CN101240775B - Wind Turbine hydraulic variable pitch system control method - Google Patents

Abstract

Wind electric set hydraulic pressure variable pitch systemic control method provides a improvement minimum variance control method for prolonging forecast step length and combined with time-varying limiting amplitude policy and flexible control action against deficiency of conventional minimum variance controlling means. The method resolves problems that conventional minimum variance control method is non- boundary to non-minimum phase system and balanced null point system control with near unit circle, control action too big, etc. The system control method adopts minimum variance control, controller on-line real-time records all controlled object input control signal {u(k-1), u(k-2) ...} to present sampling time k, and output propeller pitch angle observational data {Theta (k), Theta (k-1)...}, and achieves control systemic controlling quantity u(k) according to expectant propeller pitch angle signal Theta<SUB>m</SUB>(k).

Description

The controlling method of Wind Turbine hydraulic variable pitch system

Technical field

The present invention a kind ofly regulates Wind Turbine hydraulic variable pitch system by improving minimum variance control strategy, make the blade pitch angle fast, a kind of method of stable, agonic tracking setting value.

Background technique

The wind-powered electricity generation set pitch control by the pitched device, is finished the adjusting at vanepiston angle apart from system, below rated wind speed, guarantees maximal wind-energy capture efficient, when high wind speed, and power-limiting output.Hydraulic variable-pitch regulation by pitch device passing ratio valve is realized.Controller according to position sensor signal provide one-10～+ the control voltage of 10V, the passing ratio valve control converts the current signal of certain limit to, the direction and the size of control ratio valve output flow.The size of current signal, direct proportaion decision Proportional valve valve seat opening is regulated the oil circuit flow.Current signal positive and negative determined the direction of oil circuit.Fluid arrives oil hydraulic cylinder, and the direction of valve output and flow promotion piston rod advance or retreat in proportion, and control blade pitch angle moves within the specific limits.

Because the randomness and the uncertainty of wind speed, the load disturbance that tower shadow, wind shear, driftage revolution etc. cause, the reciprocating action of feather switch oar, the inertial element of the big quality impeller of hydraulic driving load makes variable-pitch control system that technical characterstics such as parametrical nonlinearity, parameter time varying, hysteresis quality be arranged.

The minimum variance controlling method is very useful for the control of Large-lag System, simultaneously for parametrical nonlinearity and time-varying system, certain practical value is arranged also.It must be minimum phase system that tradition minimum variance controlling method requires object, very sensitive to the balanced null point near unit circle.To non-minimum phase system, owing to contain unstable zero point, cause controlling the non-bounded of input and can't design control system.Simultaneously, control action may be excessive, and the uncertain etc. of inaccurate initial conditions, retard time all may the appreciable impact optimum prediction, and control procedure is dispersed.

Summary of the invention

Technical problem: the purpose of this invention is to provide a kind of controlling method of Wind Turbine hydraulic variable pitch system, be used for Wind Turbine hydraulic variable pitch system, promptly solve problems such as variable-pitch control system parametrical nonlinearity, time variation, hysteresis quality.

Technological scheme: in order to overcome the problems referred to above, by adopting improved minimum variance controlling method, remedy the deficiency of conventional method, be used for the hydraulic variable-pitch control system, make system response time fast, performance of dynamic tracking is good, no regulating error, simultaneously, need not the on-line identification object model, make full use of the robustness of controlling method.

The controlling method of Wind Turbine hydraulic variable pitch system of the present invention adopts minimum variance control, and performing step is as follows:

Step 1: according to the pure delay time of hydraulic variable-pitch system controlled device, prolong prediction step, select pure delay time in a certain moment afterwards, make L greater than the object pure delay time as prediction step L;

Step 2: by the parametric polynomial of prediction step L and controlled device discrete model $A\left(q^{-1}\right)=1+\underset{i=1}{\overset{n_n}{\mathrm{\&Sigma;}}}{a}_i{q}^{-i}$ With $B\left(q^{-1}\right)=\underset{i=0}{\overset{n_b}{\mathrm{\&Sigma;}}}{b}_i{q}^{-i},$ And relation 1=E (q ^-1) A (q ^-1) Δ+q ^-LG (q ^-1) and F (q ^-1)=E (q ^-1) B (q ^-1), obtain multinomial $E\left(q^{-1}\right)=1+\underset{i=0}{\overset{L-1}{\mathrm{\&Sigma;}}}{e}_i{q}^{-i},$ $G\left(q^{-1}\right)=\underset{i=0}{\overset{n_a}{\mathrm{\&Sigma;}}}{g}_i{q}^{-i},$ $F\left(q^{-1}\right)=\underset{i=0}{\overset{n_b+L-1}{\mathrm{\&Sigma;}}}{f}_i{q}^{-i},$ Deposit in the controller module, be used to obtain the controlled quentity controlled variable of control system,

Δ=1-q wherein ^-1, q ^-1Be backward shift operator, n _a, n _bBe respectively object discrete model parametric polynomial A (q ^-1), B (q ^-1) order, a _i(i=1 ... n _a), b _i(i=0 ... n _b), e _i(i=1 ... L-1),

g _i(i=0 ... n ₀), f _i(i=0 ... n _b+ L-1) be respectively corresponding polynomial coefficient; Step 3: all control of controller was believed till the online real time record of control system arrived current sampling instant k

Number u (k-1), u (k-2) ... and the propeller pitch angle observation data { θ (k) of pitch-variable system output, θ (k-1) ..., increment { the Δ u (k-1) of the amount of record controls simultaneously, Δ u (k-2) ..., and receive the expectation propeller pitch angle signal θ that wind-powered electricity generation unit master controller provides _m(k), utilize the multinomial G (q that stores in the control module ^-1) and F (q ^-1), by the controlled quentity controlled variable of the controlled system of following relation $u\left(k\right):\left\{\begin{array}{c}\mathrm{\&Delta;u}\left(k\right)=\frac{1}{\mathrm{\&alpha;}{f}_0}[{\mathrm{\&theta;}}_m\left(k\right)-\underset{i=0}{\overset{n_a}{\mathrm{\&Sigma;}}}{g}_i\mathrm{\&theta;}(k-i)-\underset{i=1}{\overset{n_b+L-1}{\mathrm{\&Sigma;}}}{f}_i\mathrm{\&Delta;u}(k-i)]\\ u\left(k\right)=u(k-1)+\mathrm{\&Delta;u}\left(k\right)\end{array}\right.,$ Wherein: Δ u (k) is the control increment of current time control output than previous moment control output, and α is arbitrarily positive constant;

Step 4: the controlled quentity controlled variable u of control system (k), be converted into after the output one-10～+ control voltage signal in the 10V scope, the passing ratio valve control converts the current signal of certain limit to, this current signal is pressed positive-negative polarity control ratio valve and is connected different loops, and determine valve valve seat opening size by the size of current direct proportaion, the flow of pilot pressure oil, make pressure oil by connecting front end or the rear end that the loop flows into oil hydraulic cylinder, thereby promote hydraulic cylinder piston backward or travel forward, the oar handling elongation changes in determining scope, follows the tracks of the propeller pitch angle signal of expectation.

Prediction step L can be after the pure delay time predicts to any time of stable state between constantly.

During control increment Delta u (k) calculates, become the amplitude limit strategy during employing, that is, get big α f at the control initial stage ₀Value, the restriction span of control limit of control reduces α f gradually in the control later stage ₀Value becomes α f when accelerating convergent ₀Design method.

When the selection pure delay time, a certain moment afterwards was as prediction step L, can also after the pure delay time, select prediction step L constantly to stable state ₁And L ₂, make L ₂＞L ₁, L wherein ₁Near the response phase after the object pure delay time, L ₂Near the object steady-state process, to these two controlled quentity controlled variable u that prediction step obtains ₁(k) and u ₂(k) be weighted compromise: u (k)=(1-β) u ₁(k)+β u ₂(k), β is input softening coefficient, and 0≤β≤1, and the u that obtains (k) is re-used as the controlled quentity controlled variable output of control system.

Beneficial effect: become methods such as amplitude limit strategy and softening control action during by prolongation prediction step, employing traditional minimum variance control is improved, be used for the Wind Turbine hydraulic variable pitch control system, make system responses rapid, no dynamic deviation.Simultaneously,, make full use of the robustness of this method, need not the on-line identification object model, still can obtain good control effect for the time variation of object model.

Description of drawings

Fig. 1 is the schematic representation of Wind Turbine hydraulic variable pitch control system.

Embodiment

The controlling method of Wind Turbine hydraulic variable pitch system of the present invention adopts minimum variance control, the online real time record of controller all input control signal { u (k-1) of controlled device till the current sampling instant k, u (k-2), and output propeller pitch angle observation data { θ (k), θ (k-1),, and according to the propeller pitch angle signal θ that expects _m(k), according to the controlled quentity controlled variable u (k) of the controlled system of following relation:

$\left\{\begin{array}{c}\mathrm{\&Delta;u}\left(k\right)=\frac{1}{\mathrm{\&alpha;}{f}_0}[{\mathrm{\&theta;}}_m\left(k\right)-\underset{i=0}{\overset{n_a}{\mathrm{\&Sigma;}}}{g}_i\mathrm{\&theta;}(k-i)-\underset{i=1}{\overset{n_b+L-1}{\mathrm{\&Sigma;}}}{f}_i\mathrm{\&Delta;u}(k-i)]\\ u\left(k\right)=u(k-1)+\mathrm{\&Delta;u}\left(k\right)\end{array}\right.$

Controller output controlled quentity controlled variable u (k) be converted into one-10～+ control voltage signal in the 10V scope, the passing ratio valve control converts the current signal of certain limit to, this current signal is pressed positive-negative polarity control ratio valve and is connected different loops, and determine valve valve seat opening size by the size of current direct proportaion, the flow of pilot pressure oil, make pressure oil by connecting front end or the rear end that the loop flows into oil hydraulic cylinder, thereby promote hydraulic cylinder piston backward or travel forward, the oar handling elongation changes within the specific limits, follows the tracks of the propeller pitch angle signal of expectation.

Prediction step L can be after the pure delay time predicts to any time of stable state between constantly.

During control increment Delta u (k) calculates, become the amplitude limit strategy during employing, that is, get big α f at the control initial stage ₀Value, the restriction span of control limit of control reduces α f gradually in the control later stage ₀Value becomes α f when accelerating convergent ₀Design method.

When the selection pure delay time, a certain moment afterwards was as prediction step L, can also after the pure delay time, select prediction step L constantly to stable state ₁And L ₂, make L ₂＞L ₁, L wherein ₁Near the response phase after the object pure delay time, L ₂Near the object steady-state process, to these two controlled quentity controlled variable u that prediction step obtains ₁(k) and u ₂(k) be weighted compromise: u (k)=(1-β) u ₁(k)+β u ₂(k), β is input softening coefficient, and 0≤β≤1, and the u that obtains (k) is re-used as the controlled quentity controlled variable output of control system.

The present invention is a kind of at Wind Turbine hydraulic variable pitch system parametrical nonlinearity, time variation, hysteresis quality characteristics, adopts a kind of improved minimum variance controlling method, makes the control system response rapidly, and no dynamic deviation need not the on-line identification object model.

Improved minimum variance controlling method specific implementation process is as follows:

1, off-line identification plant model is selected the sampling time, with the object model discretization, adopts controlled autoregressive integration moving average model $A\left(q^{-1}\right)\mathrm{\&theta;}\left(k\right)=q^{-d}B\left(q^{-1}\right)u\left(k\right)+\frac{\mathrm{\&xi;}\left(k\right)}{\mathrm{\&Delta;}}$ Describe controlled device, k is sampling instant, and θ (k) is a k propeller pitch angle signal constantly, the disturbing signal that u (k) is subjected at k for hydraulic system constantly for k controller output constantly control signal, ξ (k), and d is the pure delay of controlled device.

By traditional minimum variance control control law as can be known, current input control action will be done the optimum prediction in following d step to the object that has the d step to postpone and exist than mistake in next sampling instant generation effect of d, may make the control action amplitude excessive.At this situation, according to object pure delay d, the proper extension prediction step is got L ₁Step and L ₂Step is as prediction step, wherein L ₁Step is near the response phase behind the object pure delay d, L ₂Step is near the object steady-state process.

2,, find the solution Diophantine equation 1=E (q by the parametric polynomial of prediction step and controlled device discrete model ^-1) A (q ^-1) Δ+q ^-LG (q ^-1) and relation F (q ^-1)=E (q ^-1) B (q ^-1), thereby obtain L ₁Step and L ₂The multinomial that step is corresponding

With

3, online real time record all control signal { u (k-1) of controller till the current sampling instant k, u (k-2), and the propeller pitch angle observation data { θ (k) of pitch-variable system output, θ (k-1),, increment { Δ u (k-1), the Δ u (k-2) of the amount of record controls simultaneously,, and receive the expectation propeller pitch angle signal θ that wind-powered electricity generation unit master controller provides _m(k), utilize in second step and obtain

With

By following relation: $\left\{\begin{array}{c}\mathrm{\&Delta;u}\left(k\right)=\frac{1}{\mathrm{\&alpha;}{f}_0}[{\mathrm{\&theta;}}_m\left(k\right)-\underset{i=0}{\overset{n_a}{\mathrm{\&Sigma;}}}{g}_i\mathrm{\&theta;}(k-i)-\underset{i=1}{\overset{n_b+L-1}{\mathrm{\&Sigma;}}}{f}_i\mathrm{\&Delta;u}(k-i)]\\ u\left(k\right)=u(k-1)+\mathrm{\&Delta;u}\left(k\right)\end{array}\right.$ Obtain L respectively ₁Step and L ₂The controlled quentity controlled variable u that step is corresponding ₁(k) and u ₂(k).

In the control convergence process, α f ₀Size directly influence the size of control action, and then influence the speed of convergence rate.Generally, maximum span of control limit of control often appears at the initial stage of mutation process, becomes α f when therefore adopting ₀Design method, in control initial stage restriction span of control limit of control, add rapid convergence in the control later stage.

For the restriction control action significantly change, accelerate convergence rate simultaneously, with control action at u ₁(k) and u ₂(k) trade off between: u (k)=(1-β) u ₁(k)+β u ₂(k), β is input softening coefficient, and 0≤β≤1.U (k) is promptly as the output of controller.

4, the controlled quentity controlled variable u of control system (k), be converted into after the output one-10～+ control voltage signal in the 10V scope, the passing ratio valve control converts the current signal of certain limit to, this current signal is pressed positive-negative polarity control ratio valve and is connected different loops, and determine valve valve seat opening size by the size of current direct proportaion, the flow of pilot pressure oil, make pressure oil by connecting front end or the rear end that the loop flows into oil hydraulic cylinder, thereby promote hydraulic cylinder piston backward or travel forward, the oar handling elongation changes in determining scope, follows the tracks of the propeller pitch angle signal of expectation.

Claims (4)

1. the controlling method of a Wind Turbine hydraulic variable pitch system is characterized in that this system control method adopts minimum variance control, and performing step is as follows:

Step 1: according to the pure delay time of hydraulic variable-pitch system controlled device, prolong prediction step, select pure delay time in a certain moment afterwards, make the pure delay time of L greater than described controlled device as prediction step L;

Step 2: by the parametric polynomial of prediction step L and controlled device discrete model

With

And relation 1=E (q ^-1) A (q ^-1) Δ+q ^-LG (q ^-1) and F (q ^-1)=E (q ^-1) B (q ^-1), obtain multinomial

Deposit in the controller module, be used to obtain the controlled quentity controlled variable of control system, wherein Δ=1-q ^-1, q ^-1Be backward shift operator, n _a, n _bBe respectively object discrete model parametric polynomial A (q ^-1), B (q ^-1) order, a _i(i=1 ... n _a), b _i(i=0 ... n _b), e _i(i=1 ... L-1), g _i(i=0 ... n _a), f _i(i=0 ... n _b+ L-1) be respectively corresponding polynomial coefficient;

Step 3: the online real time record of control system all control signal { u (k-1) of controller till the current sampling instant k, u (k-2), and the propeller pitch angle observation data { θ (k) of pitch-variable system output, θ (k-1),, increment { Δ u (k-1), the Δ u (k-2) of the amount of record controls simultaneously,, and receive the expectation propeller pitch angle signal θ that wind-powered electricity generation unit master controller provides _m(k), utilize the multinomial G (q that stores in the control module ^-1) and F (q ^-1), press the controlled quentity controlled variable u (k) of the controlled system of following relation:

Wherein: Δ u (k) is the control increment of current time control output than previous moment control output, and α is arbitrarily positive constant;

Step 4: the controlled quentity controlled variable u of control system (k), be converted into after the output one-10～+ control voltage signal in the 10V scope, the passing ratio valve control converts the current signal of certain limit to, this current signal is pressed positive-negative polarity control ratio valve and is connected different loops, and determine valve valve seat opening size by the size of current direct proportaion, the flow of pilot pressure oil, make pressure oil by connecting front end or the rear end that the loop flows into oil hydraulic cylinder, thereby promote hydraulic cylinder piston backward or travel forward, the oar handling elongation changes in determining scope, follows the tracks of the propeller pitch angle signal of expectation.

2. the controlling method of Wind Turbine hydraulic variable pitch system according to claim 1 is characterized in that prediction step L predicts to any time of stable state between constantly after the pure delay time.

3. the controlling method of Wind Turbine hydraulic variable pitch system according to claim 1 is characterized in that controlling in increment Delta u (k) calculating, becomes the amplitude limit strategy during employing,, gets big α f at the control initial stage that is ₀Value, the restriction span of control limit of control reduces α f gradually in the control later stage ₀Value becomes α f when accelerating convergent ₀Design method.

4. the controlling method of Wind Turbine hydraulic variable pitch system according to claim 2, when it is characterized in that selecting a certain moment after the pure delay time as prediction step L, also the pure delay time after to stable state constantly between selection prediction step L ₁And L ₂, make L ₂＞L ₁, L wherein ₁Near the response phase after the object pure delay time, L ₂Near the object steady-state process, to these two controlled quentity controlled variable u that prediction step obtains ₁(k) and u ₂(k) be weighted compromise: u (k)=(1-β) u ₁(k)+β u ₂(k), β is input softening coefficient, and 0≤β≤1, and the u that obtains (k) is re-used as the controlled quentity controlled variable output of control system.