CN104795825A - Method for configuring capacity of asynchronous wind power plant reactive power compensation device under grid fault - Google Patents

Abstract

The invention discloses a method for configuring capacity of an asynchronous wind power plant reactive power compensation device under a grid fault. The method comprises the following steps: (A) calculating minimum PCC point voltage of the asynchronous wind power plant capable of meeting the grid code low-voltage ride through requirement when the fault is restored; (B) calculating the capacity of the reactive power compensation device corresponding to the minimum PCC point voltage; the capacity of the asynchronous wind power plant reactive power compensation device is configured to be not less than the minimum capacity S<C>. By adopting the method, the minimum value of the capacity of the reactive power compensation device for the asynchronous wind power plant PCC point capable of meeting the grid code middle-low-voltage ride through requirement can be calculated, the method is applicable to the existing synchronization wind power plant reactive power compensation device capacity plan, reference can be provided for the configuration of the reactive power compensation device for the real asynchronous wind power plant, the feasibility and economical performance of the real asynchronous wind power plant low-through modification scheme can be effectively improved, and the low-voltage ride-through capacity of a wind power plant and the transient voltage stability of the regional grid containing the asynchronous wind power plant can be improved.

Description

Asynchronous Reactive Compensation in Wind Farm place capacity collocation method under electric network fault

Technical field

The present invention relates to the reactive-load compensation equipment capacity configuration field of the asynchronous wind energy turbine set of Large Copacity, particularly for the asynchronous Reactive Compensation in Wind Farm installed capacity collocation method that low voltage crossing in Grid code requires.

Background technology

New wind farm grid-connected directive/guide " GB/T 19963-2011 wind energy turbine set access power system technology regulation " proposes the strict demand of " when wind farm grid-connected point voltage falls to 20% nominal voltage, the Wind turbines in wind energy turbine set should ensure that off-grid does not run 625ms continuously ".For the uncontrollability of the asynchronous Wind turbines of traditional constant speed, Chinese scholars proposes at asynchronous wind energy turbine set PCC point (wind energy turbine set points of common connection, point ofcommon coupling, is called for short PCC point) the low voltage crossing modification scheme of installing reactive-load compensation equipment completes fault traversing with auxiliary its.Low voltage crossing for the asynchronous wind energy turbine set of constant speed type is transformed, reactive-load compensation equipment capacity be configured in the feasibility and economy that determine transformation to a certain extent.At present, the reactive-load compensation equipment capacity collocation method for asynchronous wind energy turbine set has following open source literature:

(1) Zhu Xueling, Zhang Yang, Gao Kun, etc. the research [J] of Reactive Compensation in Wind Farm problem. protecting electrical power system and control, 2009,37 (16): 68-72.

(2) Liu Peijin, Gu Lichen. containing the power system reactive power plan optimization [J] of wind energy turbine set. electric power network technique, 2010,34 (7): 175-180.

(3)Philippe Maibach,Carsten Ritter,Mohamed Saleh,et al.STATCOM size optimizationthrough wind turbine operation with fixed power factor[C].Proceedings of the 2011-14thEuropean Conference on Power Electronics andApplications,2011:1-11.

Theoretic discussion has been done in the reactive compensation capacity configuration of document (1) to wind energy turbine set, and proposing wind energy turbine set should determine its reactive-load compensation equipment capacity according to reactive power required during its steady operation.Document (2) proposes to save the method that energy loss expense is the reactive-load compensation equipment allocation optimum capacity of target to the maximum.Document (3) then proposes by keeping asynchronous wind energy turbine set PCC point power factor to be definite value but not unity power factor operational mode can reduce the configuration capacity of STATCOM reactive-load compensation equipment, and Q-U curve of giving chapter and verse determines the method for STATCOM configuration capacity.Although the determination of reactive-load compensation equipment capacity configuration provides foundation during more than research can be asynchronous wind energy turbine set steady operation, all do not relate to the allocation problem of the reactive-load compensation equipment capacity of asynchronous wind energy turbine set transient state run duration.

Summary of the invention

For existing collocation method above shortcomings, the object of the invention is to the capacity collocation method proposing asynchronous Reactive Compensation in Wind Farm equipment under a kind of electric network fault based on asynchronous wind energy turbine set parameter, this collocation method can calculate the reactive-load compensation equipment capacity minimum value that asynchronous wind energy turbine set meets the required configuration of " when wind farm grid-connected point voltage falls to 20% nominal voltage, the Wind turbines in wind energy turbine set should ensure that off-grid does not run 625ms continuously " requirement in " GB/T 19963-2011 wind energy turbine set access power system technology regulation ".

Technical scheme of the present invention is achieved in that

Asynchronous Reactive Compensation in Wind Farm place capacity collocation method under electric network fault, step is as follows,

A) the minimum PCC point voltage that fault recovery initial stage asynchronous wind energy turbine set can meet the requirement of Grid code low voltage crossing is calculated;

A1) the breakdown slip s of asynchronous wind energy turbine set is required to calculate according to the wind energy turbine set low voltage crossing of " GB/T 19963-2011 wind energy turbine set access power system technology specifies " _cr;

A2) by A1) gained breakdown slip s _crcalculate the minimum PCC point voltage U that fault recovery initial stage asynchronous wind energy turbine set can meet the requirement of Grid code low voltage crossing _pCCmin, be shown below:

$U_{\mathrm{PCC}\min }=\sqrt{\frac{T_m{\mathrm{\&Omega;}}_s\{{[R_L+c_2(R_1+c_1{R}_2^{\&prime;}/s_{\mathrm{cr}})]}^2+{[X_L+X_T+c_2(X_{1\mathrm{\&sigma;}}+c_1{X}_{2\mathrm{\&sigma;}}^{\&prime;})]}^2\}}{m_1\&CenterDot;R_2^{\&prime;}/s_{\mathrm{cr}}}}$

In formula: m ₁for the stator winding number of phases; Ω _sfor synchronous angular velocity; T _mfor machine torque; R ₁, X _{1 σ}be respectively stator resistance and stator leakage reactance; R ₂', X _{2 σ}' be respectively the rotor resistance after conversion and rotor leakage reactance; R _l, X _lbe respectively wind energy turbine set and also site top-stitching road resistance and reactance; X _tfor wind farm side step-up transformer short-circuit reactance; c ₁=1+X _{1 σ}/ X _m, be correction factor; c ₂=1+ (X _l+ X _t)/X _c//m; X _c//m=X _cx _m/ (X _c+ X _m), be X _cwith X _mvalue in parallel; X _m, X _cbe respectively the capacitive reactance of excitatory reactance and machine end shunt reactor;

B) capacity of reactive power compensation device corresponding to minimum PCC point voltage is calculated;

B1) by A1) gained breakdown slip s _crand A2) gained minimum PCC point voltage U _pCCmincalculate the active-power P that fault recovery initial stage asynchronous wind energy turbine set sends to electrical network _fSIGwith the reactive power Q absorbed _fSIG;

B2) by A2) gained U _pCCmin, B1) gained P _fSIGand Q _fSIGcalculate fault recovery initial stage asynchronous wind energy turbine set trend, obtain sending reactive power Q needed for PCC point reactive-load compensation equipment that fault recovery initial stage asynchronous wind energy turbine set can meet the requirement of Grid code low voltage crossing _c:

$Q_C=Q_{\mathrm{FSIG}}-\frac{U_{\mathrm{PCC}\min }(U_g-U_{\mathrm{PCC}\min })+P_{\mathrm{FSIG}}{R}_L}{X_L+X_T}$

B3) by B2) gained Q _cwith A2) gained U _pCCminbe divided by and namely obtain reactive-load compensation equipment lowest capacity S _c: asynchronous Reactive Compensation in Wind Farm place capacity configuration is not less than this lowest capacity S _c;

$S_C=\frac{Q_C}{U_{\mathrm{PCC}\min }}$

Compared to existing technology, the present invention has following beneficial effect:

This collocation method can calculate the reactive-load compensation equipment capacity minimum value of the required installing of asynchronous wind energy turbine set PCC point when can meet low voltage crossing requirement in Grid code, be applicable to existing grid-connected asynchronous Reactive Compensation in Wind Farm place capacity planning, can be actual asynchronous wind energy turbine set to carry out reactive-load compensation equipment capacity configuration reference is provided, low feasibility and the economy of wearing modification scheme of the actual asynchronous wind energy turbine set of effective raising, is conducive to the Enhancement of Transient Voltage Stability improving the low voltage ride-through capability of wind energy turbine set and the regional power grid containing asynchronous wind energy turbine set.

Accompanying drawing explanation

Fig. 1 is asynchronous Reactive Compensation in Wind Farm place capacity collocation method flow chart under electric network fault of the present invention.

Fig. 2 is the asynchronous wind energy turbine set topology diagram of the Large Copacity (C in figure of parallel reactive compensation equipment ₁for machine end shunt capacitor, T ₁for machine end step-up transformer, Z ₁for circuit between wind energy turbine set and PCC point, T is wind energy turbine set outlet step-up transformer, Z _lfor circuit between wind energy turbine set PCC point and infinitely great electrical network, Grid is infinitely great electrical network).

Fig. 3 is Large Copacity asynchronous wind energy turbine set trend topological diagram (Q in figure _cby reactive-load compensation equipment is sent out reactive power).

Asynchronous wind energy turbine set simulation result figure under electric network fault condition when Fig. 4 is critical compensation.

Embodiment

Below in conjunction with calculated examples and accompanying drawing, specific embodiment of the invention scheme is described in detail.

Calculation process shown in composition graphs 1, under electric network fault, the concrete implementation step of the capacity collocation method of asynchronous Reactive Compensation in Wind Farm equipment is as follows:

(A) gather wind energy turbine set and connect operation of power networks parameter:

In this example, the asynchronous Wind turbines of constant speed that wind energy turbine set is 1MW by 30 separate unit rated power composes in parallel, and system topology as shown in Figure 2.Asynchronous machine machine end exit potential is 0.69kV, wind energy turbine set internal electric network is linked through 0.69/35kV transformer, after 2km transmission line access 35/110kV booster stations, local 110kV electrical network is accessed by 100km transmission line, reactive-load compensation equipment is connected on 35/110kV booster stations low-pressure side bus, i.e. wind energy turbine set points of common connection.Wherein line parameter circuit value Z ₁=0.17+j0.38 Ω/km, Z _l=0.1153+0.3299 Ω/km, transformer and non-synchronous motor parameter as shown in table 1.

Table 1 transformer and asynchronous wind energy turbine set parameter

(B) the minimum PCC point voltage that fault recovery initial stage asynchronous wind energy turbine set can meet the requirement of Grid code low voltage crossing is calculated:

B1) by the asynchronous machine equation of motion and relational expression between revolutional slip and rotor mechanical angular speed:

$J\frac{\mathrm{d\&omega;}}{\mathrm{dt}}=T_m-T_e---\left(1\right)$

$s=\frac{{\mathrm{\&omega;}}_s-\mathrm{\&omega;}}{{\mathrm{\&omega;}}_s}---\left(2\right)$

Obtain asynchronous machine critical clearing time expression formula:

$T_{\mathrm{CCT}}=-J{\mathrm{\&omega;}}_s{\&Integral;}_{s_N}^{s_{\mathrm{cr}}}\frac{1}{T_m-T_e}\mathrm{ds}---\left(3\right)$

Wherein J is moment of inertia; s _nrated motor runs slip; T _mfor machine torque; Te is electromagnetic torque; By asynchronous machine operational factor J, s _n, T _m, asynchronous wind energy turbine set critical clearing time 625ms of requiring in the asynchronous wind energy turbine set Te-s characteristic equation of grid-connected point voltage when dropping to 20% and " GB/T19963-2011 wind energy turbine set access power system technology regulation " brings formula (3) into, is met the asynchronous wind energy turbine set breakdown slip s of Grid code low voltage crossing requirement _cr.

B2) by B1) gained breakdown slip s _crcalculate the minimum PCC point voltage U that fault recovery initial stage asynchronous wind energy turbine set can meet the requirement of Grid code low voltage crossing _pCCmin, be shown below:

$U_{\mathrm{PCC}\min }=\sqrt{\frac{T_m{\mathrm{\&Omega;}}_s\{{[R_L+c_2(R_1+c_1{R}_2^{\&prime;}/s_{\mathrm{cr}})]}^2+{[X_L+X_T+c_2(X_{1\mathrm{\&sigma;}}+c_1{X}_{2\mathrm{\&sigma;}}^{\&prime;})]}^2\}}{m_1\&CenterDot;R_2^{\&prime;}/s_{\mathrm{cr}}}}---\left(4\right)$

In formula: m ₁for the stator winding number of phases; Ω _sfor synchronous angular velocity; T _mfor machine torque; R ₁, X _{1 σ}be respectively stator resistance and stator leakage reactance; R ₂', X _{2 σ}' be respectively the rotor resistance after conversion and rotor leakage reactance; R _l, X _lbe respectively wind energy turbine set and also site top-stitching road resistance and reactance; X _tfor wind farm side step-up transformer short-circuit reactance; c ₁=1+X _{1 σ}/ X _m, be correction factor; c ₂=1+ (X _l+ X _t)/X _c//m; X _c//m=X _cx _m/ (X _c+ X _m), be X _cwith X _mvalue in parallel; X _m, X _cbe respectively the capacitive reactance of excitatory reactance and machine end shunt reactor;

(C) capacity of reactive power compensation device corresponding to minimum PCC point voltage is calculated:

C1) by B1) gained breakdown slip s _crand B2) gained minimum PCC point voltage U _pCCmincalculate the active-power P that fault recovery initial stage asynchronous wind energy turbine set sends to electrical network _fSIGwith the reactive power Q absorbed _fSIG.

$\left\{\begin{array}{c}{P}_{\mathrm{FSIG}}={U_{\mathrm{PCC}\min }}^2\frac{R_{\mathrm{PCC}}}{R_{\mathrm{PCC}}^2+X_{\mathrm{PCC}}^2}\\ Q_{\mathrm{FSIG}}={U_{\mathrm{PCC}\min }}^2\frac{X_{\mathrm{PCC}}}{R_{\mathrm{PCC}}^2+X_{\mathrm{PCC}}^2}\end{array}\right.---\left(5\right)$

R in formula _pCCand X _pCCbe respectively substitutional resistance and the inductance of asynchronous wind farm grid-connected point.

C2) by B2), C1) gained U _pCCmin, P _fSIGand Q _fSIGcalculate fault recovery initial stage asynchronous wind energy turbine set trend, wind energy turbine set trend topology as shown in Figure 3, obtains sending reactive power Q needed for PCC point reactive-load compensation equipment that fault recovery initial stage asynchronous wind energy turbine set can meet the requirement of Grid code low voltage crossing _c:

$Q_C=Q_{\mathrm{FSIG}}-\frac{U_{\mathrm{PCC}\min }(U_g-U_{\mathrm{PCC}\min })+P_{\mathrm{FSIG}}{R}_L}{X_L+X_T}---\left(6\right)$

C3) by C2) gained reactive power Q _cwith B2) gained minimum PCC point voltage U _pCCminbe divided by and namely obtain reactive-load compensation equipment lowest capacity S _c: asynchronous Reactive Compensation in Wind Farm place capacity configuration is not less than this lowest capacity S _c.

$S_C=\frac{Q_C}{U_{\mathrm{PCC}\min }}---\left(7\right)$

Result of calculation shows, and when in this example, asynchronous wind energy turbine set can complete electric network fault, reactive power compensator need provide reactive power 9.08Mvar, and its capacity is 10.42MVA.Fig. 4 is the simulation result adopting emulation repeatedly to arrange reactive power compensation installing capacity asynchronous wind power system fault traversing when being critical compensation capacity.Simulation result shows asynchronous wind energy turbine set when can complete electric network fault, and reactive power compensator need provide reactive power 7.63Mvar, and its capacity is 9.61MVA.Contrasted from calculating and simulation result, the capacity collocation method of asynchronous Reactive Compensation in Wind Farm equipment under adopting electric network fault proposed by the invention, can be actual asynchronous wind energy turbine set to carry out reactive-load compensation equipment capacity configuration reference is provided, low feasibility and the economy of wearing modification scheme of the actual asynchronous wind energy turbine set of effective raising, is conducive to the Enhancement of Transient Voltage Stability improving the low voltage ride-through capability of wind energy turbine set and the regional power grid containing asynchronous wind energy turbine set.

Finally it should be noted that, above embodiment is only in order to illustrate technical scheme of the present invention and unrestricted, although applicant's reference preferred embodiment is to invention has been detailed description, those of ordinary skill in the art is to be understood that, technical scheme of the present invention is modified or equivalent replacement, and do not depart from aim and the scope of the technical program, all should be encompassed in the middle of right of the present invention.

Claims (1)

1. asynchronous Reactive Compensation in Wind Farm place capacity collocation method under electric network fault, is characterized in that: step is as follows,

A) the minimum PCC point voltage that fault recovery initial stage asynchronous wind energy turbine set can meet the requirement of Grid code low voltage crossing is calculated;

A1) require according to wind energy turbine set low voltage crossing the breakdown slip s calculating asynchronous wind energy turbine set _cr;

A2) by A1) gained breakdown slip s _crcalculate the minimum PCC point voltage U that fault recovery initial stage asynchronous wind energy turbine set can meet the requirement of Grid code low voltage crossing _pCCmin, be shown below:

$U_{\mathrm{PCC}\min }=\sqrt{\frac{T_m{\mathrm{\&Omega;}}_s\{{[R_L+c_2(R_1+c_1{R}_2^{\&prime;}/s_{\mathrm{cr}})]}^2+{[X_L+X_T+c_2(X_{1\mathrm{\&sigma;}}+c_1{X}_{2\mathrm{\&sigma;}}^{\&prime;})]}^2\}}{m_1\&CenterDot;R_2^{\&prime;}/s_{\mathrm{cr}}}}$

In formula: m ₁for the stator winding number of phases; Ω _sfor synchronous angular velocity; T _mfor machine torque; R ₁, X _{1 σ}be respectively stator resistance and stator leakage reactance; R ₂', X _{2 σ}' be respectively the rotor resistance after conversion and rotor leakage reactance; R _l, X _lbe respectively wind energy turbine set and also site top-stitching road resistance and reactance; X _tfor wind farm side step-up transformer short-circuit reactance; c ₁=1+X _{1 σ}/ X _m, be correction factor; c ₂=1+ (X _l+ X _t)/X _c//m; X _c//m=X _cx _m/ (X _c+ X _m), be X _cwith X _mvalue in parallel; X _m, X _cbe respectively the capacitive reactance of excitatory reactance and machine end shunt reactor;

B) capacity of reactive power compensation device corresponding to minimum PCC point voltage is calculated;

B1) by A1) gained breakdown slip s _crand A2) gained minimum PCC point voltage U _pCCmincalculate the active-power P that fault recovery initial stage asynchronous wind energy turbine set sends to electrical network _fSIGwith the reactive power Q absorbed _fSIG;

B2) by A2) gained U _pCCmin, B1) gained P _fSIGand Q _fSIGcalculate fault recovery initial stage asynchronous wind energy turbine set trend, obtain sending reactive power Q needed for PCC point reactive-load compensation equipment that fault recovery initial stage asynchronous wind energy turbine set can meet the requirement of Grid code low voltage crossing _c:

$Q_C=Q_{\mathrm{FSIG}}-\frac{U_{\mathrm{PCC}\min }(U_g-U_{\mathrm{PCC}\min })+P_{\mathrm{FSIG}}{R}_L}{X_L+X_T}$

B3) by B2) gained Q _cwith A2) gained U _pCCminbe divided by and namely obtain reactive-load compensation equipment lowest capacity S _c: asynchronous Reactive Compensation in Wind Farm place capacity configuration is not less than this lowest capacity S _c;

$S_C=\frac{Q_C}{U_{\mathrm{PCC}\min }}.$