale of the internal channel of each recording file is consistent. Designating a reference wave recording file as A, and selecting reference wave recording signals including A;

step 1.1: selecting a certain recording channel from the file A, wherein the signal can be represented as:

wherein D istFor a sampling interval, Dt=1/f _s ，f _s Is the sampling frequency;n=0,1,2,…,N-1，Ncounting the number of sampling points;

step 1.2: will be provided withx[n]Defining as reference recording signal, taking the sampling time of said signal as reference time, and solving the relative time deviation of other recording signals to be aligned

。

Step 2: setting the recording file to be aligned as B, selecting the signal channel to be aligned in the B file, and defining the signal to be aligned asy[n]It can be expressed as:

and step 3: the selection principle of the signal to be aligned comprises the following steps:

step 3.1: channel signal selected by wave recording file By[n]Reference signal selected from recording file Ax[n]Both are voltage or current signals;

step 3.2: the signals are collected at the same electrical node of the power system;

and 4, step 4: if the sampling frequencies of the two signals are not consistent, the two signals are respectivelyf _s1Andf _s2if, iff _s1≠f _s2Then, the high frequency sampling signal needs to be resampled, and the resampling frequency is min: (f _s1,f _s2)；

And 5: extracting a signal to be alignedy[n]Comprises:

step 5.1- △ near the start of recordingNThe total harmonic distortion rate is calculated over the range, expressed as:

wherein the content of the first and second substances,G _h is as followshThe effective value of the sub-harmonic component,G ₁is the effective value of the fundamental component, and the window length is calculated as the sampling pointnThe number of sampling points of the previous cycle,Hthe highest harmonic frequency needing to be calculated;

step 5.2: the total harmonic distortion maximum is calculated, expressed as:

step 5.3: sampling pointn _p The total harmonic distortion of (A) is the highest, and can be calculatedkComprises the following steps:

step 5.4: signal to be alignedy[n]The characteristic signal band of (a) may be expressed as:

wherein the content of the first and second substances,kfor the start time of the characteristic signal interval,h[n]a rectangular window, shown as:

wherein the content of the first and second substances,Mthe window length is a rectangular window length and is also a characteristic signal length;

step 6: definition ofx[n]Andy _s [n]the short-time normalized correlation coefficient of (a) may be expressed as:

wherein the content of the first and second substances,lthe number of sampling points for the rectangular window movement, an

；

And 7: considering that recording polarities of different devices are possibly inconsistent, defining deviation time identification index

Expressed as:

and 8: calculating the position of the maximum value of the deviation time identification index, and expressing as:

wherein the content of the first and second substances,l _p the calculated deviation time is the maximum value position of the identification index;

and step 9: the difference between the two sets of signal times is obtained as:

step 10:y[n]the signal modification time scale is expressed as:

step 11: definition oft _SWx Andt _SWy respectively calculating the recording waveform of different secondary equipment and the time scale alignment result of SOE according to the recording waveform of the secondary equipment and the time scale alignment result of SOE to which the reference signal and the signal to be aligned belong:

wherein the content of the first and second substances,

the time after the correction of the recording waveform of the secondary equipment to which the signal to be aligned belongs and the SOE event.

In order to verify the accuracy and the adaptability of the secondary equipment time scale alignment method based on the recording file reference channel, the simulation current signal is constructed according to the principlex[n]Derived from a sine wave simulation, with a sampling frequency off _s =1200Hz, mutation point ofnAt =250, the amplitude changes from 4A to 2A, and willx[n]Leftwards moving △n _set=50 sampling points and are obtained in antiphasey[n]And simulating recording channel signals with inconsistent time scales and opposite CT polarities. Then to givex[n]Andy[n]gaussian white noise with the signal-to-noise ratio of 20dB is added to the signals respectively, and bad recording sampling results in actual working conditions are simulated. Fig. 1 shows a reference signal and a signal to be aligned according to an embodiment of the present invention. The sampling rate of the reference signal and the signal to be aligned in the embodiment is consistent, so resampling is not needed.

Can be provided withMNumber of sampling points for a cycle, i.e.M=24, orderH=2, figure 2 shows the result of selecting the characteristic signal band of the signal to be aligned, wherek=292。

The final time parameter calculation results are shown in figure 3,l _p =242, last available time offset △n=50, and △n _set=50 alignment twiceThe time scale of the device record and SOE is reduced by 1/24 seconds compared to the reference secondary device overall time.

In summary, by adopting the technical scheme of the invention, a signal selection principle is provided for fault recording files of different devices, the characteristic signal wave band of the signal to be aligned is extracted by utilizing the distribution characteristics of the total harmonic distortion rate, a short-time normalized correlation system model is established, time scale correction of different recording files is realized, the accuracy of the calculation result is high, the influence of a CT polarity wiring mode is avoided, the influence of noise is small, the anti-interference capability is good, and the accuracy of fault time sequence analysis under the same time coordinate is improved.

The above embodiments are only for illustrating the technical solutions of the present invention and not for limiting the same, and although the present invention is described in detail, those of ordinary skill in the art should understand that: modifications and equivalents may be made to the embodiments of the invention without departing from the spirit and scope of the invention, which is to be covered by the claims.