Power grid broadband oscillation signal detection method and device based on frequency domain matched filtering

Abstract

The invention relates to the technical field of electromagnetic measurement, in particular to a power grid broadband oscillation signal detection method and device based on frequency domain matched filtering, and the method comprises the steps: obtaining an oscillation detection frequency domain and an oscillation signal amplitude threshold value of a target power grid, and obtaining a windowing DFT sequence of a non-causal sequence corresponding to a current sampling sequence of the target power grid, and performing matched filtering on the windowed DFT sequence based on a matched filtering coefficient of a target frequency domain matched filter, performing spectrum peak search in an oscillation detection frequency domain according to an amplitude waveform of a matched filtering output sequence, and detecting a broadband oscillation component based on an oscillation signal amplitude threshold. According to the embodiment of the invention, windowing DFT can be carried out on the power grid sampling sequence, matched filtering is carried out in the frequency domain, broadband oscillation is found and positioned based on spectrum peak search, spectrum leakage of fundamental waves and other frequency components at the oscillation frequency is weakened, the signal-to-noise ratio is improved, and the spectrum peak at the oscillation frequency is highlighted, so that the accuracy of frequency detection is improved; the reliability is higher.

Description

Technical Field

[0001] The present application relates to the field of electromagnetic measurement technology, and in particular to a method and device for detecting broadband oscillation signals of a power grid based on frequency domain matching filtering. Background Art

[0002] With the rapid transformation of new power systems, the access of a high proportion of new energy and a high proportion of power electronic equipment has triggered a series of wide-band oscillation events, posing a threat to the safe operation of the power grid.

[0003] In the related art, monitoring of broadband oscillation signals first requires finding and locating each oscillation signal component within a broadband band, i.e., oscillation signal detection. Detecting oscillation signals is a key step in broadband measurement, which can be achieved by frequency domain search using the windowed discrete Fourier transform (DFT) method or by spectrum estimation based on a parameter model.

[0004] However, in the related technologies, the detection results of the parameter model in a complex signal environment are random and difficult to apply in actual engineering. The frequency domain search method based on Fourier transform has a frequency resolution capability limited by the length of the data window in the process of broadband oscillation detection, and the spectrum leakage of DFT may cause spectrum peak distortion and submerge the real spectrum peak, resulting in false alarms and missed reports of broadband oscillation detection, which reduces the reliability and accuracy of power system oscillation detection and needs to be solved urgently. Summary of the invention

[0005] The present application provides a method and device for detecting broadband oscillation signals of a power grid based on frequency domain matching filtering, so as to solve the problems in the related art that the detection results of the parameter model in a complex signal environment are random and difficult to be applied in practical projects, and the frequency domain search method based on Fourier transform has the frequency resolution capability in the broadband oscillation detection process limited by the length of the data window, and the spectrum leakage of DFT may cause spectrum peak distortion and submerge the real spectrum peak, resulting in false alarm and underreporting of broadband oscillation detection, and reducing the reliability and accuracy of power system oscillation detection.

[0006] In a first aspect, an embodiment of the present application provides a method for detecting broadband oscillation signals of a power grid based on frequency domain matched filtering, comprising the following steps: obtaining an oscillation detection task of a target power grid, and confirming the oscillation detection frequency domain and an oscillation signal amplitude threshold of the target power grid based on the oscillation detection task; acquiring a current sampling sequence of the target power grid, defining the current sampling sequence at zero time to obtain a non-causal sequence, and adding an even symmetric window to the non-causal sequence to obtain a windowed discrete Fourier transform sequence of the non-causal sequence; performing matched filtering on the windowed discrete Fourier transform sequence based on a matched filter coefficient of a target frequency domain matched filter to obtain a matched filter output sequence; extracting spectral peaks that meet preset spectral peak search conditions in the oscillation detection frequency domain according to the amplitude waveform of the matched filter output sequence to obtain all target spectral peaks, and performing detection based on all target spectral peaks and the oscillation signal amplitude threshold to obtain broadband oscillation components of the target power grid.

[0007] Optionally, in one embodiment of the present application, before matching filtering the windowed discrete Fourier transform sequence based on the matched filter coefficients of the target frequency domain matched filter, it also includes: confirming a target even-symmetric window function and a target window length based on the oscillation detection frequency domain and the oscillation signal amplitude threshold, and generating the target frequency domain matched filter according to the target even-symmetric window function and the target window length; and confirming the matched filter coefficients of the target frequency domain matched filter according to the spectral main lobe width of the target even-symmetric window function after discrete-time Fourier transform.

[0008] Optionally, in one embodiment of the present application, the detection based on all the target spectrum peaks and the oscillation signal amplitude threshold is performed to obtain the broadband oscillation component of the target power grid, including: based on all the target spectrum peaks, detecting whether there is at least one target spectrum peak whose peak value is greater than the oscillation signal amplitude threshold; in the case of detecting that there is at least one target spectrum peak whose peak value is greater than the oscillation signal amplitude threshold, determining the target spectrum peak whose peak value is greater than the oscillation signal amplitude threshold as the broadband oscillation component, and confirming the oscillation amplitude and frequency of the broadband oscillation component according to the peak height and position of the corresponding target spectrum peak.

[0009] Optionally, in one embodiment of the present application, the preset spectrum peak search condition is to search for q that satisfies the following conditions:

[0010] |Y t [q]|>|Y t [q-1]|,

[0011] |Y t [q]|>|Y t [q+1]|,

[0012]

[0013] Among them, Y t [m] is the matched filter output sequence, A is the effective value of the fundamental wave, and ε is the amplitude ratio threshold of the oscillation signal to the fundamental wave.

[0014] In a second aspect, an embodiment of the present application provides a power grid broadband oscillation signal detection device based on frequency domain matched filtering, comprising: an acquisition module, used to acquire an oscillation detection task of a target power grid, and confirm the oscillation detection frequency domain and oscillation signal amplitude threshold of the target power grid based on the oscillation detection task; a windowing module, used to collect a current sampling sequence of the target power grid, define the current sampling sequence at zero time to obtain a non-causal sequence, and add an even symmetric window to the non-causal sequence to obtain a windowed discrete Fourier transform sequence of the non-causal sequence; a filtering module, used to match filter the windowed discrete Fourier transform sequence based on a matched filter coefficient of a target frequency domain matched filter to obtain a matched filter output sequence; a detection module, used to extract spectrum peaks that meet preset spectrum peak search conditions in the oscillation detection frequency domain according to the amplitude waveform of the matched filter output sequence, to obtain all target spectrum peaks, and to perform detection based on all target spectrum peaks and the oscillation signal amplitude threshold to obtain broadband oscillation components of the target power grid.

[0015] Optionally, in one embodiment of the present application, the device also includes: a generation module, used to confirm the target even-symmetric window function and the target window length based on the oscillation detection frequency domain and the oscillation signal amplitude threshold before matching filtering the windowed discrete Fourier transform sequence based on the matched filter coefficient of the target frequency domain matched filter, and generate the target frequency domain matched filter according to the target even-symmetric window function and the target window length; a confirmation module, used to confirm the matched filter coefficient of the target frequency domain matched filter according to the spectral main lobe width of the target even-symmetric window function after discrete-time Fourier transform.

[0016] Optionally, in one embodiment of the present application, the detection module includes: a detection unit, used to detect whether there is at least one target spectrum peak whose peak value is greater than the oscillation signal amplitude threshold based on all the target spectrum peaks; a judgment unit, used to, when it is detected that there is at least one target spectrum peak whose peak value is greater than the oscillation signal amplitude threshold, judge the target spectrum peak whose peak value is greater than the oscillation signal amplitude threshold as the broadband oscillation component, and confirm the oscillation amplitude and frequency of the broadband oscillation component according to the peak height and position of the corresponding target spectrum peak.

[0017] Optionally, in one embodiment of the present application, the preset spectrum peak search condition is to search for q that satisfies the following conditions:

[0018] |Y t [q]|>|Yt [q-5]|,

[0019] |Y t [q]|>|Y t [q+5]|,

[0020]

[0021] Among them, Y t [m] is the matched filter output sequence, A is the effective value of the fundamental wave, and ε is the amplitude ratio threshold of the oscillation signal to the fundamental wave.

[0022] The third aspect of the present application provides an electronic device, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the method for detecting a wideband oscillation signal of a power grid based on frequency domain matching filtering as described in the above embodiment.

[0023] The fourth aspect of the present application provides a computer-readable storage medium, which stores a computer program. When the program is executed by a processor, it implements the above-mentioned method for detecting broadband oscillation signals of a power grid based on frequency domain matching filtering.

[0024] A fifth aspect of the present application provides a computer program, which, when executed, implements the above-mentioned method for detecting a wide-band oscillation signal of a power grid based on frequency-domain matching filtering.

[0025] The embodiment of the present application can perform windowed DFT on the power grid sampling sequence and perform matched filtering in the frequency domain, discover and locate broadband oscillations based on spectrum peak search, weaken the spectrum leakage of the fundamental wave and other frequency components at the oscillation frequency and improve the signal-to-noise ratio, highlight the spectrum peak at the oscillation frequency, thereby improving the accuracy of frequency detection and making it more reliable. Thus, the problem that the detection results of the parameter model in a complex signal environment in the related art are random and difficult to apply in actual engineering, and the frequency domain search method based on Fourier transform has a frequency resolution ability in the process of broadband oscillation detection limited by the length of the data window, and the spectrum leakage of DFT may cause spectrum peak distortion and submerge the real spectrum peak, resulting in false alarms and missed reports of broadband oscillation detection, and reducing the reliability and accuracy of power system oscillation detection.

[0026] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0028] Figure 1 A flowchart of a method for detecting a broadband oscillation signal of a power grid based on frequency domain matching filtering according to an embodiment of the present application;

[0029] Figure 2 A schematic diagram of Hamming window coefficients according to an embodiment of the present application;

[0030] Figure 3 A schematic diagram of the amplitude-frequency characteristic of the Hamming window according to an embodiment of the present application;

[0031] Figure 4 A schematic diagram of the Hamming window frequency domain matched filter coefficients according to an embodiment of the present application;

[0032] Figure 5 The static test original method detection statistical results (f δ =2Hz) schematic diagram;

[0033] Figure 6 The static test method of the present invention detects the statistical results (f δ =2Hz) schematic diagram;

[0034] Figure 7 A static test (f δ =1Hz and 2Hz) schematic diagram of missed detection probability statistics;

[0035] Figure 8 A schematic diagram of the statistical results of the original method detection under the amplitude / phase modulation dynamic test of an embodiment of the present application;

[0036] Fig. 9 This is a schematic diagram of the detection statistical results of the method of the present invention under the amplitude / phase modulation dynamic test of one embodiment of the present application;

[0037] Fig.10 A schematic diagram of the statistical results of the original method detection under the frequency ramp dynamic test of an embodiment of the present application;

[0038] Fig.11 This is a schematic diagram of the statistical results of the detection of the method of the present invention under the frequency ramp dynamic test of one embodiment of the present application;

[0039] Fig.12 A schematic diagram of the statistical results of the original method detection under the noise test of an embodiment of the present application;

[0040] Fig.13 This is a schematic diagram of the detection statistical results of the method of the present invention under a noise test in one embodiment of the present application;

[0041] Fig.14This is a schematic diagram of the control principle of realizing broadband oscillation detection of power grid signals based on frequency domain matching filtering according to an embodiment of the present application;

[0042] Fig.15 Schematic diagram of the structure of a power grid broadband oscillation signal detection device based on frequency domain matching filtering according to an embodiment of the present application;

[0043] Fig.16 Schematic diagram of the structure of an electronic device according to an embodiment of the present application. DETAILED DESCRIPTION

[0044] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0045] The following describes the method and device for detecting broadband oscillation signals of a power grid based on frequency domain matching filtering according to the embodiment of the present application with reference to the accompanying drawings. In view of the related technologies mentioned in the above background technology, the detection results of the parameter model in a complex signal environment are random and difficult to be applied in practical engineering. The frequency domain search method based on Fourier transform has the frequency resolution ability in the broadband oscillation detection process limited by the length of the data window, and the spectrum leakage of DFT may cause spectrum peak distortion and submerge the real spectrum peak, resulting in false alarm and missed alarm of broadband oscillation detection, and reducing the reliability and accuracy of power system oscillation detection. The present application provides a method for detecting broadband oscillation signals of a power grid based on frequency domain matching filtering. In the method, a windowed DFT can be performed on the power grid sampling sequence, and matched filtering can be performed in the frequency domain. Based on the spectrum peak search, the broadband oscillation is found and located, the spectrum leakage of the fundamental wave and other frequency components at the oscillation frequency is weakened, the signal-to-noise ratio is improved, and the spectrum peak at the oscillation frequency is highlighted, thereby improving the accuracy of frequency detection and making it more reliable. Thus, the problem in related technologies that the detection results of parameter models in complex signal environments are random and difficult to apply in actual engineering projects is solved; the frequency domain search method based on Fourier transform has a frequency resolution capability limited by the length of the data window in the process of broadband oscillation detection, and the spectrum leakage of DFT may cause spectrum peak distortion and submerge the real spectrum peak, resulting in false alarms and omissions in broadband oscillation detection, and reducing the reliability and accuracy of power system oscillation detection.

[0046] Specifically, Figure 1 A schematic flow chart of a method for detecting a broadband oscillation signal in a power grid based on frequency domain matching filtering provided in an embodiment of the present application.

[0047] like Figure 1As shown, the method for detecting a wide-band oscillation signal of a power grid based on frequency domain matching filtering comprises the following steps:

[0048] In step S101, an oscillation detection task of a target power grid is acquired, and an oscillation detection frequency domain and an oscillation signal amplitude threshold of the target power grid are confirmed based on the oscillation detection task.

[0049] It is understandable that in the embodiments of the present application, the oscillation detection frequency range and the oscillation signal amplitude threshold can be set according to the specific requirements of the broadband measurement device for the detection task of the target power grid, and the threshold of the ratio of the oscillation amplitude to be detected to the fundamental wave amplitude is defined as ε.

[0050] In step S102, the current sampling sequence of the target power grid is collected, the zero time of the current sampling sequence is defined to obtain a non-causal sequence, and an even symmetric window is added to the non-causal sequence to obtain a windowed discrete Fourier transform sequence of the non-causal sequence.

[0051] It can be understood that in the embodiment of the present application, x[k]=x(t k ) is the sampling sequence of the power grid signal x(t) at time t, where t k =t0+k / f s , f s is the sampling frequency, and the detection time t = t m The non-causal sequence defined as time zero is denoted by x t [n], n = -(N-1) / 2, ..., (N-1) / 2, where x t [n] = x[m+n]; non-causal sequence x t The L-point windowed DFT of [n] is defined as:

[0052]

[0053] Among them, X t (f) is the non-causal sequence x t DTFT of [n], Δf = f s / L. Select the data centered at time t and add a window to calculate the L-point FFT (Fast Fourier Transform), and perform phase compensation to obtain the causal sequence DFT. The fast algorithm FFT and phase compensation are used to achieve x t The calculation of [m] is:

[0054]

[0055] Among them, {x t [n]} is considered as a causal sequence for FFT calculation.

[0056] In step S103, matched filtering is performed on the windowed discrete Fourier transform sequence based on the matched filter coefficients of the target frequency domain matched filter to obtain a matched filter output sequence.

[0057] It can be understood that in the embodiments of the present application, a target frequency domain matched filter can be generated by selecting a window function type and length, and a matched filter output sequence corresponding to a windowed discrete Fourier transform sequence can be calculated by the matched filter coefficients of the target frequency domain matched filter.

[0058] Optionally, in one embodiment of the present application, before matching filtering is performed on the windowed discrete Fourier transform sequence based on the matched filter coefficients of the target frequency domain matched filter, it also includes: confirming the target even-symmetric window function and the target window length based on the oscillation detection frequency domain and the oscillation signal amplitude threshold, and generating the target frequency domain matched filter according to the target even-symmetric window function and the target window length; and confirming the matched filter coefficients of the target frequency domain matched filter according to the spectral main lobe width of the target even-symmetric window function after discrete-time Fourier transform.

[0059] In the actual implementation process, an even symmetric window function and its length are selected based on the oscillation detection frequency domain and the oscillation signal amplitude threshold corresponding to the detection task, and an even symmetric window function and its length are selected, denoted as w[n], n = -(N-1) / 2, ..., (N-1) / 2, satisfying w[-n] = w[n], and Where N is an odd number. The DTFT (Discrete-Time Fourier Transform) of the window function is recorded as W(ω), and the main lobe part of the non-causal window function spectrum is selected as the matched filter coefficient, which is:

[0060] [m]=αW(-mΔω), m=-(L-1) / 2,..., (L-1) / 2,

[0061] Where Δω=2π / L, and L h Δω does not exceed W(ω) the main lobe width, The matched filter output sequence is recorded as {Y t [m]}, where Y t [m] is calculated as:

[0062]

[0063] In step S104, spectrum peaks satisfying preset spectrum peak search conditions are extracted in the oscillation detection frequency domain according to the amplitude waveform of the matched filter output sequence, and all target spectrum peaks are obtained, so as to perform detection based on all target spectrum peaks and the oscillation signal amplitude threshold to obtain the broadband oscillation component of the target power grid.

[0064] It should be noted that the preset spectrum peak search conditions can be set by those skilled in the art according to actual conditions and are not specifically limited here.

[0065] It is understandable that in the embodiments of the present application, a spectrum peak search can be performed on the amplitude waveform of the matched filter output sequence within the oscillation frequency band to be detected, and a spectrum peak with a peak value exceeding a specific threshold can be identified as a broadband oscillation component.

[0066] Optionally, in one embodiment of the present application, detection is performed based on all target spectrum peaks and oscillation signal amplitude thresholds to obtain a broadband oscillation component of the target power grid, including: based on all target spectrum peaks, detecting whether there is at least one target spectrum peak whose peak value is greater than the oscillation signal amplitude threshold; in the case where it is detected that there is at least one target spectrum peak whose peak value is greater than the oscillation signal amplitude threshold, determining the target spectrum peak whose peak value is greater than the oscillation signal amplitude threshold as a broadband oscillation component, and confirming the oscillation amplitude and frequency of the broadband oscillation component according to the peak height and position of the corresponding target spectrum peak.

[0067] In the actual implementation process, a search can be performed in the target spectrum peak, and the spectrum peak whose peak value exceeds the oscillation signal amplitude threshold is identified as a broadband oscillation component, and the oscillation frequency and amplitude are obtained from the peak position and height of the spectrum peak.

[0068] Optionally, in one embodiment of the present application, the preset spectrum peak search condition is to search for q that satisfies the following conditions:

[0069] |Y t [q]|>|Y t [q-1]|,

[0070] |Y t [q]|>|Y t [q+1]|,

[0071]

[0072] Among them, Y t [m] is the matched filter output sequence, A is the effective value of the fundamental wave, and ε is the amplitude ratio threshold of the oscillation signal to the fundamental wave.

[0073] In the actual execution process, ε is the amplitude ratio threshold of the oscillation signal to the fundamental wave set to limit the minimum amplitude of the oscillation component. From all q∈Q that meet the above conditions, the oscillation signal detection result at time t is obtained as follows: Amplitude q∈Q.

[0074] The following is a detailed description of the working content of the embodiment of the present application using a specific embodiment. s=4.0kHz, the standard frequency of the power grid f0=50Hz, the frequency range of the oscillation signal is the interharmonic frequency band within 2.5~300Hz, the threshold value of the amplitude ratio of the oscillation signal to the fundamental wave ε=1%, and the window function is selected as a 0.4s Hamming window. Figure 2 and Figure 3 The window function coefficients and spectrum function (low frequency band) of the Hamming window are given respectively. Figure 4 The frequency domain matched filter coefficients are given.

[0075] With reference to the Technical Specifications Q / GDW 12214-2022 for Wideband Measurement Devices for Power Systems, test conditions are set to test the detection performance of the embodiments of the present application. For typical patterns of broadband oscillations, the windowed DFT method (hereinafter referred to as the original method) and the frequency domain matched filter detection algorithm (hereinafter referred to as the method of the present invention) are used to implement oscillation signal detection. By comparing the performance of the two, the improvement of detection performance by matched filtering is tested. Considering that the detection of high-frequency oscillation signals is relatively simple (far away from the fundamental wave), and false alarms and missed detections mainly occur near the fundamental wave frequency, the simulation test is mainly aimed at sub / supersynchronous oscillation signals within 2.5 to 100 Hz. Based on the common patterns of oscillation signals, the following simulation test data are designed.

[0076] Test waveform 1 (standard sine static test): The signal frequency band includes the fundamental wave, the third and fifth harmonics, and the broadband oscillation signal. Each component is an ideal sine wave. The frequency and normalized effective value of each sine wave are shown in Table 1, which is the signal parameter table of simulation test 1. The fundamental frequency is set to 50.2 Hz, and Δf is within the range of 5 to 15 Hz. In addition, Gaussian white noise with a standard deviation of 0.01 is added to the signal.

[0077] Table 1

[0078]

[0079] Test waveform 2 (AM / FM dynamic test): The signal components, the center frequency and the average power of each signal are the same as those of test waveform 1, but the sine wave amplitude and phase of the fundamental wave, harmonics and each oscillation signal are modulated by a low-frequency sine signal at the same time, the amplitude and phase modulation depth are set to 10%, and the sine modulation frequency is 2Hz. Gaussian white noise with a standard deviation of 0.01 is added to the signal.

[0080] Test waveform 3 (frequency ramp dynamic test): The signal components and the center frequency and average power of each signal are basically the same as those of test waveform 1, but the fundamental, subsynchronous 2 and supersynchronous 2 frequencies change at a uniform speed (i.e., frequency ramp pattern) within 0.5 to 4.5 seconds, with the change ranges of 49 to 51 Hz, 40 to 42 Hz and 58 to 60 Hz respectively. Gaussian white noise with a standard deviation of 0.01 is added to the signal.

[0081] Test waveform 4 (noise test): The signals are exactly the same as those in test waveform 1, but Gaussian white noise with a standard deviation of 0.01 to 0.1 is added.

[0082] Let the real frequency of the signal be f i ∈f J , the ideal peak value is A i , the frequency and peak value obtained by signal detection are recorded as If exists and f i ∈f J , so that and Then f i and To pair, and f i are the test value and the true value of each other. i If there is no corresponding detection value, it is said to be missed; if If it does not correspond to any true value, it is called a false alarm. The proportion of missed detection in the true value is called the missed detection rate, and the proportion of false alarm in the detection value is called the false alarm rate. The two represent the accuracy and reliability of detection and are the main performance indicators of signal detection. In windowed DFT detection, Γ can usually be set D =1 / 2,Γ U =2,f δ 2Hz and 1Hz can be selected according to the specific requirements of the detection task for frequency accuracy.

[0083] Figure 5 and Figure 6 The statistical results of false alarm, missed detection and total false detection probability of the original method based on Hamming window and the method of the present invention for the test waveform 1 (static test) are given respectively, where the allowed detection frequency difference is f δ =2Hz. The variable Δf in the figure is the frequency interval between the subsynchronous signal 2 and the supersynchronous signal 2 and the fundamental wave in Table 1, which is used to test the frequency resolution ability of the detection algorithm. It can be seen from the statistical results that the original method has a high false alarm probability for all Δf, and the total false detection rate is also high; the method of the present invention effectively eliminates false alarms, and the total false detection probability is 0 for Δf≥8Hz. Figure 7 Given f δ =2Hz and 1Hz static test missed detection probability curve, it can be found that with f δ The probability of missed detection in the original method increases sharply from 0, while the change in the method of the present invention is very small. This shows that the frequency error detected by the method of the present invention is mainly within 1 Hz, while the original method has a higher proportion exceeding 1 Hz, that is, the method of the present invention significantly improves the frequency accuracy.

[0084] Figure 8-Figure 11The statistical results of detection error probability of two dynamic tests, test waveform 2 (amplitude and phase modulation) and test waveform 3 (frequency ramp), are given respectively (where f δ =2Hz). Compared with the static test results, the error probability of each detection under dynamic test of the original method and the method of the present invention increases, but the overall trend of the false detection probability curve with the change of Δf is the same. For the method of the present invention, when Δf≥9Hz, the total false detection probability of dynamic test is close to 0.

[0085] Fig.12 and Fig.13 The statistical results of the false detection rate of noise test by the original method and the method of the present invention are given respectively, where Δf = 8 Hz, f δ =2Hz. It can be seen that at a higher signal-to-noise ratio, the influence of noise on the false detection rate is not significant. For the method of the present invention, when SNR≥30dB, the false detection probability caused by noise is 0.

[0086] In summary, frequency domain matched filtering can greatly improve the performance of the detection algorithm. For the 0.4s Hamming window matched filtering, it not only eliminates the false alarm errors existing in the original method, but also significantly improves the accuracy of the detection frequency. It can realize high-reliability detection of oscillation signals outside the fundamental neighborhood of 8Hz, and has important application value in engineering fields such as broadband measurement.

[0087] Furthermore, the control principle in the actual implementation process is as follows Fig.14 As shown in the figure, the oscillation detection frequency range and the oscillation signal amplitude threshold are set according to the specific requirements of the detection task of the broadband measurement device; an even-symmetric window function and its length are selected to generate a frequency domain matched filter, and the main lobe part of the spectrum of the non-causal window function is selected as the matching filter coefficient; an input sequence centered at time t is selected, an even-symmetric window is added to the power grid sampling sequence centered at the detection time, and the windowed DFT of the non-causal sequence is calculated with the detection time as the local clock zero time; the windowed DFT of the non-causal sequence is subjected to frequency domain matched filtering to obtain a matched filter output sequence; the spectrum peak is searched within the specified frequency band to determine the frequency and amplitude of the oscillation signal.

[0088] According to the method for detecting broadband oscillation signals of a power grid based on frequency domain matching filtering proposed in the embodiment of the present application, a windowed DFT can be performed on the power grid sampling sequence, and matched filtering can be performed in the frequency domain. Based on the spectrum peak search, broadband oscillations can be found and located, spectrum leakage of the fundamental wave and other frequency components at the oscillation frequency can be weakened, the signal-to-noise ratio can be improved, and the spectrum peak at the oscillation frequency can be highlighted, thereby improving the accuracy of frequency detection and making it more reliable. Thus, the problem that the detection results of the parameter model in a complex signal environment in the related art are random and difficult to be applied in practical engineering is solved, and the frequency domain search method based on Fourier transform has a frequency resolution ability in the process of broadband oscillation detection limited by the length of the data window, and the spectrum leakage of DFT may cause spectrum peak distortion and drown the real spectrum peak, resulting in false alarms and missed reports of broadband oscillation detection, and reducing the reliability and accuracy of power system oscillation detection.

[0089] Next, a power grid broadband oscillation signal detection device based on frequency domain matching filtering proposed in an embodiment of the present application is described with reference to the accompanying drawings.

[0090] Fig.15 It is a structural schematic diagram of a power grid broadband oscillation signal detection device based on frequency domain matching filtering in an embodiment of the present application.

[0091] like Fig.15 As shown, the power grid broadband oscillation signal detection device 10 based on frequency domain matched filtering includes: an acquisition module 100 , a windowing module 200 , a filtering module 300 and a detection module 400 .

[0092] The acquisition module 100 is used to acquire the oscillation detection task of the target power grid, and confirm the oscillation detection frequency domain and oscillation signal amplitude threshold of the target power grid based on the oscillation detection task.

[0093] The windowing module 200 is used to collect the current sampling sequence of the target power grid, define the zero time of the current sampling sequence to obtain a non-causal sequence, and add an even symmetric window to the non-causal sequence to obtain a windowed discrete Fourier transform sequence of the non-causal sequence.

[0094] The filtering module 300 is used to perform matched filtering on the windowed discrete Fourier transform sequence based on the matched filter coefficients of the target frequency domain matched filter to obtain a matched filter output sequence.

[0095] The detection module 400 is used to extract spectrum peaks that meet preset spectrum peak search conditions in the oscillation detection frequency domain according to the amplitude waveform of the matched filter output sequence, obtain all target spectrum peaks, and perform detection based on all target spectrum peaks and the oscillation signal amplitude threshold to obtain the broadband oscillation component of the target power grid.

[0096] Optionally, in one embodiment of the present application, the device 10 further includes: a generation module and a confirmation module.

[0097] Among them, the generation module is used to confirm the target even-symmetric window function and target window length based on the oscillation detection frequency domain and the oscillation signal amplitude threshold before matching filtering the windowed discrete Fourier transform sequence based on the matched filter coefficients of the target frequency domain matched filter, and generate the target frequency domain matched filter according to the target even-symmetric window function and the target window length.

[0098] The confirmation module is used to confirm the matched filter coefficient of the target frequency domain matched filter according to the frequency spectrum main lobe width of the target even-symmetric window function after discrete-time Fourier transform.

[0099] Optionally, in one embodiment of the present application, the detection module 300 includes: a determination unit and a detection unit.

[0100] The detection unit is used to detect whether there is at least one target spectrum peak whose peak value is greater than the oscillation signal amplitude threshold based on all target spectrum peaks.

[0101] A determination unit is used to determine the target spectrum peak whose peak value is greater than the oscillation signal amplitude threshold as a broadband oscillation component when it is detected that there is at least one target spectrum peak whose peak value is greater than the oscillation signal amplitude threshold, and to confirm the oscillation amplitude and frequency of the broadband oscillation component according to the peak height and position of the corresponding target spectrum peak.

[0102] Optionally, in one embodiment of the present application, the preset spectrum peak search condition is to search for q that satisfies the following conditions:

[0103] |Y t [q]|>|Y t [q-5]|,

[0104] |Y t [q]|>|Y t [q+5]|,

[0105]

[0106] Among them, Y t [m] is the matched filter output sequence, A is the effective value of the fundamental wave, and ε is the amplitude ratio threshold of the oscillation signal to the fundamental wave.

[0107] It should be noted that the above explanation of the embodiment of the method for detecting a wide-band oscillation signal of a power grid based on frequency domain matching filtering is also applicable to the device for detecting a wide-band oscillation signal of a power grid based on frequency domain matching filtering of this embodiment, and will not be repeated here.

[0108] According to the power grid broadband oscillation signal detection device based on frequency domain matching filtering proposed in the embodiment of the present application, the broadband oscillation can be found and located based on the spectrum peak search by performing windowed DFT on the power grid sampling sequence and matching filtering in the frequency domain, thereby weakening the spectrum leakage of the fundamental wave and other frequency components at the oscillation frequency and improving the signal-to-noise ratio, highlighting the spectrum peak at the oscillation frequency, thereby improving the accuracy of frequency detection and making it more reliable. Thus, the problem that the detection results of the parameter model in a complex signal environment in the related art are random and difficult to apply in actual engineering, and the frequency domain search method based on Fourier transform has a frequency resolution ability in the broadband oscillation detection process that is limited by the length of the data window, and the spectrum leakage of DFT may cause spectrum peak distortion and drown the real spectrum peak, resulting in false alarms and missed reports of broadband oscillation detection, and reducing the reliability and accuracy of power system oscillation detection.

[0109] Fig.16 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application. The electronic device may include:

[0110] A memory 1601 , a processor 1602 , and a computer program stored in the memory 1601 and executable on the processor 1602 .

[0111] When the processor 1602 executes the program, the method for detecting a wide-band oscillation signal of a power grid based on frequency domain matched filtering provided in the above embodiment is implemented.

[0112] Furthermore, the electronic device further comprises:

[0113] The communication interface 1603 is used for communication between the memory 1601 and the processor 1602 .

[0114] The memory 1601 is used to store computer programs that can be executed on the processor 1602 .

[0115] The memory 1601 may include a high-speed RAM memory, and may also include a non-volatile memory (non-volatile memory), such as at least one disk memory.

[0116] If the memory 1601, the processor 1602 and the communication interface 1603 are implemented independently, the communication interface 1603, the memory 1601 and the processor 1602 can be connected to each other through a bus and communicate with each other. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus. The bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Fig.16 Only one thick line is used in the diagram, but this does not mean that there is only one bus or only one type of bus.

[0117] Optionally, in a specific implementation, if the memory 1601, the processor 1602 and the communication interface 1603 are integrated on a chip, the memory 1601, the processor 1602 and the communication interface 1603 can communicate with each other through an internal interface.

[0118] The processor 1602 may be a central processing unit (CPU), or an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of the present application.

[0119] This embodiment further provides a computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, the above-mentioned method for detecting a wide-band oscillation signal of a power grid based on frequency-domain matched filtering is implemented.

[0120] This embodiment also provides a computer program, which, when executed, implements the above-mentioned method for detecting a wide-band oscillation signal of a power grid based on frequency domain matching filtering.

[0121] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0122] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, "N" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0123] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or N executable instructions for implementing the steps of a custom logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present application belong.

[0124] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in combination with these instruction execution systems, devices or apparatuses. For the purpose of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in combination with these instruction execution systems, devices or apparatuses. More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or N wirings (electronic devices), a portable computer disk box (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), a fiber optic device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically by optically scanning the paper or other medium and then editing, interpreting or processing in other suitable ways as necessary and then storing it in a computer memory.

[0125] It should be understood that the various parts of the present application can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiment, the N steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0126] A person skilled in the art may understand that all or part of the steps in the method for implementing the above-mentioned embodiment may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiment.

[0127] In addition, each functional unit in each embodiment of the present application may be integrated into a processing module, or each unit may exist physically separately, or two or more units may be integrated into one module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

[0128] The storage medium mentioned above may be a read-only memory, a magnetic disk or an optical disk, etc. Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limiting the present application. A person of ordinary skill in the art may change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A method for detecting broadband oscillation signals of a power grid based on frequency domain matched filtering, characterized in that: The following steps are involved: Acquire an oscillation detection task of a target power grid, and determine an oscillation detection frequency domain and an oscillation signal amplitude threshold of the target power grid based on the oscillation detection task; Collecting a current sampling sequence of the target power grid, defining the current sampling sequence at time zero to obtain a non-causal sequence, and adding an even symmetric window to the non-causal sequence to obtain a windowed discrete Fourier transform sequence of the non-causal sequence; Performing matched filtering on the windowed discrete Fourier transform sequence based on the matched filter coefficients of the target frequency domain matched filter to obtain a matched filter output sequence; According to the amplitude waveform of the matched filter output sequence, spectrum peaks that meet preset spectrum peak search conditions are extracted in the oscillation detection frequency domain to obtain all target spectrum peaks, so as to perform detection based on all target spectrum peaks and the oscillation signal amplitude threshold to obtain the broadband oscillation component of the target power grid.

2. The method according to claim 1, characterized in that Before performing matched filtering on the windowed discrete Fourier transform sequence based on the matched filter coefficient of the target frequency domain matched filter, the method further includes: Determine a target even-symmetric window function and a target window length based on the oscillation detection frequency domain and the oscillation signal amplitude threshold, and generate the target frequency domain matched filter according to the target even-symmetric window function and the target window length; According to the frequency spectrum main lobe width of the target even-symmetric window function after discrete-time Fourier transform, the matched filter coefficient of the target frequency domain matched filter is confirmed.

3. The method according to claim 1, characterized in that The detecting based on all the target spectrum peaks and the oscillation signal amplitude threshold to obtain the broadband oscillation component of the target power grid includes: Based on all the target spectrum peaks, detecting whether there is at least one target spectrum peak whose peak value is greater than the oscillation signal amplitude threshold; When it is detected that there is at least one target spectrum peak whose peak value is greater than the oscillation signal amplitude threshold, the target spectrum peak whose peak value is greater than the oscillation signal amplitude threshold is determined to be the broadband oscillation component, and the oscillation amplitude and frequency of the broadband oscillation component are confirmed based on the peak height and position of the corresponding target spectrum peak.

4. The method according to claim 1, characterized in that: The preset peak search condition is to search for q that satisfies the following conditions: |And t [q]|>|And t [q-1]|, |And t [q]|>|And t [q+1]|, Among them, Y t [m] is the matched filter output sequence, A is the effective value of the fundamental wave, and ε is the amplitude ratio threshold of the oscillation signal to the fundamental wave.

5. A power grid broadband oscillation signal detection device based on frequency domain matching filtering, characterized in that: include: An acquisition module, used for acquiring an oscillation detection task of a target power grid, and confirming an oscillation detection frequency domain and an oscillation signal amplitude threshold of the target power grid based on the oscillation detection task; A windowing module is used to collect the current sampling sequence of the target power grid, define the current sampling sequence at zero time to obtain a non-causal sequence, and add an even symmetric window to the non-causal sequence to obtain a windowed discrete Fourier transform sequence of the non-causal sequence; A filtering module, used for performing matched filtering on the windowed discrete Fourier transform sequence based on the matched filter coefficient of the target frequency domain matched filter to obtain a matched filter output sequence; A detection module is used to extract spectrum peaks that meet preset spectrum peak search conditions in the oscillation detection frequency domain according to the amplitude waveform of the matched filter output sequence, and obtain all target spectrum peaks, so as to perform detection based on all target spectrum peaks and the oscillation signal amplitude threshold to obtain the broadband oscillation component of the target power grid.

6. The device according to claim 5, characterized in that Also includes: A generating module, used for confirming a target even-symmetric window function and a target window length based on the oscillation detection frequency domain and the oscillation signal amplitude threshold before matching filtering the windowed discrete Fourier transform sequence based on the matched filter coefficient of the target frequency domain matched filter, and generating the target frequency domain matched filter according to the target even-symmetric window function and the target window length; The confirmation module is used to confirm the matched filter coefficient of the target frequency domain matched filter according to the frequency spectrum main lobe width of the target even-symmetric window function after discrete-time Fourier transform.

7. The device according to claim 5, characterized in that The detection module comprises: a detection unit, configured to detect, based on all the target spectrum peaks, whether there is at least one target spectrum peak whose peak value is greater than the oscillation signal amplitude threshold; A determination unit is used to determine the target spectrum peak whose peak value is greater than the oscillation signal amplitude threshold as the broadband oscillation component when it is detected that there is at least one target spectrum peak whose peak value is greater than the oscillation signal amplitude threshold, and to confirm the oscillation amplitude and frequency of the broadband oscillation component according to the peak height and position of the corresponding target spectrum peak.

8. The device according to claim 5, characterized in that The preset peak search condition is to search for q that satisfies the following conditions: |And t [q]|>|And t [q-5]|, |And t [q]|>|And t [q+5]|, Among them, Y t [m] is the matched filter output sequence, A is the effective value of the fundamental wave, and ε is the amplitude ratio threshold of the oscillation signal to the fundamental wave.

9. An electronic device, characterized in that: include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the method for detecting a wideband oscillation signal of a power grid based on frequency domain matching filtering as described in any one of claims 1 to 4.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: The program is executed by a processor to implement the method for detecting a wide-band oscillation signal of a power grid based on frequency domain matched filtering as described in any one of claims 1 to 4.

11. A computer program product, comprising a computer program, characterized in that The computer program is executed to implement the method for detecting broadband oscillation signals of a power grid based on frequency domain matched filtering as described in any one of claims 1 to 4.

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