CN105515040A - Slip form and repeation-based DFIG control method - Google Patents

Abstract

The invention discloses a Slip form and repeation-based DFIG control method. The d-axis rotor current and the q-axis rotor current of a DFIG are directly controlled in the slip form control manner. In this way, the decoupling control over the active power and the reactive power of the DFIG is realized, so that the dynamic response capability of the system is greatly improved. According to the technical scheme of the invention, the stator current is adjusted in the repeated control manner, so that the harmonic component of an arbitrary order in the stator current, caused by the harmonic wave of an arbitrary order in the voltage of a power grid, can be eliminated. Therefore, the sinusoidal three-phase stator current output can be balanced. Compared with the conventional control method, the method is better in dynamic adjustment capability, and can inhibit the harmonic stator current of an arbitrary order. Furthermore, the control effect of the DFIG is enhanced. The method can be better applied to the actual condition of the power grid with the harmonic contamination condition thereof to be difficult to forecast.

Description

A kind of DFIG control method based on sliding formwork+repetition

Technical field

The invention belongs to wind power generation control technology field, be specifically related to a kind of DFIG control method based on sliding formwork+repetition.

Background technology

AC excitation double-fed asynchronous generator (doublyfedinductiongenerator, DFIG) have that variable speed constant frequency runs, active power and reactive power independence uneoupled control and the advantage such as frequency inverter capacity is little, be widely used in wind power generation field.Wherein the stator of DFIG is directly connected with electrical network, and grid condition will the operation of direct influential system.China standard GB/T/T15543-2008 " quality of power supply imbalance of three-phase voltage " and GB/T14549-1993 " quality of power supply-utility network harmonic wave ", allows normal operation in electrical network, there is certain negative sequence voltage and each harmonic voltage.Under this electrical network, will there is uneven and harmonic distortion in DFIG stator output current, exceed set upper limit value in GB/T14549-1993 " quality of power supply-utility network harmonic wave " most probably.If grid-connected by force, power grid quality will be reduced further, affect the power grid environment of power load etc.Therefore, inquire into the control technology of DFIG under imperfect grid conditions, to eliminate the uneven and harmonic component of stator current introduced thus.At present, both at home and abroad this research is mainly contained: 1) based on the vector control method of resonant controller; 2) resonance sliding-mode control.Wherein HuJiabing etc. are at document " CoordinatedcontrolofDFIG ' sRSCandGSCundergeneralizedunbalancedanddistortedgridvolt ageconditions " (IEEETransationsonIndustrialElectronics, 2013) resonant regulator is added in traditional vector control in, full space and year the top gem of a girdle-pendant at document " uneven and harmonic voltage under doubly fed induction generator resonance sliding formwork control technology " (Proceedings of the CSEE, 2015) in sliding formwork controls, resonant regulator is added in, all make the control ability of system acquisition to the harmonic current components at this resonance point place.But a resonant regulator can only control the specific subharmonic being in resonance frequency place, therefore all belong to and specify subharmonic control technology.But in actual electric network, also may there are other each harmonics.Now adopt and specify subharmonic control technology, the current distortion brought by other harmonic voltages cannot be suppressed, be difficult to the requirement meeting grid-connected specification.When if desired the harmonic current likely occurred being controlled, need the resonant regulator of the sizable different resonance frequency of number.Too much resonant regulator makes system occur more closed-loop pole, causes adverse effect, as shown in Figure 1 to the stability of a system.

Summary of the invention

For the above-mentioned technical problem existing for prior art, the invention provides a kind of DFIG control method based on sliding formwork+repetition, go for the power grid environment that any subharmonic pollutes, also can reduce and control time delay and have response characteristic faster.

Based on a DFIG control method for sliding formwork+repetition, comprise the steps:

(1) gather the threephase stator voltage of DFIG, threephase stator electric current, three-phase rotor current, rotating speed and rotor position angle, determine that the threephase stator voltage of DFIG, threephase stator electric current, three-phase rotor current, stator magnetic linkage and rotor flux rotate the component in d-q coordinate system in synchronous speed according to rotor position angle by coordinate transform;

(2) the d axle component of given rotor current reference value is made with q axle component deduct the d axle component I of rotor current actual value respectively _rdwith q axle component I _rq, obtain the d axle component Δ I of the rotor current margin of error _rdwith q axle component Δ I _rq; Respectively to the d axle component Δ I of the rotor current margin of error _rdwith q axle component Δ I _rqcarry out PI adjustment, obtain d axle sliding formwork value S _dwith q axle sliding formwork value S _q;

(3) according to described d axle sliding formwork value S _dwith q axle sliding formwork value S _q, calculate synchronous speed and rotate the switch control rule amount that in d-q coordinate system, sliding formwork controls; According to the electric parameters gathered and DFIG model parameter, calculate synchronous speed and rotate the equivalent control amount that in d-q coordinate system, sliding formwork controls; Switch control rule and equivalent control amount are added, obtain the sliding-mode control law in synchronous speed rotation d-q coordinate system;

(4) the d axle component of given stator current reference is made with q axle component deduct the d axle component I of stator current actual value respectively _sdwith q axle component I _sq, respectively to the d axle component Δ I of stator current error amount _sdwith q axle component Δ I _sqcarry out Repetitive controller adjustment, obtain the Repetitive controller amount in synchronous speed rotation d-q coordinate system;

(5) make the sliding-mode control law in synchronous speed rotation d-q coordinate system and Repetitive controller amount be added, obtain the rotor voltage instruction in synchronous speed rotation d-q coordinate system; Park conversion is carried out to the component that rotor voltage instruction rotates in d-q coordinate system in synchronous speed, obtains the component of rotor voltage instruction in stationary rotor alpha-beta coordinate system; And then obtain one group of pwm signal to control DFIG pusher side current transformer according to the component of rotor voltage instruction in stationary rotor alpha-beta coordinate system by SVPWM technical construction.

In described step (1), calculate stator magnetic linkage and the component of rotor flux in synchronous speed rotation d-q coordinate system according to following formula:

ψ _sd＝L _sI _sd+L _mI _rdψ _rd＝L _rI _rd+L _mI _sd

ψ _sq＝L _sI _sq+L _mI _rqψ _rq＝L _rI _rq+L _mI _sq

Wherein: Ψ _sdand Ψ _sqbe respectively stator magnetic linkage and rotate d axle component in d-q coordinate system and q axle component in synchronous speed, Ψ _rdand Ψ _rqbe respectively rotor flux and rotate d axle component in d-q coordinate system and q axle component in synchronous speed, I _sdand I _sqbe respectively threephase stator electric current and rotate d axle component in d-q coordinate system and q axle component in synchronous speed, I _rdand I _rqbe respectively three-phase rotor current and rotate d axle component in d-q coordinate system and q axle component in synchronous speed, L _sand L _rbe respectively stator inductance and the inductor rotor of DFIG, L _mfor the rotor mutual inductance of DFIG.

In described step (2), calculate the d axle sliding formwork value S in synchronous speed rotation d-q coordinate system according to following formula _dwith q axle sliding formwork value S _q:

$S_d=(k_p+\frac{k_i}{s})\·{\mathrm{\ΔI}}_{rd}$

$S_q=(k_p+\frac{k_i}{s})\·{\mathrm{\ΔI}}_{rq}$

Wherein: Δ I _rdwith Δ I _rqbe respectively rotor current error and rotate d axle component in d-q coordinate system and q axle component in synchronous speed, with be respectively d axle rotor current reference quantity and q axle rotor current reference quantity, I _rdand I _rqbe respectively three-phase rotor current and rotate d axle component in d-q coordinate system and q axle component in synchronous speed, k _pfor given proportionality coefficient, k _ifor given integral coefficient, s is Laplacian.

In described step (3), calculate the switch control rule amount of sliding formwork control according to following formula:

ΔV _d＝k _ssat(S _d)+k _iΔI _rd

ΔV _q＝k _ssat(S _q)+k _iΔI _rq

Wherein: Δ V _rdwith Δ V _rqbe respectively sliding formwork control in switch control rule amount rotate d axle component in d-q coordinate system and q axle component in synchronous speed, sat is saturation function, k _sfor given sliding formwork control coefrficient.

The equivalent control amount of sliding formwork control is calculated according to following formula:

$V_{d\_eq}=\frac{L_m}{L_s}(U_{sd}-{\mathrm{\ω}}_{sl}{\mathrm{\ψ}}_{sq})+R_r{I}_{rd}-{\mathrm{\σL}}_r{\mathrm{\ω}}_{sl}{I}_{rq}$

$V_{q\_eq}=\frac{L_m}{L_s}(U_{sq}+{\mathrm{\ω}}_{sl}{\mathrm{\ψ}}_{sd})+R_r{I}_{rq}+{\mathrm{\σL}}_r{\mathrm{\ω}}_{sl}{I}_{rd}$

Wherein: V _{d_eq}and V _{q_eq}be respectively sliding formwork control in equivalent control amount rotate d axle component in d-q coordinate system and q axle component in synchronous speed; Ψ _sdand Ψ _sqbe respectively stator magnetic linkage and rotate d axle component in d-q coordinate system and q axle component in synchronous speed; I _sdand I _sqbe respectively threephase stator electric current and rotate d axle component in d-q coordinate system and q axle component in synchronous speed, U _sdand U _sqbe respectively threephase stator voltage and rotate d axle component in d-q coordinate system and q axle component in synchronous speed; ω _slfor slip angular velocity; L _sand L _rbe respectively stator inductance and the inductor rotor of DFIG, L _mfor the rotor mutual inductance of DFIG; σ=1-L _m ²/ (L _sl _r), be leakage inductance coefficient.

Switch control rule amount and equivalent control amount are added, obtain the d axle component V of synovial membrane controlled quentity controlled variable in synchronous speed rotation d-q coordinate system _dˊ and q axle component V _qˊ:

V _d′＝ΔV _d+V _{d_eq}

V _q′＝ΔV _q+V _{q_eq}

In described step (4), calculate Repetitive controller amount according to following formula:

${V_d}^{\′\′}=\frac{k_r{e}^{-sT}}{1-k_f{e}^{-sT}}\·{\mathrm{\ΔI}}_{sd}$

${V_q}^{\′\′}=\frac{k_r{e}^{-sT}}{1-k_f{e}^{-sT}}\·{\mathrm{\ΔI}}_{sq}$

Wherein: V _dˊ ˊ and V _qˊ ˊ is respectively Repetitive controller amount and rotates d axle component in d-q coordinate system and q axle component in synchronous speed; Δ I _sdwith Δ I _sqbe respectively stator current error and rotate d axle component in d-q coordinate system and q axle component in synchronous speed, with be respectively d axle and the q axle component of stator harmonic current reference quantity, i _sdand I _sqbe respectively threephase stator electric current and rotate d axle component in d-q coordinate system and q axle component in synchronous speed; k _rfor given Repetitive controller coefficient; k _ffor improving the given coefficient of Repetitive controller stability; S is Laplacian; T=0.01.

The present invention, without the need to carrying out complicated positive-negative sequence and harmonic component extraction, also calculating without the need to carrying out complicated rotor current reference value, can greatly reduce control time delay, strengthen rapidity and the stability of system.The present invention adopts rotor current and stator current double-closed-loop control; Wherein rotor current closed loop adopts sliding formwork control technology, ensures system dynamic response capability fast; Stator current closed loop adopts Repetitive Control Technique, makes the rejection ability of system acquisition to any order harmonic components of stator current, can eliminate the Stator Current Harmonic component caused by order harmonic components any in line voltage.Therefore, it is possible to guarantee to keep sinusoidal stator output current under any subharmonic pollutes power grid environment, thus effectively improve the operation control performance of DFIG under actual electric network voltage conditions, to meet the harmonic injection restriction that industry standard specifies, guarantee stability and the safety of the quality of power supply and electric power system.

Compared to traditional control method, reduce shared software space, have stronger dynamic adjustments ability, the most important thing is, the harmonic component caused by any subharmonic of line voltage in stator current can be eliminated, be more applicable for the unpredicted actual electric network of distortion situation.

Therefore under the line voltage condition adopting the inventive method can pollute at any subharmonic, realize the enhancing control objectives of DFIG electricity generation system, effectively improve the output quality of power supply under such generator actual electric network.The inventive method is also applicable to effective control of the dynamoelectric machine convertor assembly in the electric power regulator drive of the three-phase inversion device formation that other all kinds of form PWM adopting HF switch self-turn-off device to form except DFIG blower fan control simultaneously.

Accompanying drawing explanation

Fig. 1 is the principle schematic of tradition based on the control method of appointment 5 times and 7 subharmonic.

Fig. 2 is the principle schematic of control method of the present invention.

Fig. 3 (a) be at electrical network containing 5%5 times and the distortion of 5%7 subharmonic, adopt the simulation waveform figure of DFIG under tradition appointment 5 times and 7 subharmonic control methods.

Fig. 3 (b) is at electrical network containing 5%7 times and the distortion of 5%13 subharmonic, the simulation waveform figure of DFIG under employing tradition appointment subharmonic control method.

Fig. 3 (c) is at electrical network containing 5%17 times and the distortion of 5%19 subharmonic, the simulation waveform figure of DFIG under employing tradition appointment subharmonic control method.

Fig. 4 (a) distorts containing 10%5 times and 10%7 subharmonic at electrical network, adopts the simulation waveform figure of DFIG under control method of the present invention.

Fig. 4 (b) distorts containing 10%7 times and 10%13 subharmonic at electrical network, adopts the simulation waveform figure of DFIG under control method of the present invention.

Fig. 4 (c) distorts containing 10%17 times and 10%19 subharmonic at electrical network, adopts the simulation waveform figure of DFIG under control method of the present invention.

Embodiment

In order to more specifically describe the present invention, below in conjunction with the drawings and the specific embodiments, DFIG control method of the present invention is described in detail.

In the present embodiment, the parameter of electric machine of the DFIG that control is as shown in table 1:

Table 1

As shown in Figure 2, a kind of DFIG control method based on sliding formwork+repetition, comprises the steps:

(1) Hall voltage transducer 1 is utilized to gather the threephase stator voltage U of DFIG _sa~ U _sc, utilize Hall current sensor 2 to gather the threephase stator electric current I of DFIG _sa~ I _scwith three-phase rotor current I _ra~ I _rc; Encoder 3 is utilized to detect rotational speed omega and the rotor position angle θ of DFIG _r;

First, Parke conversion module 4 is utilized according to following formula respectively to threephase stator voltage U _sa~ U _scwith threephase stator electric current I _sa~ I _sccarry out Parke conversion, obtain the d axle component U of threephase stator voltage in synchronous speed rotation d-q coordinate system _sdwith q axle component U _sqand threephase stator electric current rotates the d axle component I in d-q coordinate system in synchronous speed _sdwith q axle component I _sq; The transformation matrix of Parke conversion is as follows:

$\left[\begin{array}{c}{U}_d\\ U_q\end{array}\right]=\frac{2}{3}\left[\begin{array}{ccc}\cos \mathrm{\θ}& \cos (\mathrm{\θ}-\frac{2\mathrm{\π}}{3})& \cos (\mathrm{\θ}+\frac{2\mathrm{\π}}{3})\\ -\sin \mathrm{\θ}& -\sin (\mathrm{\θ}-\frac{2\mathrm{\π}}{3})& -\sin (\mathrm{\θ}+\frac{2\mathrm{\π}}{3})\end{array}\right]\·\left[\begin{array}{c}{U}_a\\ U_b\\ U_c\end{array}\right]$

$\left[\begin{array}{c}{I}_{sd}\\ I_{sq}\end{array}\right]=\frac{2}{3}\left[\begin{array}{ccc}\cos \mathrm{\θ}& \cos (\mathrm{\θ}-\frac{2\mathrm{\π}}{3})& \cos (\mathrm{\θ}+\frac{2\mathrm{\π}}{3})\\ -\sin \mathrm{\θ}& -\sin (\mathrm{\θ}-\frac{2\mathrm{\π}}{3})& -\sin (\mathrm{\θ}+\frac{2\mathrm{\π}}{3})\end{array}\right]\·\left[\begin{array}{c}{I}_{sa}\\ I_{sb}\\ I_{sc}\end{array}\right]$

Wherein: θ is the instantaneous electrical degree of three-phase primary voltage.

In like manner, Parke conversion module 5 couples of three-phase rotor current I are utilized _ra~ I _rccarry out Parke conversion and obtain the d axle component I of three-phase rotor current in synchronous speed rotation d-q coordinate system _rdwith q axle component I _rq; The transformation matrix of Parke conversion is as follows:

$\left[\begin{array}{c}{I}_{rd}\\ I_{rq}\end{array}\right]=\frac{2}{3}\left[\begin{array}{ccc}{\mathrm{cos\θ}}_{sl}& \cos ({\mathrm{\θ}}_{sl}-\frac{2\mathrm{\π}}{3})& \cos ({\mathrm{\θ}}_{sl}+\frac{2\mathrm{\π}}{3})\\ -{\mathrm{sin\θ}}_{sl}& -\sin ({\mathrm{\θ}}_{sl}-\frac{2\mathrm{\π}}{3})& -\sin ({\mathrm{\θ}}_{ls}+\frac{2\mathrm{\π}}{3})\end{array}\right]\·\left[\begin{array}{c}{I}_{ra}\\ I_{rb}\\ I_{rc}\end{array}\right]$

Wherein: the angle of Parke conversion is slippage angle θ _sl=θ-θ _r.

Then, flux linkage calculation module 6 is utilized to calculate stator magnetic linkage and the component of rotor flux in synchronous speed rotation d-q coordinate system according to following formula:

ψ _sd＝L _sI _sd+L _mI _rdψ _rd＝L _rI _rd+L _mI _sd

ψ _sq＝L _sI _sq+L _mI _rqψ _rq＝L _rI _rq+L _mI _sq

Wherein: Ψ _sdand Ψ _sqbe respectively stator magnetic linkage and rotate d axle component in d-q coordinate system and q axle component in synchronous speed, Ψ _rdand Ψ _rqbe respectively rotor flux and rotate d axle component in d-q coordinate system and q axle component in synchronous speed, L _sand L _rbe respectively stator inductance and the inductor rotor of DFIG, L _mfor the rotor mutual inductance of DFIG.In present embodiment, L _s=2.5773mH, L _r=2.5834mH, L _m=2.5mH.

(2) the d axle sliding formwork value S in synchronous speed rotation d-q coordinate system is calculated according to following formula _dwith q axle sliding formwork value S _q:

$S_d=(k_p+\frac{k_i}{s})\·{\mathrm{\ΔI}}_{rd}$

$S_q=(k_p+\frac{k_i}{s})\·{\mathrm{\ΔI}}_{rq}$

Wherein: Δ I _rdwith Δ I _rqbe respectively rotor current error and rotate d axle component in d-q coordinate system and q axle component in synchronous speed, with be respectively d axle rotor current reference quantity and q axle rotor current reference quantity, I _rdand I _rqbe respectively three-phase rotor current and rotate d axle component in d-q coordinate system and q axle component in synchronous speed, k _pfor given proportionality coefficient, k _ifor given integral coefficient, s is Laplacian.

(3) the switch control rule amount of sliding formwork control is calculated according to following formula:

ΔV _d＝k _ssat(S _d)+k _iΔI _rd

ΔV _q＝k _ssat(S _q)+k _iΔI _rq

Wherein: Δ V _rdwith Δ V _rqbe respectively sliding formwork control in switch control rule amount rotate d axle component in d-q coordinate system and q axle component in synchronous speed, sat is saturation function, k _sfor given sliding formwork control coefrficient.

The equivalent control amount of sliding formwork control is calculated according to following formula:

$V_{d\_eq}=\frac{L_m}{L_s}(U_{sd}-{\mathrm{\ω}}_{sl}{\mathrm{\ψ}}_{sq})+R_r{I}_{rd}-{\mathrm{\σL}}_r{\mathrm{\ω}}_{sl}{I}_{rq}$

$V_{q\_eq}=\frac{L_m}{L_s}(U_{sq}+{\mathrm{\ω}}_{sl}{\mathrm{\ψ}}_{sd})+R_r{I}_{rq}+{\mathrm{\σL}}_r{\mathrm{\ω}}_{sl}{I}_{rd}$

Wherein: V _{d_eq}and V _{q_eq}be respectively sliding formwork control in equivalent control amount rotate d axle component in d-q coordinate system and q axle component in synchronous speed; Ψ _sdand Ψ _sqbe respectively stator magnetic linkage and rotate d axle component in d-q coordinate system and q axle component in synchronous speed; I _sdand I _sqbe respectively threephase stator electric current and rotate d axle component in d-q coordinate system and q axle component in synchronous speed, U _sdand U _sqbe respectively threephase stator voltage and rotate d axle component in d-q coordinate system and q axle component in synchronous speed; ω sl is slip angular velocity; L _sand L _rbe respectively stator inductance and the inductor rotor of DFIG, L _mfor the rotor mutual inductance of DFIG; σ=1-L _m ²/ (L _sl _r), be leakage inductance coefficient.

Switch control rule amount and equivalent control amount are added, obtain the d axle component V of synovial membrane controlled quentity controlled variable in synchronous speed rotation d-q coordinate system _dˊ and q axle component V _qˊ:

V _d′＝ΔV _d+V _{d_eq}

V _q′＝ΔV _q+V _{q_eq}

(4) Repetitive controller amount is calculated according to following formula:

${V_d}^{\′\′}=\frac{k_r{e}^{-sT}}{1-k_f{e}^{-sT}}\·{\mathrm{\ΔI}}_{sd}$

${V_q}^{\′\′}=\frac{k_r{e}^{-sT}}{1-k_f{e}^{-sT}}\·{\mathrm{\ΔI}}_{sq}$

Wherein: V _dˊ ˊ and V _qˊ ˊ is respectively Repetitive controller amount and rotates d axle component in d-q coordinate system and q axle component in synchronous speed; Δ I _sdwith Δ I _sqbe respectively stator current error and rotate d axle component in d-q coordinate system and q axle component in synchronous speed, with be respectively d axle and the q axle component of stator harmonic current reference quantity, i _sdand I _sqbe respectively threephase stator electric current and rotate d axle component in d-q coordinate system and q axle component in synchronous speed; k _rfor given Repetitive controller coefficient; k _ffor improving the given coefficient of Repetitive controller stability; S is Laplacian; T=0.01.

(5) the dq axle component of the dq axle component and Repetitive controller amount that synchronous speed are rotated the sliding-mode control law in d-q coordinate system is added respectively, obtains the rotor voltage instruction in synchronous speed rotation d-q coordinate system;

V _rd＝V _d′+V _d″

V _rq＝V _q′+V _q″

Wherein: V _rdand V _rqbe respectively rotor voltage instruction and rotate d axle component in d-q coordinate system and q axle component in synchronous speed;

The component utilizing the 7 pairs of rotor voltage instructions of Parker inverse transform block to rotate in d-q coordinate system in synchronous speed carries out Park inverse transformation, obtains the component of rotor voltage instruction in stationary rotor alpha-beta coordinate system; The transformation matrix of Parke inverse transformation is as follows:

$\left[\begin{array}{c}{V}_{r\mathrm{\α}}\\ V_{r\mathrm{\β}}\end{array}\right]=\left[\begin{array}{cc}{\mathrm{cos\θ}}_r& -{\mathrm{sin\θ}}_r\\ {\mathrm{sin\θ}}_r& {\mathrm{cos\θ}}_r\end{array}\right].\left[\begin{array}{c}{V}_{rd}\\ V_{rq}\end{array}\right]$

And then according to the component V of rotor voltage instruction in stationary rotor alpha-beta coordinate system _{r α}~ V _{r β}, utilize SVPWM modulation module 8 to obtain one group of pwm signal S by SVPWM technical construction _a~ S _cto carry out switch control rule to the device for power switching in DFIG pusher side current transformer 9.

We specify the DFIG of subharmonic control method and present embodiment to emulate to adopting tradition respectively below, and concrete simulation result is as follows:

Adopt tradition to specify subharmonic control method, eliminate the specific subharmonic of electrical network to the adverse effect of DFIG.Specified subharmonic is 5 times and 7 subharmonic, controls object sinusoidal for eliminating DFIG stator current.In Fig. 3 (a), line voltage distorts containing 10%5 times and 10%7 subharmonic voltages, adopts traditional appointment subharmonic control method, and 5 times of the DFIG stator current caused by 5 times and 7 subharmonic voltages and 7 subharmonic have been eliminated.In Fig. 3 (b), electrical network is containing 10%7 times and the distortion of 10%13 subharmonic voltages, adopt traditional appointment subharmonic control method, eliminate by stator current 7 subharmonic of specifying time 7 subharmonic voltages to cause, but stator 13 subharmonic current caused due to electrical network 13 subharmonic is not eliminated.In Fig. 3 (c), electrical network is containing 10%17 times and the distortion of 10%19 subharmonic voltages, because 17 times and 19 subharmonic are not all in appointment subharmonic control range, traditional appointment subharmonic control method can not eliminate the stator current 17 times and 19 subharmonic that are caused by 17 times and 19 subharmonic voltages.As can be seen here, adopt traditional appointment subharmonic control method, the specific subharmonic of electrical network can only be eliminated to the distortion effects of output stator electric current, and when electrical network exists the pollution of other subharmonic, its other subharmonic caused still exist.

Adopt present embodiment under any subharmonic distortion of electrical network condition, the harmonic component of DFIG stator current is all able to effective suppression.In Fig. 4 (a), line voltage is containing 10%5 times and the distortion of 10%7 subharmonic voltages, and the stator current caused by 5 times and 7 subharmonic voltages 5 times and 7 subharmonic have all been eliminated.In Fig. 4 (b), electrical network distorts containing 10%7 times and 10%13 subharmonic voltages, and 7 times of stator current and 13 subharmonic have also all been eliminated.In Fig. 4 (c), electrical network distorts containing 10%17 times and 10%19 subharmonic voltages, causes stator current 17 times and 19 subharmonic are also eliminated substantially by 17 times and 19 subharmonic voltages.As can be seen here, any order harmonic components of the stator current that any subharmonic adopting present embodiment can eliminate electrical network causes.

Therefore, present embodiment improves the runnability of system under any subharmonic, not only increases dynamic performance, also improves the runnability of system under any subharmonic.

Claims (6)

1., based on a DFIG control method for sliding formwork+repetition, comprise the steps:

(1) gather the threephase stator voltage of DFIG, threephase stator electric current, three-phase rotor current, rotating speed and rotor position angle, determine that the threephase stator voltage of DFIG, threephase stator electric current, three-phase rotor current, stator magnetic linkage and rotor flux rotate the component in d-q coordinate system in synchronous speed according to rotor position angle by coordinate transform;

(2) the d axle component of given rotor current reference value is made with q axle component deduct the d axle component I of rotor current actual value respectively _rdwith q axle component I _rq, obtain the d axle component Δ I of the rotor current margin of error _rdwith q axle component Δ I _rq; Respectively to the d axle component Δ I of the rotor current margin of error _rdwith q axle component Δ I _rqcarry out PI adjustment, obtain d axle sliding formwork value S _dwith q axle sliding formwork value S _q;

(3) according to described d axle sliding formwork value S _dwith q axle sliding formwork value S _q, calculate synchronous speed and rotate the switch control rule amount that in d-q coordinate system, sliding formwork controls; According to the electric parameters gathered and DFIG model parameter, calculate synchronous speed and rotate the equivalent control amount that in d-q coordinate system, sliding formwork controls; Switch control rule and equivalent control amount are added, obtain the sliding-mode control law in synchronous speed rotation d-q coordinate system;

(4) the d axle component of given stator current reference is made with q axle component deduct the d axle component I of stator current actual value respectively _sdwith q axle component I _sq, respectively to the d axle component Δ I of stator current error amount _sdwith q axle component Δ I _sqcarry out Repetitive controller adjustment, obtain the Repetitive controller amount in synchronous speed rotation d-q coordinate system;

(5) make the sliding-mode control law in synchronous speed rotation d-q coordinate system and Repetitive controller amount be added, obtain the rotor voltage instruction in synchronous speed rotation d-q coordinate system; Park conversion is carried out to the component that rotor voltage instruction rotates in d-q coordinate system in synchronous speed, obtains the component of rotor voltage instruction in stationary rotor alpha-beta coordinate system; And then obtain one group of pwm signal to control DFIG pusher side current transformer according to the component of rotor voltage instruction in stationary rotor alpha-beta coordinate system by SVPWM technical construction.

2. a kind of DFIG control method based on sliding formwork+repetition according to claim 1, is characterized in that: calculate stator magnetic linkage and the component of rotor flux in synchronous speed rotation d-q coordinate system according to following formula:

ψ _sd＝L _sI _sd+L _mI _rdψ _rd＝L _rI _rd+L _mI _sd

ψ _sq＝L _sI _sq+L _mI _rqψ _rq＝L _rI _rq+L _mI _sq

Wherein: Ψ _sdand Ψ _sqbe respectively stator magnetic linkage and rotate d axle component in d-q coordinate system and q axle component in synchronous speed, Ψ _rdand Ψ _rqbe respectively rotor flux and rotate d axle component in d-q coordinate system and q axle component in synchronous speed, I _sdand I _sqbe respectively threephase stator electric current and rotate d axle component in d-q coordinate system and q axle component in synchronous speed, I _rdand I _rqbe respectively three-phase rotor current and rotate d axle component in d-q coordinate system and q axle component in synchronous speed, L _sand L _rbe respectively stator inductance and the inductor rotor of DFIG, L _mfor the rotor mutual inductance of DFIG.

3. a kind of DFIG control method based on sliding formwork+repetition according to claim 1, is characterized in that: in described step (2), calculates the d axle sliding formwork value S in synchronous speed rotation d-q coordinate system according to following formula _dwith q axle sliding formwork value S _q:

$S_d=(k_p+\frac{k_i}{s})\·{\mathrm{\ΔI}}_{rd}$

$S_q=(k_p+\frac{k_i}{s})\·{\mathrm{\ΔI}}_{rq}$

Wherein: Δ I _rdwith Δ I _rqbe respectively rotor current error and rotate d axle component in d-q coordinate system and q axle component in synchronous speed, with be respectively d axle rotor current reference quantity and q axle rotor current reference quantity, I _rdand I _rqbe respectively three-phase rotor current and rotate d axle component in d-q coordinate system and q axle component in synchronous speed, k _pfor given proportionality coefficient, k _ifor given integral coefficient, s is Laplacian.

4. a kind of DFIG control method based on sliding formwork+repetition according to claim 1, is characterized in that: in described step (3), calculates the switch control rule amount of sliding formwork control according to following formula:

ΔV _d＝k _ssat(S _d)+k _iΔI _rd

ΔV _q＝k _ssat(S _q)+k _iΔI _rq

Wherein: Δ V _rdwith Δ V _rqbe respectively sliding formwork control in switch control rule amount rotate d axle component in d-q coordinate system and q axle component in synchronous speed, sat is saturation function, k _sfor given sliding formwork control coefrficient.

5. a kind of DFIG control method based on sliding formwork+repetition according to claim 1, is characterized in that: in described step (3), calculates the equivalent control amount of sliding formwork control according to following formula:

$V_{d\_eq}=\frac{L_m}{L_s}(U_{sd}-{\mathrm{\ω}}_{sl}{\mathrm{\ψ}}_{sq})+R_r{I}_{rd}-{\mathrm{\σL}}_r{\mathrm{\ω}}_{sl}{I}_{rq}$

$V_{q\_eq}=\frac{L_m}{L_s}(U_{sq}+{\mathrm{\ω}}_{sl}{\mathrm{\ψ}}_{sd})+R_r{I}_{rq}+{\mathrm{\σL}}_r{\mathrm{\ω}}_{sl}{I}_{rd}$

Wherein: V _{d_eq}and V _{q_eq}be respectively sliding formwork control in equivalent control amount rotate d axle component in d-q coordinate system and q axle component in synchronous speed; Ψ _sdand Ψ _sqbe respectively stator magnetic linkage and rotate d axle component in d-q coordinate system and q axle component in synchronous speed; I _sdand I _sqbe respectively threephase stator electric current and rotate d axle component in d-q coordinate system and q axle component in synchronous speed, U _sdand U _sqbe respectively threephase stator voltage and rotate d axle component in d-q coordinate system and q axle component in synchronous speed; ω _slfor slip angular velocity; L _sand L _rbe respectively stator inductance and the inductor rotor of DFIG, L _mfor the rotor mutual inductance of DFIG; σ=1-L _m ²/ (L _sl _r), be leakage inductance coefficient;

Switch control rule amount and equivalent control amount are added, obtain the d axle component V of synovial membrane controlled quentity controlled variable in synchronous speed rotation d-q coordinate system _dˊ and q axle component V _qˊ:

V _d′＝ΔV _d+V _{d_eq}

V _q′＝ΔV _q+V _{q_eq}。

6. a kind of DFIG control method based on sliding formwork+repetition according to claim 1, is characterized in that: in described step (4), calculates Repetitive controller amount according to following formula:

${V_d}^{\′\′}=\frac{k_r{e}^{-sT}}{1-k_f{e}^{-sT}}\·{\mathrm{\ΔI}}_{sd}$

${V_q}^{\′\′}=\frac{k_r{e}^{-sT}}{1-k_f{e}^{-sT}}\·{\mathrm{\ΔI}}_{sq}$

Wherein: V _d" and V _q" be respectively Repetitive controller amount and rotate d axle component in d-q coordinate system and q axle component in synchronous speed; Δ I _sdwith Δ I _sqbe respectively stator current error and rotate d axle component in d-q coordinate system and q axle component in synchronous speed, with be respectively d axle and the q axle component of stator harmonic current reference quantity, i _sdand I _sqbe respectively threephase stator electric current and rotate d axle component in d-q coordinate system and q axle component in synchronous speed; k _rfor given Repetitive controller coefficient; k _ffor improving the given coefficient of Repetitive controller stability; S is Laplacian; T=0.01.