CN102072083B - Maximum wind energy tracking method for double-fed wind power generation system - Google Patents

Abstract

The invention provides a maximum wind energy tracking control method. The method comprises the following steps of: first, supposing an instantaneous wind speed to be V1, and detecting the power PA of a wind turbine which operates to a point A at the wind speed V1; then, supposing the power PA of the wind turbine at the point A at the wind speed V1 to be the power PB (max) of the wind turbine at a maximum power point B at a certain virtual wind speed V2, namely PB(max)=PA, and calculating an optimal rotating speed wopt of the virtual wind speed V2 according to a characteristic formula of the power absorbed from wind energy by the wind turbine; and finally, taking the optimal rotating speed wopt as a give speed of the wind turbine at the wind speed V1 at the next time, searching the optimal rotating speed of the wind speed V1 by continuing searching according to the above method at new working points, and simultaneously obtaining the maximum power of the wind speed V1. The method has the advantages that: the wind power generation system can be operated in a working state with high wind energy capture rate all the time at an increasing wind speed, a decreasing wind speed and a stepped wind speed; the dynamic performance of maximum wind energy tracking at gradient wind speed is improved; the wind energy capture rate at the gradient wind speed is improved; the method does not need to perform wind speed detection; and an algorithm is simple.

Description

A kind of dual feedback wind power generation system maximal wind-energy tracking

Technical field

The invention belongs to the Control Technology of Wind Power Generation System field, relate to a kind of dual feedback wind power generation system maximal wind-energy tracking.

Background technique

Wind energy is a kind of have randomness, probabilistic energy, how to design a kind of tracking Control strategy, and making wind energy conversion system the highest to the capture rate of wind energy under different wind speed is one of wind-power electricity generation key technology.The general at present search by hill climbing method that need not measuring wind that adopts; Through detecting wind energy conversion system output power and angular velocity, calculate the slope of wind energy conversion system power then to wind energy conversion system angular velocity, draw suitable rotating speed disturbing quantity; This method has obtained under the step wind speed and has controlled effect preferably; But the dynamic tracing performance is not good under the gradual change wind speed, changes when very fast when wind speed especially, and the wind energy capture rate significantly descends.

Summary of the invention

The purpose of this invention is to provide a kind of dual feedback wind power generation system maximal wind-energy tracking, solve the problem that the search by hill climbing algorithm descends to the wind energy tracking performance under the gradual change wind speed.

The technological scheme that the present invention adopted is, a kind of dual feedback wind power generation system maximal wind-energy tracking, and this method is implemented according to following steps:

Step 1,

Suppose certain in a flash wind speed be V ₁, detect V ₁Wind energy conversion system runs to the power P that A is ordered under the wind speed _A

Step 2,

Suppose V ₁The power P that wind energy conversion system A is ordered under the wind speed _ABe a certain virtual wind speed V ₂The power P that maximum power point B is ordered _{B (max)}, P just _{B (max)}=P _A, calculate virtual wind speed V from wind energy power absorbed characteristic formula according to wind turbine ₂:

$V_2=\sqrt[3]{{2P}_{B\left(\mathrm{Max}\right)}/{\mathrm{\ρ\; SC}}_{p\mathrm{Max}}}$ Formula 1

In the formula, C _PmaxBe wind energy conversion system peak output utilization factor, S is the wind energy conversion system swept area, and ρ is an air density;

Then according to calculating virtual wind speed V ₂Reach wind wheel blade tip linear velocity and respective relationships function and obtain virtual wind speed V ₂Optimized rotating speed w _Opt:

$w_{\mathrm{Opt}}=\frac{{\mathrm{\λ}}_{\mathrm{Opt}}\×V_2}{R}$ Formula 2

In the formula, λ _OptBe best tip speed ratio, R is the wind wheel radius;

Step 3,

With virtual wind speed V ₂Optimized rotating speed w _OptAs V ₁The rotational speed setup of next moment wind energy conversion system of wind energy conversion system under the wind speed: wind energy conversion system runs to C point, the angular velocity omega that C is ordered _CEqual virtual wind speed V ₂Optimized rotating speed w _Opt, the angular velocity of ordering according to C again and the running state of wind energy conversion system detect the output power Pc of wind energy conversion system this moment, again with P _CAs virtual wind speed V ₃The maximum power point D power P of ordering _{D (max)}, with P _{D (max)}Bring formula 1 into and obtain virtual wind speed V ₃, obtain virtual wind speed V according to formula 2 again ₃Optimized rotating speed, again with virtual wind speed V ₃Optimized rotating speed as V ₁The rotational speed setup that next moment E of wind energy conversion system is ordered under the wind speed, wind energy conversion system runs to the E point, continues search more according to the method described above in new operation point, can search V ₁Optimized rotating speed under the wind speed obtains V simultaneously ₁The peak output of wind speed.

The invention has the beneficial effects as follows; Can cumulative, decrescence reach and make wind-power generating system run on the higher working state of wind energy capture rate under the step wind speed all the time; Improved maximal wind-energy tracking dynamic performance under the gradual change wind speed; Improved wind energy capture rate under the gradual change wind speed, this method need not to carry out wind speed and detects, and algorithm is simple.

Description of drawings

Fig. 1 is wind energy conversion system power characteristic figure;

Fig. 2 is the schematic diagram (a is initialization point maximal wind-energy tracking tracing process schematic diagram when the optimized rotating speed point left side, and b is initialization point maximal wind-energy tracking tracing process schematic diagram when optimized rotating speed point the right) of maximal wind-energy tracking of the present invention;

Fig. 3 is under the cumulative wind speed, search by hill climbing method and the inventive method tracing process comparison diagram (a is a search by hill climbing method maximal wind-energy tracing process schematic diagram under the cumulative wind speed, and b is the inventive method maximal wind-energy tracing process schematic diagram under the cumulative wind speed);

Fig. 4 is decrescence under the wind speed, search by hill climbing method and the inventive method tracing process comparison diagram (a is search by hill climbing method maximal wind-energy tracing process schematic diagram under the wind speed decrescence, and b is the inventive method maximal wind-energy tracing process schematic diagram under the wind speed decrescence);

Fig. 5 is under the typical wind speed; (a is typical wind speed curve figure for search by hill climbing method and the inventive method rotating-speed tracking control plotted curve and power coefficient plotted curve; B is optimized rotating speed calculated value and search by hill climbing method speed curves figure; C is a search by hill climbing method power coefficient Cp plotted curve, and d is optimized rotating speed calculated value and the inventive method speed curves figure, and e is the inventive method power coefficient Cp plotted curve);

Fig. 6 is under the simulating nature wind speed; (a is a simulating nature wind speed plotted curve for search by hill climbing method and the inventive method rotating-speed tracking plotted curve and power coefficient plotted curve; B is optimized rotating speed curve and search by hill climbing method generator actual speed plotted curve; C is a search by hill climbing method power coefficient Cp plotted curve, and d is optimized rotating speed curve and the inventive method generator actual speed plotted curve, and e is the inventive method power coefficient Cp plotted curve).

Embodiment

Below in conjunction with accompanying drawing and embodiment the present invention is elaborated.

As can beappreciated from fig. 1, wind energy conversion system power curve shape and quadratic curve are similar; Under certain wind speed, the output mechanical power P of wind energy conversion system _mAngular velocity omega with wind energy conversion system _wChange and change, v1, v2, v3, v4, v5, v6 are wind speed, P _MaxPeak output for wind energy conversion system under each wind speed.If wind energy conversion system angular velocity corresponding during the peak output of wind energy conversion system is the optimized rotating speed under the corresponding wind speed.

Embodiment 1

Shown in Fig. 2 (a), suppose certain in a flash wind speed be V ₁, the angular velocity of wind energy conversion system is ω _w, wind energy conversion system runs to certain 1 A point on the maximum power point left side, and the power that the A point is corresponding is P _A, because the wind speed V of this moment ₁Be unknown, therefore can suppose the power P that A is ordered _ABe a certain virtual wind speed V ₂The power that following maximum power point B is ordered is made as P _{B (max)}=P _ASo, can calculate virtual wind speed V from wind energy power absorbed characteristic formula according to wind turbine ₂:

$V_2=\sqrt[3]{{2P}_{B\left(\mathrm{Max}\right)}/{\mathrm{\ρ\; SC}}_{p\mathrm{Max}}}$ Formula 1

In the formula, C _PmaxBe wind energy conversion system peak output utilization factor; S is the wind energy conversion system swept area; ρ is an air density; Then according to calculating virtual wind speed V ₂Reach wind wheel blade tip linear velocity and respective relationships function and obtain virtual wind speed V ₂Optimized rotating speed w _Opt1:

$w_{\mathrm{Opt}1}=\frac{{\mathrm{\λ}}_{\mathrm{Opt}}\×V_2}{R}$ Formula 2

In the formula, λ _OptBe best tip speed ratio; R is the wind wheel radius;

With virtual wind speed V ₂Optimized rotating speed w _Opt1As V ₁Next moment C point wind energy conversion system angular velocity of wind energy conversion system is given under the wind speed: when wind energy conversion system runs to C point, the angular velocity omega that its C is ordered _CEqual virtual wind speed V ₂Optimized rotating speed w _Opt1, the angular velocity omega of ordering according to C again _CObtain the power P that C is ordered _C, again with P _CAs virtual wind speed V ₃The maximum power point D power P of ordering _{D (max)}, with P _{D (max)}Substitution formula 1 obtains virtual wind speed V ₃, obtain virtual wind speed V according to formula 2 again ₃Optimized rotating speed w _Opt2, again with virtual wind speed V ₃Optimized rotating speed as V ₁The rotational speed setup that next moment E of wind energy conversion system is ordered under the wind speed, wind energy conversion system runs to the E point, continues search more according to the method described above in new operation point, can search V ₁The optimized rotating speed of wind speed has also obtained V simultaneously ₁The peak output of wind speed.

Embodiment 2

Shown in Fig. 2 (b), suppose certain in a flash wind speed be V ₁, the angular velocity of wind energy conversion system is ω _w, wind energy conversion system runs to certain 1 A point on maximum power point the right, and the power that the A point is corresponding is P _A, because the wind speed V of this moment ₁Be unknown, therefore can suppose the power P that A is ordered _ABe a certain virtual wind speed V ₂The power that following maximum power point B is ordered is made as P _{B (max)}=P _ASo, can calculate virtual wind speed V from wind energy power absorbed characteristic formula according to wind turbine ₂:

$V_2=\sqrt[3]{{2P}_{B\left(\mathrm{Max}\right)}/{\mathrm{\ρ\; SC}}_{p\mathrm{Max}}}$ Formula 1

In the formula, C _PmaxBe wind energy conversion system peak output utilization factor; S is the wind energy conversion system swept area; ρ is an air density; Then according to calculating virtual wind speed V ₂Reach wind wheel blade tip linear velocity and respective relationships function and obtain virtual wind speed V ₂Optimized rotating speed w _Opt1:

$w_{\mathrm{Opt}1}=\frac{{\mathrm{\λ}}_{\mathrm{Opt}}\×V_2}{R}$ Formula 2

In the formula, λ _OptBe best tip speed ratio; R is the wind wheel radius;

With virtual wind speed V ₂Optimized rotating speed w _Opt1As V ₁Next moment C point wind energy conversion system angular velocity of wind energy conversion system is given under the wind speed: when wind energy conversion system runs to C point, the angular velocity omega that its C is ordered _CEqual virtual wind speed V ₂Optimized rotating speed w _Opt1, the angular velocity omega of ordering according to C again _CObtain the power P that C is ordered _C, again with P _CAs virtual wind speed V ₃The maximum power point D power P of ordering _{D (max)}, with P _{D (max)}Bring formula 1 into and obtain virtual wind speed V ₃, obtain virtual wind speed V according to formula 2 again ₃Optimized rotating speed w _Opt2, again with virtual wind speed V ₃Optimized rotating speed w _Opt2As V ₁The rotational speed setup that next moment E of wind energy conversion system is ordered under the wind speed, then wind energy conversion system runs to the E point, continues search more according to the method described above in new operation point, can search V ₁The optimized rotating speed of wind speed has also obtained V simultaneously ₁The peak output of wind speed.

Embodiment 3

Fig. 3 (a) is under the cumulative wind speed, variable step search by hill climbing method maximal wind-energy search procedure: suppose that current wind speed is V4, wind energy conversion system runs on the A point; Suddenly wind speed rises to V3; Variable step search by hill climbing method detects power and rises and rotation speed change; Apply the rotating speed disturbance, have two kinds of situation shown in Fig. 3 (a) according to the size that applies the rotating speed disturbance: (1) when disturbing quantity dw1 hour, then be in the C1 point in maximum power point left side; (2) when disturbing quantity dw2 is big, be in the C2 point on maximum power point right side.Suppose that under first kind of situation when wind energy conversion system moved to the C1 point, wind speed rose to V2 again, wind energy conversion system real work point is the D1 point so, and the direction of search is correct.Suppose under second kind of situation, when wind energy conversion system moves to the C2 point, if wind speed no longer changes, because P _C2＜P _B, then along the optimizing of L direction.But if this moment, wind speed rose to V2 again, wind energy conversion system real work point then is the D2 point, because P _D2＞P _B, system takes for the operation point also on the optimum point left side, so continue to increase rotating speed, so just departs from optimized rotating speed.Therefore rotating speed disturbance size and amplitude limit value are chosen very crucially, and also difficulty relatively if value is less than normal, is followed the tracks of slowly, under the very fast wind speed that changes, is difficult to realize quick tracking, and value is bigger than normal the optimized rotating speed point just may to occur departing from.

Fig. 3 (b) is under the cumulative wind speed; The inventive method search procedure: suppose that current wind speed is V7; Wind energy conversion system runs on the A point, and suddenly wind speed rises to V5, and B point (wind energy conversion system order at A point and B angular velocity consistent) has been put in wind energy conversion system real work this moment; Calculate the pairing virtual wind speed V6 of B point through detecting power and the wind turbine that wind energy conversion system orders at B from wind energy power absorbed formula (formula 1); Utilize formula 2 to calculate the optimized rotating speed of this virtual wind speed V6 again, wind energy conversion system continues to suppose that to the operation of C point (wind energy conversion system order at C angular velocity equate with the optimized rotating speed of virtual wind speed V6) wind speed rises to V3 again at this moment; D point (wind energy conversion system order at C point and D angular velocity consistent) has been put in the wind turbine real work; Can calculate the optimized rotating speed of the pairing virtual wind speed V4 of D point and this virtual wind speed equally, wind energy conversion system continues to the operation of E point, by that analogy.

Embodiment 4

Fig. 4 (a) is under the wind conditions decrescence, search by hill climbing method maximal wind-energy search procedure.Suppose that current wind speed is V1, wind energy conversion system runs on the A point; Suddenly wind speed decreased is to V2, and variable step search by hill climbing method detects power and descends and rotation speed change, applies the rotating speed disturbance, reduces rotating speed, and at this moment system is to the operation of C point, if wind speed no longer changes, because P _C＞P _B, then along the optimizing of L direction.If this moment, wind speed dropped to V3 again, blower fan real work point position D point then is owing to power P _D＜P _B, system can take for the left side that has run to optimal power point, and then increases rotating speed, and then system can obviously depart from the optimized rotating speed point this moment to the operation of E point.

Fig. 4 (b) is under the wind conditions decrescence; Maximal wind-energy track algorithm search procedure of the present invention: suppose that current wind speed is V1; Wind energy conversion system runs on the A point, and this moment, wind speed dropped to V2 suddenly, and B point (wind energy conversion system order at A point and B angular velocity consistent) has been put in wind energy conversion system real work this moment; Calculate the pairing virtual wind speed V3 of B point through detecting power and the wind turbine that wind energy conversion system orders at B from wind energy power absorbed formula (formula 1); Utilize formula 2 to calculate the optimized rotating speed wc under this virtual wind speed V3 again, wind energy conversion system continues to suppose that to the operation of C point (wind energy conversion system order at C angular velocity equate with the optimized rotating speed of virtual wind speed V3) wind speed drops to again to V4 at this moment; D point (wind energy conversion system order at D point and C angular velocity consistent) has been put in the wind turbine real work; Can calculate the optimized rotating speed we of D point corresponding virtual wind speed V5 and this virtual wind speed equally, wind energy conversion system continues to the operation of E point, by that analogy.Can find out by Fig. 4 (b), maximal wind-energy track algorithm of the present invention not reverse adjustment rotating speed in search procedure under wind speed decrescence, so tracking dynamic performance is improved.

Can find out that from Fig. 5 (b) under the typical wind speed shown in 5 (a), the wind energy conversion system actual speed when wind speed is cumulative under search by hill climbing method optimized rotating speed more in theory has than large deviation; When wind speed decrescence the time, occur reverse adjustment rotating speed in the search by hill climbing method rotating speed search procedure and make that rotation speed change is very little, also departed from optimized rotating speed.Can find out that from Fig. 5 (d) under the typical wind speed shown in 5 (a), maximal wind-energy track algorithm rotating-speed tracking of the present invention is very steady, and still can well follow the tracks of optimized rotating speed in theory under the gradual change wind speed.Can know by Fig. 5 (c) and Fig. 5 (e); Under the typical wind speed shown in 5 (a); During the wind speed gradual change; The power coefficient of maximal wind-energy tracking of the present invention remains near maximum use coefficient (emulation is with the peak output utilization factor 0.48 of wind energy conversion system), and the power coefficient of search by hill climbing method is starkly lower than the maximum use coefficient.

Can find out from Fig. 6 (b) and Fig. 6 (c); Under the natural wind speed shown in 6 (a); Because wind speed changes, cause search by hill climbing method rotating-speed tracking to occur than large deviation, power coefficient is starkly lower than maximum use coefficient 0.48; If rising for a long time or descending appears in wind speed, even cause following the tracks of failure.Can find out that from Fig. 6 (d) and Fig. 6 (e) maximal wind-energy tracking tracking effect of the present invention is fine; The actual speed of wind energy conversion system and theoretical optimized rotating speed are more identical under the inventive method, and power coefficient remains near maximum use coefficient (it is 0.48 that the peak output utilization factor of wind energy conversion system is used in emulation).

Claims (1)

1. dual feedback wind power generation system maximal wind-energy tracking is characterized in that this method is implemented according to following steps:

Step 1,

Suppose certain in a flash wind speed be V ₁, detect V ₁Wind energy conversion system runs to the power P that A is ordered under the wind speed _A

Step 2,

Suppose V ₁The power P that wind energy conversion system A is ordered under the wind speed _ABe a certain virtual wind speed V ₂The power P that maximum power point B is ordered _{B (max)}, P just _{B (max)}=P _A, calculate virtual wind speed V from wind energy power absorbed characteristic formula according to wind turbine ₂:

$V_2=\sqrt[3]{{2P}_{B\left(\mathrm{Max}\right)}/{\mathrm{\ρ\; SC}}_{p\mathrm{Max}}}$ Formula 1

In the formula, C _PmaxBe wind energy conversion system peak output utilization factor, S is the wind energy conversion system swept area, and ρ is an air density;

Then according to calculating virtual wind speed V ₂Reach wind wheel blade tip linear velocity and respective relationships function and obtain virtual wind speed V ₂Optimized rotating speed w _Opt:

$w_{\mathrm{Opt}}=\frac{{\mathrm{\λ}}_{\mathrm{Opt}}\×V_2}{R}$ Formula 2

In the formula, λ _OptBe best tip speed ratio, R is the wind wheel radius;

Step 3,

With virtual wind speed V ₂Optimized rotating speed w _OptAs V ₁The rotational speed setup of next moment wind energy conversion system of wind energy conversion system under the wind speed: wind energy conversion system runs to C point, the angular velocity omega that C is ordered _CEqual virtual wind speed V ₂Optimized rotating speed w _Opt, the angular velocity of ordering according to C again and the running state of wind energy conversion system detect the output power Pc of wind energy conversion system this moment, again with P _CAs virtual wind speed V ₃The maximum power point D power P of ordering _{D (max)}, with P _{D (max)}Bring formula 1 into and obtain virtual wind speed V ₃, obtain virtual wind speed V according to formula 2 again ₃Optimized rotating speed, again with virtual wind speed V ₃Optimized rotating speed as V ₁The rotational speed setup that next moment E of wind energy conversion system is ordered under the wind speed, wind energy conversion system runs to the E point, continues search more according to the method described above in new operation point, can search V ₁Optimized rotating speed under the wind speed obtains V simultaneously ₁The peak output of wind speed.

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