CN103915853B - The acquisition methods of Double-feed wind power field reactive capability - Google Patents

Abstract

The invention provides the acquisition methods of a kind of Double-feed wind power field reactive capability, comprise the following steps: the active power-reactive capability characteristic setting up unit; According to the active power-reactive capability characteristic of double-fed blower fan, linear regression is carried out in sampling, sets up unit active power-reactive capability linear regression model (LRM); The active power of unit-reactive capability regression model is equivalent to the fail safe of the active power-reactive capability characteristic of wind turbine cohort by checking, makes the reactive capability of the grid connected wind power machine group calculated be not more than the summation of the reactive capability of each double-fed fan motor unit; In conjunction with grid-connected blower fan number of units, calculate the double-fed fan motor field reactive capability of grid-connected blower fan number of units; And superpose the reactive capability of Reactive Compensation in Wind Farm equipment and the reactive capability of transformer absorption, calculate final double-fed fan motor field reactive capability.The acquisition methods of Double-feed wind power field provided by the invention reactive capability has higher precision.

Description

The acquisition methods of Double-feed wind power field reactive capability

Technical field

The invention belongs to electric power system field of new energy generation, especially when double-fed fan motor field participates in reactive power optimization, comparatively accurately obtain the method for double-fed fan motor field reactive capability.

Background technology

Wind-powered electricity generation is a kind of intermittent energy, and for the safe and stable operation of electrical network brings a lot of adverse influence after grid-connected, the reactive voltage problem particularly after wind-electricity integration seems particularly outstanding.Field operation experiences shows, wind farm grid-connected exist without merits and demerits benefit and the situation of idle deficient benefit simultaneously afterwards, and when wind speed is less than 5m/s, to cross benefit phenomenon comparatively outstanding in double-fed fan motor field, and power factor is substantially all defective.Except power factor is defective, the wind energy turbine set problem that also voltage fluctuation of ubiquity points of common connection is excessive, voltage flicker number of times is more, simultaneously blower fan large area off-grid Frequent Accidents.Therefore set up wind power plant reactive voltage control system, strengthen idle schedulability, the controllability of wind-powered electricity generation, and the tertiary voltage control system being included in electrical network is an important and urgent problem.

The double-fed fan motor field reactive power/voltage control including electrical network tertiary voltage control system in needs the common interaction of electrical network and double-fed fan motor field to complete.Under tertiary voltage control system, electrical network implements reactive power/voltage control to wind energy turbine set, first need the adjustable extent knowing double-fed fan motor field reactive voltage, then just can carry out containing the idle work optimization of double-fed fan motor field at interior regional power grid, and then assign reactive power/voltage control instruction to wind energy turbine set.And double-fed fan motor field reactive capability is the key factor determining double-fed fan motor field reactive voltage adjustable extent, therefore, setting up the acquisition methods of double-fed fan motor field reactive capability participating in reactive power optimization, is carry out the key issue that first double-fed fan motor field reactive power/voltage control need to solve.

But the acquisition methods of current double-fed fan motor field reactive capability exists following defect, on the one hand, need state and the parameter of double-fed fan motor unit inside based on the method measured in real time, measured value is difficult to obtain and cost is very high; In addition, within the single cycle of reactive power optimization, along with the change of wind speed, the active power of double-fed fan motor unit may there occurs great changes, therefore the reactive capability of double-fed fan motor field may there occurs great changes, makes to determine to participate in the double-fed fan motor field reactive capability of reactive power optimization by the method for real-time measurement and unreasonable.On the other hand, utilize unit equivalence wind energy turbine set to determine that the method for reactive capability lacks rationale and detailed derivation is proved, the double-fed fan motor field reactive capability confidence level determined accordingly cannot ensure.

Summary of the invention

In sum, necessaryly a kind of acquisition methods that accurately can calculate the reactive capability of double-fed fan motor field is provided.

An acquisition methods for Double-feed wind power field reactive capability, comprises the following steps: step S10, sets up the active power-reactive capability characteristic of unit; Step S20, according to the active power-reactive capability characteristic of double-fed blower fan, linear regression is carried out in sampling, sets up unit active power-reactive capability linear regression model (LRM); Step S30, the active power of unit-reactive capability regression model is equivalent to the fail safe of the active power-reactive capability characteristic of wind turbine cohort by checking, makes the reactive capability of the grid connected wind power machine group calculated be not more than the summation of the reactive capability of each double-fed fan motor unit; Step S40, in conjunction with grid-connected blower fan number of units, calculates the double-fed fan motor field reactive capability of grid-connected blower fan number of units; And step S50, the reactive capability that the reactive capability of superposition Reactive Compensation in Wind Farm equipment and transformer absorb, calculates final double-fed fan motor field reactive capability.

Relative to prior art, the acquisition methods of double-fed fan motor field provided by the invention reactive capability, based on unit active power-reactive capability characteristic, regression model is utilized to calculate double-fed fan motor field reactive capability, accurately can calculate the reactive capability of double-fed fan motor field, can be used for the idle work optimization of electrical network.

Accompanying drawing explanation

Fig. 1 is the flow chart of the acquisition methods of Double-feed wind power field provided by the invention reactive capability.

Fig. 2 is the flow chart of the computational process of Double-feed wind power field provided by the invention reactive capability.

Embodiment

Also in conjunction with specific embodiments technical scheme of the present invention is stated further in detail according to Figure of description below.

See also Fig. 1 and Fig. 2, Fig. 1 is the flow chart of the acquisition methods of Double-feed wind power field provided by the invention reactive capability, comprises the following steps:

Step S10, sets up the active power-reactive capability characteristic of unit;

Step S20, according to the active power-reactive capability characteristic of double-fed blower fan, linear regression is carried out in sampling, sets up unit active power-reactive capability linear regression model (LRM);

Step S30, the active power of unit-reactive capability regression model is equivalent to the fail safe of the active power-reactive capability characteristic of wind turbine cohort by checking, makes the reactive capability of the grid connected wind power machine group calculated be not more than the summation of the reactive capability of each double-fed fan motor unit;

Step S40, in conjunction with grid-connected blower fan number of units, calculates the double-fed fan motor field reactive capability of grid-connected blower fan number of units; And

Step S50, the reactive capability that the reactive capability of superposition Reactive Compensation in Wind Farm equipment and transformer absorb, calculates final double-fed fan motor field reactive capability.

In step slo, the foundation of described active power-reactive capability characteristic mainly can comprise the steps:

Step S11, determines the range of operation of double feedback electric engine stator side reactive power.

First, by the restriction of double feedback electric engine rated capacity, the reactive power scope that calculating double feedback electric engine stator side sends to electrical network is:

(1-a)

(1-b)

In formula, for the rated capacity of double feedback electric engine, for the reactive power that double feedback electric engine stator side sends to electrical network, for the active power that double feedback electric engine sends to electrical network, for rotation speed of fan.

Secondly, the maximum current that double feedback electric engine stator side is gained merit, the range of operation of reactive power is also subject to rotor-side converter restriction, calculating the reactive power scope that double feedback electric engine stator side sends to electrical network is:

(2-a)

(2-b)

To sum up can obtain, the scope of double feedback electric engine stator side reactive capability is respectively:

(3-a)

(3-b)

Wherein for stator side voltage, for the magnetizing inductance of double feedback electric engine, for the stator inductance of double feedback electric engine, for synchronous speed.

Be appreciated that the expression formula of the scope of described double feedback electric engine stator side reactive capability is only a specific embodiment, also can determine according to other physical parameters of described wind energy turbine set.

Step S12, determines the range of operation of double fed electric machine rotor side reactive power.

Be subject to net side converter and hold quantitative limitation, net side converter is respectively as the scope of the reactive power that electrical network sends:

(4-a)

(4-b)

In formula, for the reactive power that net side converter sends to electrical network, for the rated capacity of net side converter.

Be appreciated that the expression formula of described double fed electric machine rotor side reactive power operation scope is only a specific embodiment, also can determine according to other physical parameters of described wind energy turbine set.

Step S13, according to the range of operation of the reactive power of double feedback electric engine stator side and rotor-side, obtains the Reactive-power control scope of double-fed fan motor unit:

(5-a)

(5-b)

In formula, for double-fed fan motor unit perceptual reactive capability, for the capacitive reactive power capacity of double-fed fan motor unit; for stator side perceptual reactive capability, for the capacitive reactive power capacity of stator side; for net side converter perceptual reactive capability, for the capacitive reactive power capacity of net side converter.

Step S14, the rotating speed in cancellation double-fed fan motor unit Reactive-power control scope, draws unit active power-reactive capability characteristic.

Under maximal power tracing pattern, the rotating speed of described double-fed blower fan can calculate according to double-fed fan motor unit active power output valve:

(6)

K _optfor double-fed blower fan intrinsic constant, can by the gain of parameter that dispatches from the factory of described double-fed blower fan.Therefore consider that (5-a), (5-b) and (6) can obtain the characteristic of double-fed fan motor unit active power-reactive capability, the function namely between reactive capability and active power output valve:

(7)

Being appreciated that the foundation of the active power-reactive capability characteristic of described unit also can be stated by other physical quantitys, also can comprising other step as revised.

In step S20, by taking some sample points, linear regression can be carried out to the active power of unit and reactive capability, obtaining regression model:

(8)

Wherein for the reactive capability regression estimates value of double feedback electric engine, for the active power of double feedback electric engine, , expression formula is as follows:

(9)

In formula,

(10)

(11)

(12)

(13)

Wherein, x _irepresent the active power of single blower fan, for the average active power of described wind turbine cohort; y _ifor the actual value of single blower fan reactive capability sampling, for the mean value of wind turbine cohort reactive capability sampling.

Be appreciated that the mode of described linear regression is only specific embodiment, also can carry out linear regression processing according to other physical quantitys of wind energy turbine set, also can revise etc. according to wind energy turbine set actual conditions.

In step s 30, by following methods checking, the active power of unit-reactive capability regression model is equivalent to the fail safe of the active power-reactive capability characteristic of wind turbine cohort:

When in wind turbine cohort, the active power value of double-fed blower fan is the arbitrary value in rated capacity, whether checking following formula is set up:

(14)

In formula, , be respectively lower limit, the upper limit of the wind turbine cohort equivalence reactive capability scope that regression model calculates, , be respectively of wind turbine cohort the perceptual reactive capability of platform double-fed fan motor unit and capacitive reactive power capacity, for the number of units of double-fed fan motor unit in wind turbine cohort.

Further, see also Fig. 2, if (14) set up, then enter next step; If (14) be false, then return step S20 and revise.

In step s 40, by conjunction with grid-connected blower fan number of units, the double-fed fan motor field reactive capability taking into account grid-connected blower fan number of units can be set up, comprise the computational methods of capacitive reactive power capacity and perceptual reactive capability, be shown below:

(15)

In formula, for the total number of units of double-fed fan motor unit of double-fed fan motor field, n is grid-connected blower fan number of units, for the active power output valve of double-fed fan motor field, what P represented wind energy turbine set has work value.

In step s 50, consider the reactive capability of described Reactive Compensation in Wind Farm equipment and the reactive capability of transformer absorption, obtain the reactive capability of described final double-fed fan motor field, mainly comprise:

Calculate the reactive power Q that wind energy turbine set transformer absorbs _t:

(16)

In formula, for no-load current percentage; for short-circuit impedance percentage; for transformer working capacity; for transformer nominal capacity.

, the reactive-load compensation equipment in wind energy turbine set and the idle of miscellaneous equipment are taken into account meanwhile, calculate double-fed fan motor field reactive capability, as shown in the formula:

(17)

(18)

In formula, for double-fed fan motor field perception reactive capability, for double-fed fan motor field capacitive reactive power capacity. for double-fed fan motor units be incorporated into the power networks all in double-fed fan motor field total perceptual reactive capability, for total capacitive reactive power capacity of double-fed fan motor units be incorporated into the power networks all in double-fed fan motor field. for the reactive-load compensation equipment (as capacitor, reactor, Static Var Compensator, static reacance generator etc.) in double-fed fan motor field total perceptual reactive capability, for total capacitive reactive power capacity of the reactive-load compensation equipment in double-fed fan motor field.

The acquisition methods of double-fed fan motor field provided by the invention reactive capability, based on unit active power-reactive capability characteristic, utilize regression model to calculate double-fed fan motor field reactive capability, accurately can calculate the reactive capability of double-fed fan motor field, can be used for the idle work optimization of electrical network; And determine the method for double-fed fan motor field reactive capability compared to current according to rated capacity equal proportion, there is rationale and detailed derivation demonstration, improve the confidence level of double-fed fan motor field reactive capability.

In addition, those skilled in the art also can do other change in spirit of the present invention, and these changes done according to the present invention's spirit, all should be included in the present invention's scope required for protection certainly.

Claims (9)

1. an acquisition methods for Double-feed wind power field reactive capability, comprises the following steps:

Step S10, sets up the active power-reactive capability characteristic of unit;

Step S20, according to the active power-reactive capability characteristic of double-fed blower fan, linear regression is carried out in sampling, sets up unit active power-reactive capability linear regression model (LRM);

Step S30, the active power of unit-reactive capability regression model is equivalent to the fail safe of the active power-reactive capability characteristic of wind turbine cohort by checking, makes the reactive capability of the grid connected wind power machine group calculated be not more than the summation of the reactive capability of each double-fed fan motor unit;

Step S40, in conjunction with grid-connected blower fan number of units, calculates the double-fed fan motor field reactive capability of grid-connected blower fan number of units; And

Step S50, the reactive capability that the reactive capability of superposition Reactive Compensation in Wind Farm equipment and transformer absorb, calculates final double-fed fan motor field reactive capability;

Wherein, the reactive capability of final double-fed fan motor field calculates by the following method:

Calculate the reactive power Q that wind energy turbine set transformer absorbs _t:

$Q_T=I_0{\mathrm{\%S}}_n+U_k{\mathrm{\%S}}_n\left(\frac{S}{S_n}\right);$

In formula, I ₀% is no-load current percentage; U _k% is short-circuit impedance percentage; S is transformer working capacity; S _nfor transformer nominal capacity;

Reactive-load compensation equipment in wind energy turbine set and the idle of miscellaneous equipment are taken into account, calculate double-fed fan motor field reactive capability:

$Q_{wf}^{\min }=Q_{d\mathrm{\Σ}}^{\min }+Q_{dev\mathrm{\Σ}}^{\min }-Q_T;$

$Q_{wf}^{\max }=Q_{d\mathrm{\Σ}}^{\max }+Q_{dev\mathrm{\Σ}}^{\max }-Q_T;$

In formula, for double-fed fan motor field perception reactive capability, for double-fed fan motor field capacitive reactive power capacity; for double-fed fan motor units be incorporated into the power networks all in double-fed fan motor field total perceptual reactive capability, for total capacitive reactive power capacity of double-fed fan motor units be incorporated into the power networks all in double-fed fan motor field; for the reactive-load compensation equipment in double-fed fan motor field total perceptual reactive capability, for total capacitive reactive power capacity of the reactive-load compensation equipment in double-fed fan motor field.

2. the acquisition methods of Double-feed wind power field as claimed in claim 1 reactive capability, is characterized in that,

The foundation of the active power-reactive capability characteristic of unit comprises the steps:

Determine the range of operation of double feedback electric engine stator side reactive power;

Determine the range of operation of double fed electric machine rotor side reactive power;

According to the range of operation of the reactive power of double feedback electric engine stator side and rotor-side, obtain the Reactive-power control scope of double-fed fan motor unit; And

Rotating speed in cancellation double-fed fan motor unit Reactive-power control scope, draws unit active power-reactive capability characteristic.

3. the acquisition methods of Double-feed wind power field as claimed in claim 2 reactive capability, it is characterized in that, the range of operation of double feedback electric engine stator side reactive power is determined by the following method:

First, by the restriction of double feedback electric engine rated capacity, the reactive power scope that calculating double feedback electric engine stator side sends to electrical network is:

$Q_s\≥-\sqrt{S_n^2-{(P_d/{\mathrm{\ω}}_r)}^2}---(1-a);$

$Q_s\≤\sqrt{S_n^2-{(P_d/{\mathrm{\ω}}_r)}^2}---(1-b);$

In formula, S _nfor the rated capacity of double feedback electric engine, Q _sfor the reactive power that double feedback electric engine stator side sends to electrical network, P _dfor the active power that double feedback electric engine sends to electrical network, ω _rfor rotation speed of fan;

Secondly, the maximum current I that double feedback electric engine stator side is gained merit, the range of operation of reactive power is also subject to rotor-side converter _rmaxrestriction, calculating the reactive power scope that double feedback electric engine stator side sends to electrical network is:

$Q_s\≥-\frac{3U_s^2}{2{\mathrm{\ω}}_s{L}_s}-\sqrt{{\left(\frac{3L_m}{2L_s}{U}_s{I}_{r\max }\right)}^2-{\left(\frac{{\mathrm{\ω}}_s}{{\mathrm{\ω}}_r}{P}_d\right)}^2}---(2-a);$

$Q_s\≤-\frac{3U_s^2}{2{\mathrm{\ω}}_s{L}_s}+\sqrt{{\left(\frac{3L_m}{2L_s}{U}_s{I}_{r\max }\right)}^2-{\left(\frac{{\mathrm{\ω}}_s}{{\mathrm{\ω}}_r}{P}_d\right)}^2}---(2-b);$

To sum up can obtain, the scope of double feedback electric engine stator side reactive capability is respectively:

$Q_s^{min}=max(-\sqrt{S_n^2-{(P_d/{\mathrm{\ω}}_r)}^2},-\frac{3U_s^2}{2{\mathrm{\ω}}_s{L}_s}-\sqrt{{\left(\frac{3L_m}{2L_s}{U}_s{I}_{r\max }\right)}^2-{\left(\frac{{\mathrm{\ω}}_s}{{\mathrm{\ω}}_r}{P}_d\right)}^2})---(3-a);$

$Q_s^{nax}=min(\sqrt{S_n^2-{(P_d/{\mathrm{\ω}}_r)}^2},-\frac{3U_s^2}{2{\mathrm{\ω}}_s{L}_s}+\sqrt{{\left(\frac{3L_m}{2L_s}{U}_s{I}_{r\max }\right)}^2-{\left(\frac{{\mathrm{\ω}}_s}{{\mathrm{\ω}}_r}{P}_d\right)}^2})---(3-b);$

Wherein U _sfor stator side voltage, L _mfor the magnetizing inductance of double feedback electric engine, L _sfor the stator inductance of double feedback electric engine, ω _sfor synchronous speed.

4. the acquisition methods of Double-feed wind power field as claimed in claim 3 reactive capability, it is characterized in that, the range of operation of double fed electric machine rotor side reactive power is determined in the following manner:

$Q_g^{\min }=-\sqrt{S_g^2-{\left(\frac{{\mathrm{\ω}}_s-{\mathrm{\ω}}_r}{{\mathrm{\ω}}_s}{P}_d\right)}^2}---(4-a);$

$Q_g^{max}=\sqrt{S_g^2-{\left(\frac{{\mathrm{\ω}}_s-{\mathrm{\ω}}_r}{{\mathrm{\ω}}_s}{P}_d\right)}^2}---(4-b);$

In formula, Q _gfor the reactive power that net side converter sends to electrical network, S _gfor the rated capacity of net side converter.

5. the acquisition methods of Double-feed wind power field as claimed in claim 4 reactive capability, it is characterized in that, the Reactive-power control scope of double-fed fan motor unit is:

$Q_d^{\min }{Q}_s^{min}+Q_g^{min}=f_{min}(P_d,{\mathrm{\ω}}_r)---(5-a)$

$Q_d^{max}=Q_s^{max}+Q_g^{max}=f_{max}(P_d,{\mathrm{\ω}}_r)---(5-b)$

In formula, for double-fed fan motor unit perceptual reactive capability, for the capacitive reactive power capacity of double-fed fan motor unit; for stator side perceptual reactive capability, for the capacitive reactive power capacity of stator side; for net side converter perceptual reactive capability, for the capacitive reactive power capacity of net side converter.

6. the acquisition methods of Double-feed wind power field as claimed in claim 5 reactive capability, it is characterized in that, the rotating speed of described double-fed blower fan calculates according to double-fed fan motor unit active power output valve:

${\mathrm{\ω}}_r=\sqrt[3]{\frac{P_d}{k_{opt}}}---\left(6\right),$ Wherein,

Wherein k _optfor double-fed blower fan intrinsic constant;

Consider that (5-a), (5-b) and (6) obtain the characteristic of double-fed fan motor unit active power-reactive capability, the function namely between reactive capability and active power output valve:

$\left\{\begin{array}{c}{Q}_d^{\min }=f_{\min }\left(P_d\right)\\ Q_d^{\max }=f_{max}\left(P_d\right)\end{array}\right..$

7. the acquisition methods of Double-feed wind power field as claimed in claim 6 reactive capability, it is characterized in that, the double-fed fan motor field reactive capability of grid-connected blower fan number of units calculates by the following method:

$\left\{\begin{array}{cc}{Q}_{d\mathrm{\Σ}}^{\min }=\frac{n}{N}{Q}_d^{\min }& (P=\frac{P_{wf}}{n}N)\\ Q_{d\mathrm{\Σ}}^{\max }=\frac{n}{N}{Q}_d^{\max }& (P=\frac{P_{wf}}{n}N)\end{array}\right.;$

In formula, N is the total number of units of double-fed fan motor unit of double-fed fan motor field, and n is grid-connected blower fan number of units, P _wffor the active power output valve of double-fed fan motor field, what P represented wind energy turbine set has work value.

8. the acquisition methods of Double-feed wind power field as claimed in claim 1 reactive capability, is characterized in that, carries out linear regression comprise the steps: the active power of unit and reactive capability

Order $\hat{y}=\hat{a}+\hat{b}x;$

Wherein for the reactive capability regression estimates value of double feedback electric engine, x is the active power of double feedback electric engine, expression formula is as follows:

$\left\{\begin{array}{c}\hat{a}=\stackrel{\‾}{y}-\hat{b}\stackrel{\‾}{x}\\ \hat{b}=\frac{l_{xy}}{l_{xx}}\end{array}\right.;$

In formula,

$\stackrel{\‾}{x}=\frac{1}{n}\underset{i=1}{\overset{n}{\Σ}}{x}_i;$

$\stackrel{\‾}{y}=\frac{1}{n}\underset{i=1}{\overset{n}{\Σ}}{y}_i;$

$l_{xx}=\underset{i=1}{\overset{n}{\Σ}}{(x_i-\stackrel{\‾}{x})}^2;$

$l_{xy}=\underset{i=1}{\overset{n}{\Σ}}(x_i-\stackrel{\‾}{x})(y_i-\stackrel{\‾}{y});$

Wherein, x _irepresent the active power of single blower fan, for the average active power of described wind turbine cohort; y _ifor the actual value of single blower fan reactive capability sampling, for the mean value of wind turbine cohort reactive capability sampling.

9. the acquisition methods of Double-feed wind power field as claimed in claim 1 reactive capability, is characterized in that, verify the fail safe of the active power-reactive capability characteristic active power of unit-reactive capability regression model being equivalent to wind turbine cohort in the following manner:

When in wind turbine cohort, the active power value of double-fed blower fan is the arbitrary value in rated capacity, whether checking following formula is set up:

$\left\{\begin{array}{c}{Q}_{dcom}^{\min }\≥\underset{i=1}{\overset{n}{\Σ}}{Q}_{dcomi}^{\min }\\ Q_{dcom}^{\max }\≤\underset{i=1}{\overset{n}{\Σ}}{Q}_{dcomi}^{\max }\end{array}\right.;$

In formula, be respectively lower limit, the upper limit of the wind turbine cohort equivalence reactive capability scope that regression model calculates, be respectively perceptual reactive capability and the capacitive reactive power capacity of i-th double-fed fan motor unit of wind turbine cohort, n is the number of units of double-fed fan motor unit in wind turbine cohort.