CN103606939B - Based on the wind bavin hybrid power system LOAD FREQUENCY control method that sliding formwork controls - Google Patents

Abstract

The present invention relates to a kind of wind bavin hybrid power system LOAD FREQUENCY control method controlled based on sliding formwork, comprise the following steps: the control inputs 1) using the power output of wind power generation subsystem as diesel engine subsystem, adopt the sliding-mode control based on BP Neural Network Observer to control the power output of diesel engine subsystem simultaneously, set up system state equation, and use sliding mode controller to calculate control inputs u (t) of diesel engine subsystem in hybrid power system; 2) by step 1) in the control inputs u that calculated by sliding mode controller ₂as the control command of wind power generation subsystem, adopt PID variable pitch control method to control the power output of wind-driven generator according to this control command, optimize the frequency departure of whole hybrid power system.Compared with prior art, the present invention has that control precision is high, effective improves the advantages such as power system load frequency departure.

Description

Based on the wind bavin hybrid power system LOAD FREQUENCY control method that sliding formwork controls

Technical field

The present invention relates to a kind of power system load control method for frequency, especially relate to a kind of wind bavin hybrid power system LOAD FREQUENCY control method controlled based on sliding formwork.

Background technology

In the last few years, the conventional electric power generation forms such as thermoelectricity were day by day serious to the pollution of environment, and under the background exhausted rapidly at traditional energy, the new forms of energy being main representative with wind energy, solar energy etc. are more and more taken seriously and study.Such as, but the resourceful area of new forms of energy is general all more remote, and the wind resource on island, the solar energy resources of Xinjiang region are all very abundant.From far-off regions and isolated island is due to the inconvenience of traffic, and bulk power grid cannot to its continued power.Like this, these areas also utilize the condition of new forms of energy with regard to more possessing Devoting Major Efforts To Developing.But wind speed is not constant, the output mechanical power of wind turbine generator be about wind speed cube with the function affected by by wind generating set undulate quantity.So the intermittence of wind energy and fluctuation also become its main defect.In order to address this problem, the normal bavin hybrid system that becomes a common practice with diesel engine unit of blower fan is powered to load, and by diesel engine starting soon, the feature that efficiency is high makes up rapidly the defect of wind energy instability.The frequency of electric power system is one of important indicator of the quality of power supply, and control in (LFC) in the LOAD FREQUENCY of electric power system, many scholars carry out optimization frequency deviation by diverse ways.

Have in prior art and the PID of classics is controlled to be applied in the design of governing system, but, for the electric power system of the non-linear of complexity with coupling, only controlling frequency modulation by PID is inadequate completely, so many modern control method obtain application.Wind bavin hybrid system is as compact electrical generating systems, it is to the requirement of frequency quality also unusual height, so when have fluctuation and the wind-powered electricity generation of larger permeability exports in access small electrical system, due to the effect that the regulation mechanism only by diesel engine self cannot make frequency reach satisfied, so wind bavin mixing small electrical system still need realize frequency modulation by modern scientist.For the Mathematical Modeling of wind bavin hybrid power system in document " LOAD FREQUENCY of blower fan-diesel engine hybrid system controls; 2011 Chinese Control Conference collections of thesis ", devise internal mode controller and carry out regulating frequency, but internal model control is actual is the improvement controlled PI, so when there is some uncertain parameter item in system, control effects may be poor.Document " Atsushi Yona; Hideomi Sekine; Chul-Hwan Kim; Output power control for large wind power penetration in small powersystem, Renewable Energy, 2009 " is for single domain wind bavin hybrid power system, achieved by fuzzy control method and carry out frequency modulation with wind power output power, but the permeability of wind-powered electricity generation must be reduced like this, although method is feasible, do not utilize new forms of energy fully.Document " Toshiaki Kaneko, Akie Uehara, Atsushi Yona.Tomonobu Senjyu and Chul-Hwan Kim, A new control methodology of wind turbinegenerators for frequency control ofpower system in isolated island, Wind Energy.2011, , same for wind bavin hybrid power system model, devise minimum Order Observers, and obtain wind-powered electricity generation output order by disturbance-observer value and air speed value, in order to realize good effect, the method will reduce wind-powered electricity generation permeability equally.

Summary of the invention

Object of the present invention be exactly in order to overcome above-mentioned prior art exist defect and provide a kind of control precision high, effective improve power system load frequency departure based on sliding formwork control wind bavin hybrid power system LOAD FREQUENCY control method.

Object of the present invention can be achieved through the following technical solutions:

Based on the wind bavin hybrid power system LOAD FREQUENCY control method that sliding formwork controls, described wind bavin hybrid power system comprises wind power generation subsystem and diesel engine subsystem, and described LOAD FREQUENCY control method comprises the following steps:

1) control inputs using the power output of wind power generation subsystem as diesel engine subsystem, adopt the sliding-mode control based on BP Neural Network Observer to control the power output of diesel engine subsystem simultaneously, set up following system state equation, and use sliding mode controller to calculate control inputs u (t) of diesel engine subsystem in hybrid power system:

Wherein,

X (t) is state variable matrix; A is state variable coefficient matrix; it is control inputs coefficient matrix; it is control inputs; D (t) is disturbance; H is coefficient of disturbance matrix; Δ f (t) is frequency departure; P _dt () is diesel engine generator power output; x _dt () is speed regulator valve location; T _git is speed regulator time constant; T _tit is diesel engine time constant; T _pit is electric power system model time constant; K _pit is electric power system gain; R is that speed regulator speed regulates; P _lit is unknowable load disturbance; K _εit is integration control gain; E (t) is the change of integral control increment;

2) by step 1) in the control inputs u that calculated by sliding mode controller ₂as the control command of wind power generation subsystem, adopt PID variable pitch control method to control the power output of wind-driven generator according to this control command, optimize the frequency departure of whole hybrid power system.

Described step 1) in, the sliding-mode control based on BP Neural Network Observer is specially:

1a) design diverter surface S to meet as equation: S=Cx, C are handoff gain matrix;

Reaching law method 1b) is adopted to design sliding mode controller, order:

$\stackrel{\·}{S}=C\stackrel{\·}{x}=C(\mathrm{Ax}+\mathrm{Bu}+\mathrm{Hd}\left(t\right))=-\mathrm{\ϵsgn}\left(s\right)$

Solve and can obtain control inputs:

u=-(CB)- ^1[CAx+CHd(t)+εsgn(s)]

Wherein x is state variable, and u is control inputs, and A is state variable coefficient matrix, B and H is coefficient matrix, and d (t) is disturbance; ε is gain, and sgn (s) is sign function, for: $\mathrm{sgn}\left(s\right)=\left\{\begin{array}{c}1,s>0\\ -1,s<0\end{array}\right.;$

1c) use the approximation of BP Neural Network Observer calculation perturbation d (t) to substitute into sliding mode controller, obtain final u.

Described BP Neural Network Observer design is as follows:

If state equation is

$\left\{\begin{array}{c}\stackrel{\&CenterDot;}{x}=\mathrm{Ax}+\mathrm{Bu}+d\left(t\right)\\ y=\mathrm{Dx}\end{array}\right.$

Wherein D=1,0,0,0], using input u with export y and approach as the input of three layers of BP neural net $d\left(t\right)=\stackrel{\&CenterDot;}{x}-\mathrm{Ax}-\mathrm{Bu},$ :

d(t)=Wσ(Vx)+ε(x)

Wherein, σ 0 is the excitation function of hidden layer neuron, and V represents that input layer is to the weight matrix of hidden layer and first row comprises threshold values vector, W represents the weight matrix of hidden layer to output layer, ε (x) represents neural net approximate error, so the approximation of d (t) is:

$\hat{d}\left(t\right)=\hat{W}\mathrm{\&sigma;}\left(\hat{V}\hat{x}\right)$

Design of Observer is:

$\begin{array}{c}\stackrel{\&CenterDot;}{\tilde{x}}=A_L\tilde{x}\tilde{W}\mathrm{\&sigma;}\left(\hat{V}\hat{x}\right)+\mathrm{\&omega;}\left(t\right)\\ \tilde{y}=D\tilde{x}\end{array}$

Wherein, a _l=A-LD is the Hurwitz matrix of asymptotically stability, and L is the observer gain matrix of design, be the disturbance of a bounded, meet it is normal number.

Described step 2) in, the power output adopting PID variable pitch control method to control wind-driven generator is specially:

2a) calculating generator power output P _gwith control command P _cmddeviation delta P _g=P _g-P _cmd, P _cmd=u ₂;

The variation delta β of propeller pitch angle 2b) is calculated according to following exact function;

$G\left(\mathrm{\&beta;}\right)=\frac{\mathrm{\&Delta;\&beta;}}{\mathrm{\&Delta;}{P}_g}=\frac{1}{A_1+A_2{V}_w^2}$

In formula, A ₁=a ₁₂+ 2a ₁₃β+3a ₁₄β ², A ₂=a ₂₂+ 2a ₂₃+ 3a ₂₄β ², a ₁₂~ a ₂₄for constant, β is propeller pitch angle, V _wfor wind speed;

2c) with step 2b) variable quantity of propeller pitch angle that calculates controls the propeller pitch angle of blower fan, and then controls the power output of wind-driven generator.

Compared with prior art, the present invention has following beneficial effect:

1, the present invention propose in blower fan side improvement variable pitch PID control optimize power output, by in the Variable-pitch Controller design that wind power output power variable quantity thereof using PID controls, the PID controller that the present invention is proposed has better effect compared with traditional PID controller;

2, diesel engine side of the present invention then adopts the sliding-mode control based on BP Neural Network Observer, namely design BP Neural Network Observer estimates the interference indeterminate in electric power system, and the estimated value of interference is applied in the design of sliding mode controller, utilize the boundary of indeterminate to carry out CONTROLLER DESIGN in controlling with traditional sliding formwork and there is better chattering suppress effect;

3, false wind electric output power of the present invention is not by the restriction of rated power, using the control inputs of wind power output power as diesel engine system, according to system state equation, sliding formwork is used to control to calculate, then using the instruction of the control inputs amount obtained as wind power output power, thus blower fan side just can be come by award setting wind power output power according to this instruction, and blower fan finally can be made to participate in frequency modulation, make blower fan participate in frequency modulation, effectively improve the frequency departure of system.

Accompanying drawing explanation

Fig. 1 is wind bavin mixing small electrical system construction drawing;

Fig. 2 is wind generator system structure chart;

Fig. 3 is diesel-electric system loading frequency control model figure;

Fig. 4 is that blower variable-pitch is apart from control strategy;

Fig. 5 is that power of fan feedback PID controls;

Fig. 6 is the relation of G (β) function and propeller pitch angle;

Fig. 7 is wind bavin mixing small electrical system loading frequency control model;

Fig. 8 is BP Neural Network Observer structure principle chart;

Fig. 9 is three layers of BP neural networks principles figure;

Figure 10 is CO-WD control system block diagram;

Blower variable-pitch when Figure 11 is CO-WD control strategy is apart from control block diagram;

The measured value curve chart that Figure 12 (a) obtains for BP Neural Network Observer;

The error curve diagram that Figure 12 (b) is neural net disturbance-observer value and actual value;

Figure 12 (c) is output error curve chart;

Figure 12 (d) is neural net disturbance-observer value and the error of actual value and the application condition figure of interference observer method;

Figure 13 (a) is the wind speed simulation curve figure based on Kaimal spectrum;

The Wind turbines output power curve figure that Figure 13 (b) is variable pitch control;

Figure 13 (c) is without Wind turbines output power curve figure during variable pitch control;

Figure 14 (a) is for wind bavin is all without frequency departure curve chart when controlling;

Figure 14 (b) is WO frequency departure curve chart;

Figure 14 (c) is DO frequency departure curve chart;

Figure 14 (d) is WD frequency departure curve chart;

Figure 14 (e) is CO-DW frequency departure curve chart;

The frequency departure comparison diagram that Figure 14 (f) is CO-WD and diesel engine self frequency modulation mechanism;

The frequency departure comparison diagram that Figure 14 (g) is CO-WD and CO-WDD;

Figure 15 is CO-WD output order and power output comparison diagram;

Figure 16 is CO-WDD control system block diagram.

Embodiment

Below in conjunction with the drawings and specific embodiments, the present invention is described in detail.The present embodiment is implemented premised on technical solution of the present invention, give detailed execution mode and concrete operating process, but protection scope of the present invention is not limited to following embodiment.

(1) Mathematical Modeling of wind bavin mixing small electrical system

Set up the Mathematical Modeling of wind power generation subsystem:

C _p(λ，β)=c ₁(β)λ ²+c ₂(β)λ ³+c ₃(β)λ ⁴

$\left.\begin{array}{c}{c}_1\left(\mathrm{\&beta;}\right)=c_{10}+c_{11}\mathrm{\&beta;}+c_{12}{\mathrm{\&beta;}}^2+c_{13}{\mathrm{\&beta;}}^3+c_{14}{\mathrm{\&beta;}}^4\\ c_2\left(\mathrm{\&beta;}\right)=c_{20}+c_{21}\mathrm{\&beta;}+c_{22}{\mathrm{\&beta;}}^2+c_{23}{\mathrm{\&beta;}}^3+c_{24}{\mathrm{\&beta;}}^4\\ c_3\left(\mathrm{\&beta;}\right)=c_{30}+c_{31}\mathrm{\&beta;}+c_{32}{\mathrm{\&beta;}}^2+c_{33}{\mathrm{\&beta;}}^3+c_{34}{\mathrm{\&beta;}}^4\end{array}\right\}$

$\mathrm{\&lambda;}=\frac{{\mathrm{\&omega;}}_{r}R}{V_w}$

${\mathrm{\&omega;}}_r^2=\&Integral;\frac{2}{J}(P_w-P_g)\mathrm{dt}$

$s=\frac{{\mathrm{\&omega;}}_0-{\mathrm{\&omega;}}_r}{{\mathrm{\&omega;}}_0}$

Wherein, C _p(λ, β) is power coefficient, and λ is tip speed ratio, and β is propeller pitch angle, c ₁₀~ c ₃₄for the definite value of power coefficient parameter, R is Wind wheel paddle radius, V _wfor wind speed, ω _rfor blower fan angular speed, J is the moment of inertia of blower fan, and s is revolutional slip, ω ₀for synchronous speed, the mechanical output P of wind turbine _wobtained by following equation:

$P_w=\frac{C_p(\mathrm{\&lambda;},\mathrm{\&beta;})V_w^3\mathrm{\&rho;A}}{2}$

In formula, ρ is atmospheric density, and A is the cross section of Wind wheel paddle rotor;

Output of a generator P _gobtained by following equation:

$P_g=\frac{-3{\mathrm{\&pi;}}^{2}s(1+s)R_2}{{(R_2-s{R}_1)}^2+s^2{(X_1+X_2)}^2}$

In formula, V is phase voltage, R ₁for stator resistance, R ₂for rotor resistance, X ₁for stator reactance, X ₂for rotor reactance.

Using the diesel engine without reheating link as prime mover, set up following diesel engine subsystem Mathematical Modeling:

$\mathrm{\&Delta;}\stackrel{\&CenterDot;}{f}\left(t\right)=-\frac{1}{T_p}\mathrm{\&Delta;f}\left(t\right)+\frac{K_p}{T_p}{P}_d\left(t\right)-\frac{K_p}{T_p}{P}_L\left(t\right)$

${\stackrel{\&CenterDot;}{P}}_d\left(t\right)=-\frac{1}{T_t}{P}_d\left(t\right)+\frac{1}{T_t}{X}_d\left(t\right)$

${\stackrel{\&CenterDot;}{X}}_d\left(t\right)=-\frac{1}{{\mathrm{RT}}_g}\mathrm{\&Delta;f}\left(t\right)+\frac{1}{T_g}{X}_d\left(t\right)-\frac{1}{T_g}E\left(t\right)+\frac{1}{T_g}u\left(t\right)$

$E\left(t\right)=K_{\mathrm{\&epsiv;}}{\&Integral;}_0^t\mathrm{\&Delta;f}\left(\mathrm{\&tau;}\right)\mathrm{d\&tau;}$

$\stackrel{\&CenterDot;}{x}\left(t\right)=\mathrm{Ax}\left(t\right)+\mathrm{Bu}\left(t\right)+\mathrm{Hd}\left(t\right)$

Wherein

X (t) is state variable matrix; A is state variable coefficient matrix; B is control inputs coefficient matrix; U (t) is control inputs; D (t) is disturbance; H is coefficient of disturbance matrix; Δ f (t) is frequency departure; P _dt () is diesel engine generator power output; X _dt () is speed regulator valve location; T _git is speed regulator time constant; T _tit is diesel engine time constant; T _pit is electric power system model time constant; K _pit is electric power system gain; R is that speed regulator speed regulates, P _lit is unknowable load disturbance.

(2) design principle of wind bavin mixing small electrical system loading FREQUENCY CONTROL strategy of the present invention and method for designing

The present invention is directed to the small electrical system of wind bavin mixed power generation, the variable pitch PID that blower fan side proposes improvement controls to optimize power output, diesel engine side then adopts the sliding-mode control based on Neural Network Observer, and makes blower fan participate in frequency modulation, is described as follows.

The control strategy of independent control wind power generation subsystem (WO) is: blower fan side uses the PID variable pitch control improved to control output of a generator; Diesel engine side uses the regulation mechanism of self to regulate frequency.The principle of variable pitch control is when wind speed exceedes rated wind speed, limits wind turbine and obtains wind energy, thus limit and maintain generator active power of output on rated power by the position changing wind turbine blade.

As shown in Figure 5, the power output adopting PID variable pitch control method to control wind-driven generator is specially:

Be defined as follows the variation delta β that exact function calculates propeller pitch angle:

$G\left(\mathrm{\&beta;}\right)=\frac{\mathrm{\&Delta;\&beta;}}{\mathrm{\&Delta;}{P}_g}=\frac{1}{A_1+A_2{V}_w^2}$

In formula, Δ P _gfor the deviate of wind driven generator output power and rated power, A ₁=a ₁₂+ 2a ₁₃β+3a ₁₄β ², A ₂=a ₂₂+ 2a ₂₃β+3a ₂₄β ², a ₁₂~ a ₂₄for constant, V _wfor wind speed.Fig. 6 indicates the situation of change of G (β) and its value depends on equally from rated wind speed 12.5m/s to the wind speed of cut-out wind speed 24m/s and changes.Such as, as wind speed V _w=15m/s, during propeller pitch angle β=20 °, G (β)=0.05.

Variable pitch control can only limit the part exceeding rated power, if and optimize the power output of blower fan with the storage battery that Mathematical Modeling Approximate Equivalent is first-order lag link, then can supplement the part of below rated power, Wind turbines power output after its optimization and the power output comparison diagram before optimizing are as shown in Figure 13 (b), and both frequency departure comparison diagrams are as shown in Figure 14 (b).

The control strategy of independent control diesel engine subsystem (DO) is: blower fan side does not control, and Shen power output of keeping watch directly accesses in LOAD FREQUENCY control system, and diesel engine side uses the sliding formwork based on BP Neural Network Observer to control frequency modulation.

For the wind bavin hybrid power system LOAD FREQUENCY state of a control equation of Fig. 7, design con-trol rate u carrys out regulating frequency deviation.The design of sliding mode controller divides two steps, and the first step is design diverter surface S, and second step is only design sliding mode controller.Final target is that the controller designed by guarantee can make the state trajectory of system arrive diverter surface rapidly from initial arbitrary value and to remain near sliding mode.

Design diverter surface S meets as equation: S=Cx;

Wherein handoff gain Matrix C is obtained by the POLE PLACEMENT USING of system, meets S=0 when system arrives sliding mode.

Adopt reaching law method design sliding mode controller, order:

$\stackrel{\&CenterDot;}{S}=C\stackrel{\&CenterDot;}{x}=C(\mathrm{Ax}+\mathrm{Bu}+\mathrm{Hd}\left(t\right))=-\mathrm{\&epsiv;sgn}\left(s\right)$

Solve and can obtain control rate:

u=-(CB) ^-1[CAx+CHd(t)+εsgn(s)]。

Wherein d (t) only comprises unknowable load P _lalthough the steady state value that traditional sliding formwork controls to get an approximate load lower bound substitutes, in order to obtain better control effects, BP Neural Network Observer can be used obtain the approximation of interference d (t) and being updated in controller.The design of BP Neural Network Observer is as follows:

Traditional sliding formwork control inputs is known, then:

$\left\{\begin{array}{c}\stackrel{\&CenterDot;}{x}=\mathrm{Ax}+\mathrm{Bu}+d\left(t\right)\\ y=\mathrm{Dx}\end{array}\right.$

Wherein D=1,0,0,0], be considerable by the known system of (D, A) full rank and u is known, then by input u with export y and approach as the input of three layers of BP neural net :

d(t)=wσ(Vx)+ε(x)

Wherein σ 0 is the excitation function of hidden layer neuron, v represents that input layer is to the weight matrix of hidden layer and first row comprises threshold values vector, W represents the weight matrix of hidden layer to output layer, and ε (x) represents neural net approximate error, and three layers of BP neural networks principles figure as shown in Figure 9.So d (t) can be approximated to be:

$\hat{d}\left(t\right)=\hat{W}\mathrm{\&sigma;}\left(\hat{V}\hat{x}\right)$

So observer can be designed as:

$\begin{array}{c}\stackrel{\&CenterDot;}{\hat{x}}=A\hat{x}+\mathrm{Bu}+\tilde{W}\mathrm{\&sigma;}\left(\hat{V}\hat{x}\right)+L(y-D\hat{x})\\ \hat{y}=D\hat{x}\end{array}$

Definition status error and output by above formula, arrange:

$\begin{array}{c}\stackrel{\&CenterDot;}{\tilde{x}}=\mathrm{Ax}+\mathrm{W\&sigma;}\left(\mathrm{Vx}\right)-A\hat{x}-\hat{W}\mathrm{\&sigma;}\left(\hat{V}\hat{x}\right)\\ -G(\mathrm{Dx}-D\hat{x})+\mathrm{\&epsiv;}\left(x\right)\\ \stackrel{\&CenterDot;}{\tilde{y}}=D\tilde{x}\end{array}$

Right formula above adds arrange:

$\begin{array}{c}\stackrel{\&CenterDot;}{\tilde{x}}=A_L\tilde{x}\tilde{W}\mathrm{\&sigma;}\left(\hat{V}\hat{x}\right)+\mathrm{\&omega;}\left(t\right)\\ \tilde{y}=D\tilde{x}\end{array}$

Wherein, a _l=A-LD is the Hurwitz matrix of asymptotically stability, $\mathrm{\&omega;}\left(t\right)=W[\mathrm{\&sigma;}\left(\mathrm{Vx}\right)-\mathrm{\&sigma;}\left(\hat{V}\hat{x}\right)]+\mathrm{\&epsiv;}\left(x\right)$ Be the interference of a bounded, meet $\left|\right|\mathrm{\&omega;}\left(t\right)\left|\right|\&le;\stackrel{\&OverBar;}{\mathrm{\&xi;}},$ it is normal number.

It is exactly that the decentralized control of WO, DO is applied simultaneously that wind bavin all carries out controlling (WD), and namely blower fan side adopts variable pitch control, and diesel engine side adopts the sliding formwork based on BP Neural Network Observer to control.

Cooperation control (CO-DW) based on diesel engine side refers on the basis of WD control strategy using the distracter that Wind turbines power output can be surveyed in sliding formwork control, substitute in diesel engine side sliding mode controller u, make sliding formwork control to contemplate when regulating frequency deviation the amount of Wind turbines power output, improve the validity that frequency departure regulates.State equation becomes:

Wherein

Wherein system mode coefficient matrices A does not change, so handoff gain Matrix C is also constant.Same employing reaching law method designs sliding mode controller, then:

As shown in Figure 10 and Figure 11, the cooperation control (CO-WD) that blower fan participates in frequency modulation refers to when diesel engine controls without sliding formwork, false wind electric output power is not by the restriction of rated power, using the control inputs of wind power output power as diesel engine system, according to system state equation, sliding formwork is used to control to calculate the amount of this control output, then using the instruction of the control inputs amount obtained as wind power output power, thus blower fan side just can be come by award setting wind power output power according to this instruction, the final blower fan that can make participates in frequency modulation, optimize the frequency departure of whole system, and further increase the validity of frequency departure adjustment.

System state equation now becomes:

Wherein,

As shown in figure 16, the present invention is based on the wind bavin hybrid power system LOAD FREQUENCY control method CO-WDD that sliding formwork controls, refer to adopt in diesel engine side and control its power output P based on the sliding-mode control of BP neural net _dtime (t), using wind power output power also as the control inputs of diesel engine system, according to system state equation, second sliding formwork is used to control to calculate the amount of this control output, then using the instruction of the control inputs amount obtained as wind power output power, thus blower fan side just can be come by award setting wind power output power P according to this instruction _gt (), by P _g(t), P _d(t) and P _lt () input electric power system obtains frequency variation Δ f (t) and exports and feed back to diesel generation pusher side, blower fan finally can be made to participate in frequency modulation, further increase the validity that frequency departure regulates.System shape now

Wherein,

Use Reaching Law can calculate u respectively ₁, u ₂, method for solving and process illustrate above:

u ₁=-(CB) ^-1[CAx+CHd(t)+εsgn(s)]

$u_2\left(t\right)=-{\left(C\hat{B}\right)}^{-1}[\mathrm{CAx}+\mathrm{CHd}\left(t\right)+\mathrm{\&epsiv;sgn}\left(s\right)].$

(4) sample calculation analysis

The validity of proposed control strategy will be verified in the present invention by matlab simulation result.The method of the present invention's proposition and the effect of conventional method is contrasted by six kinds of situations.First three kind situation is decentralized control: the first situation, controls separately wind turbine generator (WO); The second situation, controls separately diesel engine (DO); The third situation, wind bavin all controls (WD).Rear three kinds of situations are cooperation control: the 4th kind of situation, the cooperation control (CO-DW) based on diesel engine side; 5th kind of situation, the cooperation control (CO-WD) based on blower fan; Last a kind of situation, in DO situation, blower fan participates in the cooperation control (CO-WDD) of frequency modulation.In matlab simulation process, the training function of BP neural net adopts Levenberg-Marquardt (LM) algorithm to revise weights and bias, although LM algorithm operationally can committed memory space greatly, its velocity of approch is then the hundred times of general algorithm.

1) example 1

In this example, blower fan side uses the PID variable pitch control improved to limit output of a generator; Diesel engine side uses the regulation mechanism of self to regulate frequency.The principle of variable pitch control is when wind speed exceedes rated wind speed, limits wind turbine and obtains wind energy, thus limit and maintain generator active power of output on rated power by the position changing wind turbine blade.Wherein Fig. 4 is variable pitch control strategy, and Fig. 5 is that Feedback of Power PID controls, and Fig. 6 is the relation of G (β) function and propeller pitch angle.

Frequency departure when Figure 14 (b) is WO control strategy, can find out, through storage battery optimization and the frequency departure weak effect optimized without storage battery few, eliminate the part that part deviation amplitude is larger after storage battery optimization.From the frequency modulation of entirety, do not have greatly improved.

2) example 2

In this example, blower fan side does not control, and wind power output power is directly accessed in LOAD FREQUENCY control system, and diesel engine side uses the sliding formwork based on BP Neural Network Observer to control frequency modulation.Fig. 7 is wind bavin mixing small electrical system loading frequency control model, and Fig. 8 is BP Neural Network Observer, Fig. 9 tri-layers of BP neural networks principles figure,

Figure 14 (c) is the frequency departure under DO control strategy, even without variable pitch control, controlled by the sliding formwork of diesel engine side or good most deviation to be limited in ± 0.1 within, the amplitude that pole individual deviation is larger exceedes ± 0.2.

3) example 3

In this example, blower fan side adopts the variable pitch PID improved to control to optimize power output, and diesel engine side then adopts the sliding-mode control based on Neural Network Observer, is called WD decentralized control strategy, and two kinds of methods use non-interference respectively.

Figure 14 (d) is the impact of WD control strategy on frequency, eliminates indivedual higher magnitude of frequency departure during DO control strategy.

4) example 4

In this example, using the distracter that Wind turbines power output can be surveyed in sliding formwork control on the basis of WD control strategy, substitute in diesel engine side sliding mode controller u, make sliding formwork control to contemplate when regulating frequency deviation the amount of Wind turbines power output.

Frequency departure when Figure 14 (e) is cooperation control CO-DW, substitute in sliding mode controller u using wind power output power as interference, frequency departure is well limited in ± 0.05 within, effect is ideal.

5) example 5

In this example, when diesel engine controls without sliding formwork, false wind electric output power is not by the restriction of rated power, using the control inputs of wind power output power as diesel engine system, according to system state equation, sliding formwork is used to control to calculate the amount of this control output, then using the instruction of the control inputs amount obtained as wind power output power, thus blower fan side just can be come by award setting wind power output power according to this instruction, blower fan finally can be made to participate in frequency modulation, optimize the frequency departure of whole system.Figure 10 CO-WD control system block diagram, during Figure 11 CO-WD control strategy, blower variable-pitch is apart from controlling.

When Figure 14 (f) is cooperation control CO-WD, to wind power be added and allow it participate in the frequency departure after frequency modulation and (only have diesel engine system with classical power system load frequency control model, do not add wind power output power) the comparison diagram of frequency departure, when having absolutely proved that system adds the new forms of energy of fluctuation, there is improvement on the contrary for frequency departure.Due to wind power output power is calculated as the control inputs of the state equation of logical whole system the reference value that its concrete amount is used as wind power output power, realize real output by variable pitch control and equal reference value, finally achieve blower fan and participate in frequency modulation.The comparison diagram of the control inputs calculated and actual wind power output power as shown in figure 15, indicates power output and has well followed the tracks of output order.

6) example 6

In this example, when diesel engine has sliding formwork to control, using wind power output power also as the control inputs of diesel engine system, according to system state equation, second sliding formwork is used to control to calculate the amount of this control output, then using the instruction of the control inputs amount obtained as wind power output power, thus blower fan side just can be come by award setting wind power output power according to this instruction, and blower fan finally can be made to participate in frequency modulation.The method is also the improvement to cooperation control CO-WD.

Figure 14 (g) is the comparison diagram of frequency departure between two kinds of control strategy cooperation control CO-WDD and CO-WD proposing of the present invention, the former controls than the sliding formwork of the latter in the many DO control strategy of diesel engine side, make CO-WDD have two sliding formworks to control, so the control effects of its frequency departure is also just more better than CO-WD's.

Claims (4)

1., based on the wind bavin hybrid power system LOAD FREQUENCY control method that sliding formwork controls, described wind bavin hybrid power system comprises wind power generation subsystem and diesel engine subsystem, it is characterized in that, described LOAD FREQUENCY control method comprises the following steps:

1) control inputs using the power output of wind power generation subsystem as diesel engine subsystem, adopt the sliding-mode control based on BP Neural Network Observer to control the power output of diesel engine subsystem simultaneously, set up following system state equation, and use sliding mode controller to calculate the control inputs of diesel engine subsystem in hybrid power system

Wherein, $x\left(t\right)=\left[\begin{array}{c}\mathrm{\&Delta;f}\left(t\right)\\ P_d\left(t\right)\\ X_d\left(t\right)\\ E\left(t\right)\end{array}\right],$ $A=\left[\begin{array}{cccc}-\frac{1}{T_p}& \frac{K_p}{T_p}& 0& 0\\ 0& -\frac{1}{T_t}& \frac{1}{T_t}& 0\\ -\frac{1}{{\mathrm{RT}}_g}& 0& -\frac{1}{T_g}& -\frac{1}{T_g}\\ K_{\mathrm{\&epsiv;}}& 0& 0& 0\end{array}\right],$ $B=\left[\begin{array}{c}0\\ 0\\ \frac{1}{T_g}\\ 0\end{array}\right],$ $\hat{B}=\left[\begin{array}{c}\frac{K_p}{T_P}\\ 0\\ 0\\ 0\end{array}\right],$ $d\left(t\right)=\left[\begin{array}{c}{P}_L\\ 0\\ 0\\ 0\end{array}\right],$ $H=\left[\begin{array}{c}-\frac{K_p}{T_p}\\ 0\\ 0\\ 0\end{array}\right];$

X (t) is state variable matrix; A is state variable coefficient matrix; it is control inputs coefficient matrix; control inputs, wherein, u ₁for the first control inputs obtained based on the sliding-mode control of BP Neural Network Observer, u ₂for the second control inputs that described sliding mode controller obtains; D (t) is disturbance; H is coefficient of disturbance matrix; Δ f (t) is frequency departure; P _dt () is diesel engine generator power output; X _dt () is speed regulator valve location; T _git is speed regulator time constant; T _tit is diesel engine time constant; T _pit is electric power system model time constant; K _pit is electric power system gain; R is that speed regulator speed regulates; P _lit is unknowable load disturbance; K _εit is integration control gain; E (t) is the change of integral control increment;

2) by step 1) in the second control inputs u of being calculated by sliding mode controller ₂as the control command of wind power generation subsystem, adopt PID variable pitch control method to control the power output of wind-driven generator according to this control command, optimize the frequency departure of whole hybrid power system.

2. a kind of wind bavin hybrid power system LOAD FREQUENCY control method controlled based on sliding formwork according to claim 1, is characterized in that, described step 1) in, the sliding-mode control based on BP Neural Network Observer is specially:

1a) design diverter surface S to meet as equation: S=Cx, C are handoff gain matrix;

Reaching law method 1b) is adopted to design sliding mode controller, order:

$\stackrel{.}{S}=C\stackrel{.}{x}=C(\mathrm{Ax}+\mathrm{Bu}+\mathrm{Hd}\left(t\right))=-\mathrm{\&epsiv;sgn}\left(s\right)$

Solve and can obtain control inputs:

u＝-(CB) ^-1[CAx+CHd(t)+εsgn(s)]

Wherein x is state variable, and u is control inputs, and A is state variable coefficient matrix, B and H is coefficient matrix, and d (t) is disturbance; ε is gain, and sgn (s) is sign function, for: $\mathrm{sgn}\left(s\right)=\left\{\begin{array}{c}1,s>0\\ -1,s<0\end{array}\right.;$

1c) use the approximation of BP Neural Network Observer calculation perturbation d (t) to substitute into sliding mode controller, obtain final u.

3. a kind of wind bavin hybrid power system LOAD FREQUENCY control method controlled based on sliding formwork according to claim 2, is characterized in that, described BP Neural Network Observer design is as follows:

If state equation is

$\left\{\begin{array}{c}\stackrel{.}{x}=\mathrm{Ax}+\mathrm{Bu}+d\left(t\right)\\ y=\mathrm{Dx}\end{array}\right.$

Wherein D=[1,0,0,0], approaches input u and output y as the input of three layers of BP neural net $d\left(t\right)=\left(\stackrel{.}{x}\right)-\mathrm{Ax}-\mathrm{Bu},$ :

d(t)＝Wσ(Vx)+ε(x)

Wherein, σ () is the excitation function of hidden layer neuron, V represents that input layer is to the weight matrix of hidden layer and first row comprises threshold values vector, W represents the weight matrix of hidden layer to output layer, ε (x) represents neural net approximate error, so the approximation of d (t) is:

$\hat{d}\left(t\right)=\hat{W}\mathrm{\&sigma;}\left(\hat{V}\hat{x}\right)$

Design of Observer is:

$\begin{array}{c}\stackrel{.}{\stackrel{~}{x}}=A_L\tilde{x}+\tilde{W}\mathrm{\&sigma;}\left(\hat{V}\hat{x}\right)+\mathrm{\&omega;}\left(t\right)\\ \tilde{y}=D\tilde{x}\end{array}$

Wherein, a _l=A-LD is the Hurwitz matrix of asymptotically stability, and L is the observer gain matrix of design, $\mathrm{\&omega;}\left(t\right)=W[\mathrm{\&sigma;}\left(\mathrm{Vx}\right)-\mathrm{\&sigma;}\left(\hat{V}\hat{x}\right)]+\mathrm{\&epsiv;}\left(x\right)$ Be the disturbance of a bounded, meet it is normal number.

4. a kind of wind bavin hybrid power system LOAD FREQUENCY control method controlled based on sliding formwork according to claim 1, is characterized in that, described step 2) in, the power output adopting PID variable pitch control method to control wind-driven generator is specially:

2a) calculating generator power output P _gwith control command P _cmddeviation delta P _g=P _g-P _cmd, P _cmd=u ₂;

The variation delta β of propeller pitch angle 2b) is calculated according to following exact function:

$G\left(\mathrm{\&beta;}\right)=\frac{\mathrm{\&Delta;\&beta;}}{\mathrm{\&Delta;}{P}_g}=\frac{1}{A_1+A_2{V}_w^2}$

In formula, A ₁=a ₁₂+ 2a ₁₃β+3a ₁₄β ², A ₂=a ₂₂+ 2a ₂₃β+3a ₂₄β ², a ₁₂~ a ₂₄for constant, β is propeller pitch angle, V _wfor wind speed;

2c) with step 2b) variable quantity of propeller pitch angle that calculates controls the propeller pitch angle of blower fan, and then controls the power output of wind-driven generator.