Energy Capture, Conversion, and Control Study of DFIG Wind Turbine under Weibull Wind Distribution

A doubly-fed induction generator (DFIG) is a,special variable speed induction machine widely used in modern large wind turbines. Unlike a fixed-speed wind turbine, a DFIG wind turbine depends strongly on the controls of the system under variable wind conditions. This paper investigates statistical properties of energy capture, conversion, and control of a DFIG wind turbine under Weibull wind distribution. Power extracted from the wind and variable speed operation of the induction generator are studied by considering DFIG control properties and statistical characteristics of the wind. DFIG speed control characteristics are investigated under random wind conditions by considering the effects of gear ratio, generator pole number, and grid frequency. An evaluation study is performed to investigate how different generator speed probability distribution affects DFIG power characteristics. Extensive simulation results are given to illustrate DFIG operating properties under random wind and different dq control conditions.