CN102723727A - Grid connection control method of double-fed wind-driven generator - Google Patents

Abstract

The invention discloses a grid connection control method of a double-fed wind-driven generator. The method comprises the steps of: acquiring values of grid voltage Ug, stator three-phase voltage Us, rotor three-phase current Ir and rotor position angle thetam, transforming to a synchronous rotating coordinate system, carrying out grid voltage phase outer loop control, carrying out grid voltage amplitude outer loop control, carrying out rotor current inner loop control, and determining whether amplitude error epsilonv of stator voltage and grid voltage, phase error epsilontheta of stator voltage and grid voltage and sustainable cycles are in a set range or not. If yes, grid connection is realized through grid connection cocontactor closing. According to an embodiment provided by the invention, the control method is easy, stable and reliable. As the controller structure is simplified, grid connection is easy to be realized. Simultaneously, rotor current decoupling control is further realized, thereby convenience is provided to active and reactive power decoupling control mode switching after grid connection. Power mode smooth switching is realized by adopting a state parameter transfer way when mode switching is carried out after grid connection.

Description

The double-fed wind power generator grid-connected control method

Technical field

The present invention relates to technical field of wind power generation, be specifically related to a kind of double-fed wind power generator grid-connected control method.

Background technology

The variable speed constant frequency doubly-fed induction wind driven generator of grid type is a kind of application wind turbine generator the most widely, and it also is to be applied in the wind turbine generator one of mature technique at present that the two PWM of the back-to-back formula supporting with it hand over orthogonal rotor-exciting technology.

The efficient utilization of wind energy has become the focus of present research, reaches when cutting people's wind speed at wind speed, and how rapid and reliable realizes being incorporated into the power networks synchronously of wind turbine generator, how to reduce the impulse current that is incorporated into the power networks, also existing many researchs.To the variable speed constant frequency doubly-fed induction wind driven generator of grid type, using at present has two kinds of interconnection technologies more widely, and a kind of is the stator interconnection technology, and a kind of is the soft interconnection technology of rotor.The stator interconnection technology is applied to the wind-powered electricity generation set grid-connection under the desirable electrical network condition usually; And the soft interconnection technology of rotor is applied in running to take place low-voltage usually and falls, in the process that the wind turbine generator current transformer is realized restarting.

And about the stator interconnection technology, because application is the most extensive, detailed introduction has been made in also existing many patent applications; For example publication number is the grid-connected control method that discloses a kind of double-fed wind power generator in the patent document of CN102005782A; This application provides a kind of double circle controling mode through electrical network outer shroud and current inner loop to realize the tracking of stator voltage amplitude to the line voltage amplitude, but this application is to suppose to realize that the voltage magnitude outer shroud has adopted proportional and integral controller (pi regulator) to add the control mode of feedforward term in addition under the known situation of initial position of rotor; To cause that like this electric current impacts for the step that fixes on the starting stage; In addition, in the process of following the tracks of, because the existence of proportionality coefficient Kp in the pi regulator; With increasing the adjustment process of following the tracks of, be unfavorable for that flexibility is incorporated into the power networks.Equally, publication number is that the patent document of CN101499665A also is under the known situation of initial position of rotor, to realize being incorporated into the power networks, and all reckons without the unknown sight of initial position of rotor.

Again for example; Publication number is to disclose a kind of speed-varying frequency constant dual feedback wind power generation system and grid-connected control method thereof in the Chinese patent file of CN101267117A, and this application provides a kind of interconnection technology based on voltage magnitude compensator and rotor position angle compensator to realize being incorporated into the power networks synchronously of wind turbine generator.Its voltage magnitude compensator is regulated control as the reference value and the value of feedback of pi regulator respectively with line voltage and stator voltage amplitude, and output is as the amplitude of exciting current; And the rotor position angle compensator with torque current as controlling object, through pi regulator torque current is controlled to be 0, correct to guarantee rotor position angle.Adopted the control strategy of two outer shrouds, two interior rings, realized tracking, still line voltage amplitude and phase place; Because it is when carrying out the electric network voltage phase tracking through the rotor-position angle compensation; The contrast feedback of stator voltage phase place and electric network voltage phase is not arranged, have certain risk, especially in stator phase sequence mistake; Might and network process in, cause the failure of being incorporated into the power networks owing to impulse current is excessive.

The wind-powered electricity generation unit utilization ratio that causes owing to the be incorporated into the power networks failure or the overlong time that is incorporated into the power networks is low, has become the problem that wind energy turbine set more and more can not be ignored.Shorten and be incorporated into the power networks lock in time, reduce the impulse current that is incorporated into the power networks, improve the reliability that is incorporated into the power networks, guarantee that the safe operation of wind turbine generator has become the important issue of interconnection technology.

Summary of the invention

The present invention provides a kind of double-fed wind power generator grid-connected control method, can solve the interior ring control that under the initial position of rotor condition of unknown, realizes line voltage amplitude, the control of phase place outer shroud and realize rotor current.

The present invention provides a kind of double-fed wind power generator grid-connected control method, comprises step:

A: obtain line voltage U _g, the stator three-phase voltage U _s, the rotor three-phase electric current I _rAnd rotor position angle θ _m

B: with line voltage U _g, the stator three-phase voltage U _s, the rotor three-phase electric current I _rTransform to synchronous rotating frame respectively;

C: with line voltage U _gWith the stator three-phase voltage U _sPhase theta with respect to rest frame α axle ₁With phase theta _sRespectively as reference set-point and value of feedback on the pure integrator input, with the output of this pure integrator as initial position angle of rotor θ ₀And with electrical network phase angle θ ₁With rotor position angle θ _mThrough the adder stack, obtain the rotor three-phase electric current I _rBe transformed into the coordinate transform phase angle θ of synchronous rotating frame _Slip, form the control of electric network voltage phase outer shroud;

D: with line voltage d axle component U _GdWith stator three-phase voltage d axle component U _SdRespectively as the reference set-point and the value of feedback of pure integrator input, with the output of this pure integrator reference set-point I as rotor current q axle component ^* _Rq, the reference set-point I of setting rotor current d axle component ^* _RdBe 0, form the control of line voltage amplitude outer shroud;

E: with the reference set-point I of rotor current q axle component ^* _RqWith rotor current q axle component value of feedback I _RqExport the set-point U that proportional and integral controller obtains rotor voltage q axle component to through adder ^* _Rq, with the reference set-point I of rotor current d axle component ^* _RdWith rotor current d axle component value of feedback I _RdExport the set-point U that proportional and integral controller obtains rotor voltage d axle component to through adder ^* _Rd, form ring control in the rotor current;

F: the amplitude error ε that judges stator voltage and line voltage _v, phase error _θAnd continue cycle whether in setting range, if the contactor that then is incorporated into the power networks closes a floodgate and realizes being incorporated into the power networks.

Preferably, be incorporated into the power networks in the said step F and also comprise step after contactor close a floodgate to be realized being incorporated into the power networks:

System is switched to the power decoupled control model.

Preferably, amplitude error ε in the said step F _vLess than 10V, phase error _θLess than 5 °, continue cycle greater than 5 weeks.

Technique scheme can be found out; Because the embodiment of the invention adopts the control mode of ring in two outer shroud lists, realize outer shroud control, so the control method of the embodiment of the invention is compared with traditional control method to line voltage amplitude and phase place; Simple, reliable and stable.On the ring controller, adopted pure integral controller outside, simplified the structure of controller, be easy to realize.When realizing being incorporated into the power networks synchronously, also realized the decoupling zero control of rotor current, the providing convenience property of decoupling zero control model of, reactive power meritorious for switching to after being incorporated into the power networks.When being incorporated into the power networks the back mode switch, the mode that has adopted state parameter to transmit has realized taking over seamlessly of power mode.

Description of drawings

In order to be illustrated more clearly in the embodiment of the invention or technical scheme of the prior art; To do to introduce simply to the accompanying drawing of required use in embodiment or the description of the Prior Art below; Obviously, the accompanying drawing in describing below only is some embodiments of the present invention, for those of ordinary skills; Under the prerequisite of not paying creative work, can also obtain other accompanying drawing according to these accompanying drawings.

Fig. 1 is the flow chart of double-fed wind power generator grid-connected control method in the embodiment of the invention;

The theory diagram that Fig. 2 is incorporated into the power networks and controls for double-fed wind power generator in the embodiment of the invention;

Fig. 3 is the control principle block diagram of line voltage amplitude tracking outer shroud in the embodiment of the invention;

Fig. 4 is the control principle block diagram that electric network voltage phase is followed the tracks of outer shroud in the embodiment of the invention;

Fig. 5 is stator α in the embodiment of the invention _sβ _sCoordinate system, rotor α _rβ _rCoordinate system and the graph of a relation that rotates the dq coordinate system synchronously;

Back system switches to theory diagram meritorious, reactive power decoupling zero control by the synchronous tracing mode of line voltage to Fig. 6 for the embodiment of the invention is incorporated into the power networks.

Embodiment

To combine the accompanying drawing in the embodiment of the invention below, the technical scheme in the embodiment of the invention is carried out clear, intactly description, obviously, described embodiment only is the present invention's part embodiment, rather than whole embodiment.Based on the embodiment among the present invention, those of ordinary skills are not making all other embodiment that obtained under the creative work prerequisite, all belong to the scope of the present invention's protection.

The embodiment of the invention provides a kind of double-fed wind power generator grid-connected control method, and is as shown in Figure 1, and this method comprises:

Step 11: obtain line voltage U _g, the stator three-phase voltage U _s, the rotor three-phase electric current I _rAnd rotor position angle θ _m

In this step, utilize two groups of two current sensors to gather two phase rotor current signal I _Ra, I _RbWith two stator current signal I mutually _Sa, I _Sb, and through calculating acquisition third phase rotor current signal I _RcWith third phase stator current signal I _Sc, two groups of 4 voltage sensors are gathered grid line voltage signal U _Gab, U _GbcWith stator line voltage signal U _Sab, U _Sbc, and through calculating acquisition three phase network voltage signal U _Ga, U _Gb, U _GcWith stator voltage signal U _Sa, U _Sb, U _ScUtilize an increment photoelectric code disk to obtain rotor position angle θ _mSignal.

Step 12: with line voltage U _g, the stator three-phase voltage U _s, the rotor three-phase electric current I _rTransform to synchronous rotating frame respectively.

In this step, line voltage U under two-dimentional three-axis reference _g, the stator three-phase voltage U _s, the rotor three-phase electric current I _rConversion obtains each voltage, current value under the rest frame (α β coordinate system) through clarke; Under rest frame, line voltage U _g, stator voltage U _s, rotor current I _rConversion obtains each voltage, current value under the synchronous rotating frame (dq coordinate system) through park.

Step 13: with line voltage U _gWith the stator three-phase voltage U _sPhase theta with respect to rest frame α axle ₁With phase theta _sRespectively as reference set-point and value of feedback on the pure integrator input, with the output of this pure integrator as initial position angle of rotor θ ₀And with electrical network phase angle θ ₁With rotor position angle θ _mThrough the adder stack, obtain the rotor three-phase electric current I _rBe transformed into the coordinate transform phase angle θ of synchronous rotating frame _Slip, form the control of electric network voltage phase outer shroud.It is 0 integrator that so-called pure integrator is proportionality coefficient.

Like Fig. 2, shown in Figure 4, in this step, mains voltage signal U _gThrough the phase-locked loop computing, obtain line voltage vector phase theta with respect to the α axle under its static α β coordinate system ₁, according to line voltage directional vector control principle, the d axle of synchronous rotating frame is oriented on the line voltage vector, and with its synchronous rotation; Meanwhile, with stator voltage signal U _sThrough the phase-locked loop computing, obtain stator voltage vector angular position theta with respect to the α axle under its static α β coordinate system _sThe photoelectric code disk signal is through the angular position theta of DSP (∫ dt module among Fig. 2) acquisition rotor _m, and rotor is θ with respect to the physical location angle of line voltage α axle _r=θ ₀+ θ _mThereby the slippage angle θ that can be used for coordinate transform _Slip=θ ₁-θ _rThe slippage phase angle here is the coordinate transform phase angle.Slippage angle computing module is shown in the structure among Fig. 4 among Fig. 2.

Step 14: with line voltage d axle component U _GdWith stator three-phase voltage d axle component U _SdRespectively as the reference set-point and the value of feedback of pure integrator input, with the output of this pure integrator reference set-point I as rotor current q axle component ^* _Rq, the reference set-point I of setting rotor current d axle component ^* _RdBe 0, form the control of line voltage amplitude outer shroud;

In conjunction with Fig. 2 and shown in Figure 3, three phase network voltage, stator voltage, rotor current through Parker's coordinate transform, are converted under the synchronous rotating frame, so dq axle line voltage U is arranged _Gdq, dq axle stator voltage U _Sdq, dq axle rotor current I _RdqWith line voltage d axle component U _GdSignal is set-point as a reference, stator three-phase voltage d axle component U _SdSignal is as value of feedback; Through pure integral controller; Adjuster output is as the reference set-point of rotor current q axle component; The stream of setting rotor current d component is made as 0 with reference to set-point, and realizes the control to the rotor excitation current amplitude through the pi regulator of current inner loop, thereby realizes the synchronous tracking of stator voltage to the line voltage amplitude.

Step 15: with the reference set-point I of rotor current q axle component ^* _RqWith rotor current q axle component value of feedback I _RqExport the set-point U that proportional and integral controller obtains rotor voltage q axle component to through adder ^* _Rq, with the reference set-point I of rotor current d axle component ^* _RdWith rotor current d axle component value of feedback I _RdExport the set-point U that proportional and integral controller obtains rotor voltage d axle component to through adder ^* _Rd, form ring control in the rotor current;

As shown in Figure 2, in this step, interior ring is a rotor dq current inner loop, has adopted traditional proportional and integral controller.The output of line voltage amplitude tracking outer shroud be used to control the amplitude of exciting current, and rotor d shaft current remains 0 with reference to set-point, guarantees that promptly torque current is 0 as the reference set-point of interior ring q shaft current; Electric network voltage phase is followed the tracks of the output of outer shroud as the initial position angle of rotor signal; One side is as Parker's coordinate transform phase angle of interior circular current feedback signal; On the other hand as anti-Parker's coordinate transform phase angle of interior ring output voltage, thereby realize the adjustment of stator voltage phase place.

Step 16: the amplitude error ε that judges stator voltage and line voltage _v, phase error _θAnd continue cycle whether in setting range, said amplitude error ε _vLess than 10V, phase error _θLess than 5 °, continue cycle greater than 5 weeks.If then execution in step 17: the contactor that is incorporated into the power networks closes a floodgate and realizes being incorporated into the power networks.If, then do not rejudge.

Step 18: system is switched to the power decoupled control model.

To combine formula that the control method in the embodiment of the invention is made concrete introduction below.

As shown in Figure 2; The present invention is controlled to be the Mathematical Modeling that example is introduced the rotor-side field power supply with the line voltage directional vector; Adopt the motor convention, so, suc as formula 1, formula 2 is depicted as stator, rotor flux and stator, the rotor voltage Mathematical Modeling of DFIG under synchronous rotating frame:

$\left\{\begin{array}{c}{\mathrm{\ψ}}_{\mathrm{Sdq}}=I_{\mathrm{Sdq}}{L}_s+I_{\mathrm{Rdq}}{L}_m\\ {\mathrm{\ψ}}_{\mathrm{Rdq}}=I_{\mathrm{Sdq}}{L}_m+I_{\mathrm{Rdq}}{L}_r\end{array}\right.$ Formula 1

$\left\{\begin{array}{c}{V}_{\mathrm{Sdq}}=I_{\mathrm{Sdq}}{R}_s+\frac{d}{\mathrm{Dt}}{\mathrm{\&psi;}}_{\mathrm{Sdq}}+j{\mathrm{\&omega;}}_1{\mathrm{\&psi;}}_{\mathrm{Sdq}}\\ V_{\mathrm{Rdq}}=I_{\mathrm{Rdq}}{R}_r+\frac{d}{\mathrm{Dt}}{\mathrm{\&psi;}}_{\mathrm{Rdq}}+j{\mathrm{\&omega;}}_{\mathrm{Slip}}{\mathrm{\&psi;}}_{\mathrm{<figure-callout\; id="2"\; label="Rdq\; Formula"\; filenames="DEST\_PATH\_HDA00001847593200021.png"\; state="\{\{state\}\}">Rdq</figure-callout>}}& \\ \end{array},\right.$ Formula 2

Can be used for the rotor voltage equation of vector control by formula 1 and formula 2, shown in 3:

$\left\{\begin{array}{c}{V}_{\mathrm{Rd}}=I_{\mathrm{Rd}}{R}_r+{\mathrm{\&sigma;\; L}}_r\frac{d}{\mathrm{Dt}}{I}_{\mathrm{Rd}}+\frac{L_m}{L_s}\frac{d}{\mathrm{Dt}}{\mathrm{\&psi;}}_{\mathrm{Sd}}-{\mathrm{\&omega;}}_{\mathrm{Slip}}{\mathrm{\&sigma;\; L}}_r{I}_{\mathrm{Rq}}-{\mathrm{\&omega;}}_{\mathrm{Slip}}\frac{L_m}{L_s}{\mathrm{\&psi;}}_{\mathrm{Sq}}\\ V_{\mathrm{Rq}}=I_{\mathrm{Rq}}{R}_r+{\mathrm{\&sigma;\; L}}_r\frac{d}{\mathrm{Dt}}{I}_{\mathrm{Rq}}+\frac{L_m}{L_s}\frac{d}{\mathrm{Dt}}{\mathrm{\&psi;}}_{\mathrm{Sq}}+{\mathrm{\&omega;}}_{\mathrm{Slip}}{\mathrm{\&sigma;\; L}}_r{I}_{\mathrm{Rd}}+{\mathrm{\&omega;}}_{\mathrm{Slip}}\frac{L_m}{L_s}{\mathrm{\&psi;}}_{\mathrm{Sd}}\end{array}\right.$ Formula 3

When systematic steady state moves:

$\frac{d}{\mathrm{Dt}}{\mathrm{\&psi;}}_{\mathrm{Sd}}=0,$ $\frac{d}{\mathrm{Dt}}{\mathrm{\&psi;}}_{\mathrm{Sq}}=0$ Formula 4

So formula 3 can be reduced to:

$\left\{\begin{array}{c}{V}_{\mathrm{Rd}}=I_{\mathrm{Rd}}{R}_r+{\mathrm{\&sigma;\; L}}_r\frac{d}{\mathrm{Dt}}{I}_{\mathrm{Rd}}-{\mathrm{\&omega;}}_{\mathrm{Slip}}{\mathrm{\&sigma;\; L}}_r{I}_{\mathrm{Rq}}-{\mathrm{\&omega;}}_{\mathrm{Slip}}\frac{L_m}{L_s}{\mathrm{\&psi;}}_{\mathrm{Sq}}\\ V_{\mathrm{Rq}}=I_{\mathrm{Rq}}{R}_r+{\mathrm{\&sigma;\; L}}_r\frac{d}{\mathrm{Dt}}{I}_{\mathrm{Rq}}+{\mathrm{\&omega;}}_{\mathrm{Slip}}{\mathrm{\&sigma;\; L}}_r{I}_{\mathrm{Rd}}+{\mathrm{\&omega;}}_{\mathrm{Slip}}\frac{L_m}{L_s}{\mathrm{\&psi;}}_{\mathrm{Sd}}\end{array}\right.$ Formula 5

When the generator connecting in parallel with system steady operation, stator resistance can be ignored, the stator magnetic linkage constant amplitude, therefore:

$V_{\mathrm{Sdq}}=I_{\mathrm{Sdq}}{R}_s+\frac{d}{\mathrm{Dt}}{\mathrm{\&psi;}}_{\mathrm{Sdq}}+j{\mathrm{\&omega;}}_1{\mathrm{\&psi;}}_{\mathrm{Sdq}}\&ap;j{\mathrm{\&omega;}}_1{\mathrm{\&psi;}}_{\mathrm{Sdq}}$ Formula 6

Simultaneously, according to getting V based on the directed principle of vector control of line voltage d axle _Sq=0, therefore can get:

$\left\{\begin{array}{c}{\mathrm{\&psi;}}_{\mathrm{Sd}}=\frac{V_{\mathrm{Sq}}}{{\mathrm{\&omega;}}_1}=0\\ {\mathrm{\&psi;}}_{\mathrm{Sq}}=-\frac{V_{\mathrm{Sd}}}{{\mathrm{\&omega;}}_1}\end{array}\right.$ Formula 7

Can formula 5 further be reduced to by formula 7:

$\left\{\begin{array}{c}{V}_{\mathrm{Rd}}=R_r{I}_{\mathrm{Rd}}+{\mathrm{\&sigma;\; L}}_r\frac{{\mathrm{DI}}_{\mathrm{Rd}}}{\mathrm{Dt}}+\frac{{\mathrm{\&omega;}}_{\mathrm{Slip}}{L}_m}{{\mathrm{\&omega;}}_1{L}_s}{V}_{\mathrm{Sd}}-{\mathrm{\&omega;}}_{\mathrm{Slip}}{\mathrm{\&sigma;\; L}}_r{I}_{\mathrm{Rq}}\\ V_{\mathrm{Rq}}=R_r{I}_{\mathrm{Rq}}+{\mathrm{\&sigma;\; L}}_r\frac{{\mathrm{DI}}_{\mathrm{Rq}}}{\mathrm{Dt}}+{\mathrm{\&omega;}}_{\mathrm{Slip}}{\mathrm{\&sigma;\; L}}_r{I}_{\mathrm{Rd}}\end{array}\right.$ Formula 8

Wherein: $\mathrm{\&sigma;}=1-\frac{L_m^2}{L_s{L}_r},$ ω _Slip=ω ₁-ω _r

V _Sd, V _Sq, V _Rd, V _RqBe respectively d, the q axle component of stator voltage, rotor voltage d, q axle component;

Ψ _Sd, Ψ _Sq, Ψ _Rd, Ψ _RqBe respectively d, the q axle component of stator magnetic linkage, rotor flux d, q axle component;

I _Sd, I _Sq, I _Rd, I _RqBe respectively stator current d, q axle component, rotor current d, q axle component;

R _s, R _rBe stator and rotor resistance parameters;

L _s, L _rBe respectively stator and rotor equivalence two phase winding self-inductions under the synchronous rotation dq coordinate system;

L _mBe the mutual inductance between stator and rotor coaxial equivalent winding under the synchronous rotation dq coordinate system;

ω ₁, ω _rBe the synchronous anglec of rotation frequency of line voltage vector, the electric angle frequency of generator amature.

The apparent power S of DFIG stator output _sFor:

$S_s=P_s+{\mathrm{JQ}}_s=\frac{3}{2}{V}_{\mathrm{Sdq}}{\hat{I}}_{\mathrm{Sdq}}=\frac{3}{2}{V}_{\mathrm{Sdq}}\frac{1}{L_s}({\widehat{\mathrm{\&psi;}}}_{\mathrm{Sdq}}-L_m{\hat{I}}_{\mathrm{Rdq}})$ Formula 9

Under d axle stator voltage vector oriented, DFIG stator active power of output P _s, reactive power Q _sBe respectively:

$\left\{\begin{array}{c}{P}_s=\frac{{3L}_m}{{2L}_s}{V}_{\mathrm{Sd}}{I}_{\mathrm{Rd}}\\ Q_s=-\frac{{3V}_{\mathrm{Sd}}}{{2L}_s}(\frac{V_{\mathrm{Sd}}}{{\mathrm{\&omega;}}_1}+L_m{I}_{\mathrm{Rq}})\end{array}\right.$ Formula 10

Can know by formula 10; When adopting d axle stator voltage vector oriented control strategy; Rotor current d, q axle component become meritorious (torque), idle (excitation) current component respectively, can export decoupling zero control meritorious, reactive power to realize the DFIG stator through the independent regulation control to rotor current d axle component (torque current component), rotor current q axle component (excitation current component).For avoiding the impulse current that is incorporated into the power networks, the present invention has adopted the idle grid connection mode, and this meritorious, reactive power that just must guarantee stator is 0, just in rotor current, must guarantee with reference to set-point I in the ring _Rd=0, I _Rq=V _Sd/ (ω ₁* L _m).Yet, excitation current component I _RqThe reference set-point responsive to generator parameter, easily because the error of calculation of parameter causes that stator voltage amplitude and line voltage amplitude differ bigger, and then cause that the impulse current that is incorporated into the power networks is excessive, failure causes being incorporated into the power networks.Therefore, the present invention has adopted the close-loop control mode of line voltage amplitude tracking outer shroud, and the stator voltage amplitude is close with the line voltage amplitude constantly to guarantee to be incorporated into the power networks, thus the realization idle grid connection.

As shown in Figure 3, owing to adopted line voltage directional vector control mode, so the d axle component of line voltage is the phase voltage amplitude of line voltage.One of necessary condition of idle grid connection is that the stator voltage amplitude is identical with the line voltage amplitude, and the present invention realizes this necessary condition through the mode of line voltage amplitude tracking closed-loop control.For guaranteeing idle grid connection, the torque current of ring is with reference to set-point I in the rotor current ^* _RdMust remain 0.Because the output of stator voltage amplitude tracking outer shroud is encircle in the q shaft current given, and can know that by formula 10 exciting current is with reference to set-point I ^* _RqWith stator voltage d axle component V _SdBetween be zeroth order transfer function relation, therefore, only need a pure integral controller can realize closed loop compensation control.

Shown in Figure 5 is stator α _sβ _sCoordinate system, rotor α _rβ _rCoordinate system and the graph of a relation that rotates the dq coordinate system synchronously.

Can know that by figure the relation that the vector under the rotor coordinate system is converted to the stator coordinate system is following:

$F_{\mathrm{R\&alpha;\; \&beta;}}{e}^{j({\mathrm{\&theta;}}_m+{\mathrm{\&theta;}}_0)}=F_{\mathrm{S\&alpha;\; \&beta;}}$ Formula 11

Can know that by control block diagram shown in Figure 2 system realizes the control to rotor current through amplitude and the phase place that control exports the rotor voltage vector of rotor winding to, and then realize decoupling zero control meritorious, reactive power.Because control is the voltage vector that exports the rotor winding to, therefore, the locus of the dominant vector under the rotor coordinate system directly affects the phase place of the stator voltage space vector that induces under the stator coordinate.

Shown in accompanying drawing 4, line voltage calculates the line voltage space vector angular position theta of output through phase-locked loop ₁Set-point as a reference, the stator voltage control vector position angle θ that the stator voltage phase-locked loop calculates _sAs feedback signal, regulate compensator through a pure integration and control, be output as the initial position angle θ of rotor ₀Through initial position angle of rotor θ ₀Compensation control; The position angle of rotor voltage dominant vector is changed thereupon; Thereby the locus angle vectorial in the stator voltage of stator side induction also changes thereupon, and then realizes the tracking to line voltage space vector position angle realizing the electric network voltage phase tracking Control.

As long as in the error of stator voltage and line voltage amplitude less than ε _v(common ε _vBelow getting 10 volts), stator voltage and electric network voltage phase error are less than ε simultaneously _θ(get usually 5 degree in), and a lasting n cycle is when above (getting 5 usually more than the cycle), controller can send the reclosing command that is incorporated into the power networks, and the completion generating set is incorporated into the power networks.

System switches to theory diagram meritorious, reactive power decoupling zero control by the synchronous tracing mode of line voltage after being illustrated in figure 6 as generator connecting in parallel with system.Receive when being incorporated into the power networks the "on" position feedback signal at controller; Final output state with line voltage amplitude tracking outer shroud; As initial condition meritorious, the reactive power outer shroud, and operational mode is followed the tracks of outer shroud synchronously by line voltage take over seamlessly to meritorious, reactive power outer shroud; In the synchronizing process of double-fed induction wind driven generator, the final output state Y of line voltage amplitude tracking outer shroud _FinalAs initial condition X meritorious, the reactive power outer shroud _PQinit, shown in 12:

$X_{\mathrm{PQinit}}=Y_{\mathrm{Final}}=\left[\begin{array}{c}{I}_{\mathrm{Rd}}\\ I_{\mathrm{Rq}}\end{array}\right]=\left[\begin{array}{c}0\\ I_{\mathrm{Rq}}^{*}\end{array}\right]$ Formula 12

Thereby avoided in the handoff procedure, owing to the interior circular current of line voltage amplitude tracking outer shroud output causes the rush of current in the handoff procedure with reference to the output of set-point and power outer shroud with reference to the difference of set-point; The final flexibility of double-fed induction wind driven generator that realizes is incorporated into the power networks.

After adopting such scheme, the present invention adopts the synchronous tracking strategy of cascade vector control of two outer shrouds, single interior ring; And the smoothness run mode switch strategy after being incorporated into the power networks.Two outer shrouds are line voltage amplitude tracking control outer shroud and electric network voltage phase tracking Control outer shroud, and two loops have all adopted pure integral controller, have reduced the concussion in the stator voltage synchronizing process like this; Interior ring is rotor dq current inner loop, has adopted the traditional PI adjuster.The output of line voltage amplitude tracking outer shroud be used to control the amplitude of exciting current, and rotor d shaft current remains 0 with reference to set-point, guarantees that promptly torque current is 0 as the reference set-point of interior ring q shaft current; Electric network voltage phase is followed the tracks of the output of outer shroud as the initial position angle of rotor signal, encircles in the coordinate transform of feedback signal and output rotor dominant vector in adding, thus the adjustment of realization stator voltage phase place.The smoothness run mode switch is the final output state with the line voltage amplitude tracking outer shroud before switching; Be that the dq shaft current is with reference to set-point; Initial value as power outer shroud integrator; After preventing the incision of power outer shroud,, thereby cause the rush of current in the handoff procedure because the difference of reference value causes given step.Whole flexibility synchronously and network process avoided the detection of initial position angle of rotor, shortened the time of flexible and network process, improved the flexible stability that is incorporated into the power networks, the impulse current of the moment that reduced to be incorporated into the power networks.

Control method of the present invention is compared with traditional control method, and is simple, reliable and stable.On the ring controller, adopted pure integral controller outside, simplified the structure of controller, be easy to realize.When realizing being incorporated into the power networks synchronously, also realized the decoupling zero control of rotor current, the providing convenience property of decoupling zero control model of, reactive power meritorious for switching to after being incorporated into the power networks.When being incorporated into the power networks the back mode switch, the mode that has adopted state parameter to transmit has realized taking over seamlessly of power mode.

The inventive method can also be applicable to various three-phase grid inverters except that being applicable to the variable speed constant frequency doubly-fed induction wind driven generator of grid type system, like the parallel network reverse device of solar energy, battery energy storage electricity generation system.Need to prove, contents such as the information interaction between said apparatus and intrasystem each unit, implementation since with the inventive method embodiment based on same design, particular content can repeat no more referring to the narration among the inventive method embodiment here.

One of ordinary skill in the art will appreciate that all or part of step in the whole bag of tricks of the foregoing description is to instruct relevant hardware to accomplish through program; This program can be stored in the computer-readable recording medium; Storage medium can comprise: flash memory (Flash Memory), read-only memory (ROM; ReadOnly Memory), random access memory (RAM, Random Access Memory), disk or CD etc.

More than to double-fed wind power generator grid-connected control method that the embodiment of the invention provided; Carried out detailed introduction; Used concrete example among this paper principle of the present invention and execution mode are set forth, the explanation of above embodiment just is used for helping to understand method of the present invention and core concept thereof; Simultaneously, for one of ordinary skill in the art, according to thought of the present invention, the part that on embodiment and range of application, all can change, in sum, this description should not be construed as limitation of the present invention.

Claims (3)

1. the double-fed wind power generator grid-connected control method is characterized in that, comprises step:

A: obtain line voltage U _g, the stator three-phase voltage U _s, the rotor three-phase electric current I _rAnd rotor position angle θ _m

B: with line voltage U _g, the stator three-phase voltage U _s, the rotor three-phase electric current I _rTransform to synchronous rotating frame respectively;

C: with line voltage U _gWith the phase theta of stator three-phase voltage U s with respect to rest frame α axle ₁With phase theta _sRespectively as reference set-point and value of feedback on the pure integrator input, with the output of this pure integrator as initial position angle of rotor θ ₀And with electrical network phase angle θ ₁With rotor position angle θ _mThrough the adder stack, obtain the rotor three-phase electric current I _rBe transformed into the coordinate transform phase angle θ of synchronous rotating frame _Slip, form the control of electric network voltage phase outer shroud;

D: with line voltage d axle component U _GdWith stator three-phase voltage d axle component U _SdRespectively as the reference set-point and the value of feedback of pure integrator input, with the output of this pure integrator reference set-point I as rotor current q axle component ^* _Rq, the reference set-point I of setting rotor current d axle component ^* _RdBe 0, form the control of line voltage amplitude outer shroud;

E: with the reference set-point I of rotor current q axle component ^* _RqWith rotor current q axle component value of feedback I _RqExport the set-point U that proportional and integral controller obtains rotor voltage q axle component to through adder ^* _Rq, with the reference set-point I of rotor current d axle component ^* _RdWith rotor current d axle component value of feedback I _RdExport proportional and integral controller to through adder and obtain the set-point U of rotor voltage d by component ^* _Rd, form ring control in the rotor current;

F: the amplitude error ε that judges stator voltage and line voltage _v, phase error _θAnd continue cycle whether in setting range, if the contactor that then is incorporated into the power networks closes a floodgate and realizes being incorporated into the power networks.

2. double-fed wind power generator grid-connected control method as claimed in claim 1 is characterized in that, also comprises step after the contactor that is incorporated into the power networks in the said step F closes a floodgate and realizes being incorporated into the power networks:

System is switched to the power decoupled control model.

3. according to claim 1 or claim 2 double-fed wind power generator grid-connected control method is characterized in that: amplitude error ε in the said step F _vLess than 10V, phase error _θLess than 5 °, continue cycle greater than 5 weeks.

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