CN103967702B - A kind of double-fed wind power generator full blast speed frequency response controlling method - Google Patents

Abstract

The invention discloses a kind of double-fed wind power generator full blast speed frequency response controlling method, can initiative recognition wind speed interval the sagging coefficient of adaptive amendment carries out frequency response control.First according to the double-fed Wind turbine characteristic curve that manufacturer is given, the relation of double-fed wind power generator off-load rate and suboptimum tip speed ratio is set up; According to wind speed by weak extremely strong, full blast speed is divided into first to fourth wind speed interval; And according to the current off-load rate of double-fed wind power generator, online updating four sections of wind speed interval divide criterions; When system real-time frequency declines and exceedes setting dead band threshold values, according to the real-time wind velocity signal collected, carry out wind speed interval identification; And calculating real-time unit reserve capacity, self adaption revises sagging coefficient, completes frequency response and controls.The method that the present invention proposes can improve the frequency response ability of middle and high wind speed interval, and weak, low wind speed interval generator speed also can be protected to be not less than minimum permission rotating speed.

Description

A kind of double-fed wind power generator full blast speed frequency response controlling method

Technical field

The present invention relates to a kind of double-fed wind power generator full blast speed frequency response controlling method, belong to Wind turbines and participate in frequency response control field.

Background technique

The double-fed fan motor unit of current broad commercial applications is owing to have employed advanced electronic power convertor, achieve meritorious, idle uneoupled control, thus also cause the mechanical part of Wind turbines and the electromagnet portion generation decoupling zero of system, inertial response ability cannot be provided to system.Wind energy turbine set is in order to pursue maximum economic benefit simultaneously, and double-fed fan motor unit is all be operated in maximal power tracing pattern under normal circumstances, also just means and spare capacity cannot be provided to participate in the Primary regulation of system frequency to system.

The FREQUENCY CONTROL strategy of current comparative maturity adopts the methods such as virtual inertia control and droop control.But due in simulation droop control characteristic process, Wind turbines is subject to the restriction of the objective condition such as wind speed, can not imitate synchronous generator completely and carry out frequency response control, must in conjunction with the condition of self.As in " hypervelocity with become the double-fed fan motor unit FREQUENCY CONTROL coordinated of oar " paper of being proposed by Zhang Zhaosui, Sun Yuanzhang etc., full wind speed range is divided into basic, normal, high three sections of wind speed interval.Adhere to the preferential hypervelocity method that adopts to control, rear employing propeller pitch angle carries out the principle of cooperation control, can reduce propeller pitch angle time of movement like this.Therefore, for the research of double-fed wind power generator group full blast speed range frequencies response control mehtod, be the technology being badly in need of very much from now on solving.

Summary of the invention

Technical problem to be solved by this invention is to provide a kind of double-fed wind power generator full blast speed frequency response controlling method, according to the control law of double-fed wind power generator self, full blast speed is divided into first to fourth wind speed interval, online initiative recognition wind speed interval; Frequency decrease when exceeding the dead band frequency of setting, initiation culture control unit; And simultaneously according to current unit reserve capacity, the sagging coefficient of adaptive amendment, carries out frequency response control.

The present invention is for solving the problems of the technologies described above by the following technical solutions:

The invention provides a kind of double-fed wind power generator full blast speed frequency response controlling method, comprise the following steps:

Step 1, according to double-fed wind power generator characteristic curve Cp (β, λ) that manufacturer provides, adopts nonlinear solution method, sets up off-load rate del% and suboptimum tip speed ratio λ _delrelation, and be kept in storage, for data sharing, call; Wherein, Cp is power coefficient, and β is propeller pitch angle, and λ is tip speed ratio;

Step 2, according to wind speed by weak extremely strong, is divided into first to fourth wind speed interval by full blast speed; And according to the current off-load rate del of double-fed wind power generator ₀%, calls current off-load rate del ₀the suboptimum tip speed ratio that % is corresponding online updating four sections of wind speed interval divide criterion; Be specially:

First wind speed interval is the invariablenes turning speed stage, and it is as follows that it divides representation:

V _wcutin≤V _w＜V _w0

Wherein, V _wcutinfor incision wind speed; V _wfor real-time wind speed; V _w0wind speed corresponding during for just obtaining maximal wind-energy utilization factor, is the critical wind velocity of first, second wind speed interval;

V _w0formula be:

$V_{w0}=\frac{{\mathrm{\ω}}_{\min }R}{\frac{p}{2}{\mathrm{G\λ}}_{opt}}$

Wherein, ω _minfor the minimum permission rotating speed of generator; P is power generator electrode logarithm; G is gear-box no-load voltage ratio; R is wind wheel radius; λ _optfor optimum tip speed ratio;

The division representation of the second wind speed interval is as follows:

V _w0≤V _w＜V _w1

Wherein, V _w1for according to current off-load rate del ₀when % only adopts hypervelocity method to control, rotor speed just reaches maximum permissible speed ω _maxcorresponding wind speed, is the critical wind velocity of second, third wind speed interval;

V _w1formula be:

$V_{w1}=\frac{{\mathrm{\ω}}_{max}R}{\frac{p}{2}{\mathrm{G\λ}}_{{\mathrm{del}}_0}}$

Wherein, ω _maxfor maximum permissible speed, for current off-load rate del ₀suboptimum tip speed ratio corresponding to %;

The division representation of the 3rd wind speed interval is as follows:

V _w1≤V _w＜V _w2

Wherein, V _w2for under employing maximal power tracing control mode, generator speed just reaches maximum permissible speed ω _maxtime corresponding wind speed, be the critical wind velocity of the 3rd, the 4th wind speed interval;

V _w2formula be:

$V_{w2}=\frac{{\mathrm{\ω}}_{max}R}{G\frac{p}{2}{\mathrm{\λ}}_{opt}};$

The division representation of the 4th wind speed interval is as follows:

V _w2≤V _w＜V _wcutout

Wherein, V _wcutoutfor cut-out wind speed;

Step 3, the change of monitoring system frequency, when system frequency declines and exceedes the dead band threshold values of setting, initiation culture control unit, according to the real-time wind velocity signal collected, carries out wind speed interval identification, and calculate real-time unit reserve capacity, the sagging coefficients R of adaptive amendment _f, realize frequency response and control; Wherein, sagging coefficients R _fformula as follows:

$R_f=-\frac{{\mathrm{\Δf}}_{band}/f_N}{{\mathrm{\ΔP}}_{M\arg in}/P_N}$

Wherein, Δ f _bandfrequency drift lower limit; f _nfor system reference frequency; Δ P _margin=del ₀%P _mPPT, be the spare capacity of current Wind turbines; P _nfor the rated power of Wind turbines; P _mPPTfor exportable power maximum under current wind speed.

As further optimized project of the present invention, the representation of the value and power reference of described first wind speed interval is as follows:

$P_{ref}=\frac{P_{MPPT\_Vw0}(1-{\mathrm{del}}_0\%)}{{\mathrm{\ω}}_{Vw0}-{\mathrm{\ω}}_{\min }}$

$P_{MPPT\_Vw0}=\frac{1}{2}{\mathrm{\ρ\πR}}^2{\mathrm{Cp}}_{max}{V}_{w0}^3$

${\mathrm{\ω}}_{Vw0}=\frac{{\mathrm{\ω}}_{min}{\mathrm{\λ}}_{del0}}{\mathrm{\λ}opt}$

Wherein, P _{mPPT_Vw0}for wind speed is V _w0time corresponding peak output; ρ is air density; Cp _maxfor maximal wind-energy utilization factor; ω _vw0corresponding to V _w0time off-load del ₀rotating speed during %.

As further optimized project of the present invention, the representation of the value and power reference of described second wind speed interval is as follows:

P _ref＝k _delω ³

$k_{del}=\frac{1}{2}{\mathrm{\ρ\πR}}^5{\mathrm{Cp}}_{max}(1-{\mathrm{del}}_0\%+\frac{{\mathrm{\ΔfP}}_N}{R_f{P}_{MPPT}})/{{\mathrm{\λ}}_{del}}^3;$

Wherein, k _delfor the coefficient of off-load Power operation curve; Δ f is frequency departure.

As further optimized project of the present invention, in the working control process of the second wind speed interval, also need to add an amplitude limit link, in order to when frequency decrease, direct employing generator speed carries out feedback control, then completes frequency response by the constantly saltus step of off-load power curve and controls.

As further optimized project of the present invention, the method that frequency response described in step 3 controls is specific as follows:

(1) first wind speed interval: do not participate in system frequency response and control, adopts linear control strategies to carry out generator speed protecting control;

(2) second wind speed interval: by the coefficient of amendment off-load power curve, and adopt generator real-time rotate speed to carry out feedback control, complete frequency response process;

(3) the 3rd wind speed interval: jointly coordinated by rotating speed control and propeller pitch angle;

(4) the 4th wind speed interval: controlled by propeller pitch angle, and because of propeller pitch angle function be restriction generator speed be no more than maximum permissible speed, namely speed reference remains ω _ref=ω _maxconstant, be and complete control by amendment value and power reference.

The present invention adopts above technological scheme compared with prior art, has following technique effect:

(1) full blast speed according to different wind regime, can be divided into four sections of wind speed interval by the present invention, according to feature and the restrictive condition of different wind speed interval, formulates corresponding controlling method;

(2) the second wind speed interval frequency response controlling method of the present invention's proposition, when frequency decrease, directly adopts generator speed to carry out feedback control, then completes frequency response by the constantly saltus step of off-load power curve and control.Compared to droop control strategy more existing at present, owing to adding retardation area, therefore when frequency decrease, rotor kinetic energy can be discharged at short notice quickly, improve frequency response control effects, and carry out feedback control by gathering generator real-time rotate speed, can control accuracy be improved;

(3) self adaption that the present invention proposes revises sagging coefficient, compared to fixing sagging coefficient, can improve the frequency response ability of the 3rd, the 4th wind speed interval, first, second wind speed interval generator speed also can be protected to be not less than minimum permission rotating speed.

Accompanying drawing explanation

Fig. 1 is method flow diagram of the present invention.

Fig. 2 is that in low wind speed interval, frequency response controls schematic diagram.

Fig. 3 is self-defined droop characteristic.

Embodiment

Be described below in detail embodiments of the present invention, the example of described mode of execution is shown in the drawings, and wherein same or similar label represents same or similar element or has element that is identical or similar functions from start to finish.Being exemplary below by the mode of execution be described with reference to the drawings, only for explaining the present invention, and can not limitation of the present invention being interpreted as.

Those skilled in the art of the present technique are understandable that, unless expressly stated, singulative used herein " ", " one ", " described " and " being somebody's turn to do " also can comprise plural form.Should be further understood that, the wording used in specification of the present invention " comprises " and refers to there is described feature, integer, step, operation, element and/or assembly, but does not get rid of and exist or add other features one or more, integer, step, operation, element, assembly and/or their group.Should be appreciated that, when we claim element to be " connected " or " coupling " to another element time, it can be directly connected or coupled to other elements, or also can there is intermediary element.In addition, " connection " used herein or " coupling " can comprise wireless connections or couple.Wording "and/or" used herein comprises one or more arbitrary unit listing item be associated and all combinations.

Those skilled in the art of the present technique are understandable that, unless otherwise defined, all terms used herein (comprising technical term and scientific terminology) have the meaning identical with the general understanding of the those of ordinary skill in field belonging to the present invention.Should also be understood that those terms defined in such as general dictionary should be understood to have the meaning consistent with the meaning in the context of prior art, unless and define as here, can not explain by idealized or too formal implication.

Below in conjunction with accompanying drawing, technological scheme of the present invention is described in further detail:

The present invention designs a kind of double-fed wind power generator full blast speed frequency response controlling method, as shown in Figure 1, comprises the following steps:

Step 1, according to double-fed wind power generator characteristic curve Cp (β, λ) that manufacturer provides, adopts nonlinear solution method, sets up off-load rate del% and suboptimum tip speed ratio λ _delrelation, and be kept in storage, for data sharing, call; Wherein, Cp is power coefficient, and β is propeller pitch angle, and λ is tip speed ratio;

Step 2, according to wind speed by weak extremely strong, is divided into first to fourth wind speed interval by full blast speed; And according to the current off-load rate del of double-fed wind power generator ₀%, online updating four sections of wind speed interval criterions;

Step 3, the change of monitoring system frequency, when system frequency declines and exceedes the dead band threshold values of setting, initiation culture control unit, according to the real-time wind velocity signal collected, carries out wind speed interval identification, and calculate real-time unit reserve capacity, the sagging coefficients R of adaptive amendment _f, realize frequency response and control.

In " the double-fed fan motor unit FREQUENCY CONTROL that hypervelocity is coordinated with the change oar " paper proposed by Zhang Zhaosui, Sun Yuanzhang etc., full wind speed range is divided into basic, normal, high three sections of wind speed interval.Thus, first to fourth wind speed interval that in the present invention, full wind speed range divides correspondingly can be called weak, basic, normal, high wind speed interval, wherein, the division criterion of the 3rd, the 4th wind speed interval (i.e. middle and high wind speed interval) is consistent with the division criterion in " exceeding the speed limit and the double-fed fan motor unit FREQUENCY CONTROL that change oar is coordinated ".

In a specific embodiment of the present invention; full blast speed is divided into first to fourth wind speed interval (i.e. weak, basic, normal, high wind speed interval); corresponding controlling method has been formulated according to the feature of different wind speed interval and restrictive condition; and by the sagging coefficient of adaptive amendment; improve the frequency response ability of middle and high wind speed interval; also weak, low wind speed interval generator speed can be protected to be not less than minimum permission rotating speed, and concrete engineering implementation step is as follows:

(1) the characteristic Cp (β, λ) of the double-fed wind power generator provided according to manufacturer, adopts nonlinear method (as dichotomy) to carry out calculated off-line, obtains the suboptimum tip speed ratio λ that different off-load rate del% is corresponding _del, and fit to multinomial:

${\mathrm{\λ}}_{del}=\underset{i=0}{\overset{n}{\Σ}}{a}_i{\left(del\%\right)}^i$

In formula, a _ifor coefficient of polynomial fitting.

It should be noted that, the multinomial simulated is the critical wind velocity V for low, middle wind speed interval _w1calculating and low wind speed interval frequency response control time amendment coefficient k ' _del.In order to ensure fitting precision, need to calculate multi-group data, when especially off-load rate del% is less, (posterior infromation: 0% ~ 1%), needs to get the initial data of multiple data point as polynomial fitting as far as possible, because within the scope of this, tip speed ratio λ _delchange very fast with off-load rate del%, and increase further along with off-load rate del%, change then relatively slow.

(2) according to current off-load rate del ₀%, calculates the critical wind velocity V of low, middle wind speed interval _w1, thus set up the criterion of weak, basic, normal, high four sections of wind speed interval, as shown in the table:

In upper table, V _w0for the critical wind velocity of weak, low wind speed interval.

The criterion of weak wind speed interval is: described first wind speed interval is the invariablenes turning speed stage; generator speed remains at minimum permission rotating speed; the unit reserve capacity that can provide does not reach 2% of unit rated capacity; and rotating speed reaches minimum speed; therefore in this wind speed interval; do not participate in system frequency response to control, and adopt linear control strategies to carry out generator speed protecting control.

The criterion of low wind speed interval is that in whole frequency response control procedure, generator speed is all less than maximum permissible speed ω _max, propeller pitch angle does not need action, therefore utilizes the method for amendment off-load power curve coefficient, and adopts generator real-time rotate speed to carry out feedback control, complete frequency response process.As shown in Figure 2, when to incite somebody to action under system frequency and when exceeding dead band threshold values, double-fed wind power generator group output power by sudden change in another off-load power curve, the i.e. point from B point mutation to C, but the mechanical output of catching due to wind energy conversion system is not undergone mutation, generator will run slowly, thus the release rotor kinetic energy that slows down, until when system frequency returns to quasi steady state frequency gradually, double-fed fan motor unit by stable operation in D point.Therefore in whole frequency response process, by amendment coefficient k _delcome.Compare current existing droop control strategy, the present invention in low wind speed interval then owing to adding retardation area S _cDE, rotor kinetic energy can be discharged quickly at short notice, frequency response control effects can be improved.And carry out feedback control by gathering generator real-time rotate speed, also can improve control accuracy.

V _w1for the critical wind velocity of low, middle wind speed interval, its meaning is according to current off-load rate del ₀when % only adopts hypervelocity method to control, rotor speed just reaches maximum permissible speed ω _maxcorresponding wind speed; Wherein ω _maxfor generator maximum permissible speed, R is wind turbine radius, and G is roller box no-load voltage ratio for this reason, and p is power generator electrode logarithm, λ _del0for current off-load rate del ₀the suboptimum tip speed ratio that % is corresponding.When line computation, just can be obtained fast by polynomial fitting above.

V _w2for the critical wind velocity of middle and high wind speed interval, its meaning is that generator speed just reaches maximum permissible speed ω under employing maximal power tracing control mode _maxtime corresponding wind speed; V _wcutoutfor cut-out wind speed.

(3) gather wind velocity signal, carry out wind speed interval identification online; And search peak output operation curve, calculate current unit reserve capacity: Δ P _margin=del ₀%P _mPPT; Calculate sagging coefficient wherein, Δ f _bandfor the frequency drift lower limit shown in Fig. 3, f _nfor system reference frequency, P _nfor the rated power of double-fed wind power generator group.

(4) frequency monitoring unit real-time feedback system frequency, when frequency decrease and when exceeding the dead band threshold values of setting, initiation culture control unit, and the frequency response controlling method performing corresponding wind speed interval.

The above; be only the embodiment in the present invention; but protection scope of the present invention is not limited thereto; any people being familiar with this technology is in the technical scope disclosed by the present invention; the conversion or replacement expected can be understood; all should be encompassed in and of the present inventionly comprise within scope, therefore, protection scope of the present invention should be as the criterion with the protection domain of claims.

Claims (5)

1. a double-fed wind power generator full blast speed frequency response controlling method, is characterized in that, comprise the following steps:

Step 1, according to double-fed wind power generator characteristic curve Cp (β, λ) that manufacturer provides, adopts nonlinear solution method, sets up off-load rate del% and suboptimum tip speed ratio λ _delrelation, and be kept in storage, for data sharing, call; Wherein, Cp is power coefficient, and β is propeller pitch angle, and λ is tip speed ratio;

Step 2, according to wind speed by weak extremely strong, is divided into first to fourth wind speed interval by full blast speed; And according to the current off-load rate del of double-fed wind power generator ₀%, calls current off-load rate del ₀the suboptimum tip speed ratio that % is corresponding online updating four sections of wind speed interval divide criterion; Be specially:

First wind speed interval is the invariablenes turning speed stage, and it is as follows that it divides representation:

V _wcutin≤V _w＜V _w0

Wherein, V _wcutinfor incision wind speed; V _wfor real-time wind speed; V _w0wind speed corresponding during for just obtaining maximal wind-energy utilization factor, is the critical wind velocity of first, second wind speed interval;

V _w0formula be:

$V_{w0}=\frac{{\mathrm{\ω}}_{\min }R}{\frac{p}{2}{\mathrm{G\λ}}_{opt}}$

Wherein, ω _minfor the minimum permission rotating speed of generator; P is power generator electrode logarithm; G is gear-box no-load voltage ratio; R is wind wheel radius; λ _optfor optimum tip speed ratio;

The division representation of the second wind speed interval is as follows:

V _w0≤V _w＜V _w1

Wherein, V _w1for according to current off-load rate del ₀when % only adopts hypervelocity method to control, rotor speed just reaches maximum permissible speed ω _maxcorresponding wind speed, is the critical wind velocity of second, third wind speed interval;

V _w1formula be:

$V_{w1}=\frac{{\mathrm{\ω}}_{max}R}{\frac{p}{2}{\mathrm{G\λ}}_{{\mathrm{del}}_0}}$

Wherein, ω _maxfor maximum permissible speed, for current off-load rate del ₀suboptimum tip speed ratio corresponding to %;

The division representation of the 3rd wind speed interval is as follows:

V _w1≤V _w＜V _w2

Wherein, V _w2for under employing maximal power tracing control mode, generator speed just reaches maximum permissible speed ω _maxtime corresponding wind speed, be the critical wind velocity of the 3rd, the 4th wind speed interval;

V _w2formula be:

$V_{w2}=\frac{{\mathrm{\ω}}_{max}R}{G\frac{p}{2}{\mathrm{\λ}}_{opt}};$

The division representation of the 4th wind speed interval is as follows:

V _w2≤V _w＜V _wcutout

Wherein, V _wcutoutfor cut-out wind speed;

Step 3, the change of monitoring system frequency, when system frequency declines and exceedes the dead band threshold values of setting, initiation culture control unit, according to the real-time wind velocity signal collected, carries out wind speed interval identification, and calculate real-time unit reserve capacity, the sagging coefficients R of adaptive amendment _f, realize frequency response and control; Wherein, sagging coefficients R _fformula as follows:

$R_f=-\frac{{\mathrm{\Δf}}_{band}/f_N}{{\mathrm{\ΔP}}_{M\arg in}/P_N}$

Wherein, Δ f _bandfrequency drift lower limit; f _nfor system reference frequency; Δ P _margin=del ₀%P _mPPT, be the spare capacity of current Wind turbines; P _nfor the rated power of Wind turbines; P _mPPTfor exportable power maximum under current wind speed.

2. a kind of double-fed wind power generator full blast speed frequency response controlling method according to claim 1, it is characterized in that, the representation of the value and power reference of described first wind speed interval is as follows:

$P_{ref}=\frac{P_{MPPT\_Vw0}(1-{\mathrm{del}}_0\%)}{{\mathrm{\ω}}_{Vw0}-{\mathrm{\ω}}_{\min }}$

$P_{MPPT\_Vw0}=\frac{1}{2}{\mathrm{\ρ\πR}}^2{\mathrm{Cp}}_{max}{V}_{w0}^3$

${\mathrm{\ω}}_{Vw0}=\frac{{\mathrm{\ω}}_{min}{\mathrm{\λ}}_{del0}}{\mathrm{\λ}opt}$

Wherein, P _{mPPT_Vw0}for wind speed is V _w0time corresponding peak output; ρ is air density; Cp _maxfor maximal wind-energy utilization factor; ω _vw0corresponding to V _w0time off-load del ₀rotating speed during %.

3. a kind of double-fed wind power generator full blast speed frequency response controlling method according to claim 1, it is characterized in that, the representation of the value and power reference of described second wind speed interval is as follows:

P _ref＝k _delω ³

$k_{del}=\frac{1}{2}{\mathrm{\ρ\πR}}^5{\mathrm{Cp}}_{max}(1-{\mathrm{del}}_0\%+\frac{{\mathrm{\ΔfP}}_N}{R_f{P}_{MPPT}})/{{\mathrm{\λ}}_{del}}^3;$

Wherein, k _delfor the coefficient of off-load Power operation curve; Δ f is frequency departure.

4. a kind of double-fed wind power generator full blast speed frequency response controlling method according to claim 1, it is characterized in that, in the working control process of the second wind speed interval, also need to add an amplitude limit link, in order to when frequency decrease, direct employing generator speed carries out feedback control, then completes frequency response by the constantly saltus step of off-load power curve and controls.

5. a kind of double-fed wind power generator full blast speed frequency response controlling method according to claim 1, it is characterized in that, the method that frequency response described in step 3 controls is specific as follows:

(1) first wind speed interval: do not participate in system frequency response and control, adopts linear control strategies to carry out generator speed protecting control;

(2) second wind speed interval: by the coefficient of amendment off-load power curve, and adopt generator real-time rotate speed to carry out feedback control, complete frequency response process;

(3) the 3rd wind speed interval: jointly coordinated by rotating speed control and propeller pitch angle;

(4) the 4th wind speed interval: controlled by propeller pitch angle, and because of propeller pitch angle function be restriction generator speed be no more than maximum permissible speed, namely speed reference remains ω _ref=ω _maxconstant, be and complete control by amendment value and power reference.