讲座电力电子学课件

Research inNew&Renewable Energy Dr.Li RanWind PowerRecent Studies in Wind Power Gearbox Wind Turbine Doubly Fed Induction Generator 4Q Converter FilterGridDFIG Grid Fault Ride ThroughRenewable Energy NetworksGrid code sets out requirements for grid Grid code sets out requirements for grid interconnection.interconnection.Most current renewable generation systems are Most current renewable generation systems are treated as“negative”load.treated as“negative”load.Future systems MUST contribute to system Future systems MUST contribute to system frequency and voltage control.frequency and voltage control.Grid interconnection usually“makes or breaks”a Grid interconnection usually“makes or breaks”a project.project.Development of many(ALL?)renewable energy Development of many(ALL?)renewable energy converter systems have concentrated on the converter systems have concentrated on the device itself without detailed thought of how to device itself without detailed thought of how to convert the power for grid interconnection.convert the power for grid interconnection.Future developments MUST consider the system Future developments MUST consider the system as a whole REQUIRES INTEGRATED SYSTEM as a whole REQUIRES INTEGRATED SYSTEM APPROACH.APPROACH.Grid Code-Example The value of grid-fault ride-through is increasingly appreciated.Grid code,e.g.Scottish Hydro-Electric Guidance NoteA wind farm must remain connected under the following conditionsdepending on fault voltage reduction and registered capacity of wind farm.wind farm registered capacitywind farm registered capacityvoltage during faultvoltage during fault30 MW=30 MW=30 MW0%0%July 2005July 2005January 2004January 200415%15%January 2004January 2004before January 2004before January 2004 The voltage refers to that on the transmission system(275 or 132 kV).Transformer impedance and fault infeed from the wind farm are likely to result in a higher voltage at generator terminal.Fault is cleared in 140 ms for 132 kV and 100 ms for 275 kV system.Backup clearance time can extend to 300 ms.Initial Control Idea why cant it work?stator voltagerotor voltagecontrolirfaultRecent Studies in Wind Power Gearbox Wind Turbine Doubly Fed Induction Generator 4Q Converter FilterGridDFIG Grid Fault Ride ThroughFeasibility Region with Proposed Control super-synchronoussub-synchronousThis plot says that the DFIG can successfully ride through a grid fault whichbrings terminal voltage down to 0.3 pu,even it initially operates at full speed.Durham 30 kW DFIG Test Rigprime drive with programmabledirect torque controlDFIGXPC Targetboxreal time systemFilterGrid VARIAC4Q convLaboratory verification9.951010.0510.1-2-1.5-1-0.500.511.52ir-abc(pu)Time(s)9.951010.0510.1-2-1.5-1-0.500.511.52ir-abc(pu)Time(s)Rotor current constrained by control Simulation ExperimentGrid Fault Ride ThroughrPower tracking controlD.C.link voltagecontrolConfiguration with direct-in-line convertersA Proposed Research Study on the transient behaviour of and interaction in an Study on the transient behaviour of and interaction in an integrated machine-converter system,includingintegrated machine-converter system,including-Transient FE modelling of machine(HTU discovered that-Transient FE modelling of machine(HTU discovered that the equivalent the equivalent cktckt model of a DFIG gives fault current that model of a DFIG gives fault current that is about 10%too low ICEM 2004.);is about 10%too low ICEM 2004.);-Transient thermal modelling of semiconductor devices;-Transient thermal modelling of semiconductor devices;-Control of converters to satisfy machine and power system-Control of converters to satisfy machine and power system requirements.requirements.Objective:optimized design and control strategy.Objective:optimized design and control strategy.Recent Studies in Wind PowerDirect Drive(Gearless)Wind TurbinesThe Nacelle of a Geared TurbineGeneratorGearboxDrive ShaftBladesPitchMechanismLightningArresterAnemometerMechanicalBrakeHubTowerYawDriveVernier hybrid machinefor direct drive wind turbine Flux switching machine Incorporates magnetic gearing High shear stress High force/torque at low speed Low power factorFour-pole,three-phase,prototypeThe SLiM Concept(from EGL)Three key aspectsLarge diameter using pre-tensioned spokes and pre-compressed rimsIronless stator avoids magnetic pullPermanent Magnet RotorIronless Stator VersionRotor steel rimLarge Rare Earth MagnetsStator non-metallic rimStator coilsMagnet flux patternSpoked Lightweight Direct Drive Wind Machine(SLiM)EvolvingGenerationLtdInitial Power Conversion ArrangementStator coilsInverter moduleInverter moduleOutput to gridEGLOn Going ResearchResearch on power conversion and control Schemes trying to achieveFault tolerant operationFault tolerant operationAir-gap supportAir-gap supportTransformerlessTransformerless grid interface that satisfies grid interface that satisfies grid codesgrid codesLow cost 100%rated converterLow cost 100%rated converterIntegration of PE and machine coil?Integration of PE and machine coil?On Going Researchcondition monitorVoltage regulatorAuxiliary power pick upMain output coilsD.c.-d.c.converterBrake resistorH-bridgeCascade in series with other bridges in the same phaseBypass switchOptical gate signals&Thyristor and diode rectifierFigure 1:A possible module designOn Going ResearchSaiaibicec,eb,eaSbSc+-+-+-+-+-+-gridCircuit Diagram Chopper cut out speed:Chopper cut out speed:9m/s9m/s Current at cut out:3ACurrent at cut out:3A Generator cut out(using Generator cut out(using circuit breaker):18.5m/scircuit breaker):18.5m/s Generator cut out Generator cut out current:17Acurrent:17A Maximum high frequency Maximum high frequency ripple current:3Aripple current:3A Maximum transistor Maximum transistor current:3Acurrent:3A Maximum diode current:Maximum diode current:17A17AConverter design:system simulationTracking SimulationAnnual Energy CaptureAverage wind Average wind speed(speed(m/sm/s)Annual Energy Capture(kWh)Annual Energy Capture(kWh)BatteryBatteryPart ConverterPart ConverterFull ConverterFull ConverterMaximumMaximum5 53713714514514534534544546 66906907627627717717797797 7108310831144114411681168122912299 918481848189118911954195425202520Average wind Average wind speed(speed(m/sm/s)Partially rated converterPartially rated converterFully rated converterFully rated converterIncrease from Increase from direct connection direct connection(kWh)(kWh)Percentage Percentage increaseincreaseIncrease from Increase from direct connection direct connection(kWh)(kWh)Percentage Percentage increaseincrease5 5808021.6%21.6%828222.1%22.1%6 6727210.4%10.4%818111.7%11.7%7 761615.6%5.6%85857.9%7.9%9 943432.3%2.3%1061065.7%5.7%Wave EnergyDemonstration of Absorbing Wave EnergyabcdWave Energy Converters Shoreline devicesSimple maintenance and grid connectioncost of land intrusionExample:OWC Nearshore devices,typically 10-25 m deep,devices can be tight moored to the sea bed Deep water devices,slack moored to maintain geographical position onlyWave Energy Converters Terminator typePrinciple axis parallel to incident wave crestsWaves are stopped as they reach the deviceExample:Salter Duck Attenuator typePrinciple axis perpendicular to wave crestsEnergy conversion by relative motion of partsof the device as a wave passes underneathExample:Pelamis Point absorberOscillating body(next slide)Concept of Direct Drive Wave Energy Converter Couple moving part direct to generator Remove intermediate mechanical systems Slow reciprocating motionWave EnergyWavegen Oscillating water column,Oscillating water column,IslayIslayOcean Power DeliveryPelamisPelamis,SRO contract for,SRO contract for MachirMachir Bay BayTeamworks TechnologyArchimedes Wave SwingArchimedes Wave SwingDirect Drive Wave Machine 3-phase ac/ac converterPower output-300W per Power output-300W per half phasehalf phasedc link 150Vdc link 150Vnew inverter,800V dc linknew inverter,800V dc linkConverter Power Current,IVoltage,VPower in =VxIPower out of MachineInto ConverterDirect Drive Machine Electrical RequirementsAt 1m/s,100 kW,Force=100 kNConventional machines,=20-30 kN/m2Transverse Flux Machines,=200 kN/m2High force density electrical machines-problemsHigh airgap closing forcesMaxwell stress B2Airgap closing force Force at zero currentHigh force density electrical machines-problemsLow power factorHigh open circuit voltage(e.g.60 volts)Internal resistance=1.5 OhmExpected short circuit current 40 A?Expected power 2.4 kW?High force density electrical machines-problemsActual short circuit current 1.5 AmpsActual power approx.3.3 W!Require active rectifierLow force density electrical machinesGood magnetic circuit for high shear force is root of its problemsPresence of iron in circuitNo iron=poorer magnetic circuitNo Maxwell stressLower inductanceIronless/air coredCylindrical opposed rare earth PMsCoils not supported in steelAir cored tubular machinePower Conversion Scheme 1112288RR112288YY112288BBRYR,Y,BR,Y,B700 Vpeak V and I:370 V/phase75 ALarge coil resistance:by pass inactive coilsPower Conversion Scheme 2e(t)L Rcontrol target:i(t)=|e(t)|/(2R)commond.c.link from other coilscoilPower Conversion Scheme 2-coil EMF-coil currentDown Stream Power Conversionvcoil 15coil 14coil 1search coili+dc1-dc1+dc1-dc1+dc1-dc1vi+dc2-dc2RYBcurrentcontrollerbuffer ampboost d.c.-d.c.chopperincluding:1.air core choke 2.Skiip 942GB120Alstom ALSPA MV3000Cpower smoothingcontrollerduty ratioPhase APhase BPhase C1:v200V200 VTitlePower Conversion Stage:Block DiagramSizeRevDocument Number:001energy storagecapacitor bankInverter PaneldSPACE(including grid filter)vSolar PowerSolar powered pumpDurham UniversitySolar Powered CarDurham UniversitySolar Powered CarPower SystemsGrid Integration HV/MV AC or DC?150kV dc cable to networkIsolatorRectifier 123kV AC BUSTransformersCircuit breakers41 kV rms ACSix-step invertersIsolators50kV dc cables from generatorsSummary Grid fault ride through -DFIG,Direct-in-line converter semiconductor device,machine modelling,control Direct drive wind power -Fault tolerance,air-gap support,grid interface,cost,integration Direct drive linear wave machine -Low voltage high current,energy storage,active damping Solar power Power systemsDiscussion on Collaboration Fees Subsistence Visiting scholar Ph.D.studentship Industrial projects from China(local)Government research projects from China Application for China-UK or China-Europe projects