WIND POWER EXTRACTION AND CONTROL STUDY OF DFIG WIND TURBINE UNDER WEIBULL WIND DISTRIBUTION

Shuhui Li and Timothy A. Haskew

Keywords

Doubly fed induction generator, probability, Weibull distribution,wind energy extraction, d–q vector control, modelling and simulation

Abstract

At the present time, doubly fed induction generators (DFIG) are used in most commercial wind turbines for large wind power plants in North America. Unlike a conventional synchronous generator, the operation and power extraction of a DFIG wind turbine depends on the control of the system under variable wind conditions. This paper investigates statistical properties of wind power extraction and control of a DFIG wind turbine under Weibull wind distribution. Statistical properties of the power extracted from the wind by the wind turbine are studied by considering DFIG control properties and wind speed probability distributions. The maximum power extraction control characteristics are investigated under random wind conditions and by considering the influences of gear ratio, generator pole number, and grid frequency. A steady-state study is performed to investigate how probability distributions of generator speed affect the power transferred on the stator and rotor paths of the induction generator. The maximum power extraction study under a close-loop feedback control condition further demonstrates that for optimal performance, generator pole pairs and gear ratio of a DFIG wind turbine should be selected appropriately depending on Weibull wind distribution, grid system frequency, etc.

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