Manitoba HVDC Research CentreWind generatorsq Variable and fixed speed q Induction machines q Synchronous and PM machines q Doubly fed induction machines q Power electronic converters周铮 July 2008Manitoba HVDC Research CentreMain componentsManitoba HVDC Research CentreGE 3.6 MWWind speed: 3.5 14 25 m/s DFIG :IGBT based Speed : 8.5 15.3 rpm Blade Dia:111 m Modern TechnologyManitoba HVDC Research CentreVestas V90Modern TechnologyVestas V90 3 MWWind speed: 4 15 25 m/s DFIG :Opti-speed Speed : 8.6 16.1 -18.4 rpm Blade Dia:90 m Manitoba HVDC Research CentreGamesa - G90Modern Technology Aerodynamic primary brake by means of full-feathering blades Hydraulically-activated mechanical disc brake for emergencies 690 V Stator 4 pole machine Gear ratio - 1:120.5 material: Pre-impregnated epoxy glass fibre with carbon fibberDFIG :Blade Dia: 90 m Manitoba HVDC Research CentreEnercon E82Modern Technology Direct drive synchronous generator Pitch control Back- to- back converter grid coupled 6- 19.5 rpm Storm control featureManitoba HVDC Research CentreWind Turbine Available powerManitoba HVDC Research CentreIMCapacitors orSVCnetworkGear boxDirect connected induction machine:No slip rings/brushes, Squirrel cage machine has a simple robust construction Less maintenance Fixed speed operationManitoba HVDC Research CentreTorque Equation in Steady State Operating region of the machine falls over a small speed range. No reactive power control.TorqueSpeed (pu)Manitoba HVDC Research CentreEffect of varying rotor resistance in Wound Rotor MachinesTorque Equation in Steady StateRrotor increasingTypical speed variation: +/- 5%Manitoba HVDC Research CentreDirect connected induction machine (variable rotor resistance):IMTo rotor Control rotor resistance with power electronicsManitoba HVDC Research CentreDirect connected induction machines: Poor fault responseManitoba HVDC Research CentreDirect connected induction machines: Poor fault response Machine must be tripped during faults.Manitoba HVDC Research CentreSynchronous machine connected through a ac-dc-ac converter:With or without gear box Can allow variable speed operation Permanent magnet machine are used as wellSMnetworkGear boxManitoba HVDC Research CentreSynchronous machine: Fault responseManitoba HVDC Research CentreSynchronous machine: Fault responseManitoba HVDC Research CentreDouble fed induction machine:Wound rotor machine with slip rings Variable speed operation P and Q independent controlIMnetworkGear boxDFIG ControlsCurrent of variable frequency and magnitude are forced into the rotor windingsManitoba HVDC Research CentreDouble fed induction machine:Fast control of P and Q Variable speed operation Optimal power tracking at low wind speeds Store kinetic energy in the rotating system during high windsMachine and mechanical system ratings limit operating region. Rotor crow bar protection during faults Over speed limits. Manitoba HVDC Research CentreDoubly-fed Induction MachineManitoba HVDC Research CentreDoubly-fed Induction Machine - Stator fluxIdIqT IqQ IdId and Iq are rotor current componentsq Controlling rotor current components Id and Iq forms the basis of the Doubly-fed Induction machine concept. q Power electronic based converters are used to force rotor currents into the rotor windings to achieve desired operation.Manitoba HVDC Research CentreCircuit and ModulesRotor side converterManitoba HVDC Research CentrePosition of the Flux VectorInduced voltage is the rate of change of Flux LinkageIntegral of voltage gives the flux linkage across a coilManitoba HVDC Research CentreEstimation of stator flux vectorImplementation is easier in the Alfa - Beta Fame.Position of the Flux VectorManitoba HVDC Research CentreIraaIrbbIrccIra_refIrb_refIrc_refslpangto StatorDQRotoralfabetaABC2 to 3 TransformalfabetaD and Q reference currentsGeneration of current referencesFig. 4: Final step in generation of rotor phase reference currentsEstimation of rotor current injectionsNote: Id controls reactive power Q controls real powerCircuit and ModulesManitoba HVDC Research CentrehynhyT1T4Ira_refC -E+C -E+C -E+T3T6T5T2Irb_refIrc_refhyira_refira_refhyT1CPanel hysband0100.1C +E+C +E-Current-Reference PWM Controls. Hysteresis band can be adjustedIraIrbIrc* -1CRPWM Bases firing pulse for rotor side converterCircuit and ModulesManitoba HVDC Research CentreSimulation ResultsControl response and the verification of performance of the modelStep change in wind speedController response to maintain Optimum tip speed ratioReduced P outputConstant QManitoba HVDC Research CentreWind Inter-connection q Requirements q Low voltage fault ride throughDharshana Muthumuni May 2008Manitoba HVDC Research Centre Wind Generators Induction machines Squirrel cage Wound rotor Support of switchable caps, SVC or STATCOM Induction machines with controls of power electronics (DFIG) Synchronous