CN104600743A - System key variable extracting method considering wind power cluster power fluctuation - Google Patents

Abstract

The invention discloses a system key variable extracting method considering wind power cluster power fluctuation. The method is characterized in that the sensitivity analysis, PV analysis and dynamic evaluation are combined to determine the key variable for reflecting the main dynamic feature of the system under the wind power cluster power fluctuation, so as to create a system key variable set in a multi-dimensional space in order to express the main features of the system under the wind power fluctuation; when determining the key variable, the overall influence of the wind power cluster and the actual control characteristic of a wind power station are fully considered, and the bus voltage and branch power which are highly influenced by the wind power cluster power fluctuation and an asynchronous generator power angle of the system losing stability under the fault in the wind power cluster sending line are extracted as the system key variables for expressing the main features of the system under the wind power cluster power fluctuation.

Description

Consider the system core variable extracting method of wind-powered electricity generation cluster power fluctuation

Technical field

The present invention relates to wind-powered electricity generation cluster power fluctuation to effect on power system field, propose a kind of system core variable extracting method considering wind-powered electricity generation cluster power fluctuation.

Background technology

Day by day serious along with the energy and environmental problem, wind power generation is more and more subject to the attention of countries in the world.Because wind energy has randomness, intermittence, fluctuation, along with the increase of Wind turbines single-machine capacity and the continuous expansion of wind energy turbine set scale, wind-electricity integration is further remarkable on the impact of stability of power system.Be different from the Wind Power Development pattern of European countries' low capacity, distributing access, the distinguishing feature that concentrating type is grid-connected, high voltage long-distance sand transport has become China's Wind Power Development, concentrating type wind power integration will certainly bring more stern challenge to power grid operation.Under extracting wind-powered electricity generation cluster power fluctuation, system core runs variable, and for the impact of research concentrating type wind power fluctuation on electrical network, under assurance power fluctuation, the lead characteristic of system has important academic significance and using value.

At present, the influence research about wind-electricity integration relates to Wind turbines or single wind energy turbine set more, shorter mention wind-powered electricity generation cluster, and under wind power fluctuation, system core change method for determination of amount also rarely has report.Under existing wind power fluctuation in system core variable extracting method, have and utilize Sensitivity Analysis Method to determine the busbar voltage higher to the idle changing sensitivity of exerting oneself of wind energy turbine set; Also have and utilize PV analytic approach to determine to gain merit to exert oneself by wind energy turbine set to affect larger busbar voltage.But above-mentioned research, all for single wind energy turbine set, does not relate to the impact of wind-powered electricity generation cluster entirety, and the above-mentioned key variables determined are comparatively single, and under can not reflecting wind power fluctuation, system dominates dynamic characteristic comprehensively.Generally speaking, a kind of complete system core variable extracting method taking into account wind-powered electricity generation cluster power fluctuation is not formed at present.

The present invention proposes a kind of system core variable extracting method considering wind-powered electricity generation cluster power fluctuation, sensitivity analysis, PV analysis and dynamic simulation combine by the method, determine to reflect that system dominates the key variables of dynamic characteristic under wind-powered electricity generation cluster power fluctuation, and then the system core variables set in structure hyperspace characterizes the lead characteristic of system under wind power fluctuation, under can reflecting wind-powered electricity generation cluster power fluctuation comparatively all sidedly, system dominates variation tendency.

Summary of the invention

The object of the invention is to propose a kind of system core variable extracting method considering wind-powered electricity generation cluster power fluctuation, to make up the deficiency of existing research, under characterizing wind-powered electricity generation cluster power fluctuation comparatively all sidedly, system dominates dynamic characteristic.

Technical scheme of the present invention is achieved in that

Step one: adopt Sensitivity Analysis Method to determine by the larger busbar voltage of the idle variable effect of exerting oneself of wind-powered electricity generation cluster.

S1: the power flow equation setting up system

For the system containing n node (comprising m-1 PQ node, a n-m PV node and 1 balance node), node i power equation can be expressed as under polar coordinates

$\left.\begin{array}{c}{P}_i=V_i\underset{j=1}{\overset{n}{\mathrm{\Σ}}}{V}_j(G_{\mathrm{ij}}\cos {\mathrm{\θ}}_{\mathrm{ij}}+B_{\mathrm{ij}}\sin {\mathrm{\θ}}_{\mathrm{ij}})\\ Q_i=V_i\underset{j=1}{\overset{n}{\mathrm{\Σ}}}{V}_j(G_{\mathrm{ij}}\sin {\mathrm{\θ}}_{\mathrm{ij}}-B_{\mathrm{ij}}\cos {\mathrm{\θ}}_{\mathrm{ij}})\end{array}\right\}---\left(1\right)$

In formula, P _i, Q _ibe respectively meritorious, the reactive power that node i is injected; V _i, V _jfor the voltage magnitude of node i, j; θ _ijfor the phase angle difference between node i, j; G _ijfor the real part of admittance between node i and node j; B _ijfor the imaginary part of admittance between node i and node j.

Be expressed as after power equation linearisation

$\begin{array}{c}\left[\begin{array}{c}\mathrm{\ΔP}\\ \mathrm{\ΔQ}\end{array}\right]=\left[\begin{array}{cc}\frac{\∂P}{\∂\mathrm{\θ}}& \frac{\∂P}{\∂V}\\ \frac{\∂Q}{\∂\mathrm{\θ}}& \frac{\∂Q}{\∂V}\end{array}\right]\left[\begin{array}{c}\mathrm{\Δ\θ}\\ \mathrm{\ΔV}\end{array}\right]\\ \begin{array}{c}=\left[\begin{array}{cc}{J}_{\mathrm{P\θ}}& J_{\mathrm{PV}}\\ J_{\mathrm{Q\θ}}& J_{\mathrm{QV}}\end{array}\right]\left[\begin{array}{c}\mathrm{\Δ\θ}\\ \mathrm{\ΔV}\end{array}\right]\end{array}\end{array}---\left(2\right)$

Wherein, Δ P is that micro-that node injection is gained merit adds vector, has n-1 element; Δ Q is that node injects and idle micro-ly adds vector, has m-1 element; Δ θ is node voltage phase angle change column vector, has n-1 element; Δ V is node voltage amplitude change column vector, has m-1 element; $\left[\begin{array}{cc}{J}_{\mathrm{P\θ}}& J_{\mathrm{PV}}\\ J_{\mathrm{Q\θ}}& J_{\mathrm{QV}}\end{array}\right]$ For the system load flow equation Jacobian matrix under polar coordinates.

It has been generally acknowledged that, voltage and reactive power are close coupling relations, and are weak coupling relations with active power, then

$\mathrm{\ΔQ}=(J_{\mathrm{QV}}-J_{\mathrm{Q\θ}}{J}_{\mathrm{P\θ}}^{-1}{J}_{\mathrm{PV}})\mathrm{\ΔV}---\left(3\right)$

Namely

$\mathrm{\ΔV}={(J_{\mathrm{QV}}-J_{\mathrm{Q\θ}}{J}_{\mathrm{Q\θ}}^{-1}{J}_{\mathrm{PV}})}^{-1}\mathrm{\ΔQ}---\left(4\right)$

Definition for the voltage power-less sensitivity matrix of system, arbitrary element S wherein _ijfor system busbar i voltage is to the sensitivity of a jth idle change of PQ node.

S2: busbar voltage is to each wind power plant reactive power sensitivity

In Load flow calculation containing wind energy turbine set electric power system, usually according to the difference of blower fan type and control mode, different process is carried out to wind farm grid-connected point.Adopt the wind farm grid-connected point of constant power factor control mode to be generally treated to PQ node, only there is the wind energy turbine set of enough reactive power compensation planning, and when adopting constant voltage control mode, wind farm grid-connected point is just treated to PV node.The wind energy turbine set at present with idle like this control ability is little, and therefore, the wind energy turbine set of institute's Study system is all treated to PQ node.Suppose that institute's Study system comprises a wind-powered electricity generation cluster be made up of M wind energy turbine set, wind farm grid-connected some bus forms set A ₁, all buses of system form set A ₂, then .Any bus i voltage swing can be obtained to the sensitivity of wind energy turbine set j reactive power variable quantity by formula (4)

ΔV _ij＝S _ijΔQ _j，(i∈A ₂,j∈A ₁) (5)

S3: busbar voltage is to the sensitivity of wind-powered electricity generation cluster reactive power

For considering the impact of wind-powered electricity generation cluster overall power fluctuation on busbar voltage size, define here

$H_i={\mathrm{\Σ}}_{j=1}^M\mathrm{\Δ}{V}_{\mathrm{ij}},(i\∈A_2,j\∈A_1)---\left(6\right)$

H _ifor bus i voltage variety sum during each wind power plant reactive power fluctuation, { H _imaximum is designated as H _max, when time, bus i is defined as voltage and is subject to the bus that this wind-powered electricity generation cluster reactive power variable effect is larger.Wherein, k ₁for arithmetic number, its value is relevant with concrete Study system.K ₁value is large, then the busbar voltage affected by wind-powered electricity generation cluster reactive power fluctuation chosen is fewer.

Step 2: adopt PV analytical method to determine to gain merit the larger busbar voltage of variable effect and the branch power of exerting oneself by wind-powered electricity generation cluster.

If the voltage of system initial operating state Down Highway i is V _i0, the active power of branch road l is P _l0, wind-powered electricity generation cluster is exerted oneself as P ₀; The voltage of system critical limit running status Down Highway i is V _ic, the active power of branch road l is P _lc, wind-powered electricity generation cluster is exerted oneself as P _c.

Wind-powered electricity generation cluster is exerted oneself from initial operating state and is changed to critical limit running status, and bus i voltage change ratio is

K _i＝(V _ic-V _i0)/(P _c-P ₀) (7)

Branch road l active power rate of change is

R _l＝(P _lc-P _l0)/(P _c-P ₀) (8)

Then | K _i| can be similar to reflection wind-powered electricity generation cluster exert oneself change time, the intensity of variation of node i voltage, namely | K _i| larger, this busbar voltage is larger by wind-powered electricity generation cluster variable effect of exerting oneself.| K _i| maximum be designated as | K| _max, for bus i, when time, then busbar voltage V _ithe variable that variable effect of exerting oneself for gaining merit by this wind-powered electricity generation cluster is larger.Wherein k ₂be the arithmetic number that can set, its value is relevant with studied system.K ₂be worth larger, then the busbar voltage chosen is fewer.In like manner, wind-powered electricity generation cluster is exerted oneself change time, branch road active power rate of change is greater than k with the ratio of maximum branch road active power rate of change ₃branch power be defined as system core branch power.

Step 3: under adopting dynamic emulation method determination wind-powered electricity generation cluster to send line fault condition, system loses stable power angle of synchronous generator.

When in wind-powered electricity generation cluster, each wind energy turbine set is completely sent out, wind-powered electricity generation cluster sends circuit generation three phase short circuit fault, is defined as affecting larger crucial merit angle variable by wind-powered electricity generation cluster changed power by losing stable power angle of synchronous generator in system.

The system core variable extracting method of the consideration wind-powered electricity generation cluster power fluctuation that the present invention proposes, its feature and effect are, the present invention adopts sensitivity analysis, PV analyzes and the method that combines of dynamic simulation extracts the Vital Voltage variable of system under wind-powered electricity generation cluster power fluctuation, crucial branch power variable and crucial power angle of synchronous generator variable, thus sets up the system core variables set in hyperspace; Method proposed by the invention has taken into full account the resultant effect of wind-powered electricity generation cluster overall power fluctuation to system cloud gray model variable, characterizes the overall impact on system operating characteristics of wind-powered electricity generation cluster.The method adopting the present invention to propose effectively can be extracted and affect larger system core variable by wind-powered electricity generation cluster power fluctuation, when can reflect wind-powered electricity generation cluster power fluctuation comparatively all sidedly, system dominates dynamic characteristic, is conducive to determining system stability weak spot under wind-powered electricity generation cluster power fluctuation.

Accompanying drawing explanation

Fig. 1 is the system core variable extracting method basic step block diagram considering wind-powered electricity generation cluster power fluctuation in the present invention.

Fig. 2 is for using actual wind-powered electricity generation cluster schematic diagram of the present invention.

Fig. 3 is for using wind-powered electricity generation cluster of the present invention typical case day power fluctuation scene graph.

Fig. 4 is the Vital Voltage variable and the drift characteristic figure of non-key voltage quantities under wind-powered electricity generation cluster typical case day power fluctuation scene that use the present invention to extract.Wherein, covering the spring female 51 is non-key voltage quantities, and all the other are Vital Voltage variable.

Fig. 5 is the critical circuits active power variable and the drift characteristic figure of non-key circuit active power variable under wind-powered electricity generation cluster typical case day power fluctuation scene that use the present invention to extract.Wherein, covering 51 active power under Wuchuan 51-illiteracy is non-key circuit active power variable, and all the other are critical circuits active power variable.

Fig. 6 is the system core merit angle variable and the drift characteristic figure of non-key merit angle variable under wind-powered electricity generation cluster typical case day power fluctuation scene that use the present invention to extract.Wherein, covering Fengzhen G4 merit angle is non-key merit angle variable, and all the other are crucial merit angle variable.

Embodiment

Hereinafter, the preferred embodiments of the present invention are described in detail with reference to the accompanying drawings.

Fig. 1 is the system core variable extracting method basic step block diagram of the consideration wind-powered electricity generation cluster power fluctuation that the present invention proposes.Consider a system core variable extracting method for wind-powered electricity generation cluster power fluctuation, its feature mainly comprises the following steps:

Step one: adopt Sensitivity Analysis Method to determine by the larger busbar voltage of the idle variable effect of exerting oneself of wind-powered electricity generation cluster.

S1: the power flow equation setting up system

For the system containing n node (comprising m-1 PQ node, a n-m PV node and 1 balance node), node i power equation can be expressed as under polar coordinates

$\left.\begin{array}{c}{P}_i=V_i\underset{j=1}{\overset{n}{\mathrm{\Σ}}}{V}_j(G_{\mathrm{ij}}\cos {\mathrm{\θ}}_{\mathrm{ij}}+B_{\mathrm{ij}}\sin {\mathrm{\θ}}_{\mathrm{ij}})\\ Q_i=V_i\underset{j=1}{\overset{n}{\mathrm{\Σ}}}{V}_j(G_{\mathrm{ij}}\sin {\mathrm{\θ}}_{\mathrm{ij}}-B_{\mathrm{ij}}\cos {\mathrm{\θ}}_{\mathrm{ij}})\end{array}\right\}---\left(1\right)$

In formula, P _i, Q _ibe respectively meritorious, the reactive power that node i is injected; V _i, V _jfor the voltage magnitude of node i, j; θ _ijfor the phase angle difference between node i, j; G _ijfor the real part of admittance between node i and node j; B _ijfor the imaginary part of admittance between node i and node j.

Be expressed as after power equation linearisation

$\begin{array}{c}\left[\begin{array}{c}\mathrm{\ΔP}\\ \mathrm{\ΔQ}\end{array}\right]=\left[\begin{array}{cc}\frac{\∂P}{\∂\mathrm{\θ}}& \frac{\∂P}{\∂V}\\ \frac{\∂Q}{\∂\mathrm{\θ}}& \frac{\∂Q}{\∂V}\end{array}\right]\left[\begin{array}{c}\mathrm{\Δ\θ}\\ \mathrm{\ΔV}\end{array}\right]\\ \begin{array}{c}=\left[\begin{array}{cc}{J}_{\mathrm{P\θ}}& J_{\mathrm{PV}}\\ J_{\mathrm{Q\θ}}& J_{\mathrm{QV}}\end{array}\right]\left[\begin{array}{c}\mathrm{\Δ\θ}\\ \mathrm{\ΔV}\end{array}\right]\end{array}\end{array}---\left(2\right)$

Wherein, Δ P is that micro-that node injection is gained merit adds vector, has n-1 element; Δ Q is that node injects and idle micro-ly adds vector, has m-1 element; Δ θ is node voltage phase angle change column vector, has n-1 element; Δ V is node voltage amplitude change column vector, has m-1 element; $\left[\begin{array}{cc}{J}_{\mathrm{P\θ}}& J_{\mathrm{PV}}\\ J_{\mathrm{Q\θ}}& J_{\mathrm{QV}}\end{array}\right]$ For the system load flow equation Jacobian matrix under polar coordinates.

It has been generally acknowledged that, voltage and reactive power are close coupling relations, and are weak coupling relations with active power, then

$\mathrm{\ΔQ}=(J_{\mathrm{QV}}-J_{\mathrm{Q\θ}}{J}_{\mathrm{P\θ}}^{-1}{J}_{\mathrm{PV}})\mathrm{\ΔV}---\left(3\right)$

Namely

$\mathrm{\ΔV}={(J_{\mathrm{QV}}-J_{\mathrm{Q\θ}}{J}_{\mathrm{Q\θ}}^{-1}{J}_{\mathrm{PV}})}^{-1}\mathrm{\ΔQ}---\left(4\right)$

Definition for the voltage power-less sensitivity matrix of system, arbitrary element S wherein _ijfor system busbar i voltage is to the sensitivity of a jth idle change of PQ node.

S2: busbar voltage is to each wind power plant reactive power sensitivity

In Load flow calculation containing wind energy turbine set electric power system, usually according to the difference of blower fan type and control mode, different process is carried out to wind farm grid-connected point.Adopt the wind farm grid-connected point of constant power factor control mode to be generally treated to PQ node, only there is the wind energy turbine set of enough reactive power compensation planning, and when adopting constant voltage control mode, wind farm grid-connected point is just treated to PV node.The wind energy turbine set at present with idle like this control ability is little, and therefore, the wind energy turbine set of institute's Study system is all treated to PQ node.Suppose that institute's Study system comprises a wind-powered electricity generation cluster be made up of M wind energy turbine set, wind farm grid-connected some bus forms set A ₁, all buses of system form set A ₂, then .Any bus i voltage swing can be obtained to the sensitivity of wind energy turbine set j reactive power variable quantity by formula (4)

ΔV _ij＝S _ijΔQ _j，(i∈A ₂,j∈A ₁) (5)

S3: busbar voltage is to the sensitivity of wind-powered electricity generation cluster reactive power

For considering the impact of wind-powered electricity generation cluster overall power fluctuation on busbar voltage size, define here

$H_i={\mathrm{\Σ}}_{j=1}^M\mathrm{\Δ}{V}_{\mathrm{ij}},(i\∈A_2,j\∈A_1)---\left(6\right)$

H _ifor bus i voltage variety sum during each wind power plant reactive power fluctuation, { H _imaximum is designated as H _max, when time, bus i is defined as voltage and is subject to the bus that this wind-powered electricity generation cluster reactive power variable effect is larger.Wherein, k ₁for arithmetic number, its value is relevant with concrete Study system.K ₁value is large, then the busbar voltage affected by wind-powered electricity generation cluster reactive power fluctuation chosen is fewer.

Step 2: adopt PV analytical method to determine to gain merit the larger busbar voltage of variable effect and the branch power of exerting oneself by wind-powered electricity generation cluster.

If the voltage of system initial operating state Down Highway i is V _i0, the active power of branch road l is P _l0, wind-powered electricity generation cluster is exerted oneself as P ₀; The voltage of system critical limit running status Down Highway i is V _ic, the active power of branch road l is P _lc, wind-powered electricity generation cluster is exerted oneself as P _c.

Wind-powered electricity generation cluster is exerted oneself from initial operating state and is changed to critical limit running status, bus _ivoltage change ratio is

K _i＝(V _ic-V _i0)/(P _c-P ₀) (7)

Branch road l active power rate of change is

R _l＝(P _lc-P _l0)/(P _c-P ₀) (8)

Then | K _i| can be similar to reflection wind-powered electricity generation cluster exert oneself change time, the intensity of variation of node i voltage, namely | K _i| larger, this busbar voltage is larger by wind-powered electricity generation cluster variable effect of exerting oneself.| K _i| maximum be designated as | K| _max, for bus i, when time, then busbar voltage V _ithe variable that variable effect of exerting oneself for gaining merit by this wind-powered electricity generation cluster is larger.Wherein k ₂be the arithmetic number that can set, its value is relevant with studied system.K ₂be worth larger, then the busbar voltage chosen is fewer.In like manner, wind-powered electricity generation cluster is exerted oneself change time, branch road active power rate of change is greater than k with the ratio of maximum branch road active power rate of change ₃branch power be defined as system core branch power.

Step 3: under adopting dynamic emulation method determination wind-powered electricity generation cluster to send line fault condition, system loses stable power angle of synchronous generator.

When in wind-powered electricity generation cluster, each wind energy turbine set is completely sent out, wind-powered electricity generation cluster sends circuit generation three phase short circuit fault, is defined as affecting larger crucial merit angle variable by wind-powered electricity generation cluster changed power by losing stable power angle of synchronous generator in system.

Below by an actual wind-powered electricity generation cluster, system core variable extracting method under the wind-powered electricity generation cluster power fluctuation that the present invention proposes is described.

Analyze for the actual wind-powered electricity generation cluster in somewhere, this wind-powered electricity generation cluster comprises 8 wind energy turbine set, and total installation of generating capacity is 475.5MW.As shown in Figure 2, wind-powered electricity generation cluster typical case day power fluctuation scene as shown in Figure 3 for institute's Study system schematic diagram.

According to the concrete condition of institute's Study system, k ₁get 0.7, k ₂get 0.2, k ₃get 0.22.Adopt the system core variable extracting method of consideration wind-powered electricity generation cluster power fluctuation in this paper, to obtain under studied wind-powered electricity generation cluster power fluctuation system core busbar voltage and crucial branch power respectively as shown in Table 1 and Table 2.

System core busbar voltage under table 1 wind-powered electricity generation cluster power fluctuation

Bus title	Reference voltage (kV)	Bus title	Reference voltage (kV)
				Cover red well 21	230	Cover the Luanhe River 21	230
Cover white tone 21	230	Cover unit upper 21	230
				Meng Mingan 21	230	Cover Duolun 21	230
Cover emerging wide by 21	230	Cover ash and rise 51	525

System core branch power under table 2 Ming Antu wind-powered electricity generation cluster power fluctuation

Numbering	Bus title	Bus title
			1	Cover white tone K1	Cover sweat sea 51
2	Cover white tone 51	Cover sweat sea K1
			3	Cover sweat sea 51	Guyuan K1
4	Meng Mingan 21	Cover emerging wide by 21
			5	Cover sweat sea 51	Cover collection east 51
6	Cover white tone 21	Cover red well 21
			7	Cover white tone 21	Meng Mingan 21

Fig. 4 is the Vital Voltage variable and the drift characteristic figure of non-key voltage quantities under wind-powered electricity generation cluster typical case day power fluctuation scene that use the present invention to extract.Wherein, covering the spring female 51 is non-key voltage quantities, and all the other are Vital Voltage variable.

Fig. 5, Fig. 6 are respectively the critical circuits active power variable and non-key circuit active power variable and crucial merit angle variable and the drift characteristic figure of non-key merit angle variable under wind-powered electricity generation cluster typical case day power fluctuation scene that use the present invention to extract.Wherein, covering 51 active power under Wuchuan 51-illiteracy is non-key circuit active power variable, and all the other are critical circuits active power variable; Covering Fengzhen G4 merit angle is non-key merit angle variable, and all the other are crucial merit angle variable.

In sum, the system core variable extracting method of the consideration wind-powered electricity generation cluster power fluctuation using the present invention to propose, effectively can to extract under wind-powered electricity generation cluster power fluctuation and can dominate the Vital Voltage variable of dynamic characteristic, branch power variable and power angle of synchronous generator variable by characterization system, under wind-powered electricity generation cluster power fluctuation, can monitor that the variation tendency of these key variables holds the leading variation tendency of system by emphasis.

The foregoing is only preferred embodiment of the present invention, be not intended to limit protection scope of the present invention.All any amendments done within the spirit and principles in the present invention, equivalent replacement, improvement etc., be all included in protection scope of the present invention.

Claims (4)

1. consider a system core variable extracting method for wind-powered electricity generation cluster power fluctuation, it is characterized in that said method comprising the steps of:

Step one: adopt Sensitivity Analysis Method to determine by the larger busbar voltage of the idle variable effect of exerting oneself of wind-powered electricity generation cluster;

Step 2: adopt PV analytical method to determine to gain merit the larger busbar voltage of variable effect and the branch power of exerting oneself by wind-powered electricity generation cluster;

Step 3: under adopting dynamic emulation method determination wind-powered electricity generation cluster to send line fault condition, system loses stable power angle of synchronous generator.

2. the system core variable extracting method of consideration wind-powered electricity generation cluster power fluctuation according to claim 1, it is characterized in that, the concrete steps of described step one are:

S1: the power flow equation setting up system

For the system containing n node (comprising m-1 PQ node, a n-m PV node and 1 balance node), node i power equation can be expressed as under polar coordinates

$\left.\begin{array}{c}{P}_i=V_i\underset{j=1}{\overset{n}{\mathrm{\Σ}}}{V}_j(G_{\mathrm{ij}}\cos {\mathrm{\θ}}_{\mathrm{ij}}+B_{\mathrm{ij}}\sin {\mathrm{\θ}}_{\mathrm{ij}})\\ Q_i=V_i\underset{j=1}{\overset{n}{\mathrm{\Σ}}}{V}_j(G_{\mathrm{ij}}\sin {\mathrm{\θ}}_{\mathrm{ij}}-B_{\mathrm{ij}}\cos {\mathrm{\θ}}_{\mathrm{ij}})\end{array}\right\}---\left(1\right)$

In formula, P _i, Q _ibe respectively meritorious, the reactive power that node i is injected; V _i, V _jfor the voltage magnitude of node i, j; θ _ijfor the phase angle difference between node i, j; G _ijfor the real part of admittance between node i and node j; B _ijfor the imaginary part of admittance between node i and node j;

Be expressed as after power equation linearisation

$\begin{array}{c}\left[\begin{array}{c}\mathrm{\ΔP}\\ \mathrm{\ΔQ}\end{array}\right]=\left[\begin{array}{cc}\frac{\∂P}{\∂\mathrm{\θ}}& \frac{\∂P}{\∂V}\\ \frac{\∂Q}{\∂\mathrm{\θ}}& \frac{\∂Q}{\∂V}\end{array}\right]\left[\begin{array}{c}\mathrm{\Δ\θ}\\ \mathrm{\ΔV}\end{array}\right]\\ =\left[\begin{array}{cc}{J}_{\mathrm{P\θ}}& J_{\mathrm{PV}}\\ J_{\mathrm{Q\θ}}& J_{\mathrm{QV}}\end{array}\right]\left[\begin{array}{c}\mathrm{\Δ\θ}\\ \mathrm{\ΔV}\end{array}\right]\end{array}---\left(2\right)$

Wherein, Δ P is that micro-that node injection is gained merit adds vector, has n-1 element; Δ Q is that node injects and idle micro-ly adds vector, has m-1 element; Δ θ is node voltage phase angle change column vector, has n-1 element; Δ V is node voltage amplitude change column vector, has m-1 element; $\left[\begin{array}{cc}{J}_{\mathrm{P\θ}}& J_{\mathrm{PV}}\\ J_{\mathrm{Q\θ}}& J_{\mathrm{QV}}\end{array}\right]$ For the system load flow equation Jacobian matrix under polar coordinates;

It has been generally acknowledged that, voltage and reactive power are close coupling relations, and are weak coupling relations with active power, then

$\mathrm{\ΔQ}=(J_{\mathrm{QV}}-J_{\mathrm{Q\θ}}{J}_{\mathrm{P\θ}}^{-1}{J}_{\mathrm{PV}})\mathrm{\ΔV}---\left(3\right)$

Namely

$\mathrm{\ΔV}={(J_{\mathrm{QV}}-J_{\mathrm{Q\θ}}{J}_{\mathrm{P\θ}}^{-1}{J}_{\mathrm{PV}})}^{-1}\mathrm{\ΔQ}---\left(4\right)$

Definition for the voltage power-less sensitivity matrix of system, arbitrary element S wherein _ijfor system busbar i voltage is to the sensitivity of a jth idle change of PQ node;

S2: busbar voltage is to each wind power plant reactive power sensitivity

In Load flow calculation containing wind energy turbine set electric power system, usually according to the difference of blower fan type and control mode, different process is carried out to wind farm grid-connected point; Adopt the wind farm grid-connected point of constant power factor control mode to be generally treated to PQ node, only there is the wind energy turbine set of enough reactive power compensation planning, and when adopting constant voltage control mode, wind farm grid-connected point is just treated to PV node; The wind energy turbine set at present with idle like this control ability is little, and therefore, the wind energy turbine set of institute's Study system is all treated to PQ node; Suppose that institute's Study system comprises a wind-powered electricity generation cluster be made up of M wind energy turbine set, wind farm grid-connected some bus forms set A ₁, all buses of system form set A ₂, then any bus i voltage swing can be obtained to the sensitivity of wind energy turbine set j reactive power variable quantity by formula (4)

ΔV _ij＝S _ijΔQ _j，(i∈A ₂,j∈A ₁) (5)

S3: busbar voltage is to the sensitivity of wind-powered electricity generation cluster reactive power

For considering the impact of wind-powered electricity generation cluster overall power fluctuation on busbar voltage size, define here

$H_i={\mathrm{\Σ}}_{j=1}^M{\mathrm{\ΔV}}_{\mathrm{ij}},(i\∈A_2,j\∈A_1)---\left(6\right)$

H _ifor bus i voltage variety sum during each wind power plant reactive power fluctuation, { H _imaximum is designated as H _max, when time, bus i is defined as voltage and is subject to the bus that this wind-powered electricity generation cluster reactive power variable effect is larger; Wherein, k ₁for arithmetic number, its value is relevant with concrete Study system; k ₁value is large, then the busbar voltage affected by wind-powered electricity generation cluster reactive power fluctuation chosen is fewer.

3. the system core variable extracting method of consideration wind-powered electricity generation cluster power fluctuation according to claim 1, it is characterized in that, the concrete steps of described step 2 are:

If the voltage of system initial operating state Down Highway i is V _i0, the active power of branch road l is P _l0, wind-powered electricity generation cluster is exerted oneself as P ₀; The voltage of system critical limit running status Down Highway i is V _ic, the active power of branch road l is P _lc, wind-powered electricity generation cluster is exerted oneself as P _c;

Wind-powered electricity generation cluster is exerted oneself from initial operating state and is changed to critical limit running status, and bus i voltage change ratio is

K _i＝(V _ic-V _i0)/(P _c-P ₀) (7)

Branch road l active power rate of change is

R _l＝(P _lc-P _l0)/(P _c-P ₀) (8)

Then | K _i| can be similar to reflection wind-powered electricity generation cluster exert oneself change time, the intensity of variation of node i voltage, namely | K _i| larger, this busbar voltage is larger by wind-powered electricity generation cluster variable effect of exerting oneself; | K _i| maximum be designated as | K| _max, for bus i, when time, then busbar voltage V _ithe variable that variable effect of exerting oneself for gaining merit by this wind-powered electricity generation cluster is larger; Wherein k ₂be the arithmetic number that can set, its value is relevant with studied system; k ₂be worth larger, then the busbar voltage chosen is fewer; In like manner, wind-powered electricity generation cluster is exerted oneself change time, branch road active power rate of change is greater than k with the ratio of maximum branch road active power rate of change ₃branch power be defined as system core branch power.

4. the system core variable extracting method of consideration wind-powered electricity generation cluster power fluctuation according to claim 1, it is characterized in that, the concrete steps of described step 3 are:

When in wind-powered electricity generation cluster, each wind energy turbine set is completely sent out, wind-powered electricity generation cluster sends circuit generation three phase short circuit fault, is defined as affecting larger crucial merit angle variable by wind-powered electricity generation cluster changed power by losing stable power angle of synchronous generator in system.