CN103346577B - Reduce wind energy turbine set AVC powerless control system and the method for wind power loss - Google Patents

Abstract

The present invention relates to a kind of wind energy turbine set AVC powerless control system reducing wind power loss and method, belong to wind farm grid-connected operation and control technical field. The present invention includes wind energy turbine set AVC substation, wind-driven generator and reactive power compensator SVC; Tool is originally be connected with wind-driven generator server, wind energy turbine set AGC, reactive power compensator SVC and scheduling station respectively by wind energy turbine set AVC substation. The present invention improves the generating efficiency of system, it is ensured that every unit sends or the reactive power that absorbs is within the allowed band of unit, it is ensured that the safe operation of equipment. Take into full account that blower fan is gained merit and idle relation of exerting oneself, played the idle fan-out capability of blower fan to greatest extent, decreased concentration reactive power compensator switching frequency, improve its utilization benefit.

Description

Reduce wind energy turbine set AVC powerless control system and the method for wind power loss

Technical field

The present invention relates to a kind of wind energy turbine set AVC powerless control system reducing wind power loss and method, belong to wind farm grid-connected operation and control technical field.

Background technology

Along with the great attention to renewable energy power generation of fast development and country of wind generating technology, China's wind-power electricity generation construction has progressed into sound development period, and wind farm grid-connected service ability promotes gradually. For ensureing power network safety operation, current wind energy turbine set operator has started to configure AVC device in wind energy turbine set, purpose is able to regulate reactive power and the voltage of electrical network access point, carry out reactive power compensation, to ensure the voltage stabilization of electrical network access point, it is prevented that owing to wind speed changes the access point voltage pulsation brought.

But being as the extra addition of AVC, existing wind energy turbine set control strategy need to make suitable change, and considers the factors such as loss minimization. Current wind energy turbine set AVC controls System Priority and utilizes blower fan to send out the ability of reactive power, first pass through and distribute to each blower fan by constant power factor or equal proportion, when blower fan always idle exert oneself cannot meet bus requirement time, put into again and concentrate reactive-load compensation equipment, and whole process response time is long, and capacitor puts into by group, it is easy to cause the idle wasting of resources, also add loss of wind farm.

Wind power plant reactive power source mainly has two kinds: Wind turbines and concentration reactive-load compensation equipment. Concentrate reactive-load compensation equipment, such as the reactive power of wind energy turbine set can be balanced rapidly by Static VAR Compensation (SVC), but there is also that cost height, loss be big and the defect of poor stability, and SVC is by group switching, it is easy to cause economic nargin too low. It addition, although major part blower fan adopts power decoupled to control, when its idle ability of sending and reactive loss are still by air speed influence, it is impossible to reach idle specified control target. Wind energy turbine set voltage automatically controls (AVC) system and can excavate wind energy turbine set inner blower and send the ability of reactive power, coordinates with SVC, makes wind power plant reactive power reach better dynamic equilibrium.

The part producing loss in wind energy turbine set mainly includes Wind turbines, case change, main transformer, current collection circuit, concentrate reactive power compensator, and carry out the research to wind energy turbine set AVC powerless control method, it is make full use of blower fan idle to exert oneself, reduce overall loss in wind energy turbine set and improve the most effective means of wind energy turbine set operation voltage level, so that power system can safety and economic operation.

Summary of the invention

The technical problem to be solved in the present invention is to provide a kind of wind energy turbine set AVC powerless control system reducing wind power loss and method, purpose is to make it make full use of blower fan reactive power capability, realize the coordination between Reactive Compensation in Wind Farm equipment and unit operation to control, and make wind energy turbine set power loss rate minimise degree.

The technical solution adopted in the present invention is:

Reduce the wind energy turbine set AVC powerless control system of wind power loss, including: wind energy turbine set AVC substation, wind-driven generator and reactive power compensator SVC; Specifically it is connected with wind-driven generator server, wind energy turbine set AGC, reactive power compensator SVC and scheduling station respectively by wind energy turbine set AVC substation.

Reduce the control method of the wind energy turbine set AVC powerless control system of wind power loss, including wind energy turbine set AVC substation, wind-driven generator and reactive power compensator SVC; Also include processor, memory module, input/output module, MODBUS (TCP/IP) communication interface, detection module, server; Processor performs control algolithm, and memory module and input/output module are called; Input/output module is by MODBUS (TCP/IP) communication interface and detection module communication, and is communicated by the SCADA of server Yu wind turbine.

The information of the existing energy management platform exchange of described wind energy turbine set AVC substation and wind energy turbine set includes wind energy turbine set information, the status information of wind energy turbine set SVC equipment and control instruction, includes each blower fan real time status information and control instruction with the information of blower fan server exchange; Wind energy turbine set AVC substation is idle or voltage-target is directly handed down to wind energy turbine set SVC, wind energy turbine set SVC regulate and control; The function such as AVC substation system possesses communication, collection, control, calculating, storage, supervision, parameter are arranged; Wind-driven generator possesses idle fan-out capability, and blower fan SCADA can be controlled by AVC system; Reactive power compensator is mainly SVC or SVG, SVC and SVG all can realize idle smooth adjustment by controller issues idle or voltage instruction; High voltage bus voltage can be adjusted by main transformer tap.

The described wind energy turbine set AVC powerless control system reducing wind power loss, step is as follows:

The first step, AVC controls system and judges that whether voltage deviation value is out-of-limit, by also site real-time voltage U_meanThe grid-connected point target voltage U assigned with control centre_targetCompare, obtain voltage deviation value:

Δ U=| U_mean-U_target| (1);

In order to prevent the frequent adjustment of equipment, arranging voltage dead band scope, arrange and range for Δ U≤0.01, wherein Δ U isAmplitude; If voltage deviation value Δ U is more than the threshold value of error dead band module, then carries out the idle of next step and adjust;

Second step, first surveys the meritorious output valve P of current each blower fan_gen, by the meritorious real-time maximum fan-out capability Q of the every Fans of restriction relation with idle output of blower fan_reg(i)=λ P_gen(i), then the idle reference value of the Wind turbines of AVC default is total up to Q_Wref, namely blower fan always idle exert oneself givenWherein the maximum idle constraints of blower fan is:

$P_W\frac{\sqrt{1-{\mathrm{\λ}}_L^2}}{{\mathrm{\λ}}_L}\≤Q_{reg}\≤P_W\frac{\sqrt{1-{\mathrm{\λ}}_H^2}}{{\mathrm{\λ}}_H}---\left(2\right);$

In formula, λ is the power factor of blower fan, and the power factor under blower fan normal operation ranges for λ_L≤λ≤λ_H, by formula (2) it can be seen that when blower fan is completely sent out, Reactive-power control ability will be lost;

The limit computing formula of separate unit blower fan output reactive power is:

$\left\{\begin{array}{c}{Q}_{reg\max }=\sqrt{\frac{|U_1{|}^2{X}_m^2}{X_1^2}{I}_{r\max }^2-P_k^2}-\frac{{U_1}^2}{X_1}\\ Q_{reg\min }=-\frac{{U_1}^2}{X_1}-\sqrt{\frac{|U_1{|}^2{X}_m^2}{X_1^2}{I}_{r\max }^2-P_k^2}\end{array}\right.---\left(3\right);$

U in formula₁For fan stator terminal voltage, P_kFor fan outlet active power, X₁For stator leakage reactance and excitation reactance sum, I_rmaxFor current transformer current limit value, it is generally 1.5 times of current transformer rated current;

3rd step, by voltage and idle relation, calculates reactive power compensation amount:

Δ U=Δ Q/S_sc(4);

S_sc=(U_now-U_last)/(ΣQ_now/U_now-ΣQ_last/U_last) (5);

In formula (4), (5), Δ Q is reactive power variable quantity, S_scFor the capacity of short circuit of system busbar side, Σ Q_now、ΣQ_lastAlways idle and current always idle for last time, U_last、U_nowLast time busbar voltage, current busbar voltage. If total reactive power demand Δ Q idle fan-out capability Q overall more than blower fan_Wref, then the 4th step is entered; If Δ Q≤Q_Wref, then required idle all sent out by blower fan, now, separate unit blower fan is idle, and set-point is Q_reg(i)=Δ Q × Q_reg(i)/Q_Wref;

If | Q_SVCmax+Q_Wref|≤| Δ Q |, then AVC system will provide the alarm prompt regulating main transformer tap;

4th step, the main air box change of power attenuation, current collection circuit, main transformer and concentration reactive power compensator is caused inside wind energy turbine set, and under certain wind speed, blower fan active power is fixed, in order to make Power Output for Wind Power Field maximize, total active power loss in wind energy turbine set field need to be made minimum, total-power loss:

${\mathrm{\ΔP}}_{\mathrm{\Σ}}(S,V)=P_0\left(V\right)+P_S(S,V)+P_{LL}(S,V)+P_{svc}={\left(\frac{V}{V_N}\right)}^2\·P_{N0}+{\left(\frac{S}{S_N}\right)}^2\·\left(\frac{V_N}{V}\right)\·P_{NS}+{\left(\frac{S}{S_N}\right)}^2\·\left(\frac{V_N}{V}\right)\·P_{NL}+P_{svc}---\left(6\right)$

Δ P in formula_ΣFor the power attenuation that wind energy turbine set is total, P₀For transformer noload losses, P_SFor transformer short-circuit loss, P_LLFor line loss, V is transformator working voltage value, V_NFor transformator load voltage value, S is that transformator runs apparent energy value, S_NFor the specified apparent energy value of transformator, P_N0For transformator rated no-load loss, P_NSFor transformator nominal short-circuit loss, P_NLFor circuit rated power loss, P_svcPower attenuation for reactive power compensator;

Set wind energy turbine set total-power loss Δ P_ΣFor object function, due to all plant capacity losses being connected on a current collection circuit:

$P=I^{2}R={(S_N/\sqrt{3}{U}_N)}^{2}R={(P_{gen}\×n/cos\mathrm{\φ}/k/\sqrt{3}{U}_N)}^{2}R---\left(7\right);$

Wherein cos φ=λ, n is the total number of units of blower fan, and k is the percentage ratio that virtual voltage accounts for rated voltage;

The power attenuation P of reactive power compensator_svcIncluding the loss of reactor in the fixed loss of fixed capacity device group and TCR branch road, in practice, the loss of reactor changes with voltage, but change is little, TCR type SVC for 10Mvar-50Mvar, its loss is about the 0.5%-0.7% of capacity, it is possible to be set as known quantity according to wind energy turbine set practical situation;

So by formula (5)-(7) it can be seen that wind energy turbine set total-power loss Δ P_ΣOnly with the reactive power Q of each wind-driven generator_WRelevant, formula (6) is converted to blower fan idle have distribution most object function be:

T=Δ P_Σ(S, V)=Δ P_Σ(Q_gen) (8);

5th step, process that object function T is minimized, obtain wind-force when object function exists minima and send out the reactive power value of machineThe overall fan-out capability of Wind turbines isAnd this process need to consider the constraints of reactive power equilibrium in wind energy turbine set:

$\left\{\begin{array}{c}{P}_W\frac{\sqrt{1-{\mathrm{\λ}}_L^2}}{{\mathrm{\λ}}_L}\≤Q_{reg}\≤P_W\frac{\sqrt{1-{\mathrm{\λ}}_H^2}}{{\mathrm{\λ}}_H}\\ Q_{reg\min }\≤Q_{reg}\≤Q_{reg\max }\end{array}\right.---\left(9\right);$

$\mathrm{\Δ}Q=Q_{Wref}^{*}+Q_{SVC}-{\mathrm{\ΔQ}}_{\mathrm{\Σ}}---\left(10\right);$

Wherein:For the overall fan-out capability of wind energy turbine set Wind turbines;

Δ Q is reactive power variable quantity, i.e. the dispatch value of the total reactive power of wind energy turbine set;

ΔQ_ΣFor the total reactive loss of wind energy turbine set, it is possible to represent with blower fan is idle;

6th step, by Q_WrefWithCompare, ifThen blower fan is idle is given as Q_reg, concentrate that reactive power compensator is idle is given as Q_svc=Δ Q-Q_Wref-Q_T-Q_LL; IfThen blower fan is idle is given asNow concentrate that reactive power compensator is idle is given asWherein Q_TAnd Q_LLRespectively transformator and circuit reactive loss.

The control method of the described wind energy turbine set AVC powerless control system reducing wind power loss, described step is as follows:

The first step, by measuring the voltage U of also site in real time_meanThe grid-connected point target voltage U assigned with control centre_targetCompare, by U_meanWith U_targetCompare, it is judged that whether voltage deviation value is out-of-limit,

Δ U=| U_mean-U_target| (1);

In order to prevent the frequent adjustment of equipment, arranging voltage dead band scope, arrange and range for Δ U≤0.01, wherein Δ U isAmplitude; If voltage deviation value Δ U is less than the threshold value of dead band module, then stops this secondary program and perform, a moment set-point in maintenance that wind energy turbine set is idle; If voltage deviation value Δ U is more than the threshold value of error dead band module, then carries out the idle of next step and adjust;

Second step, calculates blower fan reactive power fan-out capability:

$\{\begin{array}{c}{Q}_{reg}={\mathrm{\λP}}_{gen}\\ Q_{Wref}={\Σ}_{k=1}^n{Q}_{reg}\end{array}---\left(2\right);$

Wherein Q_regConstraints be:

$\left\{\begin{array}{c}{P}_W\frac{\sqrt{1-{\mathrm{\λ}}_L^2}}{{\mathrm{\λ}}_L}\≤Q_{reg}\≤P_W\frac{\sqrt{1-{\mathrm{\λ}}_H^2}}{{\mathrm{\λ}}_H}\\ Q_{reg\min }\≤Q_{reg}\≤Q_{reg\max }\end{array}\right.---\left(3\right);$

3rd step, calculates reactive power compensation amount:

Δ U=Δ Q/S_sc(4);

S_sc=(U_now-U_last)/(ΣQ_now/U_now-ΣQ_last/U_last) (5);

In formula, Δ Q is, S_scFor the capacity of short circuit of system busbar side, Σ Q_now、ΣQ_lastAlways idle and current always idle for last time, U_last、U_nowLast time busbar voltage, current busbar voltage. If total reactive power demand Δ Q idle fan-out capability Q overall more than blower fan_Wref, then the 4th step is entered; If Δ Q≤Q_Wref, then required idle all sent out by blower fan; If | Q_SVCmax+Q_Wref|≤| Δ Q |, then AVC system will provide the alarm prompt regulating main transformer tap;

4th step, sets up the object function between wind power generating set reactive power and wind energy turbine set loss:

T=Δ P_Σ(S, V)=P₀(V)+P_S(S,V)+P_LL(S,V)+P_svc=Δ P_Σ(Q_gen) (6);

Constraints:

$\left\{\begin{array}{c}{Q}_{reg\min }\≤Q_{reg}\≤Q_{reg\max }\\ P_W\frac{\sqrt{1-{\mathrm{\λ}}_L^2}}{{\mathrm{\λ}}_L}\≤Q_{reg}\≤P_W\frac{\sqrt{1-{\mathrm{\λ}}_H^2}}{{\mathrm{\λ}}_H}\\ \mathrm{\Δ}Q=Q_{Qref}^{*}+Q_{SVC}-{\mathrm{\ΔQ}}_{\Σ}\end{array}\right.---\left(7\right);$

Object function is sought local derviation, carries out minimizing process, it is thus achieved that time the minimum blower fan of wind energy turbine set loss is always idle exerts oneself

5th step, by Q_WrefWithCompare, ifThen blower fan is idle is given as Q_reg, concentrate that reactive power compensator is idle is given as Q_svc=Δ Q-Q_Wref-Q_T-Q_LL; IfThen blower fan is idle is given asNow concentrate that reactive power compensator is idle is given asWherein Q_TAnd Q_LLRespectively transformator and circuit reactive loss;

6th step, the reactive power setting valve of wind turbine and concentration reactive power compensator as control instruction, is sent to each Wind turbines and SVC, completes the idle control of wind energy turbine set by AVC substation.

Advantages of the present invention is as follows with good effect:

It is minimum for foundation with wind power loss that the present invention controls system, distribute the idle of every Fans to exert oneself, under ensureing the premise that control point meets grid requirements, improve the generating efficiency of system, and ensure that every unit sends or the reactive power that absorbs is within the allowed band of unit, it is ensured that the safe operation of equipment. Due to the fact that and taken into full account that blower fan is gained merit and idle relation of exerting oneself, played the idle fan-out capability of blower fan to greatest extent, decrease concentration reactive power compensator switching frequency simultaneously, improve its utilization benefit.

Accompanying drawing explanation

Below in conjunction with drawings and Examples, this utility model is described further.

Fig. 1 is wind energy turbine set AVC Control system architecture schematic diagram;

Fig. 2 is that the idle setting program of wind energy turbine set AVC formulates flow chart;

Fig. 3 is that wind energy turbine set AVC of the present invention controls system hardware configuration structure chart.

Detailed description of the invention

The present invention propose the idle control strategy of wind energy turbine set AVC based on: in conjunction with the idle capacity of blower fan, control wind energy turbine set Control of Voltage point (namely line port is sent in transformer station high-pressure side) voltage in allowed limits, and make wind energy turbine set power loss minimum.

The basic ideas of the present invention are in that: wind energy turbine set AVC controls system with wind energy turbine set high side bus voltage for controlling target, take into account blower fan set end voltage in qualified scope simultaneously, maximize the idle fan-out capability of blower fan, reduce SVC switching frequency, and maximize wind power loss.

As shown in fig. 1, wind energy turbine set AVC substation is joined directly together with scheduling station, wind energy turbine set AGC, fan monitoring system and reactive power compensator SVC respectively, wind energy turbine set AVC substation is with each several part exchange information as shown in the figure, wherein wind energy turbine set AVC substation obtains each blower fan real time status information from fan monitoring system, and carried out idle given calculating by wind energy turbine set AVC control unit, result and each power of fan factor are issued to blower fan by fan monitoring system again, it is achieved control on the spot;Additionally wind energy turbine set AVC substation can directly by Q_svcTo wind energy turbine set SVC, wind energy turbine set SVC regulate and control.

In wind energy turbine set, the set end voltage of the blower fan of all operations is all in acceptability limit, after wind energy turbine set AVC substation receives scheduling controlling instruction, analyzed by its COMPREHENSIVE CALCULATING, produce drift gauge and calculate, according to controlling target, reach that high-voltage side bus controls required for desired value total without work value, then the variable capacity according to current SVC/SVG, the variable capacity of whole classifications and the variable capacity of capacitor/reactor, coordinate control blower fan and concentrate reactive power compensator, follow the wind field high side bus voltage control instruction that scheduling station issues, control time constant be about second-minute level.

As it is shown in figure 1, a kind of wind energy turbine set AVC powerless control system reducing wind power loss, including: AVC substation, wind driven generator controller, reactive power compensator SVC, main transformer tap; Wind energy turbine set AVC substation is connected with blower fan server, wind energy turbine set AGC, wind energy turbine set SVC and scheduling station respectively, the information of the existing energy management platform exchange of wind energy turbine set AVC substation and wind energy turbine set includes wind energy turbine set information, the status information of SVC equipment and control instruction, includes each blower fan real time status information and control instruction with the information of blower fan server exchange; Wind energy turbine set AVC substation is idle or voltage-target is directly handed down to wind energy turbine set SVC, wind energy turbine set SVC regulate and control. Wind energy turbine set SVC (StaticVarCompensator) SVC, what can quickly change that it sends is idle, has stronger Reactive-power control ability, can provide dynamic reactive power supply for power system.

Also include processor, memory module, input/output module, MODBUS (TCP/IP) communication interface, detection module, server; Processor performs control algolithm, and memory module and input/output module are called; Input/output module is by MODBUS (TCP/IP) communication interface and detection module communication, and is communicated by the SCADA of server Yu wind turbine.

As in figure 2 it is shown, the control method of the wind energy turbine set AVC powerless control system of a kind of wind power loss decreased as described above, step is as follows:

The first step, AVC controls system and judges that whether voltage deviation value is out-of-limit, by also site real-time voltage U_meanThe grid-connected point target voltage U assigned with control centre_targetCompare, obtain voltage deviation value:

Δ U=| U_mean-U_target|(1)

In order to prevent the frequent adjustment of equipment, arranging voltage dead band scope, arrange and range for Δ U≤0.01, wherein Δ U isAmplitude; If voltage deviation value Δ U is more than the threshold value of error dead band module, then carries out the idle of next step and adjust;

3rd step, first surveys the meritorious output valve P of current each blower fan_gen, by the meritorious real-time maximum fan-out capability Q of the every Fans of restriction relation with idle output of blower fan_reg(i)=λ P_gen(i), then the idle reference value of the Wind turbines of AVC default is total up to Q_Wref, namely blower fan always idle exert oneself givenWherein the maximum idle constraints of blower fan is:

$P_W\frac{\sqrt{1-{\mathrm{\λ}}_L^2}}{{\mathrm{\λ}}_L}\≤Q_{reg}\≤P_W\frac{\sqrt{1-{\mathrm{\λ}}_H^2}}{{\mathrm{\λ}}_H}---\left(2\right)$

In formula, λ is the power factor of blower fan, and the power factor under blower fan normal operation ranges for λ_L≤λ≤λ_H, by formula (2) it can be seen that when blower fan is completely sent out, Reactive-power control ability will be lost.

The limit computing formula of separate unit blower fan output reactive power is:

$\left\{\begin{array}{c}{Q}_{reg\max }=\sqrt{\frac{|U_1{|}^2{X}_m^2}{X_1^2}{I}_{r\max }^2-P_k^2}-\frac{{U_1}^2}{X_1}\\ Q_{reg\min }=-\frac{{U_1}^2}{X_1}-\sqrt{\frac{|U_1{|}^2{X}_m^2}{X_1^2}{I}_{r\max }^2-P_k^2}\end{array}\right.---\left(3\right);$

U in formula₁For fan stator terminal voltage, P_kFor fan outlet active power, X₁For stator leakage reactance and excitation reactance sum, I_rmaxFor current transformer current limit value, it is generally 1.5 times of current transformer rated current

Second step, by voltage and idle relation, calculates reactive power compensation amount:

Δ U=Δ Q/S_sc(4)

S_sc=(U_now-U_last)/(ΣQ_now/U_now-ΣQ_last/U_last)(5)

In formula (4), (5), Δ Q is reactive power variable quantity, S_scFor the capacity of short circuit of system busbar side, Σ Q_now、ΣQ_lastAlways idle and current always idle for last time, U_last、U_nowLast time busbar voltage, current busbar voltage.If total reactive power demand Δ Q idle fan-out capability Q overall more than blower fan_Wref, then the 4th step is entered; If Δ Q≤Q_Wref, then required idle all sent out by blower fan, now, separate unit blower fan is idle, and set-point is Q_reg(i)=Δ Q × Q_reg(i)/Q_Wref;

If | Q_SVCmax+Q_Wref|≤| Δ Q |, then AVC system will provide the alarm prompt regulating main transformer tap.

4th step, the main air box change of power attenuation, current collection circuit, main transformer and concentration reactive power compensator is caused inside wind energy turbine set, and under certain wind speed, blower fan active power is fixed, in order to make Power Output for Wind Power Field maximize, total active power loss in wind energy turbine set field need to be made minimum, total-power loss:

${\mathrm{\ΔP}}_{\mathrm{\Σ}}(S,V)=P_0\left(V\right)+P_S(S,V)+P_{LL}(S,V)+P_{svc}={\left(\frac{V}{V_N}\right)}^2\·P_{N0}+{\left(\frac{S}{S_N}\right)}^2\·\left(\frac{V_N}{V}\right)\·P_{NS}+{\left(\frac{S}{S_N}\right)}^2\·\left(\frac{V_N}{V}\right)\·P_{NL}+P_{svc}---\left(6\right)$

Δ P in formula_ΣFor the power attenuation that wind energy turbine set is total, P₀For transformer noload losses, P_SFor transformer short-circuit loss, P_LLFor line loss, V is transformator working voltage value, V_NFor transformator load voltage value, S is that transformator runs apparent energy value, S_NFor the specified apparent energy value of transformator, P_N0For transformator rated no-load loss, P_NSFor transformator nominal short-circuit loss, P_NLFor circuit rated power loss, P_svcPower attenuation for reactive power compensator.

Set wind energy turbine set total-power loss Δ P_ΣFor object function, due to all plant capacity losses being connected on a current collection circuit:

$P=I^{2}R={(S_N/\sqrt{3}{U}_N)}^{2}R={(P_{gen}\×n/\cos \mathrm{\φ}/k/\sqrt{3}{U}_N)}^{2}R---\left(7\right)$

Wherein cos φ=λ, n is the total number of units of blower fan, and k is the percentage ratio that virtual voltage accounts for rated voltage.

The power attenuation P of reactive power compensator_svcIncluding the loss of reactor in the fixed loss of fixed capacity device group and TCR branch road, in practice, the loss of reactor changes with voltage, but change is little, TCR type SVC for 10Mvar-50Mvar, its loss is about the 0.5%-0.7% of capacity, it is possible to be set as known quantity according to wind energy turbine set practical situation.

So by formula (5)-(7) it can be seen that wind energy turbine set total-power loss Δ P_ΣOnly with the reactive power Q of each wind-driven generator_WRelevant, formula (6) is converted to blower fan idle have distribution most object function be:

T=Δ P_Σ(S, V)=Δ P_Σ(Q_gen)(8)

5th step, process that object function T is minimized, obtain wind-force when object function exists minima and send out the reactive power value of machineThe overall fan-out capability of Wind turbines isAnd this process need to consider the constraints of reactive power equilibrium in wind energy turbine set:

$\left\{\begin{array}{c}{P}_W\frac{\sqrt{1-{\mathrm{\λ}}_L^2}}{{\mathrm{\λ}}_L}\≤Q_{reg}\≤P_W\frac{\sqrt{1-{\mathrm{\λ}}_H^2}}{{\mathrm{\λ}}_H}\\ Q_{reg\min }\≤Q_{reg}\≤Q_{reg\max }\end{array}\right.---\left(9\right)$

$\mathrm{\Δ}Q=Q_{Wref}^{*}+Q_{SVC}-{\mathrm{\ΔQ}}_{\mathrm{\Σ}}---\left(10\right)$

Wherein:For the overall fan-out capability of wind energy turbine set Wind turbines;

Δ Q is reactive power variable quantity, i.e. the dispatch value of the total reactive power of wind energy turbine set;

ΔQ_ΣFor the total reactive loss of wind energy turbine set, it is possible to represent with blower fan is idle;

6th step, by Q_WrefWithCompare, ifThen blower fan is idle is given as Q_reg, concentrate that reactive power compensator is idle is given as Q_svc=Δ Q-Q_Wref-Q_T-Q_LL; IfThen blower fan is idle is given asNow concentrate that reactive power compensator is idle is given asWherein Q_TAnd Q_LLRespectively transformator and circuit reactive loss.

Embodiment 1:

As in figure 2 it is shown, the idle given calculation process in wind energy turbine set AVC substation divides following steps:

The first step, by measuring the voltage U of also site in real time_meanThe grid-connected point target voltage U assigned with control centre_targetCompare, by U_meanWith U_targetCompare, it is judged that whether voltage deviation value is out-of-limit,

Δ U=| U_mean-U_target| (1);

In order to prevent the frequent adjustment of equipment, arranging voltage dead band scope, arrange and range for Δ U≤0.01, wherein Δ U isAmplitude; If voltage deviation value Δ U is less than the threshold value of dead band module, then stops this secondary program and perform, a moment set-point in maintenance that wind energy turbine set is idle; If voltage deviation value Δ U is more than the threshold value of error dead band module, then carries out the idle of next step and adjust.

Second step, calculates blower fan reactive power fan-out capability:

$\{\begin{array}{c}{Q}_{reg}={\mathrm{\λP}}_{gen}\\ Q_{Wref}={\Σ}_{k=1}^n{Q}_{reg}\end{array}---\left(2\right);$

Wherein Q_regConstraints be:

$\left\{\begin{array}{c}{P}_W\frac{\sqrt{1-{\mathrm{\λ}}_L^2}}{{\mathrm{\λ}}_L}\≤Q_{reg}\≤P_W\frac{\sqrt{1-{\mathrm{\λ}}_H^2}}{{\mathrm{\λ}}_H}\\ Q_{reg\min }\≤Q_{reg}\≤Q_{reg\max }\end{array}\right.---\left(3\right);$

3rd step, calculates reactive power compensation amount:

Δ U=Δ Q/S_sc(4);

S_sc=(U_now-U_last)/(ΣQ_now/U_now-ΣQ_last/U_last) (5);

In formula, Δ Q is, S_scFor the capacity of short circuit of system busbar side, Σ Q_now、ΣQ_lastAlways idle and current always idle for last time, U_last、U_nowLast time busbar voltage, current busbar voltage. If total reactive power demand Δ Q idle fan-out capability Q overall more than blower fan_Wref, then the 4th step is entered; If Δ Q≤Q_Wref, then required idle all sent out by blower fan; If | Q_SVCmax+Q_Wref|≤| Δ Q |, then AVC system will provide the alarm prompt regulating main transformer tap.

4th step, sets up the object function between wind power generating set reactive power and wind energy turbine set loss:

T=Δ P_Σ(S, V)=P₀(V)+P_S(S,V)+P_LL(S,V)+P_svc=Δ P_Σ(Q_gen) (6);

Constraints:

$\left\{\begin{array}{c}{Q}_{reg\min }\≤Q_{reg}\≤Q_{reg\max }\\ P_W\frac{\sqrt{1-{\mathrm{\λ}}_L^2}}{{\mathrm{\λ}}_L}\≤Q_{reg}\≤P_W\frac{\sqrt{1-{\mathrm{\λ}}_H^2}}{{\mathrm{\λ}}_H}\\ \mathrm{\Δ}Q=Q_{Qref}^{*}+Q_{SVC}-{\mathrm{\ΔQ}}_{\Σ}\end{array}\right.---\left(7\right);$

Object function is sought local derviation, carries out minimizing process, it is thus achieved that time the minimum blower fan of wind energy turbine set loss is always idle exerts oneself

5th step, by Q_WrefWithCompare, ifThen blower fan is idle is given as Q_reg, concentrate that reactive power compensator is idle is given as Q_svc=Δ Q-Q_Wref-Q_T-Q_LL; IfThen blower fan is idle is given asNow concentrate that reactive power compensator is idle is given asWherein Q_TAnd Q_LLRespectively transformator and circuit reactive loss.

6th step, the reactive power setting valve of wind turbine and concentration reactive power compensator as control instruction, is sent to each Wind turbines and SVC, completes the idle control of wind energy turbine set by AVC substation.

This controls module can realize data process, and idle link of adjusting includes utilizing voltage deviation value to calculate no-power vacancy when PI regulates, calculates the maximum output constraint of reactive power, after comparing the maximum idle output constraint of wind energy turbine set and retraining with wind power factor, the idle reference value Δ Q of gained is obtained the idle setting valve Q of wind energy turbine set_reg; Idle distribution link includes calculating field inner blower loss and namely the idle size of exerting oneself of minimum every Fans utilizes idle setting valve to be allocated according to the allocation strategy that the utility model proposes.

Claims (1)

1., based on the control method of the wind energy turbine set AVC powerless control system reducing wind power loss, described AVC powerless control system includes: wind energy turbine set AVC substation, wind driven generator controller, wind-driven generator, reactive power compensator SVC, main transformer tap; Wind energy turbine set AVC substation is connected with wind-driven generator server, wind energy turbine set AGC, reactive power compensator SVC, scheduling station respectively;

Described AVC powerless control system also includes processor, memory module, input/output module, MODBUS communication interface or tcp/ip communication interface, detection module, server; Processor performs control algolithm, and memory module and input/output module are called; Input/output module is by MODBUS communication interface or tcp/ip communication interface and detection module communication, and is communicated by the SCADA of server Yu wind turbine;

The information of the existing energy management platform exchange of described wind energy turbine set AVC substation and wind energy turbine set includes wind energy turbine set information, the status information of reactive power compensator SVC and control instruction, includes each blower fan real time status information and control instruction with the information of wind-driven generator server exchange; Wind energy turbine set AVC substation is idle or voltage-target is directly handed down to reactive power compensator SVC, reactive power compensator SVC regulate and control;

AVC substation system possesses communication, collection, control, calculating, storage, supervision, parameter setting function; Wind-driven generator possesses idle fan-out capability, and the SCADA of wind turbine can be controlled by AVC powerless control system;Reactive power compensator SVC realizes idle smooth adjustment by controller issues idle or voltage instruction; High voltage bus voltage can be adjusted by main transformer tap; It is characterized in that: the method step is as follows:

The first step, AVC powerless control system judges that whether voltage deviation value is out-of-limit, by also site real-time voltage U_meanThe grid-connected point target voltage U assigned with control centre_targetCompare, obtain voltage deviation value:

Δ U=| U_mean-U_target| (1);

In order to prevent the frequent adjustment of reactive power compensator SVC, arranging voltage dead band scope, arrange and range for Δ U≤0.01, wherein Δ U isAmplitude; If voltage deviation value Δ U is more than the threshold value of voltage dead band, then carries out the idle of next step and adjust;

Second step, first surveys the meritorious output valve P of current wind turbine_gen, the meritorious restriction relation with idle output of blower fan obtain the real-time maximum fan-out capability Q of every Fans_reg(i)=λ P_gen(i), Wind turbines that then AVC powerless control system sets is idle with reference to total value as Q_Wref, namely Wind turbines is idle with reference to total value isWherein the maximum idle constraints of blower fan is:

$P_W\frac{\sqrt{1-{\mathrm{\λ}}_L^2}}{{\mathrm{\λ}}_L}\≤Q_{reg}\≤P_W\frac{\sqrt{1-{\mathrm{\λ}}_H^2}}{{\mathrm{\λ}}_H}---\left(2\right);$

In formula, λ is the power factor of blower fan, and the power factor under blower fan normal operation ranges for λ_L≤λ≤λ_H, by formula (2) it can be seen that when blower fan is completely sent out, Reactive-power control ability will be lost;

The limit computing formula of separate unit blower fan output reactive power is:

$\left\{\begin{array}{c}{Q}_{reg\max }=\sqrt{\frac{|U_1{|}^2{X}_m^2}{X_1^2}{I}_{r\max }^2-P_k^2}-\frac{{U_1}^2}{X_1}\\ Q_{reg\min }=-\frac{{U_1}^2}{X_1}-\sqrt{\frac{|U_1{|}^2{X}_m^2}{X_1^2}{I}_{r\max }^2-P_k^2}\end{array}\right.---\left(3\right);$

U in formula₁For fan stator terminal voltage, P_kFor fan outlet active power, X₁For stator leakage reactance and excitation reactance sum, I_rmaxFor current transformer current limit value, it is generally 1.5 times of current transformer rated current;

3rd step, by voltage and idle relation, calculates reactive power compensation amount:

Δ U=Δ Q/S_sc(4);

S_sc=(U_now-U_last)/(ΣQ_now/U_now-ΣQ_last/U_last) (5);

In formula (4), (5), Δ Q is reactive power variable quantity, S_scFor the capacity of short circuit of system busbar side, Σ Q_now、ΣQ_lastFor current always idle always idle with last time, U_last、U_nowFor last time busbar voltage, current busbar voltage; If total reactive power demand Δ Q is idle more than Wind turbines with reference to total value Q_Wref, then the 4th step is entered; If Δ Q≤Q_Wref, then required idle all sent out by blower fan, now, separate unit blower fan is idle, and set-point is Q_reg(i)=Δ Q × Q_reg(i)/Q_Wref;

If | Q_SVCmax+Q_Wref|≤| Δ Q |, then AVC powerless control system will provide the alarm prompt regulating main transformer tap;

4th step, power attenuation is caused mainly to include air box change, current collection circuit, main transformer and concentration reactive power compensator inside wind energy turbine set, and under certain wind speed, blower fan active power is fixed, in order to make Power Output for Wind Power Field maximize, total active power loss in wind energy turbine set field need to be made minimum, total-power loss:

${\mathrm{\ΔP}}_{\mathrm{\Σ}}(S,V)=P_0\left(V\right)+P_S(S,V)+P_{LL}(S,V)+P_{svc}={\left(\frac{V}{V_N}\right)}^2\·P_{N0}+{\left(\frac{S}{S_N}\right)}^2\·\left(\frac{V_N}{V}\right)\·P_{NS}+{\left(\frac{S}{S_N}\right)}^2\·\left(\frac{V_N}{V}\right)\·P_{NL}+P_{svc}---\left(6\right)$

Δ P in formula_ΣFor the power attenuation that wind energy turbine set is total, P₀For transformer noload losses, P_SFor transformer short-circuit loss, P_LLFor line loss, V is transformator working voltage value, V_NFor transformator load voltage value, S is that transformator runs apparent energy value, S_NFor the specified apparent energy value of transformator, P_N0For transformator rated no-load loss, P_NSFor transformator nominal short-circuit loss, P_NLFor circuit rated power loss, P_svcPower attenuation for reactive power compensator SVC;

Set wind energy turbine set total-power loss Δ P_ΣFor object function, due to all plant capacity losses being connected on a current collection circuit:

$P=I^{2}R={(S_N/\sqrt{3}{U}_N)}^{2}R={(P_{gen}\×n/cos\mathrm{\φ}/k/\sqrt{3}{U}_N)}^{2}R---\left(7\right);$

Wherein cos φ=λ, n is the total number of units of blower fan, and k is the percentage ratio that virtual voltage accounts for rated voltage; The power attenuation P of reactive power compensator SVC_svcIncluding the loss of reactor in the fixed loss of fixed capacity device group and TCR branch road, in practice, the loss of reactor changes with voltage, but change is little, TCR type SVC for 10Mvar-50Mvar, its loss is about the 0.5%-0.7% of capacity, is set as known quantity according to wind energy turbine set practical situation;

So by formula (5)-(7) it can be seen that wind energy turbine set total-power loss Δ P_ΣOnly with the reactive power Q of each wind-driven generator_WRelevant, by the object function that formula (6) is converted to the idle optimum allocation of blower fan be:

T=Δ P_Σ(S, V)=Δ P_Σ(Q_gen) (8);

5th step, process that object function T is minimized, obtain object function and there is the reactive power value of wind-driven generator during minimaThe overall fan-out capability of Wind turbines isAnd this process need to consider the constraints of reactive power equilibrium in wind energy turbine set:

$\left\{\begin{array}{c}{P}_W\frac{\sqrt{1-{\mathrm{\λ}}_L^2}}{{\mathrm{\λ}}_L}\≤Q_{reg}\≤P_W\frac{\sqrt{1-{\mathrm{\λ}}_H^2}}{{\mathrm{\λ}}_H}\\ Q_{reg\min }\≤Q_{reg}\≤Q_{reg\max }\end{array}\right.---\left(9\right);$

$\mathrm{\Δ}Q=Q_{Wref}^{*}+Q_{SVC}-{\mathrm{\ΔQ}}_{\mathrm{\Σ}}---\left(10\right);$

Wherein:For the overall fan-out capability of wind energy turbine set Wind turbines;

Δ Q is reactive power variable quantity, i.e. the dispatch value of the total reactive power of wind energy turbine set;

ΔQ_ΣFor the total reactive loss of wind energy turbine set, represent with blower fan is idle;

6th step, by Q_WrefWithCompare, ifThen blower fan is idle is given as Q_reg, concentrate that reactive power compensator is idle is given as Q_SVC=Δ Q-Q_Wref-Q_T-Q_LL; IfThen blower fan is idle is given asNow concentrate that reactive power compensator is idle is given asWherein Q_TAnd Q_LLRespectively transformator and circuit reactive loss;

The reactive power setting valve of wind turbine and concentration reactive power compensator as control instruction, is sent to each Wind turbines and SVC, completes the idle control of wind energy turbine set by wind energy turbine set AVC substation.