CN103124075B - Reactive power configuration method for wind power base - Google Patents

Abstract

The invention provides a reactive power configuration method for a wind power base. Based on coordination of resources in a system such as adjustable spare capacity and an interruptible load, a reactive power configuration scheme for the wind power base is optimized by the aid of a genetic algorithm by considering various limitations of reactive power optimization of a wind power station and taking the minimum operation risk generated in a dynamic process after dropping of grid-connected point voltage of the wind power station as an optimal object. Compared with a minimum active power network loss configuration scheme frequently used by an existing wind power station, the reactive power configuration method has the advantages that the reactive power configuration capacity of the wind power base can be reduced, the active power spare capacity of the system is reduced, so that the operation cost of the system is reduced, various regulatory resources of the system can be sufficiently invoked, and steady state voltage level and transient voltage characteristics of a grid-connected point can be ensured.

Description

A kind of wind power base reactive configuration method

Technical field

The present invention relates to a kind of method for the idle configuration of wind power base, belong to the wind power generation control technology field in generation of electricity by new energy technology.

Background technology

The immense pressure caused to electric network reactive compensation configuration and safe and stable operation is accessed in order to tackle large-scale wind power, State Grid Corporation of China has formulated " wind energy turbine set access electric power network technique specify " and the technical requirement of the specification integrated wind plant operation such as " wind energy turbine set is idle configuration and voltage control technical stipulation ", and clearly propose, the most important requirement of idle configuration of wind energy turbine set is reactive capability and the capability of fast response of wind energy turbine set.

Along with the construction of the continuous increase, particularly large-scale wind power base of grid connected wind power installed capacity, run to power system safety and stability and bring series of challenges, line voltage control problem is particularly outstanding.In recent years, in northwest, North, Northeast China occur a lot of large-scale wind power unit off-grid accidents all have single failure in system or wind energy turbine set to cause, due to Wind turbines lack low voltage ride-through capability and reactive power compensation configuration and control unreasonable, secondary pulse is formed to system, the expansion of causing trouble scope.This exposes the deficiency of Reactive Compensation in Wind Farm configuration and the existence of line voltage control aspect to a certain extent, therefore, the reactive power compensation configuration of large-scale wind power base and voltage control problem become that wind-powered electricity generation is centralized gradually, one of the key technical problem paid close attention in great-leap-forward development process.

Current domestic wind power base reactive configuration method is not perfect, and cause system to install quick response dynamics reactive power compensator in a large number, economical operation type is poor.Wind power base realizes idle configuration by the algorithm that active power loss is minimum, namely considers the constraints of idle work optimization, carries out idle configuration so that the active power loss produced in wind power base running is minimum for optimization aim.But this algorithm does not consider that may cause large-scale wind power unit off-grid, thus cause system reserve to drop into further, even take cutting load measure, these increase the operating cost of system greatly when after system jam or the raw Voltage Drop of disturbed movable property.

In system, adjustable coordination for subsequent use, the resource such as interruptible load and reactive power compensator is consider that the wind power base reactive configuration method of operation risk provides condition.

Summary of the invention

Goal of the invention: technical problem to be solved by this invention is the idle allocation problem of wind power base, provides a kind of wind power base optimal reactive power allocation method method that can consider reactive power compensation investment and operating cost, reserve cost and cutting load cost.

The technical solution adopted for the present invention to solve the technical problems is as follows:

A kind of wind power base reactive configuration method, it comprises the steps:

(1) to judge according to the requirement of wind energy turbine set low voltage crossing technology and site Wind turbines whether off-grid, Wind turbines in wind energy turbine set grid-connected point voltage can ensure when dropping to 20% rated voltage that off-grid does not run 625ms, wind farm grid-connected point voltage is when after falling, 2s can return to 90% rated voltage, and Wind turbines can ensure that off-grid does not run; If drop to less than 90% rated voltage at the grid-connected point voltage of Wind turbines and do not take Measures of Reactive Compensation within the time that low voltage crossing allows, Wind turbines off-grid can be caused, then adopt the optimization method of following step (2) ~ step (5) to configure also site reactive compensation capacity and active reserve capacity and make the operation risk falling rear dynamic process minimum.For the diversity that simulation wind power base breaks down, what electrical network was occurred different Voltage Drop amplitude is divided into following nine kinds of scenes, and provide the probability of often kind of scene generation, to ask under different scene after Voltage Drop issuable maximum operation risk in dynamic process respectively, finally obtain the operation risk desired value after Voltage Drop.

2) in the hope of the sensitivity relation of wind energy turbine set access point i about self and wind power plant reactive power, and the best access point of reactive power compensator can be judged according to both level of sensitivity based on depression of order Jacobian matrix;

Choosing wind energy turbine set access regional area is research object, if comprise m wind energy turbine set in region, and accesses main electrical network by n access point, then only can be comprised 2 (m+n) exponent part node depression of order Jacobian matrix J of wind energy turbine set node and access point _sI, to J _sIinvert, can obtain

Can obtain i-th access point according to formula (1) about the sensitivity relation of local reactive power is

S ₁=△U _i/△Q _i=a _{2m+n+i,2m+n+i}(2)

Meanwhile, can obtain i-th access point about the sensitivity relation of a jth wind power plant reactive power is

S ₂=△U _i/△Q _j=a _2m+n+i,m+n+j(3)

If S ₁>S ₂, then reactive power compensation better effects if is carried out in wind energy turbine set access point side; Otherwise carry out reactive power compensation effect in wind energy turbine set exit more excellent.

According to the wind energy turbine set REACTIVE POWER/VOLTAGE sensitivity relation of trying to achieve, can obtain the voltage support capacity index of reactive power compensator to wind farm grid-connected point, N namely

$\mathrm{\Δ}{U}_j=S_{\mathrm{ji}}\×\underset{i=1}{\mathrm{\Σ}}{Q}_{\mathrm{iSVC}}---\left(4\right)$

Wherein, S _jifor and the voltage of site j to the sensitivity of node i reactive power compensation, Q _isvcfor and the reactive compensation capacity of site i;

The determination of dynamic passive compensation capacity should be relevant to the horizontal desired value of voltage control of each wind energy turbine set access point, therefore, for the scene that various actual motion may occur, and the cost of investment R of dynamic passive compensation _scan be expressed as

$R_S=\frac{\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{p}_i\×Q_{\mathrm{SVC}}\×k_{\mathrm{SVC}}}{N}---\left(5\right)$

$Q_{\mathrm{SVC}}=\underset{j=1}{\overset{N_W}{\mathrm{\Σ}}}\mathrm{\Δ}{U}_j/S_j---\left(6\right)$

Wherein, p _ifor the probability that a certain special scenes occurs; Q _svcfor the dynamic passive compensation capacity of wind energy turbine set access point configuration under special scenes; N is the scene number that possible occur; k _svcfor compensating the idle required cost of 1Mvar; S _jfor the voltage of access point j is about the idle sensitivity in this locality; △ U _jfor the voltage deviation of access point j; N _wfor the sum of wind energy turbine set in regional power grid;

(3) if the reactive-load compensation equipment of configuration can do nothing to help wind farm grid-connected point voltage return to rational scope, Wind turbines off-grid can be caused, need system reserve to balance the active power vacancy caused thus.For the generation of reply Wind turbines off-grid accident, system will increase a certain proportion of for subsequent use on original basis for subsequent use.System reserve can be divided into cold standby according to response speed, substitute for subsequent use, stand-by heat and spinning reserve, and wherein, the response speed of spinning reserve is the fastest.When system generation Voltage Drop causes Wind turbines off-grid, enable spinning reserve and effectively can alleviate impact on system.Generally, the spinning reserve capacity configured in system accounts for 5% ~ 10% of system total load, and operating cost is relatively high; Therefore, the operating cost R of system reserve _rcan be expressed as:

$R_R=\frac{\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{p}_i\×P_R\×k_R}{N}---\left(7\right)$

Wherein, P _rfor the active reserve capacity of regional power grid; k _rfor the cost of configuration 1MW spinning reserve capacity;

(4) under asking for scenario A according to electric network theory, false voltage propagates into and the Voltage Drop amplitude U of site j _jA.First, if system impedance matrix is Z, promise is done to system and to pause equivalence, obtain the Equivalent admittance battle array Y of system _eqand Injection Current

${\stackrel{\·}{I}}_{\mathrm{eq}}^{\left(0\right)}=Y_{\mathrm{eq}}\·{\stackrel{\·}{U}}_{\mathrm{eq}}^{\left(0\right)}---\left(8\right)$

${\stackrel{\·}{U}}_{\mathrm{eq}}^{\left(0\right)}=M_F^T\·{\stackrel{\·}{U}}^{\left(0\right)}---\left(9\right)$

Calculating non-working port voltage and current is,

${\stackrel{\·}{U}}_F={(I+Z_{\mathrm{eq}}\·Y_F)}^{-1}\·{\stackrel{\·}{U}}_{\mathrm{eq}}^{\left(0\right)}---\left(10\right)$

${\stackrel{\·}{I}}_F=Y_F\·{\stackrel{\·}{U}}_F---\left(11\right)$

Then false voltage propagates into and the Voltage Drop amplitude of site j is,

$U_{\mathrm{jA}}=Z\·M_F{\·\stackrel{\·}{I}}_F---\left(12\right)$

In formula (8) ~ formula (12), for node-port associations matrix, Y _ffor the admittance of malfunctioning node ground connection, I is unit matrix;

If dynamic passive compensation configuration and system reserve arrange unreasonable, then in order to ensure the balance of system active power, Wind turbines off-grid will likely cause cutting load measure, and cutting load amount is the difference of Wind turbines off-grid capacity and enable system reserve capacity.System takes cutting load measure to need to compensate by cutting load, will affect the economy of operation of power networks to a certain extent.Now, system cutting load realizes by means such as interruptible loads.Due to the cutting load cost of compensation R that Wind turbines off-grid causes _offcan be expressed as:

$R_{\mathrm{off}}=\left\{\begin{array}{cc}\frac{\underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}{p}_i\&times;(P_{\mathrm{off}}-P_R)\&times;k_L}{N}& P_R<P_{\mathrm{off}}\\ 0& P_R>P_{\mathrm{off}}\end{array}\right.---\left(13\right)$

$P_{\mathrm{off}}=\underset{j=1}{\overset{N_W}{\mathrm{\&Sigma;}}}{P}_{\mathrm{jW}}\&CenterDot;g\left(U_j\right)---\left(14\right)$

In formula, P _jWfor the wind-powered electricity generation capacity of also site j access; k _lfor the cost of compensation of system excision 1MW load; U _j0for under special scenes and the initial voltage value of site j; △ U _j1for the system failure under special scenes causes the Voltage Drop amplitude of wind farm grid-connected some j; △ U _j2for dynamic passive compensation under special scenes to and the voltage support amplitude of site j.

G (U _j) reflect and the running status of site j access wind energy turbine set, 1 represents off-grid, and 0 represents non-off-grid.G (U _j) by according to and the voltage U of site j _jtaking parameter on trendline shown in contrast Fig. 1.And the voltage U of site j _jcan by initial voltage U _j0, voltage support three part that provides of the Voltage Drop amplitude that causes of fault and dynamic passive compensation determines,

$U_j=U_{j0}-U_{\mathrm{jA}}+S_{\mathrm{ji}}\&times;\underset{i=1}{\overset{N_W}{\mathrm{\&Sigma;}}}{Q}_{\mathrm{iSVC}}---\left(15\right)$

(5) concept of introducing risk contributes to the consequence to large-scale wind power unit off-grid produces during electrical network generation Voltage Drop under the different reactive power compensation configuring condition of evaluation.This evaluation procedure contains the key element of two aspects altogether, i.e. the consequence of reactive power compensation configuration and Wind turbines off-grid, and the consequence of Wind turbines off-grid comprises startup reserve capacity and issuable cutting load.Therefore, the risk of large-scale wind power unit off-grid should form primarily of wind power base reactive power compensation cost of investment, reserve capacity cost and cutting load cost of compensation three part,

Risk=R _S+R _R+R _off(16)

Constraints is:

$\left\{\begin{array}{c}\mathrm{\&Delta;P}=P_{\mathrm{Gi}}-P_{\mathrm{Li}}+P_R-\\ U_i\underset{i=1}{\overset{N_1}{\mathrm{\&Sigma;}}}{U}_j(G_{\mathrm{ij}}\cos {\mathrm{\&delta;}}_{\mathrm{ij}}+B_{\mathrm{ij}}\sin {\mathrm{\&delta;}}_{\mathrm{ij}})=0\\ \mathrm{\&Delta;Q}=Q_{\mathrm{Gi}}-Q_{\mathrm{Li}}+Q_{\mathrm{iSVC}}-\\ U_i\underset{i=1}{\overset{N_1}{\mathrm{\&Sigma;}}}{U}_j(G_{\mathrm{ij}}\sin {\mathrm{\&delta;}}_{\mathrm{ij}}-B_{\mathrm{ij}}\cos {\mathrm{\&delta;}}_{\mathrm{ij}})=0\end{array}\right.---\left(17\right)$

$\left\{\begin{array}{ccccc}{Q}_{\mathrm{SVC}}^{\min }& \&le;& Q_{\mathrm{SVC}}& \&le;& Q_{\mathrm{SVC}}^{\max }\\ U_A^{\min }& \&le;& U_A& \&le;& U_A^{\max }\\ {P_R}^{\min }& \&le;& P_R& \&le;& {P_R}^{\max }\\ U_i^{\min }& \&le;& U_i& \&le;& U_i^{\max }\end{array}\right.---\left(18\right)$

Wherein, P _gi, Q _gibe respectively generating active power and the reactive power at node i place; P _li, Q _libe respectively load active power and the reactive power of node i; Q _iSVCfor the SVC compensation power of candidate compensation buses i; U _ifor the voltage of node i; G _ij, δ _ijbe respectively the conductance between node i, j and phase angle difference; N ₁for nodes; be respectively the bound of the compensation capacity of reactive power compensation point SVC; be respectively scene lower node Voltage Drop amplitude bound; be respectively wind power system active reserve capacity bound; be respectively node voltage bound.

Beneficial effect: the present invention proposes a kind of wind power base reactive configuration method considering operation risk, the method is based on the coordination of the resources such as subsequent use, interruptible load adjustable in system, consider the various restrictions of wind energy turbine set idle work optimization, the operation risk that dynamic process after falling with wind farm grid-connected point voltage produces is minimum for optimization aim, adopt genetic algorithm, make the idle allocation plan of wind power base optimum.Compared with the active power loss minimal configuration scheme that existing wind energy turbine set is conventional, adopt context of methods can reduce the idle configuration capacity of wind power base, minimizing system active reserve capacity, thus reduce system operation cost, both contributed to all kinds of regulation and control resource of abundant calling system, and be also of value to and ensure and site steady state voltage level and transient voltage characteristic.

Accompanying drawing explanation

Fig. 1 is wind energy turbine set low voltage crossing technical requirement curve.

Fig. 2 is the general flow chart of the inventive method.

Fig. 3 is power network wiring schematic diagram.

Fig. 4 is the flow chart of genetic algorithm.

Fig. 5 is that the also site of wind energy turbine set 1 adopts the inventive method, loss minimization optimized algorithm and fixed proportion algorithm voltage curve to contrast.

Fig. 6 is that the also site of wind energy turbine set 2 adopts the inventive method, loss minimization optimized algorithm and fixed proportion algorithm voltage curve to contrast.

Fig. 7 is that the also site of wind energy turbine set 3 adopts the inventive method, loss minimization optimized algorithm and fixed proportion algorithm voltage curve to contrast.

Embodiment:

With reference to the accompanying drawings and the present invention is described in further detail in conjunction with the embodiments.But the invention is not restricted to given example.

The present invention is mainly for the reactive power compensation allocation problem of wind power base.For single wind energy turbine set, multiple stage Wind turbines can equivalent become the wind energy turbine set of multiple different ruuning situation, thus the research contents of single wind energy turbine set and wind power base reactive power compensation configuration is similar, so also can adopt the method that the present invention proposes.

The present invention configures for the reactive power compensation of wind power base, and as shown in Figure 2, wherein LVRT is low voltage crossing LVRT (LowVoltageRideThrough) to domestic certain actual electric network wiring schematic diagram comprising wind-powered electricity generation.

Table 1 Voltage Drop probability distribution

For the diversity that simulation wind power base breaks down, to check the effect of optimization of method in this paper under different Voltage Drop scene, electrical network be there is different Voltage Drop amplitude and be divided into nine kinds of different scenes, and provide the probability of often kind of scene generation, as shown in table 1ly to ask under different scene after Voltage Drop issuable maximum operation risk in dynamic process respectively, finally obtain the operation risk desired value after Voltage Drop.

1, to judge according to the requirement of wind energy turbine set low voltage crossing technology and site Wind turbines whether off-grid, if drop to less than 90% rated voltage at the grid-connected point voltage of Wind turbines and do not take Measures of Reactive Compensation within the time that low voltage crossing allows, Wind turbines off-grid can be caused

Such as, the grid-connected point voltage of Wind turbines drops to 0.2, and allow be 625 milliseconds the most very much not off-grid running time according to technical requirement LVRT Capability of Wind Turbine Generator, the operate time of Quick reactive-load compensation device is greater than 0.625 millisecond.

If the Quick reactive-load compensation device action time is less than or equal to the most very much not off-grid running time and reactive capability that low voltage crossing allows when meeting service requirement, then Wind turbines not off-grid; If be greater than the most very much not off-grid running time or reactive capability that low voltage crossing allows the operate time of Quick reactive-load compensation device when can not meet the demands, Wind turbines possibility off-grid, then adopt optimization method configuration reactive compensation capacity and the active reserve capacity of following step 2 ~ step 5.

2, in the hope of the sensitivity relation of wind energy turbine set access point i about self and wind power plant reactive power, and the best access point of reactive power compensator can be judged according to both level of sensitivity based on depression of order Jacobian matrix;

Choosing wind energy turbine set access regional area is research object, if comprise m wind energy turbine set in region, and accesses main electrical network by n access point, then only can be comprised 2 (m+n) exponent part node depression of order Jacobian matrix J of wind energy turbine set node and access point _sI, to J _sIinvert, can obtain

Can obtain according to formula (1) sensitivity relation that i-th access point voltage changes about local reactive power is

S ₁=△U _i/△Q _i=a _{2m+n+i,2m+n+i}(2)

Meanwhile, can obtain the sensitivity relation that wind energy turbine set exit potential changes about access point reactive power is

S ₂=△U _i/△Q _j=a _2m+n+i,m+n+j(3)

In embodiment, read table 2 and the Voltage-Reactive Power sensitivity relation shown in table 3, judge the optimal placement of Reactive Compensation in Wind Farm device; Such as and site 1(PCC1) the sensitivity that changes about the reactive power of PCC1 of voltage be 0.01098, and the sensitivity that wind energy turbine set exit potential changes about the reactive power of PCC1 is 0.01096, then the optimal placement of the reactive power compensator of wind energy turbine set 1 is access point place; The reactive power changing sensitivity of voltage to PCC1 of such as PCC2 is 0.00601, illustrate the reactive power compensator of wind energy turbine set 1 to and site 2 has voltage support effect equally, just less relative to the action effect of the compensation arrangement of self.

Table 2 access point voltage is about each access point reactive power changing sensitivity

Table 3 wind energy turbine set exit potential is about each access point reactive power changing sensitivity

The probability of Voltage Drop under nine kinds of different scenes can be obtained by table 1, ask for the voltage deviation of each access point under often kind of scene respectively, the dynamic reactive configuration capacity of wind energy turbine set diverse access point configuration under special scenes can be asked for according to the voltage deviation of the Voltage-Reactive Power sensitivity relation asked and each access point:

$Q_{\mathrm{SVC}}=\underset{j=1}{\overset{3}{\mathrm{\&Sigma;}}}\mathrm{\&Delta;}{U}_j/S_j---\left(4\right)$

The cost of compensation that known 1MVar is idle is k _sVC=300 yuan/MVar, and then the cost of investment desired value that can calculate reactive-load compensation equipment is:

$R_S=\frac{\underset{i=1}{\overset{9}{\mathrm{\&Sigma;}}}{p}_i\&times;Q_{\mathrm{SVC}}\&times;k_{\mathrm{SVC}}}{9}---\left(5\right)$

If the reactive-load compensation equipment of 3 configurations can do nothing to help wind farm grid-connected point voltage and returns to rational scope, Wind turbines off-grid can be caused, need system reserve to balance the active power vacancy caused thus.The probability of Voltage Drop under known nine kinds of different scenes, if the active reserve capacity of regional power grid is P _r, the cost of configuration 1MW active reserve capacity is k _r=140 yuan/MW, the operating cost desired value that can calculate active reserve capacity is

$R_R=\frac{\underset{i=1}{\overset{9}{\mathrm{\&Sigma;}}}{p}_i\&times;P_R\&times;k_R}{9}---\left(6\right)$

4 and the voltage U of site j _jcan by initial voltage U _j0, voltage support three part that provides of the Voltage Drop amplitude that causes of fault and dynamic passive compensation determines,

$U_j=U_{j0}-U_{\mathrm{jA}}+S_{\mathrm{ji}}\&times;\underset{i=1}{\overset{N_W}{\mathrm{\&Sigma;}}}{Q}_{\mathrm{iSVC}}---\left(7\right)$

In formula, right side Section 1 U _j0for and the initial voltage value of site j; Right side Section 2 is the Voltage Drop amplitude that fault causes, U _jAfor false voltage under scenario A propagates into the Voltage Drop amplitude of node j; The voltage support that right side Section 3 provides for dynamic passive compensation, S _jifor and the voltage of site j to the sensitivity of node i reactive power compensation, Q _iSVCfor and the reactive compensation capacity of site i.

The off-grid capacity of Wind turbines is

$P_{\mathrm{off}}=\underset{j=1}{\overset{N_W}{\mathrm{\&Sigma;}}}{P}_{\mathrm{jW}}\&CenterDot;g\left(U_j\right)---\left(8\right)$

G (U _j) reflect and the running status of site j access wind energy turbine set, 1 represents off-grid, and 0 represents non-off-grid.G (U _j) by according to and the voltage U of site j _jtaking parameter on trendline shown in contrast Fig. 1.

Due to the cutting load cost of compensation desired value R that Wind turbines off-grid causes _offcan be expressed as:

$R_{\mathrm{off}}=\left\{\begin{array}{c}\frac{\underset{i=1}{\overset{9}{\mathrm{\&Sigma;}}}{p}_i\&times;(P_{\mathrm{off}}-P_R)\&times;k_L}{9},P_R<P_{\mathrm{off}}\\ 0,P_R>P_{\mathrm{off}}\end{array}\right.---\left(9\right)$

5, the risk of large-scale wind power unit off-grid should form primarily of wind power base reactive power compensation cost of investment, reserve capacity cost and cutting load cost of compensation three part, calculates active reserve capacity P according to formula (10) and constraints _rwith reactive compensation capacity Q _sVC:

Risk=R _S+R _R+R _off(10)

Constraints is:

$\left\{\begin{array}{c}\mathrm{\&Delta;P}=P_{\mathrm{Gi}}-P_{\mathrm{Li}}+P_R-\\ U_i\underset{i=1}{\overset{N_1}{\mathrm{\&Sigma;}}}{U}_j(G_{\mathrm{ij}}\cos {\mathrm{\&delta;}}_{\mathrm{ij}}+B_{\mathrm{ij}}\sin {\mathrm{\&delta;}}_{\mathrm{ij}})=0\\ \mathrm{\&Delta;Q}=Q_{\mathrm{Gi}}-Q_{\mathrm{Li}}+Q_{\mathrm{iSVC}}-\\ U_i\underset{i=1}{\overset{N_1}{\mathrm{\&Sigma;}}}{U}_j(G_{\mathrm{ij}}\sin {\mathrm{\&delta;}}_{\mathrm{ij}}-B_{\mathrm{ij}}\cos {\mathrm{\&delta;}}_{\mathrm{ij}})=0\end{array}\right.---\left(11\right)$

$\left\{\begin{array}{ccccc}{Q}_{\mathrm{SVC}}^{\min }& \&le;& Q_{\mathrm{SVC}}& \&le;& Q_{\mathrm{SVC}}^{\max }\\ U_A^{\min }& \&le;& U_A& \&le;& U_A^{\max }\\ P_R^{\min }& \&le;& P_R& \&le;& P_R^{\max }\\ U_i^{\min }& \&le;& U_i& \&le;& U_i^{\max }\end{array}\right.---\left(12\right)$

Wherein, P _gi, Q _gibe respectively generating active power and the reactive power at node i place; P _li, Q _libe respectively load active power and the reactive power of node i; Q _iSVCfor the SVC compensation power of candidate compensation buses i; U _ifor the voltage of node i; G _ij, δ _ijbe respectively the conductance between node i, j and phase angle difference; N ₁for nodes; be respectively the bound of the compensation capacity of reactive power compensation point SVC; be respectively scene lower node Voltage Drop amplitude bound; be respectively wind power system active reserve capacity bound; be respectively node voltage bound.

By above method, obtain the voltage curve of three wind farm grid-connected points, as Fig. 5 ~ 7.

From Fig. 5 ~ Fig. 7, adopt the idle allocation plan that fixed proportion collocation method obtains, under the condition that same fault occurs, also site transient voltage characteristic is the poorest, and the scheme that the idle allocation plan adopting context of methods to obtain and loss minimization optimization method obtain, and the transient voltage characteristic of site is substantially identical.

Can be found out by contrast above: the coordination based on resources such as subsequent use, interruptible loads adjustable in system of the present invention, consider the various restrictions of wind energy turbine set idle work optimization, all kinds of regulation and control resource of abundant calling system, in guarantee and while site steady state voltage level and transient voltage characteristic, the idle configuration capacity of wind power base can be reduced, minimizing system active reserve capacity, thus reduce system operation cost.

The above is only the preferred embodiment of the present invention; be noted that for those skilled in the art; under the premise without departing from the principles of the invention, can also make some improvements and modifications that it is expected to, these improvements and modifications also should be considered as protection scope of the present invention.

Claims (4)

1. a wind power base reactive configuration method, comprises the steps:

(1) according to the probability that system voltage under different scene falls, ask for based on electric network theory the Voltage Drop amplitude that false voltage under described different scene propagates into wind farm grid-connected point;

(2) based on the requirement curve of wind energy turbine set low voltage crossing technology, judge that system voltage falls and whether can cause grid connected wind power unit off-grid;

(3) the risk indicator model that system voltage falls is set up;

(4) according to cutting load cost of compensation, the cost of investment of reactive-load compensation equipment and the operating cost of system active reserve capacity that large-scale wind power unit off-grid during electrical network generation Voltage Drop causes, set up and take into account the wind power base optimal reactive power allocation model that system voltage falls risk, concrete steps are as follows:

minRisk＝min(R _S+R _R+R _off) (1)

In formula, R _s, R _r, R _offbe respectively the cost of compensation that the cost of investment of reactive-load compensation equipment, the cost of system active reserve capacity and Wind turbines off-grid cause cutting load to cause,

Wherein, the cost of investment R of dynamic passive compensation capacity _srelevant to the horizontal desired value of voltage control of each wind energy turbine set access point, the cost of investment R of described dynamic passive compensation _scan be expressed as

In formula, p _ifor probability, Q that a certain special scenes occurs _svcfor dynamic passive compensation capacity, the N of wind energy turbine set access point configuration under special scenes are scene number, the k that possible occur _svcfor compensating 1Mvar idle required cost, S _jfor the voltage of access point j is about the idle sensitivity in this locality, Δ U _jfor voltage deviation, the N of access point j _wfor the sum of wind energy turbine set in regional power grid;

Wherein, be the generation of reply Wind turbines off-grid accident, system will increase a certain proportion of for subsequent use on original basis for subsequent use;

When system generation Voltage Drop causes Wind turbines off-grid, enable spinning reserve and effectively can alleviate impact on system, generally, the spinning reserve capacity configured in system accounts for 5% ~ 10% of system total load, and operating cost is relatively high, the operating cost R of system reserve _rcan be expressed as:

In formula, P _rfor active reserve capacity, the k of regional power grid _rfor the cost of configuration 1MW spinning reserve capacity;

If dynamic passive compensation configuration and system reserve arrange unreasonable, then in order to ensure the balance of system active power, Wind turbines off-grid will likely cause cutting load measure, cutting load amount is the difference of Wind turbines off-grid capacity and enable system reserve capacity, the cutting load cost of compensation R that Wind turbines off-grid causes _offcan be expressed as:

In formula, P _offfor Wind turbines off-grid capacity; P _jWfor the wind-powered electricity generation capacity of also site j access; k _lfor the cost of compensation of system excision 1MW load; G (U _j) reflect and the running status of site j access wind energy turbine set, represent off-grid when it is 1,0 represents non-off-grid.And the voltage U of site j _jcan by initial voltage U _j0, the Voltage Drop amplitude Δ U that causes of fault _j1with the voltage support Δ U that dynamic passive compensation provides _j2three parts are determined, namely

U _j0for under special scenes and initial voltage value, the Δ U of site j _j1for the system failure under special scenes causes Voltage Drop amplitude, the Δ U of wind farm grid-connected some j _j2for dynamic passive compensation under special scenes to and voltage support amplitude, the S of site j _jifor and the voltage of site j to the sensitivity of node i reactive power compensation, Q _isvcfor and the reactive compensation capacity of site i;

Under different scene, false voltage propagates into the Voltage Drop amplitude, ao U of wind farm grid-connected point _j1computational process is as follows:

If system impedance matrix is Z, promise is done to system and to pause equivalence, obtain the Equivalent admittance battle array Y of system _eqand Injection Current

Calculating non-working port voltage and current is,

Then false voltage propagates into and the Voltage Drop amplitude, ao U of site j _j1for

In formula, for system initial voltage; for node-port associations matrix, with M _ftransposed matrix each other; Y _ffor the admittance of malfunctioning node ground connection; I is unit matrix;

Variable bound be divided into trend equality constraint and run variable bound:

Trend equality constraint is:

Operation variable bound is:

In formula, P _gi, Q _gibe respectively generating active power and the reactive power at node i place, P _li, Q _libe respectively load active power and the reactive power of node i, Q _iSVCfor the SVC compensation power of candidate compensation buses i, U _ifor the voltage of node i, G _ij, B _ij, δ _ijbe respectively the conductance between node i, j, susceptance and phase angle difference, N1 is nodes, be respectively the bound of the compensation capacity of reactive power compensation point SVC, be respectively scene lower node Voltage Drop amplitude bound, be respectively wind power system active reserve capacity bound, be respectively node voltage bound;

(5) adopt genetic algorithm to carry out idle work optimization calculating to the wind power base optimal reactive power allocation model that system voltage falls risk of taking into account that step (4) is set up, obtain optimal non-workcompensation capacity, active reserve capacity and system cutting load capacity.

2. whether a kind of wind power base reactive configuration method according to claim 1, is characterized in that the described requirement curve based on wind energy turbine set low voltage crossing technology of step (2), judge that system voltage falls and can cause grid connected wind power unit off-grid to be:

If the Quick reactive-load compensation device action time is less than or equal to the most very much not off-grid running time and reactive capability that low voltage crossing allows when meeting service requirement, then Wind turbines not off-grid; If be greater than the most very much not off-grid running time or reactive capability that low voltage crossing allows the operate time of Quick reactive-load compensation device when can not meet the demands, Wind turbines possibility off-grid, then adopt optimization method configuration reactive compensation capacity and the active reserve capacity of described step 2 ~ step 5.

3. a kind of wind power base reactive configuration method according to claim 1, wherein said Wind turbines grid-connected point voltage can ensure when dropping to 20% rated voltage that off-grid does not run 625ms, wind farm grid-connected point voltage is when after falling, 2s can return to 90% rated voltage, and Wind turbines can ensure that off-grid does not run; If drop to less than 90% rated voltage at the grid-connected point voltage of Wind turbines and do not take Measures of Reactive Compensation within the time that low voltage crossing allows, Wind turbines off-grid can be caused.

4. a kind of wind power base reactive configuration method according to claim 3, it is characterized in that risk indicator that the system voltage described in step (3) falls is that the consequence that in the possibility and wind energy turbine set that are occurred by system different faults, Wind turbines off-grid causes defines, its mathematical description is:

Risk(A)＝P _r,A×S _ev,A(15)

In formula, Risk represents the risk that Voltage Drop causes; P _r,Arepresent the probability that system voltage falls under different scene; S _{ev, A}for system voltage falls the consequence caused.