CN105606895B - The on-line checking and filtering method of subsynchronous oscillation of electrical power system composition - Google Patents

The on-line checking and filtering method of subsynchronous oscillation of electrical power system composition Download PDF

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CN105606895B
CN105606895B CN201610008784.1A CN201610008784A CN105606895B CN 105606895 B CN105606895 B CN 105606895B CN 201610008784 A CN201610008784 A CN 201610008784A CN 105606895 B CN105606895 B CN 105606895B
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sub
frequency
synchronous oscillation
composition
component
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CN105606895A (en
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王茂海
齐霞
牛四清
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ECONOMIC RESEARCH INSTITUTE OF STATE GRID JIBEI ELECTRIC POWER Co Ltd
State Grid Corp of China SGCC
North China Grid Co Ltd
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ECONOMIC RESEARCH INSTITUTE OF STATE GRID JIBEI ELECTRIC POWER Co Ltd
State Grid Corp of China SGCC
North China Grid Co Ltd
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R23/00Arrangements for measuring frequencies; Arrangements for analysing frequency spectra
    • G01R23/16Spectrum analysis; Fourier analysis
    • G01R23/163Spectrum analysis; Fourier analysis adapted for measuring in circuits having distributed constants
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02JCIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00Circuit arrangements for ac mains or ac distribution networks
    • H02J3/01Arrangements for reducing harmonics or ripples
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E40/00Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/40Arrangements for reducing harmonics

Abstract

The present invention provides the on-line checking and filtering method of a kind of subsynchronous oscillation of electrical power system composition, which includes: to obtain a grid power signal, and filter out power frequency component from the grid power signal, to extract sub-synchronous oscillation component;It is tested and analyzed by sub-synchronous oscillation component described in Fourier transform pairs, generates frequency, amplitude and the phase of the sub-synchronous oscillation component.The on-line checking and filtering method of the embodiment of the present invention quick and precisely can detect and filter out the sub-synchronous oscillation composition in electric power signal.

Description

The on-line checking and filtering method of subsynchronous oscillation of electrical power system composition
Technical field
The present invention relates to the on-line checking of power domain more particularly to a kind of subsynchronous oscillation of electrical power system composition and filter out Method.
Background technique
In the prior art, the monitoring method of sub-synchronous oscillation is primarily directed to subsynchronous resonance caused by series compensation (Sub-Synchronous Resonance,SSR).Monitoring can only be carried out in situ in power plant, and monitoring signals are mainly derived from hair Motor group, monitoring method can be divided into two kinds of measurement methods of mechanical value measuring and electrical quantities measurement by the difference of measuring signal.
Sub-synchronous oscillation monitoring method based on mechanical value measuring utilizes rotor of the generating set under environmental perturbation excitation Dynamic process is moved, identifies sub-synchronous oscillation mode.Consider the Generator Set of mechanical oscillatory structure characteristic inherently One kind " sensor " of power grid, for sub-synchronous oscillation, generating set equivalence is multiple lumped mass blocks, and regional power grid equivalence is One lumped mass block, generator unit shaft system can the sensitive vibrations for perceiving the system.Power grid oscillation environmental excitation mainly from Small movements perturbation is occurred for excitation electric generating set rotor by the disturbance of load fluctuation and noise, i.e. power grid environment, passes through high sensitivity Method for detecting weak signals can get power grid environment excitation under structural vibration response, pass through the vibration based on Random Decrement Technique Moving noise modal identification method may recognize that multiple Oscillatory mode shapes and the damping of the system.
Mechanical value measuring method can not although can judge whether certain generator shafting has occurred resonance on the spot in real time Accomplish early warning, also can not provide effective information to vibrate the positioning in source.Monitoring to tach signal so that this method application It can only be confined to generating set, the status of power electronic equipment large-scale application is not adapted to, cannot achieve in network-wide basis Monitoring;It is mainly accurately detected just for Oscillatory mode shape, accurate oscillation amplitude and phase information can not be provided, thus can not Positioning for sub-synchronous oscillation source provides foundation;Complexity is calculated, can not achieve online fast slowdown monitoring.
The existing sub-synchronous oscillation monitoring method based on electrical quantities measurement can theoretically extract the mode of electrical oscillation, And the early warning of sub-synchronous oscillation is realized for single unit, but the existing sub-synchronous oscillation monitoring side based on electrical quantities measurement Method, for example, the methods of Prony, wavelet analysis, TLS-ESPRIT, neural network, calculate more complicated, computationally intensive and right Noise and transient process are more sensitive, are difficult really to realize the on-line quick detection and real-time early warning of sub-synchronous oscillation.
Summary of the invention
The present invention provides the on-line checking and filtering method of a kind of subsynchronous oscillation of electrical power system composition, to solve existing skill One or more missings in art.
The present invention provides a kind of online test method of subsynchronous oscillation of electrical power system composition, comprising: obtains power grid electricity Force signal, and power frequency component is filtered out from the grid power signal, to extract sub-synchronous oscillation component;Pass through Fourier transformation The sub-synchronous oscillation component is tested and analyzed, frequency, amplitude and the phase of the sub-synchronous oscillation component are generated.
In one embodiment, power frequency component is being filtered out from the grid power signal, to extract sub-synchronous oscillation component Before, further includes: according to a setting sample frequency, the grid power comprising power frequency composition and sub-synchronous oscillation composition is believed It number is sampled.
In one embodiment, power frequency component is filtered out from the grid power signal, to extract sub-synchronous oscillation component, packet It includes: the first data window is set according to the signal frequency of the power frequency composition;According to first data window to described in after sampling Grid power signal is filtered, and to filter out power frequency component, obtains the sub-synchronous oscillation component.
In one embodiment, tested and analyzed by sub-synchronous oscillation component described in Fourier transform pairs, described in generation Frequency, amplitude and the phase of sub-synchronous oscillation component, comprising: calculate the original frequency of the sub-synchronous oscillation component;According to institute It states original frequency and sets a data window width, and using the data window width and the setting sample frequency to described subsynchronous Oscillating component carries out windowing process;Discrete Fourier transform DFT is carried out to the sub-synchronous oscillation component after adding window, obtains institute State the frequency, amplitude and phase of sub-synchronous oscillation component.
In one embodiment, the original frequency of the sub-synchronous oscillation component is calculated, comprising: using described in zero passage method calculating The original frequency of sub-synchronous oscillation component.
In one embodiment, further includes: judge the data window width according to the frequency and the setting sample frequency Whether the signal period of the sub-synchronous oscillation component is equal to;If it is not, amplitude and phase to the sub-synchronous oscillation component into Row amendment, to respectively reduce the amplitude error and phase caused by the difference by the data window width and between the signal period Position error.
In one embodiment, the grid power signal is current signal.
In one embodiment, the grid power signal after sampling is filtered according to first data window, is wrapped It includes: the grid power signal after sampling being filtered using a moving average filter according to first data window Wave.
The present invention also provides a kind of online filtering methods of subsynchronous oscillation of electrical power system composition, comprising: obtains a power grid Electric power signal, and sub-synchronous oscillation component is extracted from the grid power signal;By subsynchronous described in Fourier transform pairs Oscillating component is tested and analyzed, and frequency, amplitude and the phase of the sub-synchronous oscillation component are generated;It is set according to the frequency One second data window;The grid power comprising power frequency composition and sub-synchronous oscillation composition is believed according to second data window It number is filtered, to filter out the sub-synchronous oscillation component, obtains power frequency component.
In one embodiment, according to second data window to the electricity comprising power frequency composition and sub-synchronous oscillation composition Net electric power signal is filtered, comprising: according to second data window, using a moving average filter, to comprising power frequency at The grid power signal of part and sub-synchronous oscillation composition is filtered.
In one embodiment, before extracting sub-synchronous oscillation component in the grid power signal, further includes: according to One setting sample frequency, samples the grid power signal comprising power frequency composition and sub-synchronous oscillation composition.
In one embodiment, sub-synchronous oscillation component is extracted from the grid power signal, comprising: according to the power frequency The signal frequency of composition sets the first data window;The grid power signal after sampling is carried out according to first data window Filtering, obtains filtering out the sub-synchronous oscillation component after the power frequency composition.
In one embodiment, tested and analyzed by sub-synchronous oscillation component described in Fourier transform pairs, described in generation Frequency, amplitude and the phase of sub-synchronous oscillation component, comprising: calculate the original frequency of the sub-synchronous oscillation component;According to institute It states original frequency and sets a data window width, and using the data window width and the setting sample frequency to described subsynchronous Oscillating component carries out windowing process;Discrete Fourier transform DFT is carried out to the sub-synchronous oscillation component after adding window, obtains institute State the frequency, amplitude and phase of sub-synchronous oscillation component.
In one embodiment, the original frequency of the sub-synchronous oscillation component is calculated, comprising: using described in zero passage method calculating The original frequency of sub-synchronous oscillation component.
In one embodiment, further includes: judge the data window width according to the frequency and the setting sample frequency Whether the signal period of the sub-synchronous oscillation component is equal to;If it is not, amplitude and phase to the sub-synchronous oscillation component into Row amendment, to respectively reduce the amplitude error and phase caused by the difference by the data window width and between the signal period Position error.
In one embodiment, the grid power signal is current signal.
In one embodiment, the grid power signal after sampling is filtered according to first data window, is wrapped It includes: the grid power signal after sampling being filtered using a moving average filter according to first data window Wave.
The sub-synchronous oscillation composition online test method of the embodiment of the present invention is broken through in the prior art by every means from power grid The solidification thinking that sub-synchronous oscillation signal is filtered out in electric power signal, by specially extracting subsynchronous vibration from grid power signal Component is swung, and analyzes the specifying information of the sub-synchronous oscillation component, including frequency, amplitude and phase, that is, detects power grid electricity Sub-synchronous oscillation component in force signal.Grid power signal can be carried out using the specifying information of the sub-synchronous oscillation component Various necessary processing, such as this time is quickly filtered out from grid power signal according to the specifying information of the sub-synchronous oscillation component Synchronized oscillation component.Mechanical measuring means in the prior art is limited only to the monitoring to generator amature tach signal, cannot The status of adaptation power electronic equipment large-scale application, and the on-line checking side of the sub-synchronous oscillation composition of the embodiment of the present invention Method, the signal for carrying out sub-synchronous oscillation ingredient analysis can be a variety of electric power signals, be a kind of electric measurement method, can be realized Monitoring in network-wide basis.Sub-synchronous oscillation detection method in the prior art, is mainly accurately examined just for Oscillatory mode shape It surveys, and the detection method of the embodiment of the present invention, accurate oscillation amplitude and phase information can be provided, to be sub-synchronous oscillation The positioning in source provides foundation.Existing electrical inspection method selects DC voltage, DC current and alternating voltage virtual value conduct Signal is analyzed, so that this method may be only available for DC converter station, and the sub-synchronous oscillation ingredient analysis side of the embodiment of the present invention The grid power signal that method is utilized, can be only one of a variety of electric power signals, such as voltage or electric current, and signal selects letter It is single, it is suitable for the whole network and detects.The sub-synchronous oscillation composition filtering method of the embodiment of the present invention, according to above-mentioned sub-synchronous oscillation component Frequency, amplitude and phase, filter out above-mentioned sub-synchronous oscillation composition, can effectively inhibit sub-synchronous oscillation composition in electric power signal Influence to power frequency component.
Detailed description of the invention
In order to more clearly explain the embodiment of the invention or the technical proposal in the existing technology, to embodiment or will show below There is attached drawing needed in technical description to be briefly described, it should be apparent that, the accompanying drawings in the following description is only this Some embodiments of invention for those of ordinary skill in the art without creative efforts, can be with It obtains other drawings based on these drawings.In the accompanying drawings:
Fig. 1 is the flow diagram of the online test method of the subsynchronous oscillation of electrical power system composition of the embodiment of the present invention;
Fig. 2 is the process signal of the online test method of the subsynchronous oscillation of electrical power system composition of another embodiment of the present invention Figure;
Fig. 3 is the method flow signal for extracting sub-synchronous oscillation component in one embodiment of the invention from grid power signal Figure;
Fig. 4 is the method flow signal for extracting sub-synchronous oscillation component in one embodiment of the invention from grid power signal Figure;
Fig. 5 is that power frequency component and sub-synchronous oscillation component ratio change with sub-synchronous oscillation frequency in one embodiment of the invention Curve graph;
Fig. 6 is the method flow schematic diagram that sub-synchronous oscillation component information is generated in one embodiment of the invention;
Fig. 7 is in one embodiment of the invention to the amplitude and the method flow that is modified of phase to sub-synchronous oscillation component Schematic diagram;
Fig. 8 to Figure 10 is respectively frequency, the amplitude of the sub-synchronous oscillation component obtained using the method for the embodiment of the present invention And the measurement result of phase;
Figure 11 to Figure 13 is respectively frequency, the amplitude of the sub-synchronous oscillation component obtained using the method for the embodiment of the present invention And the measurement result of phase;
Recording curve of the Figure 14 for generator unit A phase current and the method using one embodiment of the invention are extracted subsynchronous Oscillating current curve comparison schematic diagram;
Figure 15 to Figure 17 is respectively the frequency of the sub-synchronous oscillation composition obtained using the method for one embodiment of the invention, width Value and phase measurement;
Figure 18 is the flow diagram of the online filtering method of the subsynchronous oscillation of electrical power system composition of the embodiment of the present invention;
Figure 19 is the process signal that sub-synchronous oscillation composition method in grid power signal is filtered out in one embodiment of the invention Figure.
Specific embodiment
Understand in order to make the object, technical scheme and advantages of the embodiment of the invention clearer, with reference to the accompanying drawing to this hair Bright embodiment is described in further details.Here, the illustrative embodiments of the present invention and their descriptions are used to explain the present invention, but simultaneously It is not as a limitation of the invention.
In various embodiments of the present invention, " electric system " be can refer to, by generate electricity, power (including transmission of electricity, power transformation, distribution), electricity consumption Facility, and to guarantee that these facilities operate normally required relay protection, automatic safety device, metering device, power communication The entirety of the compositions such as facility, automation installation." power frequency " can refer to the ac voltage standard frequency of power industry, can refer in China 50Hz." sub-synchronous oscillation " can refer to, and subsynchronous oscillation of electrical power system is a kind of operating status of electric system, in this state Electrical system and Turbo-generator Set are handed over the natural frequency of oscillation of some or multiple net machine association systems lower than synchronizing frequency Transducing amount.Any dress that power or velocity variations quickly can be controlled or responded in the range of sub-synchronous oscillation frequency Setting all is possible sub-synchronous oscillation excitaton source.Phasor measurement (measurement) device (Phasor Measurement Unit, PMU) Can refer to, for synchronize phasor measurement and output and carry out dynamically recording device.The core feature of PMU includes being based on The synchronous phasor measurement of standard clock signal loses and can lead in real time between punctual ability, PMU and the main website of standard clock signal Believe and follows related communication protocol.
The present invention provides a kind of online test method of subsynchronous oscillation of electrical power system composition.This method passes through first to be filtered out Then power frequency composition in grid power signal is changed by Fourier to extract sub-synchronous oscillation component and obtains this time together Walk the concrete signal information of oscillating component.
Fig. 1 is the flow diagram of the online test method of the subsynchronous oscillation of electrical power system composition of the embodiment of the present invention. As shown in Figure 1, the online test method of subsynchronous oscillation of electrical power system composition, it may include step:
S110: obtaining a grid power signal, and filter out power frequency component from above-mentioned grid power signal, secondary same to extract Walk oscillating component;
S120: being tested and analyzed by the above-mentioned sub-synchronous oscillation component of Fourier transform pairs, generates above-mentioned subsynchronous vibration Swing the frequency, amplitude and phase of component.
In above-mentioned steps S110, which can be the electric power letter that any position obtains from electric system Number.The grid power signal can be a plurality of types of signals, such as current signal or voltage signal.
In above-mentioned steps S120, which can be various Fourier transformation methods, such as discrete fourier Convert (Discrete Fourier Transform, DFT), fast Fourier variation (Fast Fourier Transform, FFT), discrete time Fourier transform (Discrete Time Fourier Transform, DTFT), aperiodicity are continuously believed Number Fourier transform (Fourier Transform, FT), periodically continued signal fourier series (Fourier Series, FS).The sub-synchronous oscillation component can be converted from time domain to frequency domain using above-mentioned Fourier transformation method, to extract this The information such as frequency, amplitude and the phase of sub-synchronous oscillation component.
In the embodiment of the present invention, breakthrough filters out sub-synchronous oscillation letter from grid power signal by every means in the prior art Number solidification thinking, conversely, by specially extracting sub-synchronous oscillation component from grid power signal, and analyze this time together The specifying information of oscillating component, including frequency, amplitude and phase are walked, that is, detects the sub-synchronous oscillation point in grid power signal Amount.Various necessary processing, such as root can be carried out to grid power signal using the specifying information of the sub-synchronous oscillation component The sub-synchronous oscillation component is quickly filtered out from grid power signal according to the specifying information of the sub-synchronous oscillation component.The prior art In mechanical measuring means, be limited only to the monitoring to generator amature tach signal, do not adapt to the big rule of power electronic equipment The status of mould application, and the online test method of the sub-synchronous oscillation composition of the embodiment of the present invention, carry out sub-synchronous oscillation composition The signal of detection can be a variety of electric power signals, is a kind of electric measurement method, can be realized the monitoring in network-wide basis.It is existing Sub-synchronous oscillation detection method in technology, is mainly accurately detected just for Oscillatory mode shape, and the inspection of the embodiment of the present invention Survey method can provide accurate oscillation amplitude and phase information, so that the positioning for sub-synchronous oscillation source provides foundation.It is existing Electrical inspection method, select DC voltage, DC current and alternating voltage virtual value as analysis signal, so that this method is only It can be suitably used for DC converter station, and the grid power letter that the sub-synchronous oscillation ingredient analysis method of the embodiment of the present invention is utilized Number, it can be only one of a variety of electric power signals, such as voltage or electric current, signal is selected simply, is suitable for the whole network and is detected.
Fig. 2 is the process signal of the online test method of the subsynchronous oscillation of electrical power system composition of another embodiment of the present invention Figure.As shown in Fig. 2, in the online test method of subsynchronous oscillation of electrical power system composition shown in FIG. 1, from above-mentioned grid power Power frequency component is filtered out in signal, before extracting sub-synchronous oscillation component, may further comprise the step of:
S130: according to a setting sample frequency, to the above-mentioned grid power comprising power frequency composition and sub-synchronous oscillation composition Signal is sampled.
In the embodiment of the present invention, by sampling to the grid power signal, digitized grid power can be carried out Signal is handled.Correspondingly, the sub-synchronous oscillation component in the grid power signal after sampling is detected, can be used Such as discrete Fourier transform DFT is detected.
Fig. 3 is the method flow signal for extracting sub-synchronous oscillation component in one embodiment of the invention from grid power signal Figure.As shown in figure 3, power frequency component is filtered out from above-mentioned grid power signal in above-mentioned steps S110, to extract subsynchronous vibration Swing the method for component, it may include step:
S111: the first data window is set according to the signal frequency of above-mentioned power frequency composition;
S112: the above-mentioned grid power signal after sampling is filtered according to above-mentioned first data window, to filter out power frequency Component obtains above-mentioned sub-synchronous oscillation component.
In above-mentioned steps S111, the signal frequency of the power frequency composition may, for example, be 50Hz in China.According to the power frequency Composition signal frequency setting for filtering data window, for example, first data window make filtering when data window width with The signal period of power frequency composition is identical, can effectively inhibit the influence of fundamental frequency, harmonic wave and noise, obtains to accurately extract Sub-synchronous oscillation component in the grid power signal.The detection method of the embodiment of the present invention, by according to above-mentioned first data Window is filtered, and can quickly filter out the power frequency composition in grid power signal.
Fig. 4 is the method flow signal for extracting sub-synchronous oscillation component in one embodiment of the invention from grid power signal Figure.As shown in figure 4, in above-mentioned steps S112, it can be using moving average filtering method to the above-mentioned grid power after sampling Signal is filtered, so, the above-mentioned grid power signal after sampling is filtered according to above-mentioned first data window, it may include Step:
S113: the above-mentioned grid power after sampling is believed using a moving average filter according to above-mentioned first data window It number is filtered.
It in the embodiment of the present invention, is filtered using moving average filter, only need to use add operation twice, it can be complete The filtering of grid power signal after sampling in pairs, calculation amount is small, in this way, facilitate rapidly extracting sub-synchronous oscillation point Amount.
As an example, if including two kinds of radio-frequency components in grid power signal x (t): one kind is power frequency composition, and another kind is secondary Synchronized oscillation composition.Wherein, the frequency of the power frequency composition is f0, amplitude X, the frequency of the sub-synchronous oscillation composition is f1, amplitude For X1, then the grid power signal x (t) is concretely:
In formula (1), ω0=2 π f0And ω1=2 π f1The respectively continuous angular frequency of the power frequency composition and the subsynchronous composition Rate.
Above-mentioned grid power signal x (t) is sampled, if sample frequency is fs, corresponding sampling time interval is Ts= 1/fs, then the grid power signal after sampling corresponding to formula (1) can are as follows:
In formula (2), n is integer, parameter Ω00TsWith parameter Ω11TsRespectively power frequency composition and subsynchronous The circular frequency of composition.
In view of power frequency quantity occupies leading position in three-phase current, ratio shared by subsynchronous component is relatively small, secondary same The measurement of step component will receive the influence of power frequency quantity, it is therefore desirable to handle sampled signal, can reduce power frequency quantity to the greatest extent Influence.
Construct following signal:
In formula (3), data window N=fs/f0(if calculated result is decimal, can round).In practical electricity In Force system, work frequency f0It can change near rated frequency, when actually calculating N, can use work frequency f0For specified frequency Rate.By taking 50Hz electric system as an example, sample frequency fsWhen for 9600Hz, data window N=9600/50=192, k are integer,For Phase angle.
Signal y (n) shown in formula (3) calculates very little, can simply recurrence calculation:
Y (n+1)=y (n)+x (n+1)-x (n-N+1) (4)
Formula (4) only need to use twice plus and minus calculation can push away and calculate signal y (n), calculation amount is small.Formula (3) institute The y (n) shown is the result that moving average filtering is carried out to original sampled signal x (n).
The above-mentioned structure for being filtered moving average filter used can are as follows:
H (z) indicates the transmission function of filter in formula (5), and Y (z) and X (z) are respectively the transform of y (n) He x (n), z For complex variable.In formula (6), e=z, using Ω as independent variable, filter H (e) it is represented by H (Ω).
Filter H (Ω) has the property that
1) (corresponding signal frequency f=0), H (Ω)=N as independent variable Ω=0;
2) (the corresponding signal frequency f=kf as independent variable Ω=2k π/N0, k=1,2 ...), H (Ω)=0.
From the foregoing, it will be observed that filter shown in formula (5) has linear phase, amplitude-frequency characteristic shows it to rated frequency Power frequency quantity and integral frequency harmonizing wave, which all have, absolute filters out effect.
According to above-mentioned filter, the right first item of formula (3) can are as follows:
The right Section 2 of formula (3) can are as follows:
In formula (7), Ω0For the circular frequency of power frequency composition, X is cosine wave cos (Ω0K) amplitude, n and k are whole Number.In formula (8), Ω1For the circular frequency of subsynchronous composition, X1For cosine waveAmplitude,For cosine wavePhase, n and k are integer.
It is considered that the frequency of the power frequency component of signal all fluctuates near rated frequency substantially in electric system, therefore can Formula (7) are approximately considered equal to zero, i.e. power frequency component is filtered out, it is thus regarded that containing only subsynchronous signal in y (n), that is, is extracted Sub-synchronous oscillation component can are as follows:
Further, error analysis can be carried out to the subsynchronous component that said extracted obtains.It is secondary it can be seen from formula (7) The error that synchronized component extracts is mainly as caused by power frequency component frequency departure rated frequency.As power system capacity is got over Come it is bigger, power frequency component deviate rated frequency range it is also smaller and smaller.By formula (7) and formula (8), filtered work is calculated The ratio of frequency component and subsynchronous component:
With f0For=50.05Hz (i.e. system frequency deviates rated frequency 0.05Hz), it is assumed that deposited in original sampled signal Amplitude be 1 power frequency component and amplitude be 1 subsynchronous component ratio K and time same can be arrived for different subsynchronous frequencies Walk the relationship of frequency of oscillation.Fig. 5 be in one embodiment of the invention power frequency component and sub-synchronous oscillation component ratio with subsynchronous vibration Swing the curve graph of frequency variation.As shown in figure 5, from ratio-frequency curve 501 as can be seen that in common subsynchronous frequency model In enclosing, the extraction error very little for the sub-synchronous oscillation component that present invention method is extracted.
Fig. 6 is the method flow schematic diagram that sub-synchronous oscillation component information is generated in one embodiment of the invention.Such as Fig. 6 institute Show, in above-mentioned steps S120, tested and analyzed by the above-mentioned sub-synchronous oscillation component of Fourier transform pairs, is generated above-mentioned time The method of the frequency of synchronized oscillation component, amplitude and phase, it may include step:
S121: the original frequency of above-mentioned sub-synchronous oscillation component is calculated;
S122: a data window width is set according to above-mentioned original frequency, and utilizes above-mentioned data window width and above-mentioned setting Sample frequency carries out windowing process to above-mentioned sub-synchronous oscillation component;
S123: discrete Fourier transform DFT is carried out to the above-mentioned sub-synchronous oscillation component after adding window, is obtained above-mentioned subsynchronous Frequency, amplitude and the phase of oscillating component.
In above-mentioned steps S121, the original frequency of the sub-synchronous oscillation component can be that initial calculation goes out this is subsynchronous The frequency of oscillation can calculate the original frequency using a variety of methods, calculate the sub-synchronous oscillation component for example, by using zero passage method Original frequency.The original frequency that quickly can be roughly calculated sub-synchronous oscillation component first using zero passage method, is then led to Sub-synchronous oscillation component after crossing windowing process carries out discrete Fourier transform DFT, obtains frequency, the width of sub-synchronous oscillation component Value and phase (step S123), have further obtained the frequency of more accurate sub-synchronous oscillation component.In this way, can be fast Speed extracts the frequency, amplitude and phase information of sub-synchronous oscillation component.
Sub-synchronous oscillation signal electrical inspection method in the prior art, using Interpolating Window FFT Algorithm and algorithm for estimating (Estimating Signal Parameters via Rational Invariant Technique, ESPRIT) identification electricity The sub-synchronous oscillation information of gas signal can not be applied to on-line quick detection so that this method calculation amount is too big.And the present invention is real The method for applying example, can be by using easier method (such as zero passage method) quickly to calculate the first of sub-synchronous oscillation component first Beginning frequency obtains the frequency, amplitude and phase information of sub-synchronous oscillation component using processing, and calculation amount is small, can be improved secondary Synchronized oscillation component on-line checking speed.
For example, calculating original frequency f' using zero passage method to the signal y (n) after above-mentioned sampling1, according to original frequency f '1, calculate data window width N1:
N1=round (fs/f1'), (11)
In formula (11), round indicates round, fsFor sample frequency.
Choose data window width N1For data window, to carrying out discrete fourier DFT meter after signal y (n) adding window after sampling It calculates, the frequency f of sub-synchronous oscillation component can be obtained1, according to formula (9), the amplitude X of sub-synchronous oscillation component can be obtained1mAnd phase Position
In formula (12) and (13), Ω1For the circular frequency of subsynchronous composition y (n), Y andRespectively signal y (n) Phase-amplitude, N1It can be respectively the data window width in formula (3) and formula (11) with N.
In formula (12) and formula (13), circular frequency Ω1=2 π f1Ts, TsFor sampling time interval, f1For subsynchronous vibration Swing the frequency of component.
Fig. 7 is in one embodiment of the invention to the amplitude and the method flow that is modified of phase to sub-synchronous oscillation component Schematic diagram.As shown in fig. 7, in the embodiment of the present invention, amplitude and phase to sub-synchronous oscillation component obtained above (such as by The amplitude and phase that method shown in Fig. 6 obtains) method that is modified, it may include step:
S140: judge whether above-mentioned data window width is equal to above-mentioned time together according to said frequencies and above-mentioned setting sample frequency Walk the signal period of oscillating component;
S150: if it is not, the amplitude and phase to above-mentioned sub-synchronous oscillation component are modified, to respectively reduce by above-mentioned number According to amplitude error caused by the difference between window width and above-mentioned signal period and phase error.
In the embodiment of the present invention, by judging whether sampling synchronizes, i.e., whether the data window width of discrete Fourier transform Equal to the signal period of sub-synchronous oscillation component, it the amplitude to sub-synchronous oscillation component and phase can be modified, obtain accordingly To the information of more accurate sub-synchronous oscillation component.
For example, for sub-synchronous oscillation frequency f obtained above1, as parameter lambda=N1f1/fsWhen ≠ 1, non-synchronous sampling (data window width N1Difference between DFT data window width) it will lead to amplitude and error occurs in phase calculation result, it can enable:
Δ λ=λ -1 (14)
To the amplitude X of sub-synchronous oscillation component1mAnd phaseIt is modified, can be obtained:
In formula (15) and formula (16), X1WithThe amplitude and phase of respectively revised sub-synchronous oscillation component.
Compared with conventional phasor measurement, the sub-synchronous oscillation detection method of the embodiment of the present invention is mainly more in calculation amount The step for subsynchronous component extracts is gone out.By formula (3) and formula (4) it is found that needing to utilize formula when except emulation just starting (3) outside, it only needs to carry out add operation twice using formula (4) when emulation operates normally, the calculating that subsynchronous component extracts is very It is small.Subsynchronous component extraction process bring time delay is about a power frequency period, can satisfy the needs of on-line checking.
Sub-synchronous oscillation composition online test method according to an embodiment of the present invention can pass through the existing phasor of simple extension The function of measuring device (PMU) is realized.
In one specific embodiment, it is assumed that include frequency f in simulation electric power signal0The power frequency composition and frequency f of=50.05Hz1 The sub-synchronous oscillation composition of=30Hz.The amplitude of subsynchronous component can be 0.1 times of power frequency component amplitude.Sample frequency can be fs =9600Hz.It may include 1% white noise in simulation electric power signal.The simulation electric power signal may be expressed as:
X (t)=cos (2 π f0t)+0.1cos(2πf1t+60°)。 (17)
Fig. 8 to Figure 10 is respectively frequency, the amplitude of the sub-synchronous oscillation component obtained using the method for the embodiment of the present invention And the measurement result of phase.Wherein, relative phase of the phase measurement of Figure 10 between measured signal and 30Hz standard signal. Therefrom Fig. 8 to Figure 10, which can be seen that, deviates rated frequency 0.05Hz in work frequency and exists in the case where 1% white noise, sharp The sub-synchronous oscillation composition measured with the method for the embodiment of the present invention, within 0.03Hz, amplitude error exists the error of frequency Within 1.5%, phase angle error is within 0.7 °.
In another specific embodiment, on the basis of above-mentioned specific embodiment, the amplitude of power frequency component is modulated, example If modulating frequency is 1.5Hz, modulation amplitude 0.1.Sample frequency can be fs=9600Hz.Contain 1% in electric power signal White noise.The electric power signal may be expressed as:
X (t)=[1+0.1cos (3 π t)] cos (2 π f0t)+0.1cos(2πf1t+60°)。 (18)
Figure 11 to Figure 13 is respectively frequency, the amplitude of the sub-synchronous oscillation component obtained using the method for the embodiment of the present invention And the measurement result of phase.In power frequency component frequency departure rated frequency 0.05Hz, power frequency point it can be seen from Figure 11 to Figure 13 There is oscillation, there are in the case where 1% white noise in amount, missed using the subsynchronous frequency resultant that the method for the embodiment of the present invention measures Poor still smaller (within 0.03Hz), amplitude error is within 3%, and phase angle error is within 1.7 °.
In still another embodiment, certain power plant accesses power grid by 500kV double-circuit line, after a certain loopback goes out route breaking Cause unit sub-synchronous oscillation, torsional oscillation protection movement, torsional oscillation mode is mode two (26Hz).Accordingly, in oscillatory process, stator There should be the sub-synchronous oscillation composition of 24Hz or so in electric current.
Recording curve of the Figure 14 for generator unit A phase current and the method using one embodiment of the invention are extracted subsynchronous Oscillating current curve comparison schematic diagram.In Figure 14, sample frequency 600Hz is filtered using formula (3) and to be extracted (numerical value of subsynchronous electric current is filtered numerical value to subsynchronous current curve in Figure 14, is equal to what true value was provided multiplied by formula (9) Coefficient).As seen from Figure 14, when electric system sub-synchronous oscillation composition occurs because of disturbance, subsynchronous vibration given herein Testing result can quickly be provided by swinging detection method.
Figure 15 to Figure 17 is respectively the frequency of the sub-synchronous oscillation composition obtained using the method for one embodiment of the invention, width Value and phase measurement.Phase therein is opposite 24Hz standard signal phase.
The on-line checking analysis of sub-synchronous oscillation is extremely important to the safety of power grid and unit.It creates and provides according to the present invention Sub-synchronous oscillation detection method, the on-line checking of sub-synchronous oscillation can be fast implemented, mentioned for the positioning in sub-synchronous oscillation source For foundation, avoid that the big axis damage of unit and power system stability is caused to destroy because of sub-synchronous oscillation.It was verified that the technology of the present invention Scheme is simple and effective, to ensure that power network safety operation and reliable power supply are laid a good foundation.
The online test method of the subsynchronous oscillation of electrical power system composition of the embodiment of the present invention, by choosing simple letter Number, such as current signal, it is monitored.By extracting sub-synchronous oscillation component from grid power signal, such as pass through shifting Dynamic average filter method rapidly extracting goes out the sub-synchronous oscillation component of power system signal, can effectively inhibit fundamental frequency, humorous The influence of wave and noise;Moving average filtering only needs add operation twice, calculation amount very little;Can provide sub-synchronous oscillation at The modal identification method of part;The information such as amplitude and the phase of sub-synchronous oscillation composition can be provided, are facilitated to sub-synchronous oscillation Signal is accurately positioned.
According to the above embodiments the sub-synchronous oscillation component in obtained grid power signal precise information (including Frequency, amplitude and phase), this kind of sub-synchronous oscillation composition can be preferably filtered out from grid power signal, to effectively press down The influence that sub-synchronous oscillation component processed monitors power frequency component.So based on above-mentioned subsynchronous oscillation of electrical power system composition Each embodiment of line detecting method, the present invention also provides a kind of online filtering methods of subsynchronous oscillation of electrical power system composition.Its In how to obtain the specific implementation of sub-synchronous oscillation frequency, amplitude and phase and can refer to above-described embodiment and implemented, repetition Place repeats no more.
Figure 18 is the flow diagram of the online filtering method of the subsynchronous oscillation of electrical power system composition of the embodiment of the present invention. As shown in figure 18, the online filtering method of the subsynchronous oscillation of electrical power system composition, it may include step:
S210: obtaining a grid power signal, and sub-synchronous oscillation component is extracted from above-mentioned grid power signal;
S220: being tested and analyzed by the above-mentioned sub-synchronous oscillation component of Fourier transform pairs, generates above-mentioned subsynchronous vibration Swing the frequency, amplitude and phase of component;
S230: one second data window is set according to said frequencies;
S240: the above-mentioned grid power comprising power frequency composition and sub-synchronous oscillation composition is believed according to above-mentioned second data window It number is filtered, to filter out the sub-synchronous oscillation component, obtains power frequency component.
In the embodiment of the present invention, the sub-synchronous oscillation in the grid power signal is obtained by step S210~S220 first Information, including frequency, amplitude and phase, further according to the sub-synchronous oscillation information, by step S230~S240 to original power grid Electric power signal is filtered, and obtains sub-synchronous oscillation component, can effectively filter out sub-synchronous oscillation in grid power signal at Part.
Figure 19 is the process signal that sub-synchronous oscillation composition method in grid power signal is filtered out in one embodiment of the invention Figure.As shown in figure 19, it in above-mentioned steps S240, can be filtered out by moving average filtering method secondary same in grid power signal Step oscillation composition.So according to above-mentioned second data window to the above-mentioned power grid electricity comprising power frequency composition and sub-synchronous oscillation composition Force signal is filtered, it may include step:
S241: according to above-mentioned second data window, using a moving average filter, to including power frequency composition and subsynchronous vibration The above-mentioned grid power signal for swinging composition is filtered.
In the embodiment of the present invention, grid power signal is filtered by moving average filter, it is only necessary to use two steps Plus and minus calculation calculates simply, helps quickly to filter out the sub-synchronous oscillation composition in electric power signal.
In one embodiment, from above-mentioned grid power signal extract sub-synchronous oscillation component (in step S210) it Before, the online filtering method of the subsynchronous oscillation of electrical power system composition may further comprise the step of:
S250: according to a setting sample frequency, to the above-mentioned grid power comprising power frequency composition and sub-synchronous oscillation composition Signal is sampled.
The implementation of above-mentioned steps S250 can refer to embodiment shown in Fig. 2 and carry out.In the embodiment of the present invention, by the electricity Net electric power signal is sampled, and can be carried out digitized grid power signal and be handled.Correspondingly, to the power grid after sampling Sub-synchronous oscillation component in electric power signal is detected, and can be detected using such as discrete Fourier transform DFT, can be with The detection speed of sub-synchronous oscillation component is improved, and then accelerates sub-synchronous oscillation composition and filters out speed.
In one embodiment, in above-mentioned steps S210, sub-synchronous oscillation component is extracted from above-mentioned grid power signal Method, it may include step:
S211: the first data window is set according to the signal frequency of above-mentioned power frequency composition;
S212: the above-mentioned grid power signal after sampling is filtered according to above-mentioned first data window, is filtered out Sub-synchronous oscillation component after stating power frequency composition.
The above-mentioned method that sub-synchronous oscillation component is extracted from above-mentioned grid power signal can refer to above-mentioned as shown in Figure 3 Embodiment is implemented.
In the embodiment of the present invention, the data window of filtering is used for according to the setting of the signal frequency of the power frequency composition, it can be effective Inhibit the influence of fundamental frequency, harmonic wave and noise, to accurately extract the sub-synchronous oscillation point obtained in the grid power signal Amount, and then sub-synchronous oscillation is accurately filtered out from original grid power signal (may include power frequency composition and sub-synchronous oscillation composition) Composition.
In one embodiment, in above-mentioned steps S220, carried out by the above-mentioned sub-synchronous oscillation component of Fourier transform pairs It tests and analyzes, the method for generating the frequency of above-mentioned sub-synchronous oscillation component, amplitude and phase, it may include step:
S221: the original frequency of above-mentioned sub-synchronous oscillation component is calculated;
S222: a data window width is set according to above-mentioned original frequency, and utilizes above-mentioned data window width and above-mentioned setting Sample frequency carries out windowing process to above-mentioned sub-synchronous oscillation component;
S223: discrete Fourier transform DFT is carried out to the above-mentioned sub-synchronous oscillation component after adding window, is obtained above-mentioned subsynchronous Frequency, amplitude and the phase of oscillating component.
The method of the frequency of above-mentioned acquisition sub-synchronous oscillation component, amplitude and phase, can refer to embodiment shown in fig. 6 into Row is implemented.
The method of the embodiment of the present invention, can be secondary by using easier method (such as zero passage method) quickly to calculate first The original frequency of synchronized oscillation component obtains the frequency, amplitude and phase information of sub-synchronous oscillation component using processing, calculates It measures small, can be improved sub-synchronous oscillation component on-line checking speed, and then that improves sub-synchronous oscillation component filters out speed.
In one embodiment, in above-mentioned steps S221, above-mentioned sub-synchronous oscillation component can be calculated using zero passage method Original frequency.With this, the original frequency can be quickly calculated, to further increase the speed for filtering out sub-synchronous oscillation composition Degree.
In one embodiment, the online filtering method of subsynchronous oscillation of electrical power system composition shown in Figure 18 may also include Step:
S260: judge whether above-mentioned data window width is equal to above-mentioned time together according to said frequencies and above-mentioned setting sample frequency Walk the signal period of oscillating component;
S270: if it is not, the amplitude and phase to above-mentioned sub-synchronous oscillation component are modified, to respectively reduce by above-mentioned number According to amplitude error caused by the difference between window width and above-mentioned signal period and phase error.
Method shown in above-mentioned steps S260~S270 can refer to embodiment shown in Fig. 7 and be implemented.
In the embodiment of the present invention, by judging whether sampling synchronizes, i.e., whether the data window width of discrete Fourier transform Equal to the signal period of sub-synchronous oscillation component, it the amplitude to sub-synchronous oscillation component and phase can be modified, obtain accordingly To the information of more accurate sub-synchronous oscillation component, and then more effectively filter out the sub-synchronous oscillation in original grid power signal Composition.
In one embodiment, above-mentioned grid power signal is current signal, is also possible to voltage signal.The embodiment of the present invention In, signal is chosen simply, and the sub-synchronous oscillation composition facilitated in the electric power signal to electric system each position filters out.
In one embodiment, in above-mentioned steps S212, moving average filtering method can be used from grid power signal In filter out power frequency composition.So the side being filtered according to above-mentioned first data window to the above-mentioned grid power signal after sampling Method, it may include step:
S213: the above-mentioned grid power after sampling is believed using a moving average filter according to above-mentioned first data window It number is filtered.
The implementation of above-mentioned steps S213 can refer to method shown in Fig. 4 and carry out.
It in the embodiment of the present invention, is filtered using moving average filter, only need to use add operation twice, it can be complete The filtering of grid power signal after sampling in pairs, calculation amount is small, in this way, facilitate rapidly extracting sub-synchronous oscillation component Information, and then improve sub-synchronous oscillation component and filter out speed.
As an example, it is contemplated that, the presence of sub-synchronous oscillation composition can also generate biggish shadow to power frequency phasor measurement precision It rings.Determining sub-synchronous oscillation frequency f1Afterwards, following signal can be constructed:
In formula (19), signal x2(n) data window N1It can be determined by formula (11), n and m are the integer not less than zero.It is public Formula (19) can efficiently filter out sub-synchronous oscillation composition, reduce its influence to power frequency phasor measurement, and equally, signal calculates Very little is measured, it can simply recurrence calculation:
x2(n+1)=x2(n)+x(n+1)-x(n-N1+1)。 (20)
In the embodiment of the present invention, it is only necessary to which, with plus and minus calculation twice, calculation amount is small, can quickly filter out grid power signal In above-mentioned sub-synchronous oscillation component.
The online filtering method of the subsynchronous oscillation of electrical power system composition of the embodiment of the present invention, by choosing simple letter Number, such as current signal, monitor sub-synchronous oscillation composition.By extracting sub-synchronous oscillation component from grid power signal, Such as go out the sub-synchronous oscillation component of power system signal by moving average filtering method rapidly extracting, it can effectively inhibit work The influence of frequency fundamental wave, harmonic wave and noise;Moving average filtering only needs add operation twice, calculation amount very little;It can provide secondary The modal identification method of synchronized oscillation composition;The information such as amplitude and the phase of sub-synchronous oscillation composition can be provided, are facilitated pair Sub-synchronous oscillation signal is accurately positioned, to effective filter out sub-synchronous oscillation composition.
In the description of this specification, reference term " one embodiment ", " some embodiments ", " example ", " specifically show The description of example " or " some examples " etc. means specific features, structure, material or spy described in conjunction with this embodiment or example Point is included at least one embodiment or example of the invention.In the present specification, schematic expression of the above terms are not Centainly refer to identical embodiment or example.Moreover, particular features, structures, materials, or characteristics described can be any One or more embodiment or examples in can be combined in any suitable manner.
It should be understood by those skilled in the art that, the embodiment of the present invention can provide as method, system or computer program Product.Therefore, complete hardware embodiment, complete software embodiment or reality combining software and hardware aspects can be used in the present invention Apply the form of example.Moreover, it wherein includes the computer of computer usable program code that the present invention, which can be used in one or more, The computer program implemented in usable storage medium (including but not limited to magnetic disk storage, CD-ROM, optical memory etc.) produces The form of product.
The present invention be referring to according to the method for the embodiment of the present invention, the process of equipment (system) and computer program product Figure and/or block diagram describe.It should be understood that every one stream in flowchart and/or the block diagram can be realized by computer program instructions The combination of process and/or box in journey and/or box and flowchart and/or the block diagram.It can provide these computer programs Instruct the processor of general purpose computer, special purpose computer, Embedded Processor or other programmable data processing devices to produce A raw machine, so that being generated by the instruction that computer or the processor of other programmable data processing devices execute for real The device for the function of being specified in present one or more flows of the flowchart and/or one or more blocks of the block diagram.
These computer program instructions, which may also be stored in, is able to guide computer or other programmable data processing devices with spy Determine in the computer-readable memory that mode works, so that it includes referring to that instruction stored in the computer readable memory, which generates, Enable the manufacture of device, the command device realize in one box of one or more flows of the flowchart and/or block diagram or The function of being specified in multiple boxes.
These computer program instructions also can be loaded onto a computer or other programmable data processing device, so that counting Series of operation steps are executed on calculation machine or other programmable devices to generate computer implemented processing, thus in computer or The instruction executed on other programmable devices is provided for realizing in one or more flows of the flowchart and/or block diagram one The step of function of being specified in a box or multiple boxes.
Particular embodiments described above has carried out further in detail the purpose of the present invention, technical scheme and beneficial effects Describe in detail it is bright, it should be understood that the above is only a specific embodiment of the present invention, the guarantor being not intended to limit the present invention Range is protected, all within the spirits and principles of the present invention, any modification, equivalent substitution, improvement and etc. done should be included in this Within the protection scope of invention.

Claims (15)

1. a kind of online test method of subsynchronous oscillation of electrical power system composition characterized by comprising
According to a setting sample frequency, the grid power signal comprising power frequency composition and sub-synchronous oscillation composition is sampled;
Grid power signal is obtained, and filters out power frequency component from the grid power signal, to extract sub-synchronous oscillation component;
It is tested and analyzed by sub-synchronous oscillation component described in Fourier transform pairs, generates the frequency of the sub-synchronous oscillation component Rate, amplitude and phase;
Wherein, it is tested and analyzed by sub-synchronous oscillation component described in Fourier transform pairs, generates the sub-synchronous oscillation point Frequency, amplitude and the phase of amount, comprising:
Calculate the original frequency of the sub-synchronous oscillation component;
A data window width is set according to the original frequency, and utilizes the data window width and the setting sample frequency pair The sub-synchronous oscillation component carries out windowing process;
Discrete Fourier transform DFT is carried out to the sub-synchronous oscillation component after adding window, obtains the sub-synchronous oscillation component Frequency, amplitude and phase.
2. the online test method of subsynchronous oscillation of electrical power system composition as described in claim 1, which is characterized in that from described Power frequency component is filtered out in grid power signal, to extract sub-synchronous oscillation component, comprising:
The first data window is set according to the signal frequency of the power frequency composition;
The grid power signal after sampling is filtered according to first data window, to filter out power frequency component, is obtained The sub-synchronous oscillation component.
3. the online test method of subsynchronous oscillation of electrical power system composition as described in claim 1, which is characterized in that calculate institute State the original frequency of sub-synchronous oscillation component, comprising:
The original frequency of the sub-synchronous oscillation component is calculated using zero passage method.
4. the online test method of subsynchronous oscillation of electrical power system composition as described in claim 1, which is characterized in that also wrap It includes:
Judge whether the data window width is equal to according to the frequency of the sub-synchronous oscillation component and the setting sample frequency The signal period of the sub-synchronous oscillation component;
If it is not, the amplitude and phase to the sub-synchronous oscillation component are modified, to respectively reduce by the data window width Amplitude error caused by difference between the signal period and phase error.
5. such as the online test method of the described in any item subsynchronous oscillation of electrical power system compositions of Claims 1-4, feature exists In the grid power signal is current signal.
6. the online test method of subsynchronous oscillation of electrical power system composition as claimed in claim 2, which is characterized in that according to institute The first data window is stated to be filtered the grid power signal after sampling, comprising:
The grid power signal after sampling is filtered using a moving average filter according to first data window Wave.
7. a kind of online filtering method of subsynchronous oscillation of electrical power system composition characterized by comprising
A grid power signal is obtained, and extracts sub-synchronous oscillation component from the grid power signal;
It is tested and analyzed by sub-synchronous oscillation component described in Fourier transform pairs, generates the frequency of the sub-synchronous oscillation component Rate, amplitude and phase;
One second data window is set according to the frequency;
The grid power signal comprising power frequency composition and sub-synchronous oscillation composition is filtered according to second data window Wave obtains power frequency component to filter out the sub-synchronous oscillation component.
8. the online filtering method of subsynchronous oscillation of electrical power system composition as claimed in claim 7, which is characterized in that according to institute The second data window is stated to be filtered the grid power signal comprising power frequency composition and sub-synchronous oscillation composition, comprising:
According to second data window, using a moving average filter, to comprising power frequency composition and sub-synchronous oscillation composition The grid power signal is filtered.
9. the online filtering method of subsynchronous oscillation of electrical power system composition as claimed in claim 7, which is characterized in that from institute It states before extracting sub-synchronous oscillation component in grid power signal, further includes:
According to a setting sample frequency, the grid power signal comprising power frequency composition and sub-synchronous oscillation composition is adopted Sample.
10. the online filtering method of subsynchronous oscillation of electrical power system composition as claimed in claim 9, which is characterized in that from institute State extraction sub-synchronous oscillation component in grid power signal, comprising:
The first data window is set according to the signal frequency of the power frequency composition;
The grid power signal after sampling is filtered according to first data window, obtains filtering out the power frequency composition Sub-synchronous oscillation component afterwards.
11. the online filtering method of subsynchronous oscillation of electrical power system composition as claimed in claim 9, which is characterized in that pass through Sub-synchronous oscillation component described in Fourier transform pairs is tested and analyzed, and frequency, the amplitude of the sub-synchronous oscillation component are generated And phase, comprising:
Calculate the original frequency of the sub-synchronous oscillation component;
A data window width is set according to the original frequency, and utilizes the data window width and the setting sample frequency pair The sub-synchronous oscillation component carries out windowing process;
Discrete Fourier transform DFT is carried out to the sub-synchronous oscillation component after adding window, obtains the sub-synchronous oscillation component Frequency, amplitude and phase.
12. the online filtering method of subsynchronous oscillation of electrical power system composition as claimed in claim 11, which is characterized in that calculate The original frequency of the sub-synchronous oscillation component, comprising:
The original frequency of the sub-synchronous oscillation component is calculated using zero passage method.
13. the online filtering method of subsynchronous oscillation of electrical power system composition as claimed in claim 11, which is characterized in that also wrap It includes:
Judge whether the data window width is equal to according to the frequency of the sub-synchronous oscillation component and the setting sample frequency The signal period of the sub-synchronous oscillation component;
If it is not, the amplitude and phase to the sub-synchronous oscillation component are modified, to respectively reduce by the data window width Amplitude error caused by difference between the signal period and phase error.
14. such as the online filtering method of the described in any item subsynchronous oscillation of electrical power system compositions of claim 7 to 13, feature It is, the grid power signal is current signal.
15. the online filtering method of subsynchronous oscillation of electrical power system composition as claimed in claim 10, which is characterized in that according to First data window is filtered the grid power signal after sampling, comprising:
The grid power signal after sampling is filtered using a moving average filter according to first data window Wave.
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