Future Directions In Wind Power Conversion Electronics
Future Directions in Wind PowerConversion ElectronicsBob EricksonColorado Power Electronics CenterUniversity of Colorado, Boulderece.colorado.edu/ pwrelectrwe@colorado.edu(303) 492-7003ECE DepartmentUniversity of Colorado, Boulder80309-0425
Power Conversion in Variable-SpeedWind Power SystemsWind turbineAc-acconverterGeneratorCritical issues: Maintaining highefficiency over a widerange of voltages andwind speeds Reduction of capitalcost Quality of electricalwaveforms injectedinto utility e-phase acAC powerto utility480 Vthree-phase60 HzWind turbineDoubly-fedGeneratorStator480 Vthree-phase60 HzAC powerto e-phase acAc-acconverter
About Power Electronics Technology Evolution of magnetics and capacitor technology is slow Evolution of microprocessor/microcontroller technology is rapid Evolution of power semiconductor technology is rapido Low voltage ( 1kV) power semiconductors are inexpensive andexhibit high performanceo Progress in high voltage controlled devices such as HVIGBT’s Major gains in packaging technologyConclusion— where to focus research thrusts:Use of silicon to make significant gains in converterperformance, size, and/or cost Use silicon to improve performance Increased intelligence and complexity; finer structure Improve efficiency, reduce capital cost, improve waveform quality,improve reliability
Conventionalconverters arenot optimizedfor variablespeed windpowerapplications Poor efficiency inRegion II reducesenergy captured A smaller convertercould attain higherefficiency at lowwind?Generatorpower orvoltageRegion IRegion IIRegion IIISpeedConverterefficiency
The Problem of Poor ConverterEfficiency at Low Wind Speed We showed that theorigin of this problem isthe reduction ofconverter efficiency thatoccurs when thegenerator voltage isreduced Other mechanisms, suchas circulating currents inresonant converters orin doubly-fed systems,can also contribute tothis phenomenon100%Typical efficiency vs. power throughputTwo-level dc link system in wind power environmentInverterRectifierEfficiency Typically observed invariable-speed windgenerator systems95%Composite Includes semiconductor conductionand switching losses90% PWM rectifier and inverter Rectifier losses dominate at light load85%0%20%40%60%P/Pmax80%100%
Indirect Power in PWM Boost RectifierInput of conventional DC linksystem reduces to boost rectifier:–vin(vout – vin) –DTsTs –iout 4vinvout3vin–When the converter is requiredto process substantial indirectpower, efficiency is degraded.This mechanism explains theobserved problems in variablespeed wind power applicationsvout2vinIndirect power iout (vout – vin)vinDirect power ioutvin00.20.40.6Transistor duty cycle0.81
Reconfigurable AC-DC converters LDCoutputHLAC input–Single-phase PWM boost converter exampleReconfigure converter to improve efficiency at low inputvoltage, while maintaining high output voltage
Measured Efficiencies ofSingle-Phase PWM Boost RectifiersTwo-Level vs. Reconfigurable Three-Level PWM0.96Three level (doubler mode)Efficiency0.94Two level0.920.9 DC link voltage 385 V Constant power0.880.8680100120140160180200AC input voltage (Vrms)220240260
Multi-Level SwitchingTwo-levelswitchingtThree-levelswitchingt
2-Level Converters100%Improvementof ConverterEfficiencyvia %85%0%20%40%60%80%100%60%80%100%P/Pmax3-Level Converters100%Predicted byexperimentallyverified model ofsemiconductorconduction andswitching max
Discussion Switching loss can be modeled by equations of the formPsw ( v) Q fsw Multilevel switching reduces the voltage step ( v), andhence improves efficiency at full loadMultilevel switching reduces the indirect power at lowinput voltageEfficiency at light load is improved, and the knee of theefficiency curve is shifted to the leftResonant conversion and/or soft switching techniques maybe unnecessaryHow to realize multilevel switching?
The Case for Small Module Size Low-voltage IGBT’s have very low cost– Less than 1 in high volume for 600V 50A 100KHzIGBT: specific cost of 0.03/KVA– Higher voltage IGBT modules typically have specificcosts of 0.50/KVA Built by machine on printed circuit boards: lowmanufacturing cost High quality utility and machine waveforms Lower switching loss and better utilization ofsilicon Improved efficiency at low wind speed
A new family of ac-ac matrix converterscapable of multilevel switchingBasic converterModular switch cellnbThree-phaseac system 1aARealizationicThree-phaseac system 2cABiAiB –aib– NCiCQ1D1aQ3 –ia– –– SymbolD3D2AD4Q2Q4At rated voltage: two-level operationAt low voltage: three-level operation
Advantages of Proposed Converters Multilevel conversion is possible, even in the basicversion. This enables improvement of the low-windefficiency of the converter, without sacrificingperformance at rated power The converter can both step up and step down the voltagemagnitude Switch commutation is simple Modular construction allows scaling to higher voltage andcurrent levels, using inexpensive low-voltage silicon Simple bus bar structures High quality waveforms
New Modular Multilevel Matrix Converterin a Wind Power -phase acSAaSAaSAaGeneratorWind turbineProposednew matrixconverterSwitch cell:Q1Converter contains a matrix ofswitch cell modulesSBaSBaSBaSCaSCaSCaD1aQ3D3D2AD4AC powerto utility60 HzQ2Q4
Variable-voltagevariable-frequencythree-phase acIncreasingthe numberof levelsAC powerto utility60 HzGeneratorWind turbineProposednew matrixconverterDoubly-fedGeneratorDoubly fedsystemStatorAC powerto utility60 HzRotorWind se acProposednew matrixconverter
Experimental DataUtility-side ACvoltage and current(60 Hz)Machine-side ACvoltage and current(30 Hz)
60 Hz to 30 Hz DataMaintenance ofDC capacitorvoltageUpper trace: capacitorvoltage of one switchmoduleLower trace: 60 Hzcurrent injected intoutility
Controller Block DiagramImplemented in Verilog and downloadedinto programmable logic arrays
Issues: Multilevel Modular Converters Complexity of control of individual modulevoltages and currents– Centralized control algorithm not feasible asnumber of modules is increased– Requires new decentralized control approaches Topologies: interconnection of modules– Other modular topologies may allow bettercontrol– Effect on efficiency
Conclusions The variable-speed wind power applicationrequires better ac-ac converters having– Lower capital cost– Improved efficiency over a wide range of wind speedsand generator voltages– Better terminal waveforms Electronic power converters having finer structureare becoming feasible:– Inexpensive, high performance silicon switches– Sophisticated controllers– High level of packaging technology
ConclusionsContinued Multilevel switching can address the issues ofvariable speed wind power– Reduced switching loss improves efficiency withoutneed for resonant techniques– Improved efficiency over wide range of wind speeds– Improved waveform quality New modular converter topologies– Allow scaling to higher powers and higher voltages– Could allow use of advances in packaging and lowvoltage silicon in megawatt applications– Need additional work in decentralized control andmodular topologies
Indirect Power in PWM Boost Rectifier Transistor duty cycle 0 0.2 0.4 0.6 0.8 1 v in 2v in 3v in 4v in Indirect power i out (v out – v in) v out Direct power i out v in – v out – v in DT s T s – i out – (v out – v in) When the converter is required to process substantial
red wind/red wind xlr h50 t-15m l 35 mm red wind/red wind xlr h80 t-16m l 65 mm red wind/red wind xlr h105 t-17m l 90 mm racing speed xlr h80 t-19m l 74 mm profile rim female valve adapter (option) red wind/red wind xlr h50 t-15f l 37 mm red wind/red wind xlr h80 t-16f l 67 mm red wind/red wind xlr h105 t-17f l 92 mm racing speed .
Common concerns about wind power, June 2017 1 Contents Introduction page 2 1 Wind turbines and energy payback times page 5 2 Materials consumption and life cycle impacts of wind power page 11 3 Wind power costs and subsidies page 19 4 Efficiency and capacity factors of wind turbines page 27 5 Intermittency of wind turbines page 33 6 Offshore wind turbines page 41
Wind power: social concerns Wind, solar and biofuels. Technologies in the wind chain 2017-09-26 Wind, solar and biofuels 10 On-shore wind Off-shore wind. 2017-09-26 Wind, solar and biofuels 11 Sample Reference Energy System Oil Gas Coal Gasification Import / Production of biomass Uranium enrichment
the wind speed is reducedto 14m/s.Finally the wind speed is reduced to zero at 6Sec.Thus a varying wind speed is applied to the wind turbine. Fig.6 Wind Speed Variations . 6.2 Active Power in the Grid . Initially the wind speed is 10m/s then power injected to the grid is nearly 300W.If the wind speed is increased to 20m/s,at
DTU Wind Energy E-0174 5 1 0BIntroduction Wind resource assessment is the process of estimating the wind resource or wind power potential at one or several sites, or over an area. One common and well-known result of the assessment could be a wind resource map, see Figure 1. Figure 1. Wind resource map for Serra Santa Luzia region in Northern .
boat wind turbines and make them facing the wind [3]. The number of blades of boat wind turbines is often 3. Three-bladed boat wind turbines can produce power at low wind speed and can be self-started by the wind. This paper is focused on three-bladed boat wind turbines with passive yaw motion.
Small Wind Turbines Are Different Utility-Scale Wind Power, 600 - 1,800 kW wind turbines – Professional maintenance crews – 15 mph (7 m/s) average wind speed Small, “Distributed” Wind Power 0.3 - 50 kW wind turbines – Installed at individual homes, farms, busine
Figure 1 Worldwide usage of wind power (WWEA, 2010) In 2010 worldwide capacity of wind power has reached to 196 MW that has showed a growth of 23.6% since 2004 (WWEA, 2010). The increasing use of wind power is very prevalent in the United States. In 2009, 1.8% of the total energy produced was from wind power. In future
