CN104993762A - Fault operation method under doubly-fed wind power generator direct power control - Google Patents
Fault operation method under doubly-fed wind power generator direct power control Download PDFInfo
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Abstract
The invention discloses a fault operation method under doubly-fed wind power generator direct power control. By adopting the control method, complicated coordinate transformation and compensation adjustment in vector control are avoided, and the control instruction is simple, direct and easy to implement. When the grid voltage sags, weak-magnetic rotor flux prediction control is adopted, the given value of rotor flux is worked out based on the actual value of stator flux, the dynamic behaviors of a doubly-fed wind power generator rotor-side converter in different switching states are predicted according to a discrete model of voltage of the converter, seven voltage vector prediction results are evaluated through a value function, and finally, a voltage vector minimizing the value function is chosen. By adopting the algorithm, the optimal switching state can be predicted as a switching signal of the converter in each sampling period. The method needs neither synchronous rotating coordinate system conversion nor PI regulator design, and has the advantages of fast dynamic response, simple control instruction, and easy implementation. The operation capacity of a doubly-fed wind power generator in fault is improved.
Description
Technical field
The invention belongs to the control technology field of double-fed wind power generator rotor side converter, is for the weak magnetic forecast Control Algorithm of rotor flux when direct Power Control method during line voltage stable state and line voltage rapid drawdown respectively.
Background technology
Wind energy is the energy of a kind of randomness, burst, uncertain type, the electric energy random fluctuation that wind generator system produces has very large impact to electrical network, how wind generator system and be all in fluctuation by electric loading state under keep grid voltage amplitude and frequency within the range of permission, how to ensure that the stability etc. of operation of power networks in Wind turbines Dynamic Regulating Process is that wind generator system is to electrical network requirement.These problems must conscientious in the face of and solve, otherwise will the further development of Wind Power Generation Industry be affected.Due to the dominant form that double-fed wind power generator group is current Large Copacity variable speed constant frequency Wind turbines, further investigate very necessary to its not off-grid serviceability when Power System Steady-state when safe operation and electric network fault and corresponding practical control strategy, this just constitutes in modernism power technology some major issues needing to study.
Current double-fed wind power generator when line voltage steady operation many employings based on grid voltage orientation or stator magnetic linkage oriented vector control, this vector control scheme needs synchronous rotating frame to change, double-fed wind power generator is fixed, inductor rotor is used for active current, cross compensation decoupling zero and the comparatively complicated current PI controller parameter of reactive current regulate, therefore the decoupling of double-fed aerogenerator stator active power and reactive power depends on that synchronous rotating frame is changed to a great extent, the precision of double-fed wind power generator rotor inductance value and the setting of PI parameter.There is complicated coordinate transform and compensated regulation in vector control, therefore propose direct Power Control method, it is that a kind of scalar controls, and permission is meritorious and idle to be changed in certain range of tolerable variance, and control command is simply direct, is easy to realize.When grid collapses; part literature research is based on crow bar protecting control strategy; the double-fed wind power generator rotor side overcurrent caused to suppress grid voltage sags; crowbar circuit is used to double fed electric machine rotor side short circuit in winding; this short circuit loop provides a path for rotor strike electric current; suitable selection resistance value can the maximum current in restrict rotor loop, and during crow bar action, double feedback electric engine departs from automatically from system.This kind of method adds hardware cost, absorbs a large amount of reactive powers during fault from electrical network, affects the stability of electrical network, to the transient state electromagnetic impact of electrical network and the mechanical shock of wind energy conversion system all very serious.When line voltage occurs single-phase 90% or three-phase symmetrical falls 70% and more serious fault, within double-fed wind power generator rotor electric current almost can not be controlled in 2 times of rated current, serious to unit infringement.The response speed of control system and the control precision of controller directly affect the inhibition of fault current.Therefore the weak magnetic PREDICTIVE CONTROL of rotor flux under a kind of electric network fault is proposed, this kind of control method without the need to hardware unit, based on two-phase rotor speed
ω rthe two-phase rotor coordinate rotated, do not need complicated Coordinate Conversion, compared with the direct Power Control adopted with steady operation, this control method carries out not fixed-frequency control from the weak magnetic degree of rotor magnetic linkage, faster to failure response speed, control precision is higher, and without saturated phenomenon under the large disturbances such as electrical network catastrophe failure, rotor current can be controlled within 1.5-1.6 times of rated current under malfunction, electromagnetic torque fluctuation is less, impact smaller to unit, above algorithm is in each switch periods circulation primary, and system has higher sample frequency.
Summary of the invention
The object of this invention is to provide a kind of failure operation method under double-fed wind power generator direct Power Control, the method is without the need to synchronous rotating frame conversion and pi regulator design, possess fast dynamic response, control command simple, be easy to realize, improve double-fed wind power generator failure operation ability in failure process.
The present invention adopts following technical scheme for achieving the above object, failure operation method under double-fed wind power generator direct Power Control, it is characterized in that: adopt direct Power Control under normal circumstances, adopt rotor flux weak magnetic PREDICTIVE CONTROL when fault occurs, the concrete steps of the weak magnetic PREDICTIVE CONTROL of this rotor flux are:
(1), line voltage steady operation time, detect threephase stator voltage
u s
a ,
u s
b ,
u s
c , threephase stator electric current
i s
a ,
i s
b ,
i s
c , three-phase rotor current
i r
a ,
i r
b ,
i r
c , detection rotor position angle
θ r;
(2) the threephase stator voltage, will detected in step (1)
u s
a ,
u s
b ,
u s
c two-phase rotor speed is obtained through Coordinate Conversion
ω rtwo-phase stator voltage under the rotor coordinate rotated
u s
α r ,
u s
β r , the threephase stator electric current detected
i s
a ,
i s
b ,
i s
c two-phase rotor speed is obtained through Coordinate Conversion
ω r two-phase stator current under the rotor coordinate rotated
i s
α r ,
i s
β r , the three-phase rotor current detected
i r
a ,
i r
b ,
i r
c two-phase rotor speed is obtained through Coordinate Conversion
ω r two-phase rotor current under the rotor coordinate rotated
i r
α r ,
i r
β r , subscript r represents two-phase rotor speed
ω r the rotor coordinate rotated;
(3), two-phase rotor speed
ω r stator magnetic linkage under the rotor coordinate rotated and the expression formula of rotor flux are respectively:
,
, the expression formula obtaining stator current is thus:
, in formula:
,
represent stator magnetic linkage vector form and rotor flux linkage vector form respectively,
,
represent stator current vector form and rotor current vector form respectively,
l s,
l r,
l mrepresent stator self inductance, mutual inductance between rotor self-induction and rotor respectively, wherein
;
(4), stator voltage vector formula is:
, the active power of stator side input is expressed and is:
, ignore stator resistance, active power and the reactive power of stator side input are expressed as:
,
, in formula:
r s represent stator resistance;
(5), stator magnetic linkage and rotor flux are with rotor speed
ω r be expressed as under the two-phase rotor coordinate rotated:
,
, in formula:
θ s=
ω 1-
ω r , in the ideal situation, ignore stator resistance, the amplitude Ψ of stator magnetic linkage
s and rotating speed
ω 1be all constant, carrying out differentiate to stator magnetic linkage can obtain,
;
(6), the stator magnetic linkage differentiate formula in the stator current formula in step (3) and step (5) is substituted into active power and reactive power expression formula that step (4) obtains stator side:
,
, in formula:
θfor the angle of rotor flux and stator magnetic linkage vector,
θ=
θ r-
θ s, can obtain active power and reactive power differentiate:
,
, in formula: because stator magnetic linkage is a definite value, the control of stator active power and reactive power is converted into the control to rotor flux;
(7), rotor resistance is ignored, rotor speed
ω rthe rotor flux differential equation under the two-phase rotor coordinate rotated is:
, control rotor flux by selecting suitable switching vector selector;
(8), active power and reactive power and its set-point are compared, produce active power and reactive power quantity of state by hysteresis comparator according to error, select corresponding voltage vector to enable active power and reactive power follow set-point fast according to power rating amount, stator magnetic linkage position and optimized switch table;
(9), when line voltage generation rapid drawdown fault, the control frequency of weak for rotor flux magnetic PREDICTIVE CONTROL is set to 10 times of direct Power Control during normal operation, obtains discrete for the rotor flux differential equation in step (7):
, write as rotor speed
the two-phase rotor rotated
α,
βaxle lower rotor part Flux estimation model is:
,
, in formula:
t s for the sampling period,
u r
α r ,
u r
β r be respectively eight voltage vectors in rotor speed
ω reight voltage vectors, in each sampling period, are substituted in formula the rotor flux obtaining the next sampling period by component under the two-phase rotor coordinate rotated respectively;
(10), by the cost function of double-fed wind power generator assessment rotor flux:
, in formula: Ψ
r
α r* (
k+ 1), Ψ
r
β r* (
k+ 1) rotor is respectively
α,
βthe set-point of axle rotor flux, Ψ
r
α i r (
k+ 1), Ψ
r
β i r (
k+ 1) the magnetic linkage value predicted under different voltage vector effect is respectively, subscript i=0,1,2 ..., 7, the minimum voltage vector of rotor flux error of selecting to send as an envoy to acts on rotor-side converter;
(11), the set-point of rotor flux calculates, that is: Ψ
r *=
mΨ
s, wherein
,
i s rfor stator current rated value, Ψ
s rfor stator magnetic linkage actual value, subscript r represents with rotor speed
ω rtwo phase coordinate systems rotated, subscript s represents the variable of stator side, between age at failure
mwith Ψ
s rtranslating self-adapting changes, and realizes the real-time optimistic control to rotor flux;
(12), by rotor flux forecast model, rotor flux dynamic behaviour under the different voltage vector effect of k+1 moment is predicted, the result of prediction is evaluated and optimized by cost function, selects optimum on off state as the control signal of subsequent time switch.
When line voltage occurs single-phase 90% or three-phase symmetrical falls 70% and more serious fault, double-fed wind power generator rotor electric current affects unit and normally runs within almost can not being controlled in 2 times of rated current.Control method of the present invention passes through coefficient between age at failure
mwith Ψ
s
α β change adaptively changing, realizes the real-time optimum weak magnetics detect to rotor flux; Simultaneously, this control method carries out not fixed-frequency control from the weak magnetic degree of rotor magnetic linkage, between age at failure, the control frequency of the weak magnetic PREDICTIVE CONTROL of rotor flux is 10 times of direct Power Control when normally running, further raising failure response speed, and controller saturated under effectively prevent electric network fault large disturbances.All variablees do not need complicated coordinate to change simultaneously, and can control rotor current under malfunction within 1.5-1.6 times of rated current, electromagnetic torque fluctuation is less.Above algorithm is in each switch periods circulation primary, and system has higher sample frequency, improves double-fed wind power generator failure operation ability.
Accompanying drawing explanation
Fig. 1 is that double-fed wind power generator is in rotor speed
ω requivalent circuit diagram under the two-phase rotor coordinate rotated;
The relation that Fig. 2 is stator magnetic linkage and rotor flux under the coordinate system of and rotor orientation directed with stator;
Fig. 3 is direct Power Control structured flowchart under line voltage stable situation;
Fig. 4 is that line voltage controls structured flowchart when falling fault;
The operation result of different control method is adopted when Fig. 5 is under line voltage stable situation and grid voltage three-phase symmetrical falls 70%;
Fig. 6 adopts the operation result of different control method when being and falling 90% with line voltage is single-phase under line voltage stable situation.
Specific implementation method
Below in conjunction with accompanying drawing, the present invention will be further described.Fig. 1 is that double-fed wind power generator is in rotor speed
ω requivalent circuit diagram under the two-phase rotor coordinate rotated,
u s r ,
u r r represent stator voltage and rotor voltage respectively,
r s,
r rrepresent stator resistance and rotor resistance respectively,
i s r ,
i r r represent stator current and rotor current respectively,
l ls,
l lr,
l mrepresent stator leakage inductance, rotor leakage inductance and rotor mutual inductance respectively, Ψ
s r , Ψ
r r represent stator magnetic linkage and rotor flux respectively.Double-fed aerogenerator stator voltage, rotor voltage, stator magnetic linkage and rotor flux formula can be write out, for place mat has been made in concrete analysis below by Fig. 1.
The relation that Fig. 2 is stator magnetic linkage and rotor flux under the coordinate system of and rotor orientation directed with stator.
Double-fed aerogenerator stator magnetic linkage and rotor flux are in rotor speed
ω requation under the two-phase rotor coordinate rotated is:
（1）
（2）
In formula:
,
represent stator magnetic linkage vector form and rotor flux linkage vector form respectively;
,
represent stator current vector form and rotor current vector form respectively;
l s,
l r,
l mrepresent stator self inductance, mutual inductance between rotor self-induction and rotor respectively; Arrow above each variable represents that this variable is vector; What subscript r represented is rotor speed
ω rthe two-phase rotor coordinate rotated is reference.
Can obtain stator current by formula (1) and formula (2) is:
（3）
In formula:
.
Double-fed aerogenerator stator voltage equation is:
（4）
In formula:
u swhat represent is stator voltage;
r swhat represent is stator resistance;
ω rthe rotor speed represented.
Ignore stator resistance, double-fed aerogenerator stator active power and reactive power can be expressed as:
（5）
（6）
In formula:
p s,
q srepresent stator active power and reactive power respectively.
Stator magnetic linkage and rotor flux can be obtained with rotor speed by Fig. 2
ω rexpression formula under the two-phase rotor coordinate rotated is:
（7）
（8）
In formula:
θ s=
ω 1-
ω r ; In the ideal situation, ignore stator resistance, the amplitude Ψ of stator magnetic linkage
s and rotating speed
ω 1all constant.
Can obtain formula (7) differentiate:
（9）
Formula (3), formula (9) substitution formula (5), formula (6) can be obtained:
（10）
（11）
Because stator magnetic linkage is a definite value, illustrate that the control of stator active power and reactive power can be converted into the control to rotor flux.
Ignore rotor resistance, rotor speed
the rotor flux differential equation under the two-phase rotor coordinate rotated is:
（12）
As can be seen from formula (12), the change of rotor voltage is followed in the change of rotor flux, by the size selecting suitable switching vector selector just can control rotor flux.
Active power and reactive power and its set-point are compared, active power, reactive power quantity of state is produced according to error by hysteresis comparator, select corresponding voltage vector according to power rating amount, stator magnetic linkage position and optimized switch table, enable active power and reactive power follow set-point fast.
When line voltage generation rapid drawdown fault, double-fed wind power generator is switched to the weak magnetic PREDICTIVE CONTROL of rotor flux, assuming that the sampling period is
t s , formula (12) is carried out discrete obtaining:
（13）
Write formula (13) as rotor speed
ω rthe two-phase rotor rotated
α,
βequation under coordinate system is:
（14）
（15）
u r
α r ,
u r
β r be respectively eight voltage vectors in rotor speed
ω rcomponent under the two-phase rotor coordinate rotated, formula (14), formula (15) are rotor flux forecast models, by each variable of k moment is substituted into formula (14), formula (15), dope the rotor flux under eight voltage vector effects, the set-point of itself and rotor flux is carried out cost function assessment, selects optimum on off state as the control signal of subsequent time switch.
Two-phase rotor speed
ω runder the coordinate system rotated, stators and rotators flux linkage equations can be expressed as:
Ψ
s r=
L s I s r+
L m I r r（16）
Ψ
r r=
L r I r r+
L m I s r（17）
Wherein
l s,
l rwith
l mrepresent the mutual inductance between stator self inductance, rotor self-induction and rotor respectively,
i swith
i rrepresent stator current and rotor current respectively, Ψ
sand Ψ
rrepresent stator magnetic linkage and rotor flux, subscript r represents with rotor speed
ω rrotate two phase coordinate systems, subscript s and r represents variable and the rotor-side variable of stator side respectively.
Can stator current be obtained by formula (16) and formula (17):
（18）
Rotor current can be obtained, in computational process by formula (16) and formula (17)
, can obtain:
（19）
In formula
l ls,
l lrrepresent stator leakage inductance and rotor leakage inductance respectively.
By the set-point Ψ of rotor flux
r *=
mΨ
ssubstitution formula (18) can obtain:
（20）
i s rfor the rated value of stator current, Ψ
s rfor the actual value of stator magnetic linkage.By the relation of rotor magnetic linkage and stator and rotor current, and rotor flux field weakening control method, obtain
mvalue size, instant of failure Ψ
s rvalue maximum, now
mget maximum, as can be seen from formula (19),
mlarger, rotor fault current value is less.Between age at failure
mcan with Ψ
s rtranslating self-adapting changes, and realizes the real-time optimistic control to rotor flux.Double-fed aerogenerator stator side is directly connected with electrical network, and the distortion of stator side electric current is very large to electrical network harm, therefore between age at failure
i s rget rated value, to realize the adjustment to stator current between age at failure, control stator current within its maximum current allowed.
The cost function of double-fed wind power generator assessment rotor flux is:
（16）
In formula: Ψ
r
α r* (
k+ 1), Ψ
r
β r* (
k+ 1) rotor is respectively
α,
βthe set-point of axle rotor flux; Ψ
r
α i r (
k+ 1), Ψ
r
β i r (
k+ 1) the magnetic linkage value for predicting under different voltage vector effect, subscript i=0,1,2 ..., 7; , the minimum voltage vector of rotor error of selecting to send as an envoy to acts on rotor-side converter.
When line voltage generation three-phase symmetrical fall 70% or single-phase fall 90% fault time, adopt the weak magnetic forecast Control Algorithm of rotor flux, this control method carries out not fixed-frequency control from the weak magnetic degree of rotor magnetic linkage, the control frequency of the weak magnetic PREDICTIVE CONTROL of rotor flux is set to 10 times of direct Power Control when normally running, faster to the response speed of fault, under electric network fault large disturbances, eliminate controller saturation.Can control rotor current under malfunction within 1.5-1.6 times of rated current, electromagnetic torque fluctuation is less, and above algorithm is in each switch periods circulation primary, and system has higher sample frequency.
Direct Power Control structured flowchart is adopted, the control structure block diagram adopted when Fig. 4 is grid voltage sags when Fig. 3 is line voltage steady operation.Concrete steps are as follows: (1), when line voltage steady-state operation, detect threephase stator voltage
u s
a ,
u s
b ,
u s
c , threephase stator electric current
i s
a ,
i s
b ,
i s
c , three-phase rotor current
i r
a ,
i r
b ,
i r
c , detection rotor position angle
θ r; (2), by the threephase stator voltage detecting in step (1)
u s
a ,
u Sb ,
u s
c Two-phase rotor speed is obtained through Coordinate Conversion
ω rTwo-phase stator voltage under the rotor coordinate of rotation
u s
α r ,
u s
β r , the threephase stator electric current detecting
i s
a ,
i s
b ,
i s
c Two-phase rotor speed is obtained through Coordinate Conversion
ω rTwo-phase stator current under the rotor coordinate of rotation
i S α r ,
i s
β r , the three-phase rotor current detecting
i r
a ,
i r
b ,
i r
c Two-phase rotor speed is obtained through Coordinate Conversion
ω rTwo-phase rotor current under the rotor coordinate of rotation
i r
α r ,
i r
β r , subscript r represents two-phase rotor speed
ω rThe rotor coordinate of rotation; (3), two-phase rotor speed
ω rRotation rotor coordinate under stator magnetic linkage and the expression formula of rotor flux:
,
, obtain the expression formula of stator current thus:
, in formula:
,
Represent respectively stator magnetic linkage vector form and rotor flux linkage vector form,
,
Represent respectively stator current vector form and rotor current vector form,
L s,
L r,
L mRepresent respectively the mutual inductance between stator self inductance, rotor self-induction and rotor, wherein
; (4), stator voltage vector formula is:
, the active power of stator side input is expressed and is:
, ignore stator resistance, active power and the reactive power of stator side input are expressed as:
,
, in formula:
R sRepresent stator resistance; (5), stator magnetic linkage and rotor flux are with rotor speed
ω rUnder the two-phase rotor coordinate of rotation, be expressed as:
,
, in formula:
θ s=
ω 1-
ω r , in the ideal situation, ignore stator resistance, the amplitude Ψ of stator magnetic linkage
s And rotating speed
ω 1Be all constant, differentiate is carried out to stator magnetic linkage can obtain:
; (6), the stator magnetic linkage differentiate formula in the stator current formula in step (3) and step (5) is put into active power and the reactive power expression formula that step (4) can obtain stator side:
,
, in formula:
θFor the angle of rotor flux and stator magnetic linkage vector,
θ=
θ r-
θ s, can obtain active power and reactive power differentiate:
,
, in formula: because stator magnetic linkage is a definite value, the control of stator active power and reactive power is converted into the control to rotor flux; (7) rotor resistance, rotor speed, is ignored
ω rThe rotor flux differential equation under the two-phase rotor coordinate of rotation is:
, rotor flux just can be controlled by selecting suitable switching vector selector; (8), active power and reactive power and its set-point are compared, active power and reactive power quantity of state is produced according to error by hysteresis comparator, select corresponding voltage vector according to power rating amount, stator magnetic linkage position and optimized switch table, enable active power and reactive power follow set-point fast; (9), when line voltage generation rapid drawdown fault, the controlled frequency that improves rotor flux weak magnetic PREDICTIVE CONTROL during to normal functioning direct Power Control frequency 10 doubly, by discrete the rotor flux differential equation in step (7) must:
, write as rotor speed
ω rThe two-phase rotor of rotation
α,
βAxle lower rotor part Flux estimation model is:
,
, in formula:
T sFor the sampling period,
U r
α r ,
U r
β r Be respectively eight voltage vectors at rotor speed ω
r Component under the two-phase rotor coordinate of rotation, in each sampling period, puts into eight voltage vectors respectively in formula, obtains the rotor flux in next sampling period; (10) cost function of rotor flux, is assessed by double-fed wind power generator:
, in formula, Ψ
r
α R* (
k+ 1), Ψ
r
β R* (
k+ 1) rotor is respectively
α,
βThe set-point of axle rotor flux; Ψ
r
α i r (
k+ 1), Ψ
r
β i r (
k+ 1) the magnetic linkage value for predicting under different voltage vector effects, subscript i=0,1,2 ..., 7, the voltage vector of rotor error minimum of selecting to send as an envoy to acts on rotor-side converter; (11), the set-point of rotor flux calculates, that is: Ψ
r *=
MΨ
s,Wherein
,
I s rFor stator current rated value, Ψ
s rFor stator magnetic linkage actual value, subscript r represents with rotor speed
ω rTwo phase coordinate systems of rotation, subscript s represents the variable of stator side, between age at failure
MWith Ψ
s rTranslating self-adapting changes, and realizes the real-time optimistic control to rotor flux; (12), by rotor flux forecast model, rotor flux dynamic behaviour under the different voltage vector effects of k+1 moment is predicted, the result of prediction is evaluated and optimized by cost function, select the control signal of optimum on off state as subsequent time switch.
Fig. 5 be under line voltage stable situation and grid voltage sags time adopt the operation result of different control method.When 0-0.3s, line voltage steady operation, the rotor current of the rotor converter under direct Power Control is stablized, and has good sine degree, the basic ripple disable of electromagnetic torque, active power and reactive power basicly stable; When 0.3s, line voltage generation three-phase symmetrical falls 70% fault, rotor converter adopts the weak magnetic forecast Control Algorithm of rotor flux, this control method controls to make between age at failure rotor current within 1.5-1.6 times of rated current, electromagnetic torque fluctuation is less, improves double-fed wind power generator failure operation ability.
Fig. 6 be under line voltage stable situation and grid voltage sags time adopt the operation result of different control method.When 0-0.3s, line voltage steady operation, the rotor current of the rotor converter under direct Power Control is stablized, and has good sine degree, the basic ripple disable of electromagnetic torque, active power and reactive power basicly stable; When 0.3s, line voltage generation is single-phase falls 90% fault, rotor converter adopts the weak magnetic forecast Control Algorithm of rotor flux, this control method controls to make between age at failure rotor current within 1.5-1.6 times of rated current, electromagnetic torque fluctuation is less, improves double-fed wind power generator failure operation ability.
Embodiment above describes general principle of the present invention, principal character and advantage; the technical staff of the industry should understand; the present invention is not restricted to the described embodiments; what describe in above-described embodiment and specification just illustrates principle of the present invention; under the scope not departing from the principle of the invention; the present invention also has various changes and modifications, and these changes and improvements all fall in the scope of protection of the invention.
Claims (1)
1. the failure operation method under double-fed wind power generator direct Power Control, is characterized in that: adopt direct Power Control under normal circumstances, and adopt rotor flux weak magnetic PREDICTIVE CONTROL when fault occurs, the concrete steps of the weak magnetic PREDICTIVE CONTROL of this rotor flux are:
(1), line voltage steady operation time, detect threephase stator voltage
u s
a ,
u s
b ,
u s
c , threephase stator electric current
i s
a ,
i s
b ,
i s
c , three-phase rotor current
i r
a ,
i r
b ,
i r
c , detection rotor position angle
θ r;
(2) the threephase stator voltage, will detected in step (1)
u s
a ,
u s
b ,
u s
c two-phase rotor speed is obtained through Coordinate Conversion
ω rtwo-phase stator voltage under the rotor coordinate rotated
u s
α r ,
u s
β r , the threephase stator electric current detected
i s
a ,
i s
b ,
i s
c two-phase rotor speed is obtained through Coordinate Conversion
ω r two-phase stator current under the rotor coordinate rotated
i s
α r ,
i s
β r , the three-phase rotor current detected
i r
a ,
i r
b ,
i r
c two-phase rotor speed is obtained through Coordinate Conversion
ω r two-phase rotor current under the rotor coordinate rotated
i r
α r ,
i r
β r , subscript r represents two-phase rotor speed
ω r the rotor coordinate rotated;
(3), two-phase rotor speed
ω r stator magnetic linkage under the rotor coordinate rotated and the expression formula of rotor flux are respectively:
,
, the expression formula obtaining stator current is thus:
, in formula:
,
represent stator magnetic linkage vector form and rotor flux linkage vector form respectively,
,
represent stator current vector form and rotor current vector form respectively,
l s,
l r,
l mrepresent stator self inductance, mutual inductance between rotor self-induction and rotor respectively, wherein
;
(4), stator voltage vector formula is:
, the active power of stator side input is expressed and is:
, ignore stator resistance, active power and the reactive power of stator side input are expressed as:
,
, in formula:
r s represent stator resistance;
(5), stator magnetic linkage and rotor flux are with rotor speed
ω r be expressed as under the two-phase rotor coordinate rotated:
,
, in formula:
θ s=
ω 1-
ω r , in the ideal situation, ignore stator resistance, the amplitude Ψ of stator magnetic linkage
s and rotating speed
ω 1be all constant, carrying out differentiate to stator magnetic linkage can obtain,
;
(6), the stator magnetic linkage differentiate formula in the stator current formula in step (3) and step (5) is substituted into active power and reactive power expression formula that step (4) obtains stator side:
,
, in formula:
θfor the angle of rotor flux and stator magnetic linkage vector,
θ=
θ r-
θ s, can obtain active power and reactive power differentiate:
,
, in formula: because stator magnetic linkage is a definite value, the control of stator active power and reactive power is converted into the control to rotor flux;
(7), rotor resistance is ignored, rotor speed
ω rthe rotor flux differential equation under the two-phase rotor coordinate rotated is:
, control rotor flux by selecting suitable switching vector selector;
(8), active power and reactive power and its set-point are compared, produce active power and reactive power quantity of state by hysteresis comparator according to error, select corresponding voltage vector to enable active power and reactive power follow set-point fast according to power rating amount, stator magnetic linkage position and optimized switch table;
(9), when line voltage generation rapid drawdown fault, the control frequency of weak for rotor flux magnetic PREDICTIVE CONTROL is set to 10 times of direct Power Control during normal operation, obtains discrete for the rotor flux differential equation in step (7):
, write as rotor speed
the two-phase rotor rotated
α,
βaxle lower rotor part Flux estimation model is:
,
, in formula:
t s for the sampling period,
u r
α r ,
u r
β r be respectively eight voltage vectors in rotor speed
ω reight voltage vectors, in each sampling period, are substituted in formula the rotor flux obtaining the next sampling period by component under the two-phase rotor coordinate rotated respectively;
(10), by the cost function of double-fed wind power generator assessment rotor flux:
, in formula: Ψ
r
α r* (
k+ 1), Ψ
r
β r* (
k+ 1) rotor is respectively
α,
βthe set-point of axle rotor flux, Ψ
r
α i r (
k+ 1), Ψ
r
β i r (
k+ 1) the magnetic linkage value predicted under different voltage vector effect is respectively, subscript i=0,1,2 ..., 7, the minimum voltage vector of rotor flux error of selecting to send as an envoy to acts on rotor-side converter;
(11), the set-point of rotor flux calculates, that is: Ψ
r *=
mΨ
s, wherein
,
i s rfor stator current rated value, Ψ
s rfor stator magnetic linkage actual value, subscript r represents with rotor speed
ω rtwo phase coordinate systems rotated, subscript s represents the variable of stator side, between age at failure
mwith Ψ
s rtranslating self-adapting changes, and realizes the real-time optimistic control to rotor flux;
(12), by rotor flux forecast model, rotor flux dynamic behaviour under the different voltage vector effect of k+1 moment is predicted, the result of prediction is evaluated and optimized by cost function, selects optimum on off state as the control signal of subsequent time switch.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN109416523A (en) * | 2016-05-03 | 2019-03-01 | 维斯塔斯风力系统集团公司 | Wind turbine is controlled using MPC during low-voltage grid event |
| US10707789B2 (en) | 2017-05-12 | 2020-07-07 | General Electric Company | Adaptive current damping module for improved power converter control in wind turbine systems |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004201357A (en) * | 2002-12-16 | 2004-07-15 | Mitsubishi Electric Corp | Controlling equipment of induction motor |
| CN102931671A (en) * | 2012-10-26 | 2013-02-13 | 河南师范大学 | Resonant control method for output power of voltage source PWM (Pulse Width Modulation) rectifier under power grid fault |
| CN103427738A (en) * | 2013-08-25 | 2013-12-04 | 浙江大学 | Optimal predictive direct power control method of doubly fed induction generator |
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2015
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004201357A (en) * | 2002-12-16 | 2004-07-15 | Mitsubishi Electric Corp | Controlling equipment of induction motor |
| CN102931671A (en) * | 2012-10-26 | 2013-02-13 | 河南师范大学 | Resonant control method for output power of voltage source PWM (Pulse Width Modulation) rectifier under power grid fault |
| CN103427738A (en) * | 2013-08-25 | 2013-12-04 | 浙江大学 | Optimal predictive direct power control method of doubly fed induction generator |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109416523A (en) * | 2016-05-03 | 2019-03-01 | 维斯塔斯风力系统集团公司 | Wind turbine is controlled using MPC during low-voltage grid event |
| CN109416523B (en) * | 2016-05-03 | 2022-06-07 | 维斯塔斯风力系统集团公司 | Controlling a wind turbine during a low voltage grid event using MPC |
| US10707789B2 (en) | 2017-05-12 | 2020-07-07 | General Electric Company | Adaptive current damping module for improved power converter control in wind turbine systems |
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