CN101741096A - Delayless control method of rotor current of grid-connection, speed-change and constant-frequency double-fed induction wind driven generator - Google Patents

Abstract

The invention discloses a delayless control method of rotor current of a grid-connection, speed-change and constant-frequency double-fed induction wind driven generator (DFIG). The conversion of a rotational coordinate is carried out by collecting three-phase rotor current signals, the feedback quantity of rotor current in a corotation synchronous-speed rotating coordinate system is obtained and is compared with a rotor current command in the same coordinate system, an error signal is inputted into a proportional-integral-complex coefficient resonance regulator for regulation, and the rotor reference voltage in the corotation synchronous-speed rotating coordinate system is obtained after feedback compensation decoupling and then converted into the rotor reference voltage used for space vector pulse width modulation (SVPWM) in the rotor coordinate system to generate a switching signal of a power device of a rotor side convertor so that DFIG grid-connected operation can be controlled. The method does not need to carry out positive and negative sequence decomposition of rotor current under balanced or unbalanced grid voltage, can not introduce decomposition time delay and can realize the reinforced control target of a power generation system under the unbalanced grid voltage, thereby effectively increasing the ride-through (uninterrupted) operation capability of a wind power system under power grid failure.

Description

The variable speed constant frequency doubly-fed induction wind driven generator rotor current non-delay control method of grid type

Technical field

The present invention relates to the control method of wind power generator rotor current, especially a kind ofly be applicable to the variable speed constant frequency doubly-fed induction wind driven generator of grid type (DFIG) rotor current non-delay control method under line voltage balance and imbalance (comprising little value stable state and the big value transient state imbalance) condition.

Background technology

Modern large-scale wind powered generation syst mainly contains two types of double fed induction generators (DFIG) and magneto alternators, is to improve generating efficiency, all carries out variable speed constant frequency generator and moves, and wherein the DFIG system is current mainstream model.The wind power technology of China rests on the operation control under the desirable electrical network condition mostly at present, because actual electric network often has all kinds of symmetries, unbalanced fault to take place, therefore must carry out the operation Control Study under the electric network fault and propose corresponding control method.In recent years in the world the research of DFIG wind-powered electricity generation running technology focus mostly under symmetric fault operation control with pass through operation, but the electrical network unbalanced fault is more frequent, probability is bigger, so the research of DFIG failure operation is extended to unbalanced fault from symmetric fault.This be because in the DFIG control system if do not consider the imbalance of line voltage, very little unbalance voltage will cause the height imbalance of stator current, cause stator winding to produce uneven heating, generator produces torque pulsation, and the power that causes transferring to electrical network vibrates.If the relative net capacity of wind-powered electricity generation unit is enough big, the wind-powered electricity generation unit of this shortage unbalanced electric grid voltage control ability off-the-line from electrical network of having to is in case cause follow-up bigger electric network fault.But consider from the power grid security angle, China State Grid Corporation of China clearly stipulates when wind farm grid-connected some negative sequence voltage degree of unbalance 2%, in short-term under transient state 4% situation, wind-powered electricity generation unit in the wind energy turbine set should be able to continue not that off-grid normally moves, and promptly has the uneven electric network fault ability that runs without interruption.At present, the home and abroad is studied the control method and the embodiment of DFIG generator under this unbalanced electric grid voltage condition and relevant excitation converter, and retrieving representative correlative study article and patent has:

I.L.Xu，and?Y.Wang，“Dynamic?Modeling?and?Control?of?DFIG?Based?Wind?Turbines?underUnbalanced?Network?Conditions，”IEEE?Trans.Power?System，Vol.22，No.1，pp.314-323，Feb.2007.

II.Jiabing?Hu，Yikang?He，Heng?Nian，“Enhanced?Control?of?DFIG?used?back-to-back?PWMVoltage-Source?Converter?under?Unbalanced?Grid?Voltage?Conditions”，Journal?of?ZhejiangUniversity，SCIENCE?A，Vol.8，No.8，pp：1330-1339，Aug.2007.

III.CARTWRIGHT?P，XU?L.System?controller?for?e.g.wind?powered?doubly?fed?inductiongenerator?attached?to?wind?turbine，has?grid?imbalance?detector?which?controls?current?to?cancelimbalance?in?grid?served?by?generators?[Patent].Patent?Number：GB2420456-A.Date：20060524.Application?Number：GB025662.Date：20041123.

Under the unbalanced electric grid voltage condition, the available Fig. 1 of the control method that above-mentioned document proposed (can be described as conventional method) illustrates, the rotor-side converter 1 of DFIG5 adopts two proportional-integral controllers 16 respectively the positive and negative preface electric current of rotor to be done independent control.But for realizing the adjusting respectively of positive and negative preface rotor current, must at first obtain to feed back the positive and negative preface component of rotor current, its processing procedure is: utilize two groups of six current Hall transducers 2 to gather three-phase stator and rotor current signal respectively, one group of three voltage sensor 7 is gathered threephase stator voltage signal, the three-phase stator and rotor current signal I that collects _SabcAnd I _Rabc, stator voltage signal U _SabcPass through static three-phase/two-phase coordinate transformation module 3 respectively, be converted to the synthetic vector I that comprises positive and negative preface component _{S α β} ^sAnd I _{R α β} ^r, U _{S α β} ^s, U wherein _{S α β} ^s, I _{S α β} ^sBe converted to forward and backward with the U that comprises DC quantity and two frequency multiplication of ac sums in the leg speed rotating coordinate system by rotating coordinate transformation module 8,9 respectively _Sdq ⁺, U _Sdq ^-, I _Sdq ⁺, I _Sdq ^-(under the unbalanced source voltage condition), I _{R α β} ^rBy 10,11 conversions of two different rotating coordinate transformation modules, obtain forward and backward respectively with the I that comprises DC quantity and two frequency multiplication of ac sums in the leg speed rotating coordinate system _Rdq ⁺, I _Rdq ^-(under the unbalanced source voltage condition).Twice mains frequency 2 ω have been adopted in this method ₁Trapper come filtered signal U _Sdq ⁺, U _Sdq ^-, I _Sdq ⁺, I _Sdq ^-And I _Rdq ⁺, I _Rdq ^-In 2 ω ₁The alternating component of frequency, wherein U _Sdq ⁺, U _Sdq ^-, I _Sdq ⁺, I _Sdq ^-Obtain its positive and negative preface component U respectively by first trapper 13-1 _Sdq+ ⁺, U _Sdq- ^-, I _Sdq+ ⁺, I _Sdq- ^-(DC quantity); I _Rdq ⁺, I _Rdq ^-Obtain its positive and negative preface component I respectively by second trapper 13-2 _Rdq+ ⁺, I _Rdq- ^-(DC quantity).On this basis, stator flux observer 14 obtains the required stator magnetic linkage component ψ of rotor current command value computing module 15 and feedback compensation decoupling zero module 12 _Sdq+ ⁺, ψ _Sdq- ^-Calculate acquisition rotor current instruction I according to the controlled target that DFIG is different under the unbalanced source voltage condition by rotor current command value computing module 15 _Rdq+ ^{+ *}, I _Rdq- ^-*, and with the feedback signal I of second trapper 13-2 output _Rdq+ ⁺, I _Rdq- ^-Relatively obtain error signal, then respectively forward and backward with the leg speed rotating coordinate system in 16 pairs of error signals of employing ratio-integrator make ratio-integration and regulate, signal after the adjusting obtains forward and backward with the positive and negative preface rotor voltage reference value U in the leg speed rotating coordinate system through feedback compensation decoupling zero module 12 compensated decouplings _Rdq+ ^{+ *}, U _Rdq- ^-*, be converted to positive and negative preface rotor voltage reference value in the rotor coordinate system by different rotating coordinate transformation modules 17,18 respectively, and obtain the reference signal U of space vector pulse width modulation (SVPWM) module 19 after the addition _{R α β} ^R*19 modulation obtain the switching signal of power device in the rotor-side converter 1 with control DFIG 5 operations through the SVPWM module, realize the DFIG 5 independent closed-loop controls of positive and negative preface rotor current in the forward and backward synchronous rotating frame under the unbalanced electric grid voltage condition, reach the desired control target.

In addition, this method adopts software phase-lock loop (PLL) 6 circuit that the frequency and the phase place of line voltage are carried out accurate detection and tracking, rotor-position and speed adopt encoder 4 to measure, and realize the forward and backward rotating coordinate transformation for stator and rotor voltage, current signal foundation is provided.

By above-mentioned analytic process as seen, the essence of traditional DFIG control method is asymmetric system to be resolved into positive and negative ordered pair weigh after the system under the unbalanced source voltage condition, realizes d, the control of q decoupler shaft more respectively in the forward and backward synchronous rotating frame.Though the positive and negative preface electric current of rotor shows as DC quantity separately in the forward and backward synchronous rotating frame, adopt two pi regulators can realize the independently tracked control of floating respectively, but the prerequisite that control is implemented is to have realized the positive and negative preface of gathering rotor current is separated.2 ω have generally been adopted in positive and negative preface separation in traditional control method shown in Figure 1 ₁The separation method of frequency trap 13.Except that introducing time-delay, the bandwidth of control system will be affected, and can cause dynamic tracking error in the separation, and it is undesirable dynamically to control effect.What is more, and it is balance or imbalance that this circuit can't be distinguished line voltage, whether needs to carry out positive and negative preface system decomposition.If DFIG operates under the strict line voltage poised state, control system will adopt trapper to come the separation rotor variable, and this will bring unnecessary time-delay to the normal control of system, have a strong impact on the dynamic control performance of system.

Therefore, need badly and explore a kind of positive and negative preface rotor current control method of not having time-delay, to adapt to the operation control of DFIG wind-powered electricity generation unit under grid balance and the uneven condition.

Summary of the invention

The purpose of this invention is to provide a kind of variable speed constant frequency doubly-fed induction wind driven generator rotor current non-delay control method of grid type that the positive and negative preface of rotor current is decomposed that under unbalanced electric grid voltage, need not to carry out.This method also can not introduced the control time-delay because of unnecessary positive and negative preface operation splitting under the strict balance of line voltage, thereby effectively improve the operation control performance of DFIG wind power system under all kinds of line voltage conditions, the operation stability and the safety of guarantee the to power quality of power supply and electric power system.

The variable speed constant frequency doubly-fed induction wind driven generator rotor current non-delay control method of grid type of the present invention may further comprise the steps:

(i) utilize two groups of six current sensors to gather the threephase stator electric current I respectively _SabcWith rotor current signal I _Rabc, one group of three voltage sensor is gathered threephase stator voltage signal U _Sabc

The threephase stator voltage signal U that (ii) collects _SabcDetect through software phase-lock loop, obtain the stator voltage angular frequency ₁And phase theta ₁Meanwhile adopt encoder to detect DFIG rotor position angle θ _rAnd rotational speed omega _rAnd calculate slippage angle ± θ through the plus-minus calculator respectively ₁-θ _rWith the slippage angular frequency _Slip+=ω ₁-ω _r, ω _SlipThe ω of-=- ₁-ω _r

(iii) with the three-phase stator and rotor current signal I that collects _Sabc, I _RabcWith stator voltage signal U _SabcPass through static three-phase/two-phase coordinate transformation module respectively, obtain comprising the stator voltage synthetic vector U of positive and negative preface component _{S α β} ^s, stator and rotor electric current synthetic vector I _{S α β} ^sAnd I _{R α β} ^r

(iv) with stator voltage, electric current synthetic vector U in the stator rest frame that obtains _{S α β} ^s, I _{S α β} ^sBy just changeing, obtain under the unbalanced source voltage condition, just changeing respectively with containing DC quantity and two frequencys multiplication, 2 ω in the leg speed rotating coordinate system with leg speed rotating coordinate transformation module ₁The voltage vector U of of ac sum _Sdq ⁺, current phasor I _Sdq ⁺, again with stator voltage synthetic vector U _{S α β} ^s, obtain under the unbalanced source voltage condition, reversing with leg speed rotational coordinates module by counter-rotating with containing DC quantity and two frequencys multiplication, 2 ω in the leg speed rotating coordinate system ₁The voltage vector U of of ac sum _Sdq ^-

(v) adopt 2 ω of twice mains frequency ₁Trapper filtering forward and backward is with voltage vector U in the leg speed rotating coordinate system _Sdq ⁺, U _Sdq ^-In 2 ω ₁The frequency alternating component obtains positive and negative sequence voltage DC component U _Sdq+ ⁺, U _Sdq- ^-

(vi) adopt stator flux observer, obtain feedback compensation decoupling zero module and carry out the required just commentaries on classics of feedforward compensation with stator magnetic linkage component ψ in the leg speed rotating coordinate system _Sdq ⁺

(vii) with the rotor current synthetic vector I that obtains _{R α β} ^rThrough the rotating coordinate transformation module converts for just to change with the rotor current feedback signal I in the leg speed rotating coordinate system _Rdq ⁺, it includes positive sequence flip-flop I under the unbalanced source voltage condition _Rdq+ ⁺With twice mains frequency 2 ω ₁The negative phase-sequence alternating component

(, calculate forward and backward with the instruction of the rotor current in leg speed rotating coordinate system I by rotor current command value computing module viii) according to the required controlled target of DFIG under the unbalanced source voltage condition _Rdq+ ^{+ *}, I _Rdq- ^-*, this current instruction value is passed through rotating coordinate transformation module converts for just to change with the rotor current command value I in the leg speed rotating coordinate system _Rdq ^{+ *}, and with just change with the rotor current feedback signal I in the leg speed rotating coordinate system _Rdq ⁺Relatively, obtain error signal Δ I _Rdq ⁺

(ix) rotor current error signal Δ I _Rdq ⁺Do ratio-integration-complex coefficient resonance adjusting through just changeing, regulate the back output signal U with the ratio-integration in the leg speed rotating coordinate system-complex coefficient resonant controller _Rdq ^{+ * '}Process feedback compensation decoupling zero module is finished and is just changeed with cross decoupling between friendship-d-axis and dynamic feedback compensation in the leg speed rotating coordinate system, obtains the rotor voltage reference value U that just changes with in the leg speed rotating coordinate system _Rdq ^{+ *}

(x) just changeing with the rotor voltage reference value U in the leg speed rotating coordinate system _Rdq ^{+ *}By the rotating coordinate transformation module, obtain the required rotor coordinate system rotor voltage reference signal U of space vector pulse width modulation module modulation _{R α β} ^R*, this signal obtains the switching signal S of the rotor-side inverter power device of control DFIG operation through space vector pulse width modulation module modulation back _a, S _b, S _c

The present invention is said just to be changeed with the ratio-integration in the leg speed rotating coordinate system-complex coefficient resonance (Proportional Integral-Complex Coefficient Resonant, PI-CCR) controller, it comprises that it is ω that a proportional component, integral element and one are just changeing with angular frequency in the leg speed rotating coordinate system ₀=-2 ω ₁The complex coefficient resonator, wherein the complex coefficient resonator realizes that align commentaries on classics is 2 ω with angular frequency in the leg speed rotating coordinate system ₁The unlimited gain-adjusted of negative phase-sequence rotor current composition.

Control method of the present invention is based on just to change with the positive and negative preface electric current of the DFIG rotor in the leg speed rotating coordinate system and need not to decompose, do not have time-delay control.At different operation controlled target under the DFIG wind power system unbalanced electric grid voltage condition, by positive and negative preface electric current of unbalance voltage lower rotor part and the relation that has, reactive power is instructed, at first establish positive and negative preface rotor current command value, and it is converted into the global command value that comprises positive and negative preface rotor current of just changeing with in the leg speed rotating coordinate system by corresponding rotating coordinate transformation respectively.No matter the present invention all need not the rotor current feedback signal is carried out positive and negative preface decomposition when line voltage balance and imbalance in the control, only need by three-phase rotor current feedback signal is made corresponding rotating coordinate transformation, obtaining is just changeing with the rotor current feedback quantity in the leg speed rotating coordinate system.This signal all shows as DC quantity and twice mains frequency of ac sum with just changeing with the global command value in the leg speed rotating coordinate system, after both are compared, its error signal is input to ratio-integration-complex coefficient resonance (PI-CCR) adjuster, output signal after Comparative Examples-integration-complex coefficient resonance current controller is regulated is carried out the feedback compensation decoupling zero, can just be changeed with the rotor voltage reference value in the leg speed rotating coordinate system, be converted into space vector pulse width modulation reference signal in the rotor coordinate system by rotating coordinate transformation again, generate the pwm switch signal of power device of inverter through ovennodulation, the output current wave and the amplitude of control rotor-side converter are to realize the operation controlled target of DFIG.

Control method of the present invention is simple.Than traditional control method, need not to increase extra hardware detection or controlling unit, only traditional forward and backward need be replaced with the positive and negative preface of the rotor current in the leg speed rotating coordinate system, two proportional-integral controller just changes with the single ratio-integration in the leg speed rotating coordinate system-complex coefficient resonance adjuster.When the rotor current control ring designs, because the positive and negative preface that need not to adopt trapper to carry out the rotor current feedback signal is decomposed, can therefore not introduce and decompose time-delay, and integral element there is unlimited gain to flip-flop in the designed PI-CCR controller, and twice mains frequency 2 ω ₁Complex coefficient resonance link only to twice mains frequency 2 ω ₁The negative phase-sequence of ac unlimited gain is arranged, when guaranteeing system stability, obtain the more control bandwidth of greater trochanter current closed-loop, thereby obtain stable output, less steady-state error and better dynamic response characteristic.Adopt this method can make the DFIG grid-connected system under line voltage balance and imbalance (comprising little value stable state and big value transient state imbalance) condition, realize that rotor current does not have time-delay control, especially under the unbalanced electric grid voltage condition, realize the enhancing controlled target of electricity generation system, effectively improve and pass through (uninterruptedly) serviceability under such wind power system electric network fault.

The inventive method is except that being applicable to the DFIG wind power system, can also be applicable to three-phase or the effective control of single-phase grid-connected inverter under balance and unbalanced electric grid voltage condition that other adopt all kinds of PWM control forms of HF switch self-turn-off device formation, parallel network reverse device as solar energy, fuel cell generation, the electronic power inversion device of flexible transmission system, and the effective control of convertor assembly of the double-fed dynamoelectric machine in the speed governing Electric Drive.

Description of drawings

Fig. 1 is under the unbalanced electric grid voltage condition, the variable speed constant frequency doubly-fed induction generator tradition of grid type control method schematic diagram.

Fig. 2 is the variable speed constant frequency doubly-fed induction wind driven generator rotor current non-delay control method of a grid type of the present invention schematic diagram.

Fig. 3 is the schematic diagram of ratio-integration-complex coefficient resonance (PI-CCR) controller among the present invention.

Fig. 4 is with positive and negative preface rotor current command value I among Fig. 2 _Rdq+ ^{+ *}, I _Rdq- ^-*Be converted to the command value I that just changes with in the leg speed rotating coordinate system _{R α β} ^{+ *}The rotating coordinate transformation module diagram.

Fig. 5 is under the uneven condition of line voltage 12.5% transient state, adopts the design sketch of traditional control method, among the figure, and (a) DFIG stator three-phase current (pu); (b) rotor three-phase electric current (pu); (c) DC bus-bar voltage (V); (d) rotor d axle forward-order current I _Rd+ ^{+ *}And I _Rd+ ⁺(pu); (e) rotor q axle forward-order current I _Rq+ ^{+ *}And I _Rq+ ⁺(pu); (f) rotor d axle negative-sequence current I _Rd- ^-*And I _Rd- ^-(pu); (g) rotor q axle negative-sequence current I _Rq- ^-*And I _Rq- ^-(pu); (h) stator active power of output (pu); (i) stator output reactive power (pu); (j) DFIG electromagnetic torque (pu).

Fig. 6 is under the uneven condition of line voltage 12.5% transient state, adopts the design sketch of control method of the present invention, among the figure, and (a) DFIG stator three-phase current (pu); (b) rotor three-phase electric current (pu); (c) DC bus-bar voltage (V); (d) rotor d axle forward-order current I _Rd+ ^{+ *}And I _Rd+ ⁺(pu); (e) rotor q axle forward-order current I _Rq+ ^{+ *}And I _Rq+ ⁺(pu); (f) rotor d axle negative-sequence current I _Rd- ^-*And I _Rd- ^-(pu); (g) rotor q axle negative-sequence current I _Rq- ^-*And I _Rq- ^-(pu); (h) stator active power of output (pu); (i) stator output reactive power (pu); (j) DFIG electromagnetic torque (pu).

Fig. 7 is the static α of stator _sβ _sCoordinate system, rotor speed rotation alpha _rβ _rCoordinate system and forward and backward are with leg speed ω ₁Rotation dq ₊, dq _-Vector correlation figure between coordinate system.

Embodiment

The present invention is further described below in conjunction with accompanying drawing and embodiment.

Fig. 2 is the schematic diagram that adopts the variable speed constant frequency doubly-fed induction wind driven generator rotor current non-delay control method of grid type of the present invention's proposition, comprise controlling object DFIG5, the rotor-side converter 1 that is connected with the DFIG rotor (two level or three level voltage type PWM inverters), be used for the Hall element 2 of three-phase stator and rotor current detecting and the Hall element 7 of threephase stator voltage detecting, be used to detect the encoder 4 of DFIG rotor-position and speed, and the control loop of realizing DFIG controlled target under the unbalanced source voltage condition.Control loop is made of feedback signal treatment channel and forward direction control channel, wherein the feedback signal treatment channel comprises the software phase-lock loop (PLL) 6 that is used for detection of grid voltage-phase and frequency, be used for the needed angle computer of various rotating coordinate transformations, be used for obtaining the three-phase/two-phase static coordinate conversion module 3 and the rotating coordinate transformation module 8 of corresponding coordinate system signal, 9,10, the stator flux observer 14 that is used to obtain the twice mains frequency trapper 13 of the positive and negative preface component of stator voltage and is used for stator flux observer; Forward direction control channel comprises the rotor current command value computing module 15 according to the required controlled target of unbalanced source voltage condition, will be just, counter-rotating is converted to the rotating coordinate transformation module 22 of just changeing with command value in the leg speed rotating coordinate system with the rotor current command value in the leg speed rotating coordinate system, the just commentaries on classics of rotor current not being had the time delay tracking Control is with ratio-integration in the leg speed rotating coordinate system-complex coefficient resonant controller (PI-CCR) 21 with for obtaining just changeing the feedback decoupling compensating module 20 with leg speed rotating coordinate system rotor voltage reference value, be used for just changeing the rotating coordinate transformation module 17 that is converted to reference value in the rotor coordinate system with the rotor voltage reference value of leg speed rotating coordinate system, and the SVPWM module 19 that is used for producing according to the rotor voltage reference value space vector pulse width modulation (SVPWM) signal.

With the commercial grid type variable speed constant frequency of 1.5MW DFIG wind power system is example, and with reference to Fig. 2, the method that adopts the present invention to propose is controlled its operation, and concrete implementation step is as follows:

(i) utilize two groups of six current sensors 2 to gather threephase stator current signal I respectively _SabcWith rotor current signal I _RabcOne group of three voltage sensor 7 is gathered threephase stator voltage signal U _Sabc

The threephase stator voltage signal U that (ii) collects _SabcDetect through software phase-lock loop 6, obtain the stator voltage angular frequency ₁And phase theta ₁, meanwhile adopt encoder 4 to detect the DFIG rotor position _rAnd rotational speed omega _rAnd calculate DFIG rotor slippage angle ± θ with angle computer respectively ₁-θ _rWith the slippage angular frequency _Slip+=ω ₁-ω _r, ω _SlipThe ω of-=- ₁-ω _r

(iii) with the three-phase stator and rotor current signal I that collects _Sabc, I _Rabc, stator voltage signal U _SabcPass through static three-phase/two-phase coordinate transformation module 3 respectively, obtain comprising the voltage synthetic vector U of positive and negative preface component _{S α β} ^s, electric current synthetic vector I _{S α β} ^sAnd I _{R α β} ^rWith the stator voltage is example, and its static three-phase/two-phase coordinate transform is as shown in the formula expression

$\left[\begin{array}{c}{U}_{\mathrm{s\α}}^s\\ U_{\mathrm{s\β}}^s\end{array}\right]=\sqrt{\frac{2}{3}}\left[\begin{array}{ccc}1& -\frac{1}{2}& -\frac{1}{2}\\ 0& \frac{\sqrt{3}}{2}& \frac{\sqrt{3}}{2}\end{array}\right]\left[\begin{array}{c}{U}_{\mathrm{sa}}\\ U_{\mathrm{sb}}\\ U_{\mathrm{sc}}\end{array}\right];$

(iv) with stator voltage, electric current synthetic vector U in the stator rest frame that obtains _{S α β} ^s, I _{S α β} ^sBy just changeing, obtain under the unbalanced source voltage condition, just changeing to contain DC quantity and two frequencys multiplication, 2 ω in the synchronous rotating frame respectively with leg speed rotating coordinate transformation module 9 ₁The voltage vector U of of ac sum _Sdq ⁺, current phasor I _Sdq ⁺, with stator voltage synthetic vector U _{S α β} ^s, obtain under the unbalanced source voltage condition, containing DC quantity and two frequencys multiplication, 2 ω in the counter-rotating synchronous rotating frame with leg speed rotational coordinates module 8 by counter-rotating ₁The voltage vector U of of ac sum _Sdq ^-

Fig. 7 is static α _sβ _sCoordinate system, spinner velocity rotation alpha _rβ _rCoordinate system and forward and backward are with leg speed ω ₁(equal the angular frequency of electrical network/stator voltage with leg speed ₁) rotation dq ₊, dq _-Vector correlation figure between coordinate system, its coordinate transformation relation is

$\begin{array}{cc}{F}_{\mathrm{dq}}^{+}=F_{\mathrm{\α\β}}^s{e}^{-j{\mathrm{\ω}}_{1}t}& F_{\mathrm{dq}}^{-}=F_{\mathrm{\α\β}}^s{e}^{j{\mathrm{\ω}1}_t}\end{array}$

$\begin{array}{cc}{F}_{\mathrm{dq}}^{+}=F_{\mathrm{\α\β}}^r{e}^{-j({\mathrm{\ω}}_1-{\mathrm{\ω}}_r)t}& F_{\mathrm{dq}}^{-}=F_{\mathrm{\α\β}}^r{e}^{j(-{\mathrm{\ω}}_1-{\mathrm{\ω}}_r)t}\end{array}$

$\begin{array}{cc}{F}_{\mathrm{dq}}^{+}=F_{\mathrm{dq}}^{-}{e}^{-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="H2009101571201E00011.png,H2009101571201E00012.png"\; state="\{\{state\}\}">j</figure-callout>}2{\mathrm{\&omega;}}_{1}t}& F_{\mathrm{dq}}^{-}=F_{\mathrm{dq}}^{+}{\mathrm{<figure-callout\; id="2"\; label="e\; j"\; filenames="H2009101571201E00011.png,H2009101571201E00012.png"\; state="\{\{state\}\}">e</figure-callout>}}^j\end{array}$

Wherein, broadly representative voltage, electric current and magnetic linkage of F; Subscript+,-, s, r represent that forward and backward is with leg speed rotating coordinate system, stator rest frame and rotor rotating coordinate system;

Under the unbalanced electric grid voltage condition, stator and rotor voltage, electric current and magnetic linkage can be expressed as forward and backward with leg speed ω ₁The form of corresponding positive and negative preface component in rotation dq+, the dq-coordinate system

$U_{\mathrm{sdq}}^{+}=U_{\mathrm{sdq}+}^{+}+U_{\mathrm{sdq}-}^{+}=U_{\mathrm{sdq}+}^{+}+U_{\mathrm{sdq}-}^{-}{e}^{-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="H2009101571201E00011.png,H2009101571201E00012.png"\; state="\{\{state\}\}">j</figure-callout>}2{\mathrm{\&omega;}}_{1}t}$

$I_{\mathrm{sdq}}^{+}=I_{\mathrm{sdq}+}^{+}+I_{\mathrm{sdq}-}^{+}=I_{\mathrm{sdq}+}^{+}+I_{\mathrm{sdq}-}^{-}{e}^{-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="H2009101571201E00011.png,H2009101571201E00012.png"\; state="\{\{state\}\}">j</figure-callout>}2{\mathrm{\&omega;}}_{1}t}$

${\mathrm{\&psi;}}_{\mathrm{sdq}}^{+}={\mathrm{\&psi;}}_{\mathrm{sdq}+}^{+}+{\mathrm{\&psi;}}_{\mathrm{sdq}-}^{+}={\mathrm{\&psi;}}_{\mathrm{sdq}+}^{+}+{\mathrm{\&psi;}}_{\mathrm{sdq}-}^{-}{e}^{-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="H2009101571201E00011.png,H2009101571201E00012.png"\; state="\{\{state\}\}">j</figure-callout>}2{\mathrm{\&omega;}}_{1}t}$

$U_{\mathrm{rdq}}^{+}=U_{\mathrm{rdq}+}^{+}+U_{\mathrm{rdq}-}^{+}=U_{\mathrm{rdq}+}^{+}+U_{\mathrm{rdq}-}^{-}{e}^{-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="H2009101571201E00011.png,H2009101571201E00012.png"\; state="\{\{state\}\}">j</figure-callout>}2{\mathrm{\&omega;}}_{1}t}$

$I_{\mathrm{rdq}}^{+}=I_{\mathrm{rdq}+}^{+}+I_{\mathrm{rdq}-}^{+}=I_{\mathrm{rdq}+}^{+}+I_{\mathrm{rdq}-}^{-}{e}^{-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="H2009101571201E00011.png,H2009101571201E00012.png"\; state="\{\{state\}\}">j</figure-callout>}2{\mathrm{\&omega;}}_{1}t}$

${\mathrm{\&psi;}}_{\mathrm{rdq}}^{+}={\mathrm{\&psi;}}_{\mathrm{rdq}+}^{+}+{\mathrm{\&psi;}}_{\mathrm{rdq}-}^{+}={\mathrm{\&psi;}}_{\mathrm{rdq}+}^{+}+{\mathrm{\&psi;}}_{\mathrm{rdq}-}^{-}{e}^{-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="H2009101571201E00011.png,H2009101571201E00012.png"\; state="\{\{state\}\}">j</figure-callout>}2{\mathrm{\&omega;}}_{1}t}$

Wherein, subscript+, the corresponding positive and negative preface component of-expression.As seen, each electric weight is just changeing with leg speed ω under the unbalanced electric grid voltage ₁Show as DC quantity and two frequencys multiplication, 2 ω in the rotation dq+ coordinate system ₁The of ac sum.With stator voltage U _Sdq ⁺Be example, U _Sdq ⁺Be illustrated in the positive sequence component in the dq+ coordinate system, be DC quantity; U _Sdq- ⁺Being illustrated in the negative sequence component in the dq+ coordinate system, is two frequency multiplication of acs

In like manner, each electric weight rotates in the dq-coordinate system with leg speed in counter-rotating and also shows as DC quantity and two frequency multiplication of ac sums;

(v) adopt 2 ω of twice mains frequency ₁Trapper 13 filtering forward and backwards are with voltage vector U in the leg speed rotating coordinate system _Sdq ⁺, U _Sdq ^-In 2 ω ₁The frequency alternating component obtains positive and negative sequence voltage DC component U _Sdq+ ⁺, U _Sdq- ^-

2 ω of twice mains frequency ₁Trapper 13 can be expressed with following formula

$\frac{{{\mathrm{\&omega;}}_0}^2}{{\mathrm{<figure-callout\; id="2"\; label="s"\; filenames="H2009101571201E00011.png,H2009101571201E00012.png"\; state="\{\{state\}\}">s</figure-callout>}}^2+2\mathrm{\&xi;}{\mathrm{\&omega;}}_{0}s+{{\mathrm{\&omega;}}_0}^2},$

In the formula, ξ is an attenuation coefficient, gets 0.707, ω ₀=2 ω ₁=200 π rad/s;

(vi) adopt stator flux observer 14 to obtain feedback compensation decoupling zero module 20 and compensate required just commentaries on classics with stator magnetic linkage component ψ in the leg speed rotation dq+ coordinate system _Sdq ⁺

(vii) with the rotor current synthetic vector I that obtains _{R α β} ^rBe converted to the rotor current amount I that just changes with in the leg speed rotation dq+ coordinate system through rotating coordinate transformation module 10 _Rdq ⁺, it includes positive sequence flip-flop I under the unbalanced source voltage condition _Rdq+ ⁺With twice mains frequency 2 ω ₁The negative phase-sequence alternating component

Rotating coordinate transformation module 10 can be expressed with following formula

$\left[\begin{array}{c}{I}_{\mathrm{rd}}^{+}\\ I_{\mathrm{rq}}^{+}\end{array}\right]=\left[\begin{array}{cc}\cos ({\mathrm{\&theta;}}_1-{\mathrm{\&theta;}}_r)& \sin ({\mathrm{\&theta;}}_1-{\mathrm{\&theta;}}_r)\\ -\sin ({\mathrm{\&theta;}}_1-{\mathrm{\&theta;}}_r)& \cos ({\mathrm{\&theta;}}_1-{\mathrm{\&theta;}}_r)\end{array}\right]\left[\begin{array}{c}{I}_{\mathrm{r\&alpha;}}^r\\ I_{\mathrm{r\&beta;}}^r\end{array}\right];$

(, calculate forward and backward with the instruction of the rotor current in leg speed rotating coordinate system I by rotor current command value computing module 15 viii) according to the required controlled target of DFIG under the unbalanced source voltage condition _Rdq+ ^{+ *}, I _Rdq- ^-*, with this current instruction value I _Rdq+ ^{+ *}, I _Rdq- ^-*Be converted to the rotor current command value I that just changes with in the leg speed rotation dq+ coordinate system through rotating coordinate transformation module 22 _Rdq ^{+ *}, and with just change with the rotor current feedback signal I in the leg speed rotation dq+ coordinate system _Rdq ⁺Relatively obtain error signal Δ I _Rdq ⁺,

Rotating coordinate transformation module 22 as shown in Figure 4, available following formula is expressed

$\left[\begin{array}{c}{I}_{\mathrm{rd}}^{+*}\\ I_{\mathrm{rq}}^{+*}\end{array}\right]=\left[\begin{array}{c}{I}_{\mathrm{rd}+}^{+*}\\ I_{\mathrm{rq}+}^{+*}\end{array}\right]+\left[\begin{array}{cc}\cos \left(2{\mathrm{\&theta;}}_1\right)& \sin \left(2{\mathrm{\&theta;}}_1\right)\\ -\sin \left(2{\mathrm{\&theta;}}_1\right)& \cos \left(2{\mathrm{\&theta;}}_1\right)\end{array}\right]\left[\begin{array}{c}{I}_{\mathrm{rd}-}^{-*}\\ I_{\mathrm{rq}-}^{-*}\end{array}\right];$

(ix) rotor current error signal Δ I _Rdq ⁺Do ratio-integration-complex coefficient resonance adjusting through just changeing, regulate the back output signal U with the ratio-integration in the leg speed rotating coordinate system-complex coefficient resonant controller 21 _Rdq ^{+ * '}Process feedback compensation decoupling zero module 20 is finished and is just changeed with cross decoupling and dynamic feedback compensation between the friendship-d-axis in the leg speed rotating coordinate system, obtains the rotor voltage reference value U that just changes with in the leg speed rotating coordinate system _Rdq ^{+ *}

As the above analysis, in the dq+ coordinate system, realize rotor current I _Rdq ⁺The floating tracking Control, must be to DC component I _Rdq+ ⁺And alternating current component Realize overall floating adjusting simultaneously.Thereby when design DFIG rotor current controller, adopt integral element, at negative phase-sequence alternating component employing-2 ω of twice mains frequency at flip-flop ₁The complex coefficient resonator has constituted rotor current ratio-integration-complex coefficient resonance (PI-CCR) controller 21 with this, as shown in Figure 3.Ratio-integration among the figure-complex coefficient resonance (PI-CCR) controller 21 bodies comprise a proportional component, an integral element and one-2 ω ₁Complex coefficient resonance link, realize rotor current error signal Δ I _Rdq ⁺=I _Rdq ^{+ *}-I _Rdq ⁺Floating regulate.

The frequency domain presentation of PI-CCR current controller 21 is

$C_{\mathrm{PI}-\mathrm{CCR}}\left(s\right)=K_{\mathrm{iP}}+\frac{K_{\mathrm{iI}}}{s}+\frac{{\mathrm{\&omega;}}_c{K}_{\mathrm{iCCR}}}{s+j{\mathrm{\&omega;}}_0+{\mathrm{\&omega;}}_c}$

In the formula, K _IP, K _Il, K _ICCRBe ratio, integration and resonance coefficient, ω _cBe frequency of fadings, ω ₀=200 π rad/s.

The output U of ratio-integration-complex coefficient resonant controller _Rdq ^{+ * '}Generate DFIG rotor voltage instruction U through feedback compensation decoupling zero module 20 _Rdq ^{+ *}To produce rotor current I _Rdq ⁺, realize the operation control under the unbalanced electric grid voltage condition, in Fig. 3 control procedure

For equivalent DFIG rotor back-emf disturbs, and F (s)=1/ (s σ L _r+ R _r) be DFIG rotor Mathematical Modeling, in the formula,

L _m, L _s, L _rBe respectively DFIG mutual inductance, stator and rotor self-induction, R _rBe rotor resistance.

Wherein, feedback compensation decoupling zero module 20 can be finished by following expression formula, is promptly just changeing with leg speed rotation dq+ coordinate system rotor voltage reference value can be expressed as

$\left\{\begin{array}{c}{U}_{\mathrm{rd}}^{+*}=U_{\mathrm{rd}}^{+*\&prime;}+\frac{L_m}{L_s}(U_{\mathrm{sd}}^{+}-R_s{I}_{\mathrm{sd}}^{+}+{\mathrm{\&omega;}}_r{\mathrm{\&psi;}}_{\mathrm{sq}}^{+})+(R_r{I}_{\mathrm{rd}}^{+}-{\mathrm{\&omega;}}_{\mathrm{slip}+}\mathrm{\&sigma;}{L}_r{I}_{\mathrm{rq}}^{+})\\ U_{\mathrm{rq}}^{+*}{=U}_{\mathrm{rq}}^{+*\&prime;}+\frac{L_m}{L_s}(U_{\mathrm{sq}}^{+}-R_s{I}_{\mathrm{rq}}^{+}-{\mathrm{\&omega;}}_r{\mathrm{\&psi;}}_{\mathrm{sd}}^{+})+(R_r{I}_{\mathrm{rq}}^{+}+{\mathrm{\&omega;}}_{\mathrm{slip}+}\mathrm{\&sigma;}{L}_r{L}_{\mathrm{rd}}^{+})\end{array}\right.$

Wherein, $\left\{\begin{array}{c}{U}_{\mathrm{rd}}^{+*\&prime;}=\frac{d}{\mathrm{dt}}{I}_{\mathrm{rd}}^{+}=C_{\mathrm{PI}+\mathrm{CCR}}\left(s\right)(I_{\mathrm{rd}}^{+*}-I_{\mathrm{rd}}^{+})\\ U_{\mathrm{rq}}^{+*\&prime;}=\frac{d}{\mathrm{dt}}{I}_{\mathrm{rq}}^{+}=C_{\mathrm{PI}+\mathrm{CCR}}\left(s\right)(I_{\mathrm{rq}}^{+*}-I_{\mathrm{rq}}^{+})\end{array}\right.,$ R _sBe stator resistance;

(x) just changeing with the rotor voltage reference value U in the leg speed rotating coordinate system _Rdq ^{+ *}After rotating coordinate transformation module 17, obtain the required rotor coordinate system rotor voltage reference signal U of space vector pulse width modulation module 19 modulation _{R α β} ^R*, after this signal is modulated through space vector pulse width modulation module 19, the switching signal S of power device in the rotor-side converter 1 of acquisition control DFIG operation _a, S _b, S _c

Comparison diagram 2 and Fig. 1 as can be seen, embodiment proposed by the invention calculate forward and backward with the leg speed rotating coordinate system in each positive and negative preface rotor current command value I _Rdq+ ^{+ *}, I _Rdq- ^-*The time, though still need adopt trapper 13 to obtain the positive and negative preface component of stator voltage, but the time-delay that this trapper 13 is introduced is outside the rotor current control ring, thereby can not influence the bandwidth and the dynamic responding speed of ring control in the rotor current, because the response speed of whole system is mainly by ring decision in the rotor current control, so the time-delay of introducing when adopting trapper 13 to obtain the positive and negative preface component of stator voltage is very little to its influence.In addition, all need not to do positive and negative preface phase sequence in this method under the unbalanced source voltage condition when rotor current is regulated decomposes, in just changeing, adopt integral operation, adopted-2 ω at the alternating component of twice mains frequency at flip-flop with leg speed rotation dq+ coordinate system ₁Complex coefficient resonator, and-2 ω _sThe complex coefficient resonator is only to 2 ω _sNegative phase-sequence alternating component on the Frequency point has unlimited gain.Under the situation of the strict balance of line voltage, because rotor current only has positive sequence component in just changeing with leg speed rotation dq+ coordinate system, promptly in just changeing, show as single flip-flop with the leg speed rotational coordinates, integral element can realize the floating of rotor current is regulated control in the PI-CCR controller at this moment, so the present invention can be suitable for effective control of AC excitation double-fed asynchronous wind power generator (DFIG) rotor current under line voltage balance and imbalance (comprising little value stable state and the big value transient state imbalance) condition simultaneously.

Fig. 5 and Fig. 6 are respectively and adopt DFIG tradition control method and the result of implementation of control method of the present invention under transient grid Voltage unbalance condition relatively.At 0.3s moment line voltage generation unbalanced fault, line voltage recovers during 0.7s.In this case study on implementation, choose and keep electromagnetic torque constant to alleviate mechanical stress to blower fan system as the controlled target of DFIG under unbalance voltage.As can be seen with just traditional, negative phase-sequence, the DFIG control method of two proportional-integral controllers relatively, (0.3s) and removing (0.7s) moment take place at the line voltage unbalanced fault, the inventive method need not DFIG wind power system rotor electric current is just being implemented, negative sequence component decomposes, realized nothing time-delay overall situation control to rotor current, as figure (d) among Fig. 6, figure (e), figure (f), figure (g), thereby realized that fast (during 0.3s～0.7s) keeps the constant controlled target of DFIG controlling electromagnetic torque under the unbalanced source voltage condition, also ripple disable of DFIG stator output reactive power simultaneously is as figure (i) among Fig. 6, shown in the figure (j).Meanwhile when the line voltage fault clearance, control system can return under the symmetrical operation state fast, reposefully, and under the strict balance of line voltage, also can not bring unnecessary decomposition and introduce corresponding time-delay to system, thereby improved the operation control ability of DFIG wind power system under various electrical network conditions, improve the dynamic quality of control system, realized the operation of passing through under the electric network fault.

Claims (2)

1. the variable speed constant frequency doubly-fed induction wind driven generator rotor current non-delay control method of grid type is characterized in that may further comprise the steps:

(i) utilize two groups six current sensors (2) to gather the threephase stator electric current I respectively _SabcWith rotor current signal I _Rabc, one group three voltage sensors (7) are gathered threephase stator voltage signal U _Sabc

The threephase stator voltage signal U that (ii) collects _SabcDetect through software phase-lock loop (6), obtain the stator voltage angular frequency ₁And phase theta ₁Meanwhile adopt encoder (4) to detect DFIG (5) rotor position angle θ _rAnd rotational speed omega _rAnd calculate slippage angle ± θ through the plus-minus calculator respectively ₁-θ _rWith the slippage angular frequency _Slip+=ω ₁-ω _r, ω _SlipThe ω of-=- ₁-ω _r

(iii) with the three-phase stator and rotor current signal I that collects _Sabc, I _RabcWith stator voltage signal U _SabcPass through static three-phase/two-phase coordinate transformation module (3) respectively, obtain comprising the stator voltage synthetic vector U of positive and negative preface component _{S α β} ^s, stator and rotor electric current synthetic vector I _{S α β} ^sAnd I _{R α β} ^r

(iv) with stator voltage, electric current synthetic vector U in the stator rest frame that obtains _{S α β} ^s, I _{S α β} ^sBy just changeing, obtain under the unbalanced source voltage condition, just changeing respectively with containing DC quantity and two frequencys multiplication, 2 ω in the leg speed rotating coordinate system with leg speed rotating coordinate transformation module (9) ₁The voltage vector U of of ac sum _Sdq ⁺, current phasor I _Sdq ⁺, again with stator voltage synthetic vector U _{S α β} ^s, obtain under the unbalanced source voltage condition, reversing with leg speed rotational coordinates module (8) by counter-rotating with containing DC quantity and two frequencys multiplication, 2 ω in the leg speed rotating coordinate system ₁The voltage vector U of of ac sum _Sdq ^-

(v) adopt 2 ω of twice mains frequency ₁Trapper (13) filtering forward and backward is with voltage vector U in the leg speed rotating coordinate system _Sdq ⁺, U _Sdq ^-In 2 ω ₁The frequency alternating component obtains positive and negative sequence voltage DC component U _Sdq+ ⁺, U _Sdq- ^-

(vi) adopt stator flux observer (14), obtain feedback compensation decoupling zero module (20) and carry out the required just commentaries on classics of feedforward compensation with stator magnetic linkage component ψ in the leg speed rotating coordinate system _Sdq ⁺

(vii) with the rotor current synthetic vector I that obtains _{R α β} ^rBe converted to the rotor current feedback signal I that just changes with in the leg speed rotating coordinate system through rotating coordinate transformation module (10) _Rdq ⁺, it includes positive sequence flip-flop I under the unbalanced source voltage condition _Rdq+ ⁺With twice mains frequency 2 ω ₁The negative phase-sequence alternating component

(, calculate forward and backward with the instruction of the rotor current in leg speed rotating coordinate system I by rotor current command value computing module (15) viii) according to the required controlled target of DFIG (5) under the unbalanced source voltage condition _Rdq+ ^{+ *}, I _Rdq- ^-*, this current instruction value is converted to the rotor current command value I that just changes with in the leg speed rotating coordinate system through rotating coordinate transformation module (22) _Rdq ^{+ *}, and with just change with the rotor current feedback signal I in the leg speed rotating coordinate system _Rdq ⁺Relatively, obtain error signal Δ I _Rdq ⁺

(ix) rotor current error signal Δ I _Rdq ⁺Do ratio-integration-complex coefficient resonance adjusting through just changeing, regulate the back output signal U with the ratio-integration in the leg speed rotating coordinate system-complex coefficient resonant controller (21) _Rdq ^{+ *}' finish and just change with cross decoupling between friendship-d-axis and dynamic feedback compensation in the leg speed rotating coordinate system through feedback compensation decoupling zero module (20), obtain the rotor voltage reference value U that just changes with in the leg speed rotating coordinate system _Rdq ^{+ *}

(x) just changeing with the rotor voltage reference value U in the leg speed rotating coordinate system _Rdq ^{+ *}By rotating coordinate transformation module (17), obtain the required rotor coordinate system rotor voltage reference signal U of space vector pulse width modulation module (19) modulation _{R α β} ^R*, this signal obtains the switching signal S of rotor-side converter (1) power device of control DFIG (5) operation through space vector pulse width modulation module (19) modulation back _a, S _b, S _c

2. the variable speed constant frequency doubly-fed induction wind driven generator rotor current non-delay control method of grid type according to claim 1, it is characterized in that just changeing with the ratio-integration in the leg speed rotating coordinate system-complex coefficient resonant controller (21), it comprises that it is ω that a proportional component, integral element and one are just changeing with angular frequency in the leg speed rotating coordinate system ₀=-2 ω ₁The complex coefficient resonator, wherein can to realize aligning commentaries on classics be 2 ω with angular frequency in the leg speed rotating coordinate system to the complex coefficient resonator ₁The unlimited gain-adjusted of negative phase-sequence rotor current composition.

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