Pitch-Controlled Variable-Speed Wind Turbine Generation

1 Pitch-Controlled variable -SpeedWind Turbine GenerationFebruary 2000 NREL/CP-500-27143E. Muljadi and ButterfieldPresented at the 1999 IEEE Industry ApplicationsSociety Annual MeetingPhoenix, ArizonaOctober 3-7, 1999 National Renewable Energy Laboratory1617 Cole BoulevardGolden, Colorado 80401-3393 NREL is a Department of Energy LaboratoryOperated by Midwest Research Institute Battelle BechtelContract No. DE-AC36-99-GO10337 NOTICEThe submitted manuscript has been offered by an employee of the Midwest Research Institute (MRI), acontractor of the US Government under Contract No.

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4 On paper containing at least 50% wastepaper, including 20% postconsumer waste1 Pitch-Controlled variable -SPEEDWIND Turbine GENERATIONE. Muljadi ButterfieldNational wind Technology CenterNational Renewable Energy Laboratory (NREL)1617 Cole BoulevardGolden, CO 80401, - wind energy is a viable option tocomplement other types of pollution-free the early development of wind energy, themajority of wind turbines were operated at constantspeed. Recently, the number of Variable-Speed windturbines installed in wind farms has increased andmore wind Turbine manufacturers are makingvariable- speed wind paper covers the operation of Variable-Speed wind turbines with pitch control.

5 The systemwe considered is controlled to generate maximumenergy while minimizing loads. The maximization ofenergy was only carried out on a static basis andonly drive train loads were considered as aconstraint. In medium wind speeds, the generatorand power converter control the wind Turbine tocapture maximum energy from the wind . In thehigh wind speed region, the wind Turbine iscontrolled to maintain the aerodynamic powerproduced by the wind Turbine . Two methods toadjust the aerodynamic power were investigated.

6 pitch control and generator load control, both ofwhich are employed to control the operation of thewind analysis and simulation shows that thewind Turbine can be operated at its optimum energycapture while minimizing the load on the windturbine for a wide range of wind TERMSWind Turbine generator, renewable energy, Pitch-Controlled , variable INTRODUCTIONThe development of wind Turbine powergeneration has been expanding during the past 10 global market for the electrical power produced bythe wind Turbine generator (WTG) has been increasingsteadily, which directly pushes the wind technology intoa more competitive arena.

7 Recently, there have beenpositive trends shown by the utilities to offer renewableenergy to customers. Many customers who areenvironmentally conscious now have the option ofsubscribing to clean energy such as wind energy fromthe power provider. The European market has shownan ever-increasing demand for wind wind Turbine Generation has beengaining momentum, as shown by the number ofcompanies joining the Variable-Speed WTG Generation is claimed to have a betterenergy capture and lower loading.

8 The effect ofturbulence on energy capture and power fluctuations invariable- speed wind turbines is affected by the overallcontrol algorithm used [1-4]. The method ofcontrolling the generator strongly affects the electricalpower generated by the generator [2]. Different typesof generators are used for Variable-Speed Generation fordirect drives [2-3]; however, control algorithms forwind Turbine operation are not discussed in goal of this project is to study the behavior ofthe wind Turbine generator operated under variablespeed with pitch -control capability under turbulentwinds.

9 The basic comparison between a constant-speedwind Turbine and a Variable-Speed wind Turbine will alsobe explained. The constant- speed wind turbinePower Converter+ GeneratorPitchable BladeGear BoxUtility(60 Hz)WindLow speed shaftHigh speed shaft Figure 1. Physical diagram of the system2operation is a very simple case that can be used as abaseline. The Variable-Speed algorithm was chosenbased on the maximum energy and steady-state limit ofthe wind Turbine . The steady-state limit is based on theCP-TSR curve provided. Thus in the steady statecalculation, wind gust and wind shear are notconsidered.

10 It turns out that using the steady state limitis a good approximation in the lower wind speeds, asshown by the performance ratio and energy captured bythe wind concept that is fundamental to the controldynamics is that the speed change is relatively slowbecause of the large inertia involved. This makes itdifficult to use the power converter to control the speedin highly variable wind applications. pitch control isrelatively fast, however, and can be better used toregulate power flow especially when near the highspeed 1 shows the system under wind Turbine is connected to a Variable-Speed windturbine.