WindgenerationPSCAD浙大研修班(仅供参考学习)解析课件

1、Wind generators Variable and fixed speed Induction machines Synchronous and PM machines Doubly fed induction machines Power electronic converters周铮July 2008第1页，共58页。Main components第2页，共58页。GE 3.6 MWWind speed: 3.5 14 25 m/sDFIG :IGBT basedSpeed : 8.5 15.3 rpmBlade Dia:111 m Modern Technology第3页，共58页

2、。Vestas V90Modern TechnologyVestas V90 3 MWWind speed: 4 15 25 m/sDFIG :Opti-speedSpeed : 8.6 16.1 -18.4 rpmBlade Dia:90 m 第4页，共58页。Gamesa - G90Modern TechnologyAerodynamic primary brake by means of full-feathering bladesHydraulically-activated mechanical disc brake for emergencies690 V Stator4 pole

3、 machineGear ratio - 1:120.5 material: Pre-impregnated epoxy glass fibre with carbon fibberDFIG :Blade Dia:90 m 第5页，共58页。Enercon E82Modern Technology Direct drive synchronous generator Pitch control Back- to- back converter grid coupled 6- 19.5 rpm Storm control feature第6页，共58页。Wind TurbineAvailable

4、 power第7页，共58页。IMCapacitors or SVCnetworkGear boxDirect connected induction machine:No slip rings/brushes, Squirrel cage machine has a simple robust constructionLess maintenance Fixed speed operation第8页，共58页。Torque Equation in Steady StateOperating region of the machine falls over a small speed rang

5、e.No reactive power control.TorqueSpeed (pu)第9页，共58页。Effect of varying rotor resistance in Wound Rotor MachinesTorque Equation in Steady StateRrotor increasingTypical speed variation:+/- 5%第10页，共58页。Direct connected induction machine (variable rotor resistance):IMTo rotorControl rotor resistance wit

6、h power electronics第11页，共58页。Direct connected induction machines: Poor fault response第12页，共58页。Direct connected induction machines: Poor fault responseMachine must be tripped during faults.第13页，共58页。Synchronous machine connected through a ac-dc-ac converter:With or without gear box Can allow variabl

7、e speed operationPermanent magnet machine are used as wellSMnetworkGear box第14页，共58页。Synchronous machine: Fault response第15页，共58页。Synchronous machine: Fault response第16页，共58页。Double fed induction machine:Wound rotor machine with slip rings Variable speed operation P and Q independent controlIMnetwor

8、kGear boxDFIG ControlsCurrent of variable frequency and magnitude are forced into the rotor windings第17页，共58页。Double 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 a

9、nd mechanical system ratings limit operating region.Rotor crow bar protection during faultsOver speed limits. 第18页，共58页。Doubly-fed Induction Machine第19页，共58页。Doubly-fed Induction Machine - Stator fluxIdIqT IqQ IdId and Iq are rotor current components Controlling rotor current components Id and Iq fo

10、rms the basis of the Doubly-fed Induction machine concept. Power electronic based converters are used to force rotor currents into the rotor windings to achieve desired operation.第20页，共58页。Circuit and ModulesRotor side converter第21页，共58页。Position of the Flux VectorInduced voltage is the rate of chan

11、ge of Flux LinkageIntegral of voltage gives the flux linkage across a coil第22页，共58页。Estimation of stator flux vectorImplementation is easier in the Alfa - Beta Fame.Position of the Flux Vector第23页，共58页。IraaIrbbIrccIra_refIrb_refIrc_refslpangto StatorDQRotoralfabetaABC2 to 3TransformalfabetaD and Q r

12、eference 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 Modules第24页，共58页。hynhyT1T4Ira_refC-E+C-E+C-E+T3T6T5T2Irb_refIrc_refhyira_refira_r

13、efhyT1CPanelhysband0100.1C+E+C+E-Current-Reference PWM Controls. Hysteresis band can be adjustedIraIrbIrc*-1CRPWM Bases firing pulse for rotor side converterCircuit and Modules第25页，共58页。Simulation ResultsControl response and the verification of performance of the modelStep change in wind speedContro

14、ller response to maintain Optimum tip speed ratioReduced P outputConstant Q第26页，共58页。Wind Inter-connection Requirements Low voltage fault ride throughDharshana MuthumuniMay 2008第27页，共58页。Wind GeneratorsInduction machines Squirrel cageWound rotorSupport of switchable caps, SVC or STATCOMInduction mac

15、hines with controls of power electronics (DFIG)Synchronous machinesPM Machines第28页，共58页。Integration of wind farms MH is considering an expansion of up to 400MW wind power Connection at either 230KV (transmission) or 66kV levels第29页，共58页。Interconnection studiesOnce the potential wind sites have been

16、selected, studies are typically carried out to determine the following aspects: Direct connection cost estimates and connection scheme- breaker terminations or new station Network Upgrade requirement and cost estimates (Load flow type studies: DC power flow or AC power flow to investigate overloadin

17、g elements , abnormal voltages and potential impacts on tie line flows)第30页，共58页。Interconnection studies Dynamic (Stability)performanceFault ride throughPower, reactive power controlAnti-islanding Transient studies:Flicker/harmonicsStarting scheme and inrushDetailed studies of controls第31页，共58页。Inte

18、rconnection requirements Voltage toleranceThe units should operate continuously for voltages in the range 0.9 pu to 1.1 pu at the point of interconnection. Frequency toleranceUnder- and over-frequency rangeContinuous operationShort time operation (10 minutes, 30 seconds or etc)第32页，共58页。Interconnect

19、ion requirements Power controlActive pitch/stall control for power adjustmentRamp down rate Reactive power controlMaintain voltage level with the power factor between a minimum of 0.95 over-excited and 0.95 under-excited第33页，共58页。Interconnection requirements Voltage ride through capability to Reduce

20、 the system “shock” Under-voltage and over-voltage specs第34页，共58页。Interconnection requirementsPost disturbance recovery: Post disturbance recovery of the wind units should be demonstrated through simulationsStart-up and synchronizing: Mitigating excessive voltage drops at the point of interconnectio

21、n during start up/synchronization.第35页，共58页。Large wind farms have to meet very strict operating conditions set out by the system operators. One of the most important requirements is that they must remain connected and supply power to the electrical system immediately after network faults. This is ca

22、lled the Fault Ride Through Capability (FRT).This is to ensure the stable operation of the power system during high wind periods when the wind generation could be supplying a significant level of power to the system. Fault Ride Through Capability requirements第36页，共58页。Fault Ride Through Capability r

23、equirementsUtility Grid Codes define the FRT requirement that the Wind Farm owner has to conform. These standards are not uniform an vary from one system owner to he other.第37页，共58页。Fault Ride Through Capability requirementsELTRA 3 phase faults cleared in first protection zone 2 phase faults with un

24、successful re-close 100-50 ms. Faults with 60%-80% voltage- 1-0 s. Restrictions on Crow-Bar operation to maintain control capabilities.NEMMCO (Australia) Zero voltage for up to 175 ms followed by 80% -100% voltage for 10 s 90% -100% voltage for 3 min.第38页，共58页。The characteristic of the generator pla

25、ys an important role . Synchronous Induction DFIGThe machine will not be tripped during the specified fault duration. Larger winding currents for a longer duration Larger magnetic forces Higher rotation speed Mechanical stressThe wind turbine will not be disconnected/stopped during this period. High

26、er stress on bladesFault Ride Through Capability requirementsFRT Requirements places technical challenges and increased equipment cost.第39页，共58页。Fault Ride Through Synchronous machine Field winding will act to increase the terminal voltage. This will help push more power to the network during the re

27、covery period.Fast response of he field circuit helps fault recovery.第40页，共58页。Fault Ride Through Induction machineNo reactive power control available.Voltage drop makes the shunt capacitors (or SVC) ineffective.Speed (slip) increases during the fault.Increased slip causes more reactive power to flo

28、w into machine. This causes a voltage drop after fault and reduce power output capability.第41页，共58页。Fault Ride Through DFIGOvercomes main drawbacks of the normal Induction machinePower can be delivered at any slip (speed) through control of rotor current.Crowbar reduces effectiveness of DFIG fault r

29、ecovery.第42页，共58页。Fault Ride Through Equipment considerationsUnits with high inertia generally can recover faster than those with lower inertia. Less speed fluctuations. High cost Larger, heavierSpecial designs and new technology required Sophisticated control. New generator concepts第43页，共58页。Grid r

30、ms voltage, generator rotor speed, active power, reactive power, DC-link voltage and (ird & irq,) generator current, response to weak voltage dip 第44页，共58页。Grid rms voltage, generator rotor speed, active power, reactive power, DC-link voltage and (ird & irq,) generator current, response to strong vo

31、ltage dip第45页，共58页。Grid rms voltage, generator rotor speed, active power, reactive power, DC-link voltage and (ird & irq,) generator current, , response to strong voltage dip 第46页，共58页。Reference machine speed to maintain Tip- Speed ratioWhen machine speeds up, Iq_ref increases in an attempt to increase power output.Simple Power control loop used in the simulation第47页，共58页。Wind Power Wind speed distribution Short term wind speed variations Modeling wind speed System impactDharshana MuthumuniMay 2008第48页，共58页。Wind Speed DistributionTypical wi