CN103034761A - Electromechanical transient simulation method for doubly-fed variable speed constant frequency wind generation set system - Google Patents

Abstract

The invention discloses an electromechanical transient simulation method for a doubly-fed variable speed constant frequency wind generation set system, and relates to a wind power generation system, in particular to a method for performing modeling analysis on a doubly-fed wind generation set system by using a computer program. The method comprises the following steps of: establishing a wind power model to simulate wind power absorbed by a wind-driven generator; establishing a wind-driven generator shaft model; establishing a blade pitch control system model; establishing an electrical simulation model for a doubly-fed asynchronous induction motor; establishing a power grid side frequency converter and rotor side frequency converter controller model; establishing a doubly-fed wind-driven generator one machine infinite bus system model by using the wind generation set simulation models; and setting the simulation running working condition and the failure state of the wind generation set system, and performing electromechanical transient simulation and failure simulation. Detailed models in line with physical characteristics of a doubly-fed variable speed constant frequency wind generation set are established for electromagnetic transient simulation and the electromechanical transient simulation, and dynamic characteristics of the wind-driven generator under various failure and working conditions can be inspected to make the simulation of the wind-driven generator in a large-scale power grid possible.

Description

Doubly-fed variable-speed constant-frequency wind turbine group system electromechanical transient simulation method

Technical field

The present invention relates to wind generator system, relate in particular to a kind of method of using computer program to carry out the modeling analysis of double-fed fan motor machine set system.

Background technology

Since the 1980s, the application of wind-power electricity generation more and more is subject to global generally attention.Along with the develop rapidly of science and technology, particularly aerodynamics, most advanced and sophisticated spationautics and high-power electric and electronic technology are applied to developing of novel wind power unit, wind-power electricity generation obtains significant progress at recent two decades.Wind-power electricity generation of today just progressively moves towards scale and industrialization, and the ratio of wind-power electricity generation in electrical network is increasing, becomes ripe, the most real a kind of clean energy resource generation mode except the waterpower generating.Greatly develop wind-power electricity generation, environmental protection, energy savings and the ecologic equilibrium are had important meaning.

Yet wind-power electricity generation is a kind of special electric power, have many characteristics that are different from the conventional energy resources generating, being incorporated into the power networks to the safety and stability of electrical network of wind park, all many-sides such as the quality of power supply all can be brought negative effect, expanding day along with the wind energy turbine set scale, the wind-powered electricity generation characteristic is also remarkable all the more on the impact of electrical network, becomes the serious hindrance of restriction wind field scale and capacity, and large-scale wind power is linked into the end and can produces what kind of impact to electrical network and become urgent problem.

Chinese utility model patent " simulator of double-fed fan motor unit " (utility model patent number: ZL201220127917.4 Granted publication number: CN202548295U) disclose a kind of simulator of double-fed fan motor unit, having comprised: double fed induction generators, wind-powered electricity generation unit prime mover, monitoring and protecting equipment and rotor-side convertor equipment.Wind-powered electricity generation unit prime mover is connected to double fed induction generators, and wind-powered electricity generation unit prime mover drives double fed induction generators under wind drive rotor rotates.The monitoring and protecting equipment connection is measured the voltage and current of double fed induction generators output to double fed induction generators.The rotor-side convertor equipment is connected to double fed induction generators, voltage magnitude and the phase place of rotor-side convertor equipment control double fed induction generators, the decoupling zero of gaining merit control and idle decoupling zero control.The simulator of the double-fed fan motor unit of this utility model can accurately reflect the physical characteristics of blower fan and the working condition of double fed induction generators, can satisfy the wind-electricity integration standard to the complete test request of the blower fan that is incorporated into the power networks.

Chinese invention patent application " a kind of emulation modelling method of double-fed blower fan equivalent simulation " (number of patent application: 201210008656.9 publication numbers: CN102592026A) disclose a kind of emulation modelling method of double-fed blower fan equivalent simulation, the frequency converter of described double-fed blower fan partly adopts controlled source simulation, described modeling method to comprise the steps: that (1) set up double-fed fan motor unit circuit model; (2) set up double-fed blower fan equivalent model; (3) set up the double-fed blower fan test macro that is incorporated into the power networks; (4) build the multi fan test macro; Wherein, in step 2: described double-fed blower fan equivalent model is set up based on the characteristic of double-fed fan frequency converter AC controlled voltage source and DC side controlled current source.The emulation modelling method of the double-fed blower fan equivalent simulation that this invention provides can accurately be simulated the transient characterisitics of double-fed blower fan, and can take into account the different qualities between many typhoons group of motors and influence each other; Need not to take into account the high frequency break-make of full-control type device, simulation efficiency significantly promotes; Emulation blower fan number of units is more, and the improved efficiency amplitude is more remarkable; When keeping precision, can adopt larger simulation step length, significantly promote simulation efficiency.

The present power system simulation software at home of wind turbine model that is used for stability study is not still realized, existing built-in blower fan model among PSS/E, the BPA, but it is not suitable for the Simulation of Dynamic Performance of blower fan under the short circuit malfunction.DIgSILENT/PowerFactory is a powerful power system simulation software, the double-fed asynchronous blower fan model of the built-in can reflect its real physical characteristics more exactly, can carry out at length electromechanical transient simulation to doubly fed machine, also can carry out electromechanical transient simulation, make the emulation of blower fan in large scale electric network become possibility.In addition, PSCAD/EMTDC can set up the electromechanical transient model of blower fan equally, and modeling accuracy can reach device level, is the ideal tools of investigating blower fan one-of-a-kind system dynamic perfromance under various operating modes and fault therefore, but is not suitable for the emulation behind the large net of blower fan access.

Summary of the invention

The purpose of this invention is to provide a kind of doubly-fed variable-speed constant-frequency wind turbine group system electromechanical transient simulation method, foundation meets the detailed model of doubly-fed variable-speed constant-frequency wind-powered electricity generation unit physical characteristics, in order to utilize this detailed model to carry out electro-magnetic transient and electromechanical transient simulation, investigate the dynamic perfromance of blower fan under various faults and operating mode.

The present invention solves the problems of the technologies described above the technical scheme that adopts:

A kind of doubly-fed variable-speed constant-frequency wind turbine group system electromechanical transient simulation method; described wind-powered electricity generation unit comprises that by wind energy conversion system model, axle be prime mover model that model and pitch control system consist of; the double-fed fan motor unit model that is consisted of by inductor generator model and rotor-side Frequency Converter Control protection system; and the grid side frequency converter control system, described electromechanical transient simulation method may further comprise the steps:

S100) set up the wind energy conversion system model, according to the relation of wind speed, wind energy conversion efficiency and tip speed ratio and blade slurry elongation, the wind power that the simulation wind energy conversion system absorbs;

S200) the two mass shafting structures that use generator matter piece and wind energy conversion system matter piece to form, setting up fan shaft is model, the energy transitive relation of simulation wind energy conversion system machine torque and generator electromagnetic torque;

S300) set up the pitch control system model, use propeller pitch angle control emulation to carry out the optimizing of the wind-powered electricity generation power of the assembling unit, seek under given wind speed, to make the maximal value of wind-powered electricity generation unit output power; The overload protection function of pitch control system when the simulation wind speed exceeds wind rating;

S400) the T-shaped equivalent electrical circuit that makes up double-fed asynchronous induction motor according to equation and the magnetic linkage equation of doubly fed induction generator is set up DFIG electrical simulation model;

S500) according to relation and the rotor voltage equation of transient electromagnetic power equation, rotor current and the stator current of DFIG electrical simulation model double fed induction generators stator, set up grid side frequency converter and rotor-side frequency converter controller model;

S600) the wind-powered electricity generation unit realistic model that uses above step to set up is set up double-fed blower fan one machine infinity bus system model;

S700) the initial launch operating mode of wind-powered electricity generation unit realistic model is set, other simulation step length of Millisecond is set, enter the electromechanical transient simulation running status of wind turbine group system;

S720) described wind energy conversion system model is applied respectively the negative step of wind speed and the positive step signal of wind speed, carry out the electromechanical transient simulation of wind speed step, analyze the wind-powered electricity generation unit meritoriously exert oneself, the response of rotating speed, wind power, wind energy utilization efficiency and propeller pitch angle, the dynamic response characteristic that the double-fed blower fan detailed model of setting up changes in the face of wind speed, the validity that the checking maximal wind-energy is followed the trail of;

S740) described double-fed blower fan one machine infinity bus system model is applied the reactive power step signal, carry out the electromechanical transient simulation of idle step, analyze the wind-powered electricity generation unit set end voltage, meritoriously exert oneself, idle exerting oneself and the variation of rotating speed, the dynamic response characteristic that the double-fed blower fan detailed model of setting up changes in the face of external electrical network load or burden without work, the dynamic perfromance of idle controlling unit in the checking double-fed blower fan vector controlled;

S760) described double-fed blower fan one machine infinity bus system model is simulated respectively external electrical network three-phase symmetrical fault and asymmetric fault; to there being, carrying out without the double-fed asynchronous blower fan of low voltage ride-through function the electromechanical transient simulation of malfunction; analyze the set end voltage of wind-powered electricity generation unit, meritorious, idle, stator current, rotor current waveform; relatively have, without the dynamic response of double-fed asynchronous blower fan under electric network fault of low voltage ride-through function, the dynamic perfromance of checking double-fed fan trouble protection.

A kind of better technical scheme of doubly-fed variable-speed constant-frequency wind turbine group system electromechanical transient simulation method of the present invention, but it is characterized in that described DFIG module use switching Crowbar device realization low voltage ride-through function, when making the rotor-side frequency converter, extraneous fault detects the rotor excess current, perhaps during the frequency changer direct current bus superpotential, switch element IGBT conducting in the Crowbar device, the Crowbar bypass rotor overcurrent of devoting oneself to work, while rotor-side trigger of frequency converter signal block, doubly fed machine rotor winding is directly through resistance in series Rc short circuit.

The invention has the beneficial effects as follows:

1. doubly-fed variable-speed constant-frequency wind turbine group system electromechanical transient simulation method of the present invention, can set up the detailed model that meets doubly-fed variable-speed constant-frequency wind-powered electricity generation unit physical characteristics, utilize this detailed model to carry out electro-magnetic transient and electromechanical transient simulation, can investigate the dynamic perfromance of blower fan under various faults and operating mode.

2. doubly-fed variable-speed constant-frequency wind turbine group system electromechanical transient simulation method of the present invention, not only can simulate the electrical specification of doubly-fed variable-speed constant-frequency wind-powered electricity generation unit, can also simulate the mechanical movement situation of wind motor, carry out the wind-force variation simulation study is carried out in the impact of wind energy turbine set, can carry out at length electromechanical transient simulation to doubly fed machine, also can carry out electromechanical transient simulation, make the emulation of blower fan in large scale electric network become possibility.

Description of drawings

Fig. 1 is the main flow chart of doubly-fed variable-speed constant-frequency wind turbine group system electromechanical transient simulation method of the present invention;

Fig. 2 is doubly-fed variable-speed constant-frequency wind turbine model structural representation;

Fig. 3 is that wind-powered electricity generation unit two mass axles are the model schematic diagram;

Fig. 4 is the transport function block diagram of wind-powered electricity generation shaft system of unit model;

Fig. 5 is the pitch control system block diagram;

Fig. 6 is the T-shaped equivalent electrical circuit of DFIG under the synchronous rotating frame;

Fig. 7 is DFIG flux linkage orientation Vector Control Model figure;

Fig. 8 is grid side frequency converter control system illustraton of model;

Fig. 9 is doubly fed machine rotor-side Frequency Converter Control protection system illustraton of model;

But Figure 10 is the illustraton of model with the double-fed asynchronous wind-powered electricity generation unit of switching Crowbar;

Figure 11 is the blower fan one machine infinity bus system illustraton of model that uses wind-powered electricity generation unit Building of Simulation Model.

Embodiment

In order to understand better technique scheme of the present invention, describe in detail further below in conjunction with drawings and Examples.

Fig. 2 is doubly-fed variable-speed constant-frequency wind turbine model structural representation; the wind-powered electricity generation unit comprises that by wind energy conversion system model 110, axle be prime mover module 100 that model 120 and pitch control system 130 consist of; the double-fed fan motor machine pack module that is consisted of by inductor generator model 210 and rotor-side Frequency Converter Control protection system 220, and grid side frequency converter control system (not shown).

Doubly-fed variable-speed constant-frequency wind-powered electricity generation unit can be realized following functions by its control system: the active power that the reactive power exchange power between control generator and the electrical network, control wind-powered electricity generation unit send is with the optimized operation point of following the trail of the wind-powered electricity generation unit or limit the wind turbine group and exert oneself under higher wind velocity condition.Above-mentioned functions mainly realizes by the rotor-side Frequency Converter Control of variable-speed wind-power unit and the propeller pitch angle control of wind energy conversion system.

Rotor-side frequency converter 220 is used for control doubly fed machine rotor-side voltage magnitude and phase place, realization is to the meritorious and idle decoupling zero control of wind-powered electricity generation unit, finish the maximum power tracing strategy of wind-powered electricity generation unit, comprise following modules: maximal wind-energy tracing module 221, power measurement module 222, voltage and current measurement module 223, power controller 224, current controller 225 and coordinate transformation module 226.The protection model 227 of double-fed fan motor unit is also contained in the model of double-fed fan motor unit.

The main flow chart of doubly-fed variable-speed constant-frequency wind turbine group system electromechanical transient simulation method of the present invention may further comprise the steps as shown in Figure 1:

S100) set up the wind energy conversion system model, according to the relation of wind speed, wind energy conversion efficiency and tip speed ratio and blade slurry elongation, the wind power that the simulation wind energy conversion system absorbs;

S200) the two mass shafting structures that use generator matter piece and wind energy conversion system matter piece to form, setting up fan shaft is model, the energy transitive relation of simulation wind energy conversion system machine torque and generator electromagnetic torque;

S300) set up the pitch control system model, use propeller pitch angle control emulation to carry out the optimizing of the wind-powered electricity generation power of the assembling unit, seek under given wind speed, to make the maximal value of wind-powered electricity generation unit output power; The overload protection function of pitch control system when the simulation wind speed exceeds wind rating;

S400) the T-shaped equivalent electrical circuit that makes up double-fed asynchronous induction motor (DFIG) according to equation and the magnetic linkage equation of doubly fed induction generator is set up DFIG electrical simulation model;

S500) according to relation and the rotor voltage equation of transient electromagnetic power equation, rotor current and the stator current of DFIG electrical simulation model double fed induction generators stator, set up grid side frequency converter and rotor-side frequency converter controller model;

S600) the wind-powered electricity generation unit realistic model that uses above step to set up is set up double-fed blower fan one machine infinity bus system model;

An embodiment of the double-fed blower fan one machine infinity bus system model of use wind-powered electricity generation unit Building of Simulation Model as shown in figure 11, the wind-powered electricity generation unit is connected to step-up transformer by the WT low-voltage bus bar, be connected to external electrical network by outlet bus PCC after boosting, the parameter of wind-powered electricity generation unit and step-up transformer, external electrical network is set, consist of double-fed blower fan one machine infinity bus system, just can carry out electromagnetic transient simulation, electromechanical transient simulation and the fault simulation of wind turbine group system.

The blower fan detailed model is carried out the dynamic property of electromagnetic transient simulation blower fan can accurately reflect electric network fault the time, but, if then speed is slower to utilize electromagnetical transient emulation method in the large network simulation, therefore need to adopt the electromechanical transient simulation method, compare with the electromagnetic transient simulation result simultaneously, verify its correctness.

Electromechanical transient process refers to that the variation of generators in power systems and electric electromechanics magnetic torque causes the change procedure of rotor mechanical motion, and the duration is usually at several seconds to tens seconds.Electromechanical transient process emulation is that calculation step is usually got about 10ms to the comprehensive analysis of mechanical transient state process and electromagnetic transient in the electric system.The emulation of electric system electromechanical transient process is mainly used in analyzing the stability of electric system, namely be used for analyzing when electric system is being subject to certain and disturbs under a certain normal operating condition after, can pass through the problem of getting back to original running status after the regular hour or being transitioned into a new steady operational status.Mainly comprise: the steady stability performance after system is subject to the transient stability after the large disturbance and is subject to microvariations.

S700) the initial launch operating mode of wind-powered electricity generation unit realistic model is set, other simulation step length of Millisecond is set, enter the electromechanical transient simulation running status of wind turbine group system;

S720) described wind energy conversion system model is applied respectively the negative step of wind speed and the positive step signal of wind speed, carry out the electromechanical transient simulation of wind speed step, analyze the wind-powered electricity generation unit meritoriously exert oneself, the response of rotating speed, wind power, wind energy utilization efficiency and propeller pitch angle, the dynamic response characteristic that the double-fed blower fan detailed model of setting up changes in the face of wind speed, the validity that the checking maximal wind-energy is followed the trail of;

The negative step emulation operating mode of wind speed is as follows: blower fan is the meritorious 4.5MW that exerts oneself initially, the idle 0.0Mvar that exerts oneself, and slippage+8%, wind speed reduces suddenly 2m/s behind the 1.0s, investigates that blower fan is meritoriously exerted oneself, rotating speed and wind energy utilization efficiency.The positive step of wind speed is under same initial operating mode, and the step of wind speed work+2m/s changes.According to wind speed jump emulation interpretation of result as can be known, electromechanical transient simulation result and electromagnetic transient simulation result are basically identical.

S740) described double-fed blower fan one machine infinity bus system model is applied the reactive power step signal, carry out the electromechanical transient simulation of idle step, analyze the wind-powered electricity generation unit set end voltage, meritoriously exert oneself, idle exerting oneself and the variation of rotating speed, the dynamic response characteristic that the double-fed blower fan detailed model of setting up changes in the face of external electrical network load or burden without work, the dynamic perfromance of idle controlling unit in the checking double-fed blower fan vector controlled;

Idle step response is mainly verified the dynamic perfromance of idle controlling unit in the double-fed blower fan vector controlled.The emulation operating mode is as follows: blower fan is the meritorious 4.5MW that exerts oneself initially, the idle 0Mvar that exerts oneself, and slippage+8%, reactive power reference qref is made the step of 0.9MVar behind the 1.0s, investigates the variation of blower fan set end voltage, meritorious, idle and rotating speed.According to the interpretation of result of the idle emulation that jumps as can be known, electromechanical transient simulation result and electromagnetic transient simulation result are basically identical.。

S760) described double-fed blower fan one machine infinity bus system model is simulated respectively external electrical network three-phase symmetrical fault and asymmetric fault; to there being, carrying out without the double-fed asynchronous blower fan of low voltage ride-through function the electromechanical transient simulation of malfunction; analyze the set end voltage of wind-powered electricity generation unit, meritorious, idle, stator current, rotor current waveform; relatively have, without the dynamic response of double-fed asynchronous blower fan under electric network fault of low voltage ride-through function, the dynamic perfromance of checking double-fed fan trouble protection.

1) symmetric fault emulation:

When the three-phase symmetrical fault appears in external electrical network, because the blower fan set end voltage descends suddenly, add the effect of rotor-side frequency converter vector controlled, rotor current suddenly increase causes the frequency converter overcurrent.Simultaneously behind the short trouble because meritorious can't sending, and grid side frequency converter active current can not suddenlyd change and caused the grid side frequency converter to charge to dc capacitor, therefore also may cause the dc capacitor overvoltage, in this case, frequency converter must be out of service.At this moment, for the blower fan that low voltage ride-through function is arranged, only excise frequency converter, doubly fed machine is hanging net operation still, then directly cuts machine for the blower fan without low voltage ride-through function, therefore, needs in detail relatively both dynamic responses under electric network fault.

Low voltage ride-through function is arranged:

For the double-fed asynchronous blower fan that low voltage ride-through function is arranged, investigate the fault dynamic perfromance under following several operating modes:

(1) blower fan initial launch point: meritorious 4.5MW, idle 0Mvar, slippage+8%, set end voltage gives blessings littlely during fault, and Crowbar is failure to actuate;

(2) blower fan initial launch point: meritorious 4.5MW, idle 0Mvar, slippage+8%, the set end voltage range of decrease is larger during fault, Crowbar action, Crowbar mute time 60ms;

(3) blower fan initial launch point: meritorious 2.8MW, idle 0Mvar, slippage-10%, the set end voltage range of decrease is larger during fault, Crowbar action, Crowbar mute time 60ms;

(4) blower fan initial launch point: meritorious 4.5MW, idle 0Mvar, slippage+8%, the set end voltage range of decrease is larger during fault, Crowbar action, Crowbar mute time 500ms;

The below electromechanical transient simulation result under above several operating mode that makes introductions all round:

(1) blower fan initial launch point: meritorious 4.5MW, idle 0Mvar, slippage+8%, the set end voltage range of decrease is less during fault, and Crowbar is failure to actuate; The blower fan one machine infinity bus system as shown in figure 11, the emulation operating mode is as follows: blower fan is the meritorious 4.5MW that exerts oneself initially, idle 0Mvar, initial slippage+8%, Crowbar mute time 60ms.During 0s, blower fan boosts and becomes outlet bus PCC generation three phase short circuit fault, impedance ground 0.1+j1.0 Ω, fault clearance behind the 0.15s.With electromagnetic transient simulation result under the identical operating mode more as can be known, not greater than the high fdrequency component of 50Hz, its waveform is essentially electromagnetic transient simulation result's mean value curve among the electromechanical transient simulation result.

(2) blower fan initial launch point: meritorious 4.5MW, idle 0Mvar, slippage+8%, the set end voltage range of decrease is larger during fault, Crowbar action, Crowbar mute time 60ms; The emulation operating mode: blower fan is the meritorious 4.5MW that exerts oneself initially, idle 0Mvar, initial slippage+8%, Crowbar mute time 60ms.During 0s, blower fan boosts and becomes outlet bus PCC generation three phase short circuit fault, impedance ground 0.01+j0.1 Ω, fault clearance behind the 0.15s.With electromagnetic transient simulation result under the identical operating mode more as can be known, the electromechanical transient simulation result is electromagnetic transient simulation result's mean value curve.

(3) blower fan initial launch point: meritorious 2.8MW, idle 0Mvar, slippage-10%, the set end voltage range of decrease is larger during fault, Crowbar action, Crowbar mute time 60ms; The emulation operating mode: blower fan is the meritorious 2.8MW that exerts oneself initially, idle 0Mvar, initial slippage-10%, Crowbar mute time 60ms.During 0s, blower fan boosts and becomes outlet bus PCC generation three phase short circuit fault, impedance ground 0.01+j0.1 Ω, fault clearance behind the 0.15s.With electromagnetic transient simulation result under the identical operating mode more as can be known, the electromechanical transient simulation result is electromagnetic transient simulation result's mean value curve.

(4) blower fan initial launch point: meritorious 4.5MW, idle 0Mvar, slippage+8%, the set end voltage range of decrease is larger during fault, Crowbar action, Crowbar mute time 500ms; The emulation operating mode: blower fan is meritorious 4.5MW initially, idle 0Mvar, initial slippage+8%, Crowbar mute time setting valve 500ms.During 0s, blower fan boosts and becomes outlet bus PCC generation three phase short circuit fault, short-circuit impedance 0.01+j0.1 Ω, fault clearance during 0.15s.With electromagnetic transient simulation result under the identical operating mode more as can be known, the electromechanical transient simulation result is electromagnetic transient simulation result's mean value curve.

Without low voltage ride-through function:

(1) the set end voltage range of decrease is larger, the blower fan excision.The emulation operating mode: blower fan is meritorious 4.5MW initially, idle 0Mvar, initial slippage+8%, three phase short circuit fault impedance ground 0.01+j0.1 Ω, 0.15s fault clearance.With electromagnetic transient simulation result under the identical operating mode more as can be known, electromechanical transient simulation result and electromagnetic transient simulation result are in full accord.

(2) the set end voltage range of decrease is less, and blower fan does not excise.The emulation operating mode: blower fan initial launch point is the same, three phase short circuit fault impedance ground 0.1+j1.0 Ω, 0.15s fault clearance.With electromagnetic transient simulation result under the identical operating mode more as can be known, the electromechanical transient simulation result is electromagnetic transient simulation result's mean value curve.

2) asymmetric fault emulation

During the three-phase unbalanced fault; blower fan can cause frequency converter overcurrent or dc capacitor overvoltage because of the unexpected reduction of set end voltage equally; simultaneously; also may be owing to three-phase imbalance too seriously causes the action of frequency converter three-phase asymmetrical protection; therefore, be necessary to analyze relatively have, without the dynamic response of blower fan under unbalanced grid faults of low voltage crossing.

Low voltage ride-through function is arranged

(1) the single-phase fault set end voltage range of decrease is less, and Crowbar is failure to actuate.The emulation operating mode: blower fan is meritorious 4.5MW initially, idle 0Mvar, and initial slippage+8%, Crowbar mute time 60ms, blower fan boosts and becomes outlet bus PCC generation a phase earth fault, short-circuit impedance 0.2+j2.0 Ω, 0.15s fault clearance during 0s.With electromagnetic transient simulation result under the identical operating mode more as can be known, the electromechanical transient simulation result is electromagnetic transient simulation result's mean value curve.

(2) the phase-to phase fault set end voltage range of decrease is less, and Crowbar is failure to actuate.The emulation operating mode: blower fan initial launch point and Crowbar parameter are the same, and during 0s, blower fan boosts and becomes outlet bus PCC generation bc phase fault, short-circuit impedance 0.35+j3.5 Ω, 0.15s fault clearance.With electromagnetic transient simulation result under the identical operating mode more as can be known, the electromechanical transient simulation result is electromagnetic transient simulation result's mean value curve.

(3) the single-phase fault set end voltage range of decrease is larger, the Crowbar action.The emulation operating mode: blower fan initial launch point and Crowbar parameter are the same, single-phase earthing impedance 0.01+j0.1 Ω, 0.15s fault clearance.The electromechanical transient simulation result of unbalanced fault is slightly different from the electromagnetic transient simulation result; because considered the three-phase asymmetrical protection of blower fan here; therefore the Crowbar action frequency is many when only considering the frequency converter overcurrent protection; 0.18s the time Crowbar just fully the excision, blower fan absorbs more idle from electrical network in the failover procedure.

(4) the phase-to phase fault set end voltage range of decrease is larger, the Crowbar action.The emulation operating mode: the initial operating mode of blower fan and Crowbar parameter are the same, during 0s, and bc phase fault impedance 0.01+j0.1 Ω, 0.15s fault clearance.Similar with singlephase earth fault, the Crowbar switching is 3 times in the fault traversing process, and blower fan absorbs necessarily idle from electrical network.

Without low voltage ride-through function

(1) the single-phase fault set end voltage range of decrease is less, and blower fan does not excise.The emulation operating mode: blower fan is meritorious 4.5MW initially, idle 0Mvar, and initial slippage+8%, during 0s, blower fan boosts and becomes outlet bus PCC a phase singlephase earth fault, short-circuit impedance 0.2+j2.0 Ω, fault clearance during 0.15s occur.With electromagnetic transient simulation result under the identical operating mode more as can be known, the electromechanical transient simulation result is electromagnetic transient simulation result's mean value curve basically.

(2) the phase-to phase fault set end voltage range of decrease is larger, the blower fan excision.The emulation operating mode: blower fan is meritorious 4.5MW initially, idle 0Mvar, and initial slippage+8%, during 0s, blower fan boosts and becomes outlet bus PCC bc phase fault, short-circuit impedance 0.01+j0.1 Ω, 0.15s fault clearance occur.With electromagnetic transient simulation result under the identical operating mode more as can be known, electromechanical transient simulation result and electromagnetic transient simulation result are in full accord.

According to an embodiment of doubly-fed variable-speed constant-frequency wind turbine group system electromechanical transient simulation method of the present invention, step S100 is according to formula

$P_{\mathrm{wind}}=\frac{1}{2}\mathrm{\ρ\π}{R}^2{C}_p(\mathrm{\β},\mathrm{\λ})V_w^3---\left(1\right)$

Set up the wind energy conversion system model, the wind power that the simulation wind energy conversion system absorbs, wherein, P _WindBe wind power, ρ is atmospheric density, and R is the draught fan impeller radius, λ=R ω _Tur/ V _wBe tip speed ratio, β is propeller pitch angle, ω _TurBe the rotating speed of wind turbine impeller, C _pBeing the wind energy conversion efficiency of wind energy conversion system, is the function of λ and β, V _wBe wind speed.In this embodiment, the relation of Cp and λ and β represents with a bivariate table, wherein β changes from-20～300, interval 0.50, λ changes from 0～19.6, and therefore interval 0.4 can form the bivariate table of a 66*49, according to this table, the method for employing spline-fitting can obtain the Cp under any β and the λ.

An embodiment according to doubly-fed variable-speed constant-frequency wind turbine group system electromechanical transient simulation method of the present invention, the two mass axles that contain generator matter piece and wind energy conversion system matter piece in the doubly-fed variable-speed constant-frequency wind-powered electricity generation unit be model as shown in Figure 3, can obtain two mass axles according to Fig. 3 is the math equation of model

$\left\{\begin{array}{c}{2H}_{\mathrm{tur}}\frac{{\mathrm{d\ω}}_{\mathrm{tur}}}{\mathrm{dt}}=T_{\mathrm{tur}}-K_s{\mathrm{\θ}}_s-D_s({\mathrm{\ω}}_{\mathrm{tur}}-{\mathrm{\ω}}_{\mathrm{gen}})-D_{\mathrm{tur}}{\mathrm{\ω}}_{\mathrm{tur}}\\ {2H}_{\mathrm{gen}}\frac{{\mathrm{d\ω}}_{\mathrm{gen}}}{\mathrm{dt}}=K_s{\mathrm{\θ}}_s+D_s({\mathrm{\ω}}_{\mathrm{tur}}-{\mathrm{\ω}}_{\mathrm{gen}})-T_E-D_{\mathrm{gen}}{\mathrm{\ω}}_{\mathrm{gen}}\\ \frac{{\mathrm{d\θ}}_s}{\mathrm{dt}}={\mathrm{\ω}}_0({\mathrm{\ω}}_{\mathrm{tur}}-{\mathrm{\ω}}_{\mathrm{gen}})\end{array}\right.---\left(2\right)$

It is model that step S200 sets up the two mass axles that are comprised of generator matter piece and wind energy conversion system matter piece according to formula 2, wherein, and H _TurWith H _GenBe respectively the inertia time constant of wind energy conversion system, generator; K _sBe the elasticity coefficient of axle, D _Tur, D _GenBe respectively the self-damping coefficient of wind mill rotor and generator amature; D _sMutual damping coefficient for wind energy conversion system matter piece and generator matter piece; θ _sBe relative angular displacement; T _TurWith T _EBe respectively wind energy conversion system machine torque and generator electromagnetic torque; ω _Tur, ω _GenBe respectively wind energy conversion system and generator amature rotating speed, ω ₀Be synchronous rotational speed.The transport function block diagram of wind-powered electricity generation shaft system of unit model as shown in Figure 4, generator matter block models has been included among the DFIG, in Fig. 4 the expression.

An embodiment according to doubly-fed variable-speed constant-frequency wind turbine group system electromechanical transient simulation method of the present invention, double-fed asynchronous blower fan when being lower than wind rating in order to make blade can absorb as far as possible many wind energies, propeller pitch angle generally is set in about 0 degree, and pitch control does not drop into when therefore being lower than wind rating.And when being higher than wind rating, owing to the restriction that is subject to the unit physical property of obtaining of energy, the wind speed round of wind energy conversion system and energy conversion must be lower than certain ultimate value, otherwise the machinery of each parts and fatigue strength are just challenged.Therefore under high wind speed, need to drop into pitch control, regulate the wind energy utilization efficiency of wind energy conversion system, thereby restriction wind-powered electricity generation unit mechanical output does not exceed its rated power, limits simultaneously the rotating speed of generator in allowed limits.The model of pitch control system as shown in Figure 5, pitch control system reads rotating speed measured value speed, compares with default maximum (top) speed reference value speed_ref, draws error signal and sends input PI controller to; Described PI controller produces propeller pitch angle reference value Beta_ref, and the propeller pitch angle Beta with reality compares again, draws the propeller pitch angle error signal, is input to propeller pitch angle control system servo control mechanism; In the pitch control system model, described pitch control system servo control mechanism represents with limit value Vrmax, the Vrmin of servo time constant T, pitch adjusting and gradient limit value Rate_max, the Rate_min that pitch changes.

An embodiment of doubly-fed variable-speed constant-frequency wind turbine group system electromechanical transient simulation method of the present invention is according to the electromagnetic equation of doubly fed induction generator under the synchronous rotating frame

$\left\{\begin{array}{c}{u}_{\mathrm{sd}}=-\frac{{\mathrm{d\ψ}}_{\mathrm{sd}}}{\mathrm{dt}}+{\mathrm{\ω}}_1{\mathrm{\ψ}}_{\mathrm{sq}}-R_s{i}_{\mathrm{sd}}\\ u_{\mathrm{sq}}=-\frac{{\mathrm{d\ψ}}_{\mathrm{sq}}}{\mathrm{dt}}-{\mathrm{\ω}}_1{\mathrm{\ψ}}_{\mathrm{sd}}-R_s{i}_{\mathrm{sq}}\\ u_{\mathrm{rd}}=\frac{{\mathrm{d\ψ}}_{\mathrm{rd}}}{\mathrm{dt}}-{\mathrm{\ω}}_s{\mathrm{\ψ}}_{\mathrm{rq}}+R_r{i}_{\mathrm{rd}}\\ u_{\mathrm{rq}}=\frac{{\mathrm{d\ψ}}_{\mathrm{rq}}}{\mathrm{dt}}+{\mathrm{\ω}}_s{\mathrm{\ψ}}_{\mathrm{rd}}+R_r{i}_{\mathrm{rq}}\end{array}\right.---\left(3\right)$

With the magnetic linkage equation

$\left\{\begin{array}{c}{\mathrm{\ψ}}_{\mathrm{sd}}=L_s{i}_{\mathrm{sd}}-L_m{i}_{\mathrm{rd}}\\ {\mathrm{\ψ}}_{\mathrm{sq}}=L_s{i}_{\mathrm{sq}}-L_m{i}_{\mathrm{rq}}\\ {\mathrm{\ψ}}_{\mathrm{rd}}=-L_m{i}_{\mathrm{sd}}+L_r{i}_{\mathrm{rd}}\\ {\mathrm{\ψ}}_{\mathrm{rq}}=-L_m{i}_{\mathrm{sq}}+L_r{i}_{\mathrm{rq}}\end{array}\right.---\left(4\right)$

Set up the T-shaped equivalent electrical circuit of double-fed asynchronous induction motor (DFIG) under the synchronous rotating frame, as shown in Figure 6.Step S400 sets up DFIG electrical simulation model, wherein, and U _Sd, U _Sq, U _Rf, u _Rd, U _RqBe respectively d axle and the q axle component of stator winding and rotor winding voltage; RS and K are respectively stator winding and rotor winding phase resistance; i _Sd, i _Sq, i _Rd.i _Rq, be respectively d axle and the q axle component of stator winding and rotor winding current, ω ₁Be synchronous angular velocity, ω _sBe slip angular velocity, Ψ _Sd, Ψ _Sq, Ψ _RdAnd Ψ _RqBe the magnetic linkage of stator and rotor d axle and q axle, L _s=L _m+ L _{σ s}, L _r=L _m+ L _{σ r}, be stator and rotor inductance, L _{σ s}, L _{σ r}, L _mBe stator and rotor leakage inductance and mutual inductance.

An embodiment of doubly-fed variable-speed constant-frequency wind turbine group system electromechanical transient simulation method of the present invention, step S500 is according to the transient electromagnetic power equation of DFIG electrical simulation model double fed induction generators stator

$\left\{\begin{array}{c}P=\frac{3}{2}(u_{\mathrm{sd}}{i}_{\mathrm{sd}}+u_{\mathrm{sq}}{i}_{\mathrm{sq}})=-\frac{3}{2}{U}_1{i}_{\mathrm{sq}}\\ Q=\frac{3}{2}(u_{\mathrm{sq}}{i}_{\mathrm{sd}}-u_{\mathrm{sd}}{i}_{\mathrm{sq}})=-\frac{3}{2}{U}_1{i}_{\mathrm{sd}}\end{array}\right.---\left(5\right)$

The relation formula of rotor current and stator current

$\left\{\begin{array}{c}{i}_{\mathrm{rd}}=\frac{L_s}{L_m}{i}_{\mathrm{sd}}-\frac{\mathrm{\ψ}}{L_m}\\ i_{\mathrm{rq}}=\frac{L_s}{L_m}{i}_{\mathrm{sq}}\end{array}\right.---\left(6\right)$

And rotor voltage equation

$\left\{\begin{array}{c}{u}_{\mathrm{rd}}=R_r{i}_{\mathrm{rd}}+{\mathrm{\σL}}_r\frac{{\mathrm{di}}_{\mathrm{rd}}}{\mathrm{dt}}-{\mathrm{\ω}}_s{\mathrm{\ψ}}_{\mathrm{rq}}+\frac{L_m}{L_s}(u_{\mathrm{sd}}-R_s{i}_{\mathrm{sd}})\\ u_{\mathrm{rq}}=R_r{i}_{\mathrm{rq}}+{\mathrm{\σL}}_r\frac{{\mathrm{di}}_{\mathrm{rq}}}{\mathrm{dt}}+{\mathrm{\ω}}_s{\mathrm{\ψ}}_{\mathrm{rd}}+\frac{L_m}{L_s}(u_{\mathrm{sq}}-R_s{i}_{\mathrm{sq}}-{\mathrm{\ω}}_1{\mathrm{\Ψ}}_{\mathrm{sd}})\end{array}\right.---\left(7\right)$

Set up grid side frequency converter and rotor-side frequency converter controller model, wherein, P is that active power, Q are reactive power.System adopts double circle structure, and outer shroud is power control loop, and interior ring is current regulator.In power ring, active power reference value P _RefCalculate reactive power reference qref Q by the optimal wind energy aircraft pursuit course _RefCan calculate the requirement of reactive power according to electrical network, also can calculate from the power consumption angle of generator.P _RefAnd Q _RefReference value and value of feedback compare, and difference is through power governor (PI type) computing, the idle and real component reference value I of output rotor electric current _{Rq_ref}And I _{Rd_ref}, I _{Rq_ref}And I _{Rd_ref}Send into current regulator (PI type) with the difference of rotor current feedback quantity after relatively, the output voltage component after the adjusting adds that the voltage compensation item just can obtain rotor voltage instruction V _{Rd_ref}, V _{Rq_ref}, just obtain generator amature three-phase voltage controlled quentity controlled variable U through rotational transform again _{Ra_ref}, U _{Rb_ref}, U _{Rc_ref}, referring to Fig. 7.

The grid side frequency converter adopts the vector controlled scheme of stator voltage vector oriented, is used for the DC bus-bar voltage of control ac-dc-ac inverter device and the reactive power that the grid side frequency converter sends.The grid side frequency converter control system is taked double circle structure equally, and outer shroud is the DC voltage control ring, and interior ring is current regulator, as shown in Figure 8.

The grid side frequency converter control system consists of the following components:

Dc voltage measurement module: the dc voltage value that is used for measuring doubly fed machine frequency converter DC link;

Inverter current measurement module: the three-phase alternating current that is used for measuring the grid side frequency converter;

PLL voltage phaselocked loop: measure the grid side voltage phase angle of grid side frequency converter access, realize grid side frequency converter decoupling zero control with the vector control method that adopts the line voltage orientation;

Coordinate transformation module: because grid side electric current and voltage amount all represents under the electrical network fixed reference frame, and the grid side frequency converter is the vector controlled way that adopts the line voltage orientation under the line voltage reference coordinate, and therefore the input/output signal at the grid side frequency converter controller all needs to carry out coordinate transform;

The grid side frequency converter: controller output pulse width modulation (PWM) instruction is to frequency converter, and frequency converter reaches corresponding control effect by adjusting the dutycycle of upper and lower bridge arm;

The grid side frequency converter controller: the two-stage PI controller by cascade consists of, and outer shroud is used for the DC voltage of control DC link and the reactive power that frequency converter sends at a slow speed, and interior ring is used for control electric current (I fast _d, I _q) to the current reference value (I that is determined by outer shroud control _{D_ref}, I _{Q_ref}); Grid side frequency converter controller output signal has defined amplitude and the phase angle of frequency converter AC output voltage, and under the voltage oriented vector control mode of grid side, inverter current is decomposed into two mutually perpendicular current components, wherein d shaft current I _dBe active current, q shaft current I _qBe reactive current, d axle active current is used for the DC voltage of control DC link, and q axle reactive current is used for the reactive power that the control frequency converter sends; The frequency converter index of modulation of ring controller output is the expression mode under the grid side frequency converter voltage orientation in the grid side inverter current, need to be only the signal that the grid side frequency converter can be processed by the expression mode that coordinate transform is converted under system's fixed reference frame;

Rotor-side Frequency Converter Control protection system consists of the following components as shown in Figure 9:

Meritorious reactive power measurement link: be used for measuring meritorious that whole double fed induction generators sends and transfer to the rotor-side frequency converter controller with reactive power and with signal;

Coordinate transformation module: carry out the coordinate transform function under the different reference frames;

Dq → α β conversion module: be used for the signal that the frequency converter index of modulation signal under the stator magnetic linkage oriented reference frame of electric current device controller output is transformed under the double fed electric machine rotor reference frame is input to DFIG;

α β → dq conversion module: be used for the double fed electric machine rotor electric current is converted to method for expressing under the stator magnetic linkage oriented coordinate system by the method for expressing under the rotor reference frame, to realize stator magnetic linkage oriented rotor-side Frequency Converter Control;

The DFIG module: by inductor generator and rotor-side frequency converter model-composing, its model equation and input and output all are to represent under the rotor reference frame, and its output signal has rotor current I _Ra, I _{R β}, rotor position angle

And stator and rotor magnetic flux real part and imaginary part Ψ _s_ r, Ψ _s_ i, Ψ _r_ r, Ψ _r_ i;

Power control module: according to formula 5 and formula 6, reconciling the q axle component of rotor excitation current can regulate meritorious, reconciling d axle component can regulate idle, therefore, the difference of the power outer shroud utilization of doubly fed machine rotor-side frequency converter vector controlled actual measurement P, Q and useful work, idle reference value obtains the reference value I of rotor excitation current d, q axle component through two PI controllers _{Rd_ref}, I _{Rq_ref}

Current control module: rotor excitation current d, the reference value I of q axle component of power outer shroud control output _{Rd_ref}, I _{Rq_ref}As the input of current inner loop control, the rotor current closed loop produces the frequency converter width modulation coefficient that is used for the control rotor excited voltage; In the PWM frequency converter, width modulation FACTOR P md and Pmq are the control variable of frequency converter, if the frequency converter DC voltage is u _Dc, then have following formula to set up:

$\left\{\begin{array}{c}{u}_{\mathrm{rd}}=\frac{\sqrt{3}}{2\sqrt{2}}{P}_{\mathrm{md}}{u}_{\mathrm{dc}}\\ u_{\mathrm{rq}}=\frac{\sqrt{3}}{2\sqrt{2}}{P}_{\mathrm{mq}}{u}_{\mathrm{dc}}\end{array}\right.---\left(8\right)$

Therefore, frequency converter width modulation FACTOR P md and Pmq that current inner loop control is obtained are input to amplitude and the phase angle that can change by frequency converter rotor excited voltage in the double feedback electric engine, thereby the control generator rotor current reaches the idle purpose of indirectly control generated power;

The maximal wind-energy tracking module: the wind-powered electricity generation unit only has by changing wind speed round could all reach the optimal wind energy utilization ratio under different wind speed, because the optimal wind energy Tracing Control is only used when being lower than wind rating, pitch control does not drop in the meantime, propeller pitch angle is 0 degree, therefore, there is optimum tip-speed ratio when being lower than wind rating, makes wind energy utilization efficiency maximum; Cp is constant in the formula 1, and Wherein k is the gear case speed increasing ratio, and R is the wind wheel radius, and this formula substitution formula 1 is obtained:

$P_{w|\max }=\frac{\mathrm{\ρ\π}{R}^5{C}_{p\max }}{{2k}^3{\mathrm{\λ}}_{\mathrm{op}}^3}{\mathrm{\ω}}_{\mathrm{gen}}^3=K{\mathrm{\ω}}_{\mathrm{gen}}^3---\left(9\right)$

Therefore, by the actual measurement generator speed, cube being directly proportional of the reference value that makes active power in the maximal wind-energy tracking module and rotating speed can be realized the tracking of maximal wind-energy and caught; Be higher than when specified at wind speed, pitch control drops into, and the active power reference value is limited in maximum output;

Another embodiment according to doubly-fed variable-speed constant-frequency wind turbine group system electromechanical transient simulation method of the present invention, but described DFIG module uses switching Crowbar device to realize low voltage ride-through function, but with the double-fed fan motor unit (DFIG) of switching Crowbar device as shown in figure 10.When making the rotor-side frequency converter, extraneous fault detects the rotor excess current, perhaps during the frequency changer direct current bus superpotential, switch element IGBT conducting in the Crowbar device, the Crowbar bypass rotor overcurrent of devoting oneself to work, while rotor-side trigger of frequency converter signal block, doubly fed machine rotor winding is directly through resistance in series Rc short circuit.

Low voltage crossing (LVRT, Low Voltage Ride Through) ability refers to that in the scope that certain voltage is fallen, the wind-powered electricity generation unit can uninterruptedly be incorporated into the power networks when electric network fault or disturbance cause that the point voltage that is incorporated into the power networks of wind park falls.But the low voltage ride-through capability of double-fed asynchronous blower fan is mainly realized by switching Crowbar device.

But the doubly-fed variable-speed constant-frequency wind-powered electricity generation set structure of band switching Crowbar device as shown in figure 10.Crowbar switching process is as follows: detect the rotor excess current when extraneous fault makes the rotor-side frequency converter, perhaps during the frequency changer direct current bus superpotential, switch element IGBT conducting in the Crowbar device, the Crowbar bypass rotor overcurrent of devoting oneself to work, while rotor-side trigger of frequency converter signal block, doubly fed machine rotor winding is directly through resistive short, the short circuit additional resistance of every phase is about about 2/3 of Crowbar series impedance, and at this moment doubly fed machine is more as a Daepori logical asynchronous generator or motor (deciding on fault front motor rotating speed).

In initial 10～15ms that Crowbar drops into, the idle impact that has a forward that doubly fed machine sends, after this doubly fed machine begins to absorb idle, and the meritorious size of sending then will and big or smallly be decided on the positive and negative of slippage.Because the resistance value of Crowbar series connection is less, set end voltage is lower during the short trouble simultaneously, and stator and rotor magnetic linkage, the electric current of doubly fed machine are all decayed comparatively fast.Crowbar drops into after 60～100ms, and rotor current decays to smaller value, and DC voltage also returns to normal value substantially, the Crowbar excision, and rotor-side trigger of frequency converter signal recovers, and doubly fed machine recovers control ability again.

If extraneous fault is comparatively serious; for example fault-time is long or the rotor overcurrent rate of decay is slower; then not only switching is once between age at failure for Crowbar; if Crowbar always perseveration then finally may make the action of overspeed protection or low-voltage variation cause cutting machine; therefore, the setting valve of Crowbar making time need carefully be chosen.

The protection of doubly fed machine and frequency converter mainly comprises following several: the frequency converter overcurrent protection, and the frequency converter asymmetrical protection, the overvoltage of Generator end, under-voltage protection, generator is overrun, low speed is protected, as shown in Figure 9.In the blower fan of low voltage ride-through function is arranged; when frequency converter overcurrent or asymmetrical protection action; bypass mark position 1; so equal zero clearing of state variable of power controller and current controller PI link; the trigger of frequency converter signal block; Crowbar puts into operation, the asynchronous machine running status that this moment, doubly fed machine entered the rotor short circuit in winding.Work as Failure elimination, when Crowbar was out of service, if frequency converter can't detect overcurrent or asymmetric, then controller put into operation again, the release of trigger of frequency converter signal, and wind energy conversion system recovers control ability.And in not having the blower fan of low voltage ride-through function, the frequency converter overcurrent, asymmetric, generator is overrun, when low speed, the overvoltage of machine end, under-voltage any one protection action, doubly fed machine is all out of service, can't again automatically drop into.

In the protection of double-fed asynchronous blower fan, the overvoltage of machine end, low-voltage variation, generator is overrun, the inverse time lag setting principle is all adopted in the low speed protection.The below introduces modeling method and the setting principle of frequency converter overcurrent protection and three-phase asymmetrical protection.

The frequency converter overcurrent protection:

By Fig. 9 and Shi 9 as can be known, the semaphore that gathers in the frequency converter overcurrent protection is that the most serious phase rotor current amplitude of overcurrent.Therefore, can the rotor current of doubly fed machine reflect that actual flow crosses the electric current of IGBT? can find by electromechanical transient simulation, the electric current that flows through each IGBT group is single-polarity PWM wave, and its envelope is the electric current of the corresponding phase of this IGBT place brachium pontis.

This shows, calculate that the most serious phase rotor current amplitude of overcurrent, can reflect rightly the overcurrent condition among the IGBT.

During short trouble, doubly fed machine rotor three-phase electric current may be asymmetric, and Fig. 9 rotor current amplitude computing module is used for calculating that the most serious phase rotor current amplitude of overcurrent, and computing formula is:

$I_{\mathrm{rot}}=\sqrt{I_{\mathrm{rd}}^2+I_{\mathrm{rq}}^2}\·\frac{S_N}{\sqrt{3}\×U_N}---\left(10\right)$

Overcurrent protection is adjusted as follows: suppose that blower fan nominal output lower rotor part electric current is I _RN(idle according to power factor 0.95 consider) actually detects and is I by the rotor current that formula 10 calculates _RotIf, I then _Rot1.21I _RN, if protection time-delay 10ms is I _Rot1.32I _RN, the protection snap action.

The three-phase asymmetrical protection:

Frequency converter three-phase asymmetrical protection is adjusted as follows: wind-powered electricity generation unit machine end arbitrary neighborhood two-phase voltage phase difference is less than 1140 or be that the imbalance of three-phase voltage degree is greater than ± 5% greater than 1260(); protection is without deferred action; Crowbar puts into operation in the blower fan of low voltage ride-through capability is arranged, and directly cuts machine in without the blower fan of low voltage ride-through capability.

When protection model is realized, can be by real part and the imaginary part of measuring machine end three-phase voltage vector, thus obtain respectively the phase place of three-phase voltage, then obtain the maximal phase potential difference between any two phase voltages, and judge whether to satisfy the protection operation condition.

Those of ordinary skill in the art will be appreciated that; above embodiment illustrates technical scheme of the present invention; and be not to be used as limitation of the invention; any variation, modification of the above embodiment being done based on connotation of the present invention all will drop in the protection domain of claim of the present invention.

Claims (2)

1. doubly-fed variable-speed constant-frequency wind turbine group system electromechanical transient simulation method; described wind-powered electricity generation unit comprises that by wind energy conversion system model, axle be prime mover model that model and pitch control system consist of; the double-fed fan motor unit model that is consisted of by inductor generator model and rotor-side Frequency Converter Control protection system; and the grid side frequency converter control system, described electromechanical transient simulation method may further comprise the steps:

S100) set up the wind energy conversion system model, according to the relation of wind speed, wind energy conversion efficiency and tip speed ratio and blade slurry elongation, the wind power that the simulation wind energy conversion system absorbs;

S200) the two mass shafting structures that use generator matter piece and wind energy conversion system matter piece to form, setting up fan shaft is model, the energy transitive relation of simulation wind energy conversion system machine torque and generator electromagnetic torque;

S300) set up the pitch control system model, use propeller pitch angle control emulation to carry out the optimizing of the wind-powered electricity generation power of the assembling unit, seek under given wind speed, to make the maximal value of wind-powered electricity generation unit output power; The overload protection function of pitch control system when the simulation wind speed exceeds wind rating;

S400) the T-shaped equivalent electrical circuit that makes up double-fed asynchronous induction motor according to equation and the magnetic linkage equation of doubly fed induction generator is set up DFIG electrical simulation model;

S500) according to relation and the rotor voltage equation of transient electromagnetic power equation, rotor current and the stator current of DFIG electrical simulation model double fed induction generators stator, set up grid side frequency converter and rotor-side frequency converter controller model;

S600) the wind-powered electricity generation unit realistic model that uses above step to set up is set up double-fed blower fan one machine infinity bus system model;

S700) the initial launch operating mode of wind-powered electricity generation unit realistic model is set, other simulation step length of Millisecond is set, enter the electromechanical transient simulation running status of wind turbine group system;

S720) described wind energy conversion system model is applied respectively the negative step of wind speed and the positive step signal of wind speed, carry out the electromechanical transient simulation of wind speed step, analyze the wind-powered electricity generation unit meritoriously exert oneself, the response of rotating speed, wind power, wind energy utilization efficiency and propeller pitch angle, the dynamic response characteristic that the double-fed blower fan detailed model of setting up changes in the face of wind speed, the validity that the checking maximal wind-energy is followed the trail of;

S740) described double-fed blower fan one machine infinity bus system model is applied the reactive power step signal, carry out the electromechanical transient simulation of idle step, analyze the wind-powered electricity generation unit set end voltage, meritoriously exert oneself, idle exerting oneself and the variation of rotating speed, the dynamic response characteristic that the double-fed blower fan detailed model of setting up changes in the face of external electrical network load or burden without work, the dynamic perfromance of idle controlling unit in the checking double-fed blower fan vector controlled;

S760) described double-fed blower fan one machine infinity bus system model is simulated respectively external electrical network three-phase symmetrical fault and asymmetric fault; to there being, carrying out without the double-fed asynchronous blower fan of low voltage ride-through function the electromechanical transient simulation of malfunction; analyze the set end voltage of wind-powered electricity generation unit, meritorious, idle, stator current, rotor current waveform; relatively have, without the dynamic response of double-fed asynchronous blower fan under electric network fault of low voltage ride-through function, the dynamic perfromance of checking double-fed fan trouble protection.

2. doubly-fed variable-speed constant-frequency wind turbine group system electromechanical transient simulation method according to claim 1, but it is characterized in that described DFIG module use switching Crowbar device realization low voltage ride-through function, when making the rotor-side frequency converter, extraneous fault detects the rotor excess current, perhaps during the frequency changer direct current bus superpotential, switch element IGBT conducting in the Crowbar device, the Crowbar bypass rotor overcurrent of devoting oneself to work, while rotor-side trigger of frequency converter signal block, doubly fed machine rotor winding is directly through resistance in series Rc short circuit.

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