CN103645422B - A kind of generating plant internal disturbance causes electrical network forced power oscillation on-line analysis - Google Patents

Abstract

The invention discloses a kind of generating plant internal disturbance and cause electrical network forced power oscillation on-line analysis, relate to operation and control of electric power system field, the oscillation of power being mainly used in judging online electrical network whether due to access generating plant the disturbance of intercycle property caused by.In the actual motion of electrical network, the forced power oscillation produced by generator disturbance is a kind of oscillation form the most common, but electrical network vibration is difficult to directly judge that vibration is caused by access power plant internal disturbance by the feature such as oscillation amplitude, frequency, or due to electrical network end disturbance caused by.For this reason, the invention provides a kind of based on the measurement data parameter identification of FFT Fast Fourier Transform (FFT) to generating plant access grid nodes, by phase differential analysis can be flowed, judge that electrical network vibrates whether caused by accessed generating plant internal disturbance.The present invention directly can judge in measuring terminals, and it is fast to calculate easy, analysis speed, has good actual application value.

Description

A kind of generating plant internal disturbance causes electrical network forced power oscillation on-line analysis

Technical field

The present invention relates to operation and control of electric power system field, more specifically parameter identification is carried out based on FFT Fast Fourier Transform (FFT), can flow phase differential by what analyze power plant's access grid nodes, whether the oscillation of power judging online electrical network is caused by the intercycle property disturbance accessing generating plant.

Background technology

Can be there is relatively waving and causing persistent oscillation when lacking damping between rotor in electric system, surge frequency range at 0.1 ~ 2.5Hz, therefore is called low-frequency oscillation under disturbance.Forced oscillation theory has good explanation to some actual generation oscillation of powers, more and more be subject to the approval of domestic and international experts and scholars, this theory is thought when the frequency that system is subject to extraneous durations power disturbance is close to system frequency, can cause significantly oscillation of power." basic theory of Forced Power Oscillation in Power System " that Tang Yong delivers at " electric power network technique " magazine 2006,30 (10): 29-33; " the low-frequency oscillation Analysis on Mechanism based on WAMS metric data " that Yang Dongjun etc. deliver at " Automation of Electric Systems " magazine 2009,33 (23): 24-28; And Yang Dongjun etc. is at " Automation of Electric Systems " magazine 2011, in the papers such as 35 (10): 99-103 " synchronous generator asynchronous parallelizing causes THE ANALYSIS OF FORCED POWER OSCILLATION IN POWER SYSTEM " of delivering, respectively by theoretical and electrical network actual case analysis, demonstrating for the most effective treatment measures of forced power oscillation is find rapidly and excise disturbing source.

WAMS forms by based on the synchronous phasor measurement unit (PMU) of GPS (GPS) and communication system thereof, can the active power of synchronous in wide area power system, high speed acquisition unit and operational outfit, reactive power, voltage, electric current, phase angle and important switching signal, be a kind of instrument that can monitor dynamic process of electrical power system and analyze.WAMS is the monitoring of the low-frequency oscillation of electrical network, oscillation event analysis and several aspect such as vibration prevention and suppression provide new technological means.In addition, the fault wave recording device with clock synchronous function also can survey the situation of change of various electric parameters before and after record fault automatically, accurately and rapidly.The application of the measurement mechanism of these advanced persons, effectively improves fault analysis and the judgement of electrical network.

Electrical network forced power oscillation can caused by the periodic disturbance of generator or load, and the electrical network forced power oscillation especially caused with generator in engineering reality is the most common.When there is low-frequency oscillation in electrical network, be difficult to directly judge that whether vibration is owing to accessing caused by power plant's intercycle property disturbance, therefore cannot take braking measure of vibrating in time, effectively by the feature such as oscillation amplitude, frequency.

Yang Dongjun etc. are at patent of invention " a kind of method for judging position of disturbance source for forced power oscillation in regional interconnected power grid " patent No.: ZL201110390520.4 and " Automation of Electric Systems " magazine 2012, in 36 (2): 26-30 " the forced power oscillation disturbance source locating method based on parameter identification " papers delivered, propose a kind of by carrying out to the oscillation data of grid branch the disturbance source locating method that parameter identification solves the forced power oscillation of the direction of energy flow factor, main know-why is as follows:

For one machine infinity bus system, generator adopts second order classical model, and microvariations situation lower linear equation of rotor motion is:

$\left\{\begin{array}{c}M\frac{d\mathrm{\Δ}\mathrm{\ω}}{dt}={\mathrm{\ΔP}}_M-{\mathrm{\ΔP}}_e-D\mathrm{\Δ}\mathrm{\ω}\\ \frac{d\mathrm{\Δ}\mathrm{\δ}}{dt}={\mathrm{\ω}}_0\mathrm{\Δ}\mathrm{\ω}\end{array}\right.---\left(1\right)$

In formula: M is inertia constant of a set, D is Generator Damping coefficient, △ P _mfor power of disturbance variable quantity, △ P _efor electric power variable quantity, △ δ is rotor angle skew, and △ ω is rotation speed change amount, ω ₀for reference frequency.

Carry out first integral to formula (1), flowing out node direction with active power is just, the energy function that can obtain system is:

V＝V _KE+V _PE＝V _M+V _D(2)

In formula:

Energetic function: $V_{KE}=\∫M\mathrm{\Δ}\stackrel{\·}{\mathrm{\ω}}{\mathrm{\Δ\ω\ω}}_{0}dt;$

Potential-energy function: V _pE=∫ △ P _e△ ω ω ₀dt;

Execute disturbance energy function outward: V _m=∫ △ P _m△ ω ω ₀dt;

Damping work energy function: V _d=∫-D △ ω △ ω ω ₀dt;

In the steady-state process of forced power oscillation, forcing frequency and system frequency approximately equal, execute disturbance acting now equal with system damping dissipation energy, V _m≈-V _d, kinetic energy and the potential energy of system are changed completely, V _kE≈-V _pE, system shows as undamped free oscillation.

The energy executing disturbance acting injected system is outward propagated in a network by potential energy, branch road L in system _i-ji hold potential-energy function be:

$V_{PEi}\left(t\right)={\∫}_0^r{\mathrm{\ΔP}}_{ij}{\mathrm{\ω}}_i{\mathrm{\ω}}_{0}dt---\left(3\right)$

In formula: △ P _ijfor branch power variable quantity, △ ω _ifor branch road i holds frequency variation.

In the steady-state process of forced power oscillation, each quantity of state all periodically changes with forcing frequency, if wherein △ P _mij, △ ω _mibe respectively branch power, frequency change amplitude, for branch power, frequency change initial phase, ω is forcing frequency; Substitute into (3) Shi Ke get:

In formula:

$a=\frac{1}{4\mathrm{\ω}}\·{\mathrm{\ΔP}}_{mij}\·{\mathrm{\Δ\ω}}_{mi}\·{\mathrm{\ω}}_0---\left(5\right)$

Execute disturbance injected system outward and the energy propagating consumption in a network embodies primarily of the aperiodic component of formula (4) and formula (6), be defined as by b " the direction of energy flow factor " in literary composition, the direction of energy flow factor can characterize size and the direction of aperiodic component in potential energy.It is just that definition potential energy flows out node i, and it is negative for flowing into node i, and as b>0, potential energy trend flows to node j by node i, and as b<0, potential energy trend flows to node i by node j.Thus, as branch road direction of energy flow factor b>0, disturbing source is positioned at the region at branch road start node place; As b<0, disturbing source is positioned at branch road terminal node region.

Patent " a kind of method for judging position of disturbance source for forced power oscillation in regional interconnected power grid " proposes further on the basis of the branch road direction of energy flow factor: by asking algebraic sum to each region interconnection direction of energy flow factor, obtain the direction of energy flow factor in each region, direction of energy flow factor algebra and maximum region are disturbing source region.This patent is by the comprehensive analysis to the grid branch direction of energy flow factor, the disturbing source position judgment problem of large-scale interconnected power system can be solved, comprise: the generator shown in accompanying drawing 1 to the point of electrical network to net oscillation problem, and accompanying drawing 2, there is the complicated interconnected network disturbance source locating problem that hunting power is roundabout shown in 3.

Adopt Prony analytical approach as the parameter identification method of the direction of energy flow factor in patent " a kind of method for judging position of disturbance source for forced power oscillation in regional interconnected power grid ", Prony analytical approach directly carries out signal analysis to the data waveform of record in time domain, actual measurement path is considered as the linear combination of the sinusoidal signal (mode of oscillation) that some frequency is fixed, amplitude exponentially changes, its model representation is:

Wherein: n is the number of mode of oscillation, for i-th mode of oscillation, A _0ifor oscillation amplitude; σ _ifor damping factor; ω _ifor hunting angle frequency, for initial phase.Thus identification problem is summarized as to each frequency, amplitude and ratio of damping.

From formula (6), the flow direction of Branch Potential Energy is by the positive and negative decision of the direction of energy flow factor, and the direction of energy flow factor positive and negative primarily of determine.At this, if namely when then have i.e. direction of energy flow factor b>0; When time, then i.e. direction of energy flow factor b<0, therefore, by right analysis also can judge the flow direction of Branch Potential Energy.The present invention defines for can phase differential be flowed.Due to the direction of Branch Potential Energy can only be characterized, the size of Branch Potential Energy can not be characterized, therefore, by can phase differential be flowed can judge that hunting power is without the disturbing source position (as shown in Figure 1) in roundabout situation; And still will have been come by direction of energy flow factor b (as shown in accompanying drawing 2 and accompanying drawing 3) for there is the roundabout complex electric network disturbing source position judgment problem of hunting power.The present invention is by causing the on-line analysis of electrical network forced power oscillation to the property disturbance of generating plant intercycle, employing can be flowed phase differential and be judged, solves the generator shown in accompanying drawing 1 to the point of electrical network to net oscillation problem.Obviously, problems is adopted to flow phase differential more easier than the direction of energy flow factor as criterion computing method.

The basis of FFT fast fourier transform algorithm is supposition input signal is periodic function, can be decomposed into the component sum of integral multiple frequency, comprising constant DC component.One-period is the form that the function factorization of T becomes a unlimited trigonometric series sum:

In formula: ω ₁=2 π/T are the angular frequency of periodic function first-harmonic, for the amplitude of each frequency content, for the initial phase angle of each frequency content, n is frequency component number.

The formula of each coefficient can be obtained by orthogonality of trigonometric function:

$c_0=\frac{1}{T}\underset{0}{\overset{T}{\&Integral;}}f\left(t\right)dt---\left(10\right)$

$a_n=\frac{2}{T}\underset{0}{\overset{T}{\&Integral;}}f\left(t\right){\mathrm{cosn\&omega;}}_{1}tdt---\left(11\right)$

$b_n=\frac{2}{T}\underset{0}{\overset{T}{\&Integral;}}f\left(t\right)\sin {\mathrm{n\&omega;}}_{1}tdt---\left(12\right)$

By formula (11), formula (12) discretize, can formula be obtained:

$a_n=\frac{2}{N}\underset{k=0}{\overset{N-1}{\&Sigma;}}{f}_{k}cos\frac{2\mathrm{\&pi;}}{N}nk---\left(13\right)$

$b_n=\frac{2}{N}\underset{k=0}{\overset{N-1}{\&Sigma;}}{f}_{k}sin\frac{2\mathrm{\&pi;}}{N}nk---\left(14\right)$

In formula: n=0,1 ..., (N/2)-1, N is sampling number in the unit cycle.

Periodic function also can be expressed as the array configuration of exponential function:

$f\left(t\right)=\underset{-\mathrm{\&infin;}}{\overset{+\mathrm{\&infin;}}{\&Sigma;}}{F}_n{e}^{{\mathrm{jn\&omega;}}_{1}t},(n=0,\&PlusMinus;1,\&PlusMinus;2,...)---\left(15\right)$

$F_n=\frac{1}{T}\underset{0}{\overset{T}{\&Integral;}}f{\left(t\right)}_n{e}^{-{\mathrm{jn\&omega;}}_{1}t}dt---\left(16\right)$

$F_{-n}=\frac{1}{T}\underset{0}{\overset{r}{\&Integral;}}f{\left(t\right)}_n{e}^{{\mathrm{jn\&omega;}}_{1}t}dt---\left(17\right)$

Compared with Prony analytical approach, fft algorithm can not analyze damping factor and the attenuation of vibration, and this is for the △ P asked in formula (6) _mijwith △ ω _miparameter has impact.But employing can flow phase differential namely the criterion Water demand flowed to as oscillation energy dominates the phase place of branch road active power and frequency under oscillation frequency with and not Water demand △ P _mijwith △ ω _miparameter, therefore can select FFT and Fast Fourier Transform (FFT) to replace Prony analytical approach on parameter identification method.Relative to Time Domain Analysis such as Prony algorithms, FFT directly analyzes from frequency domain, there is better antijamming capability and computing velocity faster, especially when larger for the interference of vibration transient phases free component, adopt fft algorithm to carry out parameter identification and there is better accuracy, and more early can start to judge, shorten the judgement time.

In electrical network forced oscillation process, may there is the divergent oscillation of long period at vibration initial period, namely transient phases is shaken, as shown in Figure 4, if disturbing source position judgment can be realized in vibration transient phases, to shortening the malfunction elimination time and preventing vibration diffusion significant.In the transient phases of vibration, free oscillation component △ δ ₁with forced oscillation component △ δ ₂exist simultaneously; But after the sufficiently long time, due to the existence of system damping, free oscillation will fade away, unique motion existed be exactly forced oscillation, and namely it with frequencies omega without decline ground sustained vibration, will enter the steady oscillation stage.

The load angle characteristic of vibration transient phases is:

△δ(t)＝△δ ₁(t)+△δ ₂(t)(18)

In formula: △ δ ₁t () is characterized by the free oscillation component of system, △ δ ₂t () characterizes forced oscillation component;

Wherein:

In formula: ξ is damping ratio, ω _nfor system natural mode shape, ω _dfor free oscillation frequency, A ₀for free oscillation component amplitude, for free oscillation initial phase, ω is forced power oscillation frequency, for the initial phase that forced power oscillation frequency is corresponding.

From formula (18) ~ (20), in the transient phases of forced oscillation, comprise the relevant information of forced oscillation, obtain related data by parameter identification in theory.Owing to existing in transient phases free oscillation and forced oscillation component simultaneously, the identification of free oscillation component to forced oscillation component has interference effect, adopt fft algorithm to have good antijamming capability, the accuracy of parameter identification can be improved to a certain extent.

Summary of the invention

The object of this invention is to provide a kind of generating plant internal disturbance and cause electrical network forced power oscillation on-line analysis.The method mainly for the mode of oscillation (namely put net mode of oscillation) of generating plant to electrical network, the oscillation of power judging online electrical network whether due to access generating plant the disturbance of intercycle property caused by.In the actual motion of electrical network, the forced power oscillation produced by generator periodic disturbance is a kind of oscillation form the most common, but electrical network vibration is difficult to directly judge that vibration is caused by access power plant internal disturbance by the feature such as oscillation amplitude, frequency, or due to electrical network end disturbance caused by.For this reason, the invention provides a kind of method that measurement data by generating plant access electric network terminal node judges vibration producing cause, the method can directly judge in measuring terminals, and data identification can be started in the transient phases of vibration, have and calculate the feature easy, discrimination is high, analysis speed is fast and good actual application value.

In order to achieve the above object, the present invention adopts following technical scheme: when electrical network generation forced power oscillation, based on FFT, the active power of record is surveyed to the power plant access synchronous phasor measurement unit PMU of grid nodes or fault wave recording device, frequecy characteristic carries out parameter identification, and try to achieve power plant access grid nodes can flow phase differential, by can flow oscillation of power that phase differential judges electrical network online whether due to accessed generating plant the disturbance of intercycle property caused by, implementation process is as shown in Figure 5.

A kind of generating plant internal disturbance causes electrical network forced power oscillation on-line analysis, and the method comprises the following step:

A, in AC network, generating plant is connected branch road and is equiped with synchronous phasor measurement unit PMU or fault wave recording device with electrical network;

B, low-frequency oscillation as the leading oscillation frequency ω occurred in on-line monitoring monitoring of equipment to electrical network, record generating plant to be connected branch road grid side active power △ P and frequency △ ω data with electrical network are surveyed, if it is positive dirction that active power flows to direction, generating plant from electrical network by synchronous phasor measurement unit PMU or fault wave recording device;

C, adopt FFT fast Fourier transform analysis method to survey record to △ P and △ ω carry out parameter identification, obtain n the frequency component ω of △ P _piand the initial phase of correspondence with m the frequency component ω of △ ω _{ω j}and the initial phase of correspondence wherein, i ∈ 1,2,3 ..., n}, j ∈ 1,2,3 ..., m}, ω _pi, ω _{ω j}∈ (0.1Hz, 2.5Hz);

D, ask each frequency component ω of △ P _pithe minimum frequency difference △ ω of oscillation frequency ω is dominated with electrical network _p=min{| ω-ω _pi|| i=1,2 ..., n}, asks each frequency component ω of △ ω _{ω j}the minimum frequency difference △ ω of oscillation frequency ω is dominated with electrical network _ω=min{| ω-ω _{ω j}|| j=1,2 ..., m}; If frequency error threshold value is ε, if △ is ω _p< ε and △ ω _ω< ε, then can think the meritorious △ P frequency component ω that minimum frequency difference is corresponding _pito dominate oscillation frequency ω identical with electrical network, and corresponding initial phase is frequency △ ω frequency component ω _{ω j}to dominate oscillation frequency ω identical with electrical network, and corresponding initial phase is if △ is ω _p> ε or △ ω _ω> ε, then again survey record active power △ P and frequency △ ω data, return step c;

If e can flow phase differential is: if can flow phase differential is:

F, when time, then show that oscillation energy flows to generating plant from electrical network, vibration is caused by electrical network end; When time, then show that oscillation energy flows to electrical network from generating plant, vibrate caused by the property disturbance of generating plant intercycle.

The present invention has the following advantages:

1, compared with existing method, the present invention is mainly for the mode of oscillation of generating plant to electrical network, namely the mode of oscillation to net is put, can directly directly be judged by the synchronous phasor measurement unit PMU of terminal or fault wave recording device measurement data, do not need the comprehensive analysis through each branch road of electrical network, node, method is simple, efficiency of the practice is high.

2, because determination methods does not need oscillation amplitude and damping parameter as basis for estimation, therefore parameter identification directly can utilize frequency domain data analysis.The present invention adopts fft algorithm as parameter identification method, relative to Time Domain Analysis such as Prony algorithms, there is better antijamming capability and computing velocity faster, especially larger for the interference of vibration transient phases free component, and mains frequency amplitude of variation is less, when disturbing more, adopt fft algorithm to carry out parameter identification and there is better accuracy, and more early can start to judge, shorten the judgement time.

3, the present invention adopts and can flow phase differential as basis for estimation, and adopt the direction of energy flow factor as basis for estimation relative to existing method, calculated amount is less, and computing velocity is faster, is more suitable for real-time online and calculates.

Accompanying drawing explanation

The mode of oscillation schematic diagram to netting is put between Fig. 1 generating plant and electrical network

Generating plant G1 is to the mode of oscillation schematic diagram of electrical network S, and oscillation energy m1 flows to electrical network S from generating plant G1.

Fig. 2 two is interregional exists the roundabout mode of oscillation schematic diagram of oscillation energy

Mode of oscillation schematic diagram between regional power grid S1 and regional power grid S2, oscillation energy m1 flows to S1 from S2, and oscillation energy m2 flows to S2 from S1, and oscillation energy is circuitous flow between S1 and S2.

The mode of oscillation schematic diagram that between Fig. 3 complicated multizone, oscillation energy is roundabout

S1, S2, S3 tri-mode of oscillation schematic diagram between regional power grid, oscillation energy m1 flows to S2 from S1, and oscillation energy m2 flows to S3 from S2, and oscillation energy m3 flows to S1 from S3.

The each stage schematic diagram of Fig. 4 forced power oscillation

Forced power oscillation measured waveform figure, is divided into: transient phases, steady-state process, decling phase three phases, wherein about more than the 40 second duration of transient phases.

A kind of generating plant of Fig. 5 internal disturbance causes electrical network forced power oscillation on-line analysis process flow diagram

Fig. 6 generating plant access electrical network schematic diagram

Generating plant G1 accesses electrical network S, and access node K1 is equiped with synchronous phasor measurement unit PMU or fault wave recording device.

Fig. 7 active power and hunting of frequency comparison of wave shape figure

Embodiment

Below in conjunction with case study on implementation and accompanying drawing, the present invention is further illustrated.

Embodiment one

A, in AC network, generating plant is connected branch road and is equiped with synchronous phasor measurement unit PMU or fault wave recording device with electrical network;

B, low-frequency oscillation as the leading oscillation frequency ω occurred in on-line monitoring monitoring of equipment to electrical network, record generating plant to be connected branch road grid side active power △ P and frequency △ ω data with electrical network are surveyed, if it is positive dirction that active power flows to direction, generating plant from electrical network by synchronous phasor measurement unit PMU or fault wave recording device;

C, adopt FFT fast Fourier transform analysis method to survey record to △ P and △ ω carry out parameter identification, obtain n the frequency component ω of △ P _piand the initial phase of correspondence with m the frequency component ω of △ ω _{ω j}and the initial phase of correspondence wherein, i ∈ 1,2,3 ..., n}, j ∈ 1,2,3 ..., m}, ω _pi, ω _{ω j}∈ (0.1Hz, 2.5Hz);

D, ask each frequency component ω of △ P _pithe minimum frequency difference △ ω of oscillation frequency ω is dominated with electrical network _p=min{| ω-ω _pi|| i=1,2 ..., n}, asks each frequency component ω of △ ω _{ω j}the minimum frequency difference △ ω of oscillation frequency ω is dominated with electrical network _ω=min{| ω-ω _{ω j}|| j=1,2 ..., m}; If frequency error threshold value is ε, if △ is ω _p< ε and △ ω _ω< ε, then can think the meritorious △ P frequency component ω that minimum frequency difference is corresponding _pito dominate oscillation frequency ω identical with electrical network, and corresponding initial phase is frequency △ ω frequency component ω _{ω j}to dominate oscillation frequency ω identical with electrical network, and corresponding initial phase is if △ is ω _p> ε or △ ω _ω> ε, then again survey record active power △ P and frequency △ ω data, return step c;

If e can flow phase differential is: if can flow phase differential is:

F, when time, then show that oscillation energy flows to generating plant from electrical network, vibration is caused by electrical network end; When time, then show that oscillation energy flows to electrical network from generating plant, vibrate caused by the property disturbance of generating plant intercycle.

Embodiment two

In the electric system shown in accompanying drawing 6, when electrical network S surveys record to low-frequency oscillation alarm, application the present invention accesses the survey record data analysis of electrical network point K1 to power plant G1, and whether judge to vibrate caused by the intercycle property disturbance of G1, implementation step is as follows:

A, in the electric system shown in Fig. 6, generating plant G1 access electrical network S node K1 place be equiped with synchronous phasor measurement unit PMU;

B, in electrical network S, monitor the low-frequency oscillation of leading oscillation frequency 1.367Hz, namely analyze gain merit hunting power △ P and the online recorder data of frequency △ ω of the grid side of generating plant G1 and electrical network S tie point K1, record waveform comparison diagram as shown in Figure 7;

C, adopt fft analysis method to survey record to meritorious hunting power and frequency data carry out parameter identification, obtain 5 frequency component ω of △ P _piwith 5 frequency component ω of △ ω _{ω j}, and the initial phase of correspondence with

Table 1 active power FFT parameter identification result

Table 2 frequency FFT parameter identification result

D, by ω _piand ω _{ω j}survey with electrical network S and record the leading oscillation frequency 1.367Hz arrived and contrast, obtain dominating with electrical network oscillation frequency closest to and meet the frequency component of frequency error threshold value, i.e. ω in present case _p3and ω _{ω 3}frequency component.

E, ω will be passed through _p3and ω _{ω 3}corresponding initial phase with try to achieve and can flow phase differential and be:

F, due to interval, shows that oscillation energy flows to electrical network S from generating plant G1, vibrates caused by the property disturbance of generating plant intercycle.

Embodiment three

In the electric system shown in accompanying drawing 6, when electrical network S surveys record to low-frequency oscillation alarm, application the present invention accesses the survey record data analysis of electrical network point K1 to power plant G1, and whether judge to vibrate caused by the intercycle property disturbance of G1, implementation step is as follows:

A, in the electric system shown in Fig. 6, generating plant G1 access electrical network S node K1 place be equiped with synchronous phasor measurement unit PMU;

B, in electrical network S, monitor the low-frequency oscillation of leading oscillation frequency 0.62Hz, namely analyze gain merit hunting power △ P and the online recorder data of frequency △ ω of the grid side of generating plant G1 and electrical network S tie point K1, power reference direction flows to generating plant for just with electrical network;

C, adopt fft analysis method to survey record to meritorious hunting power and frequency data carry out parameter identification, obtain 5 frequency component ω of △ P _piwith 5 frequency component ω of △ ω _{ω j}, and the initial phase of correspondence with

Table 1 active power FFT parameter identification result

Table 2 frequency FFT parameter identification result

D, by ω _piand ω _{ω j}survey with electrical network S and record the leading oscillation frequency 0.62Hz arrived and contrast, obtain dominating with electrical network oscillation frequency closest to and meet the frequency component of frequency error threshold value, i.e. ω in present case _p2and ω _{ω 3}identical with electrical network dominant frequency.

E, ω will be passed through _p2and ω _{ω 3}corresponding initial phase with try to achieve and can flow phase differential and be:

F, due to interval, shows that oscillation energy flows to generating plant G1 from electrical network S, vibrates caused by grid side disturbance.

Claims (2)

1. generating plant internal disturbance causes an electrical network forced power oscillation on-line analysis, and it is characterized in that, the method comprises the following step:

A, in AC network, generating plant is connected branch road and is equiped with synchronous phasor measurement unit PMU or fault wave recording device with electrical network;

B, low-frequency oscillation as the leading oscillation frequency ω occurred in on-line monitoring monitoring of equipment to electrical network, record generating plant to be connected branch road grid side active power Δ P and frequency Δ ω data with electrical network are surveyed, if it is positive dirction that active power flows to direction, generating plant from electrical network by synchronous phasor measurement unit PMU or fault wave recording device;

C, adopt FFT fast Fourier transform analysis method to survey record to Δ P and Δ ω carry out parameter identification, obtain n the frequency component ω of Δ P _piand the initial phase of correspondence with m the frequency component ω of Δ ω _{ω j}and the initial phase of correspondence wherein, i ∈ 1,2,3 ..., n}, j ∈ 1,2,3 ..., m}, ω _pi, ω _{ω j}∈ (0.1Hz, 2.5Hz);

D, ask each frequency component ω of Δ P _pithe minimum frequency difference Δ ω of oscillation frequency ω is dominated with electrical network _p=min{| ω-ω _pi|| i=1,2 ..., n}, asks each frequency component ω of Δ ω _{ω j}the minimum frequency difference △ ω of oscillation frequency ω is dominated with electrical network _ω=min{| ω-ω _{ω j}|| j=1,2 ..., m}; If frequency error threshold value is ε, if Δ ω _p< ε and Δ ω _ω< ε, then can think the meritorious Δ P frequency component ω that minimum frequency difference is corresponding _pito dominate oscillation frequency ω identical with electrical network, and corresponding initial phase is frequency Δ ω frequency component ω _{ω j}to dominate oscillation frequency ω identical with electrical network, and corresponding initial phase is if Δ ω _p> ε or Δ ω _ω> ε, then again survey record active power Δ P and frequency Δ ω data, return step c;

If e can flow phase differential is: if can flow phase differential is:

F, when time, then show that oscillation energy flows to generating plant from electrical network, vibration is caused by electrical network end; When time, then show that oscillation energy flows to electrical network from generating plant, vibrate caused by the property disturbance of generating plant intercycle.

2. a kind of generating plant internal disturbance causes electrical network forced power oscillation on-line analysis according to claim 1, it is characterized in that: frequency component number n ∈ in described step c 5,6 ..., 20}, m ∈ 5,6 ..., 20}; Frequency error threshold epsilon=0.03Hz in described steps d.