CN103362736B - Speed-changing oar-changing wind power generating set is based on the maximum power tracing control method of internal model control - Google Patents

Abstract

The present invention discloses the maximum power tracing control method of a kind of speed-changing oar-changing wind power generating set based on internal model control.The present invention draws reference model by carrying out modeling to wind power generating set moment of resistance responding system, its analytical expression is provided based on Reference Model Design internal mode controller, realize controlling with the optimum moment of resistance of lower hub and main shaft low shaft connection place lower than wind rating based on internal model control mode, compared to traditional maximal power tracing algorithm, the present invention effectively reduces the impact followed the tracks of the optimum moment of resistance due to the factor such as aerodynamic moment fluctuation, measuring error and modeling error, realizes wind wheel wind energy more efficiently and absorbs maximum power tracing.For conventional unity negative feedback single loop control system, the present invention devises the equivalent single loop unity negative feedback control system based on internal model control and provides controller analytical expression.

Description

Speed-changing oar-changing wind power generating set is based on the maximum power tracing control method of internal model control

Technical field

The invention belongs to technical field of wind power generation, relate to speed-changing oar-changing wind power generating set lower than the maximum power tracing control method below wind rating.

Background technology

Wind energy is the regenerative resource most at present with economic worth, " Development of Wind Power In China route map 2050 " is issued according to Energy Research Institute of the China national Committee of Development and Reform, the Wind Power In China developing goal of following 40 years: to the year two thousand twenty, the year two thousand thirty and the year two thousand fifty, installed capacity of wind-driven power will reach 200,000,000,400,000,000 and 1,000,000,000 kilowatts respectively, to the year two thousand fifty, the domestic electrical demand that wind-powered electricity generation will meet 17%.

At present, wind power generating set has become the major equipment of Wind Power Utilization, and speed-changing oar-changing wind power generating set is the wind driven generators of main flow.

Speed-changing oar-changing wind power generating set absorbs wind energy by wind wheel, utilizes kinematic train that absorption wind energy is delivered to generator axle head, is electric energy by generator by changes mechanical energy, and the frictional damping of kinematic train loss is the main source of transmission efficiency loss.

For high-power speed-changing oar-changing wind power generating set, kinematic train generally can be considered to carry out simplification modeling according to desired stiffness link, to realize the relatively accurate performance analysis of kinematic train and control, usually modeling can be carried out according to the multimass block link of flexibility.

High-power speed-changing oar-changing wind power generating set is controlling lower than doing maximum power tracing in the certain wind speed section below wind rating, and what wind power generating set utilized wind wheel by control electromagnetic torque realizes maximum power tracing from optimizing aerodynamic characteristic.

Traditional maximum power tracing is controlled, to the relatively ideal that kinematic train is considered in control strategy, do not consider each link of kinematic train and drive characteristic impact, simultaneously due to wind speed undulatory property and random cause wind wheel wind-engaging after the aerodynamic moment fluctuation that produces there is very strong uncertainty, therefore in working control process, have certain deviation relative to optimal control torque track, optimum maximum power tracing can not be realized efficiently and control.

In speed-changing oar-changing wind power generating set kinematic train input element, generator electromagnetic torque is Controlled unit, wind wheel aerodynamic moment due to the randomness of wind and uncertainty be uncontrollable link.

Summary of the invention

The present invention proposes the maximum power tracing control method of a kind of speed-changing oar-changing wind power generating set below wind rating, the method is by carrying out modeling to wind power generating set moment of resistance responding system, realize controlling with the optimum moment of resistance of lower hub and main shaft low shaft connection place lower than wind rating based on internal model control mode, reduce the impact optimum moment of resistance followed the tracks of due to the factor such as aerodynamic moment fluctuation, measuring error and modeling error, effectively realize wind wheel wind energy and absorb maximum power tracing.

Technical scheme of the present invention is the maximum power tracing control method of speed-changing oar-changing wind power generating set based on internal model control.

As shown in Figure 1, when ideal thinks that wind power generating set kinematic train is strict rigid link and does not consider damping, wind power generating set, meeting optimal torque change curve as the BC section in Fig. 1 lower than in wind speed section certain below wind rating by the electromagnetic torque controlling wind energy conversion system, realizes maximum power tracing.

And for the speed-changing oar-changing wind power generating set of reality, be flexible link due to its kinematic train and there is damping, there is stronger uncertainty in wind wheel aerodynamic moment simultaneously, after control method traditionally controls, due to kinematic train drive characteristic and the influence of fluctuations of wind wheel aerodynamic moment, practical function is difficult to accurately to follow the tracks of optimal torque in wheel hub and the main shaft low shaft connection place moment of resistance opposite to the direction of rotation causes wind wheel to fail to realize maximum power tracing.

For speed-changing oar-changing wind power generating set kinematic train characteristic, when thinking that speed-changing oar-changing wind power generating set kinematic train is flexible link and there is friction, as shown in Figure 2, speed-changing oar-changing wind power generating set kinematic train can be equivalent to slow-speed shaft and high speed shaft two mass link, modeling in accordance with the following methods:

In formula

represent slow-speed shaft (wind wheel end) rotating speed;

represent wind wheel aerodynamic moment;

represent slow-speed shaft (wind wheel end) moment of inertia;

represent wheel hub and the main shaft low shaft connection place moment of resistance opposite to the direction of rotation;

represent high speed shaft (generator end) rotating speed;

represent high speed shaft (generator end) moment of inertia;

represent generator electromagnetic torque;

represent kinematic train speed increasing ratio;

represent kinematic train transmission efficiency;

represent that kinematic train equivalence is to slow-speed shaft stiffness coefficient;

represent that kinematic train equivalence is to slow-speed shaft ratio of damping.

If state variable is , input variable is , export and be , then kinematic train can be expressed as a third-order model:

Wherein

represent the moment of inertia of slow-speed shaft equivalence after high speed shaft

Then ssystem transfer function can be expressed as:

Ssystem transfer function block diagram as shown in Figure 3, can be expressed as following formula:

Generally, the moment of inertia of slow-speed shaft equivalence after high speed shaft also slow-speed shaft (wind wheel end) moment of inertia is significantly less than , therefore from the angle of steady-state gain, wheel hub and the main shaft low shaft connection place moment of resistance opposite to the direction of rotation primarily of produce, due to wind wheel aerodynamic moment in system being produced by wind wheel aerodynamic moment, is uncontrolled variable, can regard as outside input disturbance.

For speed-changing oar-changing wind power generating set electromagnetic torque response link modeling, the response speed of usual electromagnetic torque is very fast, can be similar to think transient response, and when needs accurately control, electromagnetic torque response model can be similar to and be expressed as follows with first order inertial loop:

The reference model can obtaining system based on above model is:

Go out optimum moment of resistance internal model control system as shown in Figure 4 based on Reference Model Design, in this control system, control objectives is the optimum moment of resistance , the optimum moment of resistance can calculate according to the following formula:

In formula

represent optimum moment of resistance coefficient;

represent atmospheric density;

represent that wind wheel sweeps wind radius;

represent that wind wheel is at the maximal wind-energy usage factor of blade lower than wind rating work (propeller pitch angle is minimum) constantly;

represent the optimum tip-speed ratio of when blade works lower than wind rating (propeller pitch angle is minimum).

Feedback quantity is the measured torque of wheel hub and the main shaft low end junction detected by sensor export with reference model error .

Control objectives deviation can calculate according to the following formula:

In formula

represent reference model output resistance square;

represent by sensor measuring system wheel hub and the main shaft low end junction moment of resistance;

represent moment of resistance error.

Controller is input as control objectives deviation , controller exports as electromagnetic torque setting value , controller output signal to electromagnetic torque response link, controller output signal simultaneously as reference model input.

Inner model controller specific design method is as follows:

Step 1: set up control object TRANSFER MODEL

Step 2: designing filter link and filter parameter, usual wave filter can be designed as:

In formula

for filter parameter;

for filter parameter;

be all arithmetic number, and likely identical.

Step 3: calculate internal mode controller can calculate according to the following formula:

Step 4: when control system is as Fig. 5 single loop unity negative feedback form, calculate equivalent single loop unity negative feedback controller, controller transfer function can calculate according to the following formula:

Reference model be input as electromagnetic torque setting value , reference model exports and is .

Electromagnetic torque response link be input as electromagnetic torque setting value , export as true electromagnetic torque .The input variable of transmission link is , wherein wind wheel aerodynamic moment for the uncontrollable input in outside, disturbance can be seen as, generator electromagnetic torque for controllable variable, export as wheel hub and the main shaft low shaft connection place moment of resistance opposite to the direction of rotation can sensor measurement be passed through, and measured value be deducted reference model output end is fed back into afterwards as Modeling Error Feedback.

Accompanying drawing explanation

Fig. 1 speed-changing oar-changing wind power generating set optimal torque controlling curve schematic diagram

Fig. 2 kinematic train two mass modeling schematic diagram

Fig. 3 kinematic train transport function block diagram

Fig. 4 is based on the maximum power tracing closed-loop control block diagram of internal model control

Fig. 5 is based on the unity negative feedback maximum power tracing closed-loop control block diagram of internal mold equivalence

Embodiment

The total moment of inertia of kinematic train slow-speed shaft is calculated according to speed-changing oar-changing wind generator set blade and the distribution of wheel hub quality distance rotation center ; The total moment of inertia of kinematic train high speed shaft is calculated according to speed-changing oar-changing generator of wind generating set rotor quality distance rotation center distributed data , generally speaking transmission shaft or gear case relatively rotate very little can being similar to of inertia and ignore.

Obtain speed-changing oar-changing wind generator set blade aerofoil profile data, according to momentum-foline theorem, finite element method or calculate wind wheel lower than the optimum moment of resistance parameter below wind rating according to relative commercial software for calculation .

Kinematic train modeling related data can obtain transmission efficiency according to the relevant unit data of kind of drive inquiry of kinematic train , be equivalent to the stiffness coefficient of slow-speed shaft and be equivalent to the friction factor of slow-speed shaft data, carry out modelling by mechanism based on data; Also kinematic train identification model can directly be obtained by the mode measuring the identification of Correlation Identification data model fitting parameter.

Although speed-changing oar-changing wind power generating set is in the transmission efficiency of different operating point , be equivalent to the stiffness coefficient of slow-speed shaft and be equivalent to the friction factor of slow-speed shaft different may be had etc. data, measuring error may be there is by sensor measuring system wheel hub and the main shaft low end junction moment of resistance, the fluctuation of external pneumatic moment simultaneously causes system output to there is disturbance, but because the Error Feedback of model can be fed back into end by internal model control, therefore when filter parameter selects rational situation lower hub and the main shaft low shaft connection place moment of resistance opposite to the direction of rotation can obtain good optimum moment of resistance tracking effect.

When electromagnetic torque response link time constant and drive model export corresponding time constant be more or less the same time, electromagnetic torque dynamic response characteristic must be considered, can directly obtain moment responses identification model by the mode of monitoring collection Correlation Identification data model fitting parameter identification.

Wheel hub and the main shaft low shaft connection place moment of resistance opposite to the direction of rotation accurately can be measured by installing dynamic torque sensor at wheel hub and main shaft low shaft connection place, generally for and guarantees that unit operation reliability can be installed two cover dynamic torque sensors and be improved system reliability by redundancy.

Internal model control filter parameter method for designing can be regulated by empirical method or by off-line be correlated with intelligent search algorithm such as genetic algorithm, ant group algorithm etc. optimize adjust, also can carry out parameter tuning by zero pole collocation method in classical control theory.

The present invention is directed to the imperfect drive characteristic of speed-changing oar-changing wind power generating set due to its kinematic train, simultaneously due to the interference of external pneumatic torque fluctuations, the factors such as torque sensor measuring error and modeling error cause the situation being difficult to accurately the optimum moment of resistance controlling curve of dynamically accurate tracking when carrying out maximum power tracing lower than the following unit of wind rating according to general control algolithm, propose the optimum moment of resistance of a kind of wheel hub based on internal model control and main shaft low shaft connection place and control tracking, the method can effectively make wheel hub and the main shaft low shaft connection place moment of resistance follow the tracks of optimum moment of resistance change curve, effectively eliminate the randomness due to wind speed and uncertain and measuring error simultaneously, the factors such as modeling error are on the dynamic tracking impact of the optimum moment of resistance, effectively improve the maximum power tracing ability of wind wheel.

Claims (9)

1. speed-changing oar-changing wind power generating set is based on the maximum power tracing control method of internal model control, when it is characterized in that the method considers that wind power generating set kinematic train is flexible link and there is friction, by carrying out modeling to wind power generating set kinematic train, realize wind rating based on internal model control mode to control with the optimum moment of resistance of lower hub and main shaft low shaft connection place, reduce the impact optimum moment of resistance followed the tracks of due to aerodynamic moment fluctuation, measuring error and modeling error factor, effectively realize wind wheel wind energy and absorb maximum power tracing; Kinematic train can be equivalent to slow-speed shaft and high speed shaft two mass link, modeling in accordance with the following methods:

$\left\{\begin{array}{c}\frac{{\mathrm{d\ω}}_b}{dt}=\frac{T_b}{J_b}-\frac{T}{J_b}\\ \frac{{\mathrm{d\ω}}_g}{dt}=\frac{\mathrm{\η}T}{{\mathrm{NJ}}_g}-\frac{T_e}{J_g}\\ \frac{dT}{dt}=K({\mathrm{\ω}}_b-\frac{{\mathrm{\ω}}_g}{N})+B(\frac{{\mathrm{d\ω}}_b}{dt}-\frac{1}{N}\frac{{\mathrm{d\ω}}_b}{dt})\end{array}\right.$

In formula

ω _brepresent slow-speed shaft rotating speed;

T _brepresent wind wheel aerodynamic moment;

J _brepresent slow-speed shaft moment of inertia;

T represents wheel hub and the main shaft low shaft connection place moment of resistance opposite to the direction of rotation;

ω _grepresent high speed shaft rotating speed;

J _grepresent high speed shaft moment of inertia;

T _erepresent generator electromagnetic torque;

N represents kinematic train speed increasing ratio;

η represents kinematic train transmission efficiency;

K represents that kinematic train equivalence is to slow-speed shaft stiffness coefficient;

B represents that kinematic train equivalence is to slow-speed shaft ratio of damping;

If state variable is $x=\left[\begin{array}{c}{\mathrm{\ω}}_b\\ {\mathrm{\ω}}_g\\ T\end{array}\right],$ Input variable is $u=\left[\begin{array}{c}{T}_b\\ T_e\end{array}\right],$ Export as y=T, then kinematic train is expressed as a third-order model:

$\left\{\begin{array}{c}\stackrel{\·}{x}=\left[\begin{array}{ccc}0& 0& -\frac{1}{J_b}\\ 0& 0& \frac{N}{J_t}\\ K& -\frac{K}{N}& -\frac{B}{J_b}-\frac{B}{J_t}\end{array}\right]x+\left[\begin{array}{cc}\frac{1}{J_b}& 0\\ 0& -\frac{1}{J_g}\\ \frac{B}{J_b}& \frac{B}{{\mathrm{NJ}}_g}\end{array}\right]u\\ y=\left[\begin{array}{ccc}0& 0& 1\end{array}\right]x\end{array}\right.$

Wherein

$J_t=\frac{N^2{J}_g}{\mathrm{\η}}$

J _trepresent the moment of inertia of slow-speed shaft equivalence after high speed shaft;

Then ssystem transfer function is expressed as:

$\left\{\begin{array}{c}y\left(s\right)=\[G_1\left(s\right),G_2\left(s\right)\]u\left(s\right)\\ G_1\left(s\right)=\frac{{\mathrm{BJ}}_{t}s+{\mathrm{KJ}}_t}{J_b{J}_t{s}^2+B(J_b+J_t)s+K(J_b+J_t)}\\ G_2\left(s\right)=\frac{{\mathrm{BJ}}_b{J}_{t}s+{\mathrm{KJ}}_b{J}_t}{{\mathrm{NJ}}_g{J}_b{J}_t{s}^2+{\mathrm{BNJ}}_g(J_b+J_t)s+{\mathrm{KNJ}}_g(J_b+J_t)}\end{array}\right.$

2. speed-changing oar-changing wind power generating set, based on the maximum power tracing control method of internal model control, is characterized in that electromagnetic torque response model can be similar to and is expressed as follows with first order inertial loop according to claim 1:

$G_3\left(s\right)=\frac{1}{\mathrm{\τ}s+1}$

τ represents electromagnetic torque responsive time constant.

3. speed-changing oar-changing wind power generating set, based on the maximum power tracing control method of internal model control, is characterized in that in maximum power tracing control system, control objectives is optimum moment of resistance T according to claim 1 _opt, the optimum moment of resistance calculates according to the following formula:

$\left\{\begin{array}{c}{T}_{opt}=K_{opt}{\mathrm{\ω}}_b^2\\ K_{opt}=\frac{1}{2}{\mathrm{\ρ\πR}}^5\frac{C_{Pmax}}{{{\mathrm{\λ}}_{C_{Pmax}}}^3}\end{array}\right.$

In formula

K _optrepresent optimum moment of resistance coefficient;

ρ represents atmospheric density;

R represents that wind wheel sweeps wind radius;

C _pmaxrepresent the maximal wind-energy usage factor of wind wheel when blade works lower than wind rating;

λ _cPmaxrepresent the optimum tip-speed ratio when blade works lower than wind rating.

4. speed-changing oar-changing wind power generating set, based on the maximum power tracing control method of internal model control, is characterized in that control objectives deviation e can calculate according to the following formula according to claim 1:

$\left\{\begin{array}{c}e=T_{opt}-\mathrm{\Δ}T\\ \mathrm{\Δ}T=T-T_m\end{array}\right.$

In formula

T _optrepresent the optimum moment of resistance;

T _mrepresent reference model output resistance square;

T represents by sensor measuring system wheel hub and the main shaft low end junction moment of resistance;

Δ T represents moment of resistance error.

5. speed-changing oar-changing wind power generating set, based on the maximum power tracing control method of internal model control, is characterized in that controller is input as control objectives deviation e according to claim 1, and controller exports as electromagnetic torque setting value controller output signal to electromagnetic torque response link, controller output signal simultaneously as the input with reference to model G (s).Reference model G (s) is expressed as:

G(s)＝G ₂(s)G ₃(s)

G ₂s () represents the transport function of Wind turbines electromagnetic torque to slow-speed shaft end resistance square;

G ₃s () represents electromagnetic torque response function.

6. speed-changing oar-changing wind power generating set, based on the maximum power tracing control method of internal model control, is characterized in that inner model controller specific design method is as follows according to claim 1:

Step 1: set up control object TRANSFER MODEL G (s)

$G\left(s\right)=G_2\left(s\right)G_3\left(s\right)=\frac{{\mathrm{BJ}}_b{J}_{t}s+{\mathrm{KJ}}_b{J}_t}{(\mathrm{\τ}s+1)({\mathrm{NJ}}_g{J}_b{J}_t{s}^2+{\mathrm{BNJ}}_g(J_b+J_t)s+{\mathrm{KNJ}}_g(J_b+J_t\left)\right)}$

Step 2: designing filter link and filter parameter, usual filters H (s) is designed to:

$H\left(s\right)=\frac{1}{({\mathrm{\τ}}_{1}s+1)({\mathrm{\τ}}_{2}s+1)}$

In formula

τ ₁it is the first filter parameter;

τ ₂it is the second filter parameter;

τ ₁, τ ₂be all arithmetic number, and τ ₁, τ ₂likely identical.

Step 3: calculate internal mode controller q (s), q (s) calculates according to the following formula:

$q\left(s\right)=\frac{(\mathrm{\τ}s+1)({\mathrm{NJ}}_g{J}_b{J}_t{s}^2+{\mathrm{BNJ}}_g(J_b+J_t)s+{\mathrm{KNJ}}_g(J_b+J_t\left)\right)}{({\mathrm{\τ}}_{1}s+1)({\mathrm{\τ}}_{2}s+1)({\mathrm{BJ}}_b{J}_{t}s+{\mathrm{KJ}}_b{J}_t)}$

In formula

τ is electromagnetic torque responsive time constant.

7. according to claim 1 speed-changing oar-changing wind power generating set based on the maximum power tracing control method of internal model control, it is characterized in that when control system is single loop unity negative feedback form, calculate equivalent single loop unity negative feedback controller, controller transfer function c (s) calculates according to the following formula:

$\left\{\begin{array}{c}c\left(s\right)=\frac{{\stackrel{\‾}{T}}_e\left(s\right)}{e\left(s\right)}=\frac{q\left(s\right)}{1-q\left(s\right)}=\frac{b_3{s}^3+b_2{s}^2+b_{1}s+b_0}{a_3{s}^3+b_2{s}^2+a_{1}s+a_0}\\ b_3={\mathrm{\τBJ}}_g{J}_b{J}_t\\ b_2={\mathrm{NJ}}_g\text{\[}\mathrm{\τ}\text{B}(J_b+J_t)\text{+}{J}_b{J}_t\text{\]}\\ b_{\text{1}}={\mathrm{NJ}}_g(J_b+J_t)(\mathrm{\τ}K+B)\\ b_0={\mathrm{KNJ}}_g(J_b+J_t)\\ a_3=J_b{J}_t\left({\mathrm{\τ}}_1{\mathrm{\τ}}_{\text{2}}\text{B-}\mathrm{\τ}\text{N}{J}_g\right)\\ a_2=J_b{J}_t\[{\mathrm{\τ}}_1{\mathrm{\τ}}_{\text{2}}K+B({\mathrm{\τ}}_1+{\mathrm{\τ}}_{\text{2}})\]-{\mathrm{NJ}}_g\[\mathrm{\τ}\text{B}(J_b+J_t)\text{+}{J}_b{J}_t\]\\ a_1=J_b{J}_t\[B+K({\mathrm{\τ}}_1+{\mathrm{\τ}}_{\text{2}})\]-{\mathrm{NJ}}_g(J_b+J_t)(\mathrm{\τ}K+B)\]\\ a_0=K\[J_b{J}_t-{\mathrm{NJ}}_g(J_b+J_t)\]\end{array}\right.$

In formula

Q (s) is mould controller;

τ is electromagnetic torque responsive time constant;

τ ₁it is the first filter parameter;

τ ₂it is the second filter parameter.

8. speed-changing oar-changing wind power generating set is based on the maximum power tracing control method of internal model control according to claim 1, and what it is characterized in that reference model is input as electromagnetic torque setting value reference model exports as T _m.

9. speed-changing oar-changing wind power generating set is based on the maximum power tracing control method of internal model control according to claim 1, and what it is characterized in that electromagnetic torque response link is input as electromagnetic torque setting value export as true electromagnetic torque T _e.The input variable of transmission link is $\left[\begin{array}{c}{T}_b\\ T_e\end{array}\right],$ Wherein wind wheel aerodynamic moment T _bfor the uncontrollable input in outside as, disturbance can be seen, generator electromagnetic torque T _efor controllable variable, export as wheel hub and main shaft low shaft connection place moment of resistance T opposite to the direction of rotation can by sensor measurements, and measured value is deducted reference model and export T _mend is fed back into afterwards as Modeling Error Feedback.