Efficiency calculation of wind turbine generation system with doubly-fed induction generator

This paper presents a method to calculate various losses in wind turbine generation system (WTGS) as a function of wind speed, which is based on the steady state analysis. Variable speed WTGS using a doubly-fed induction generator (DFIG) and power converters (inverter and converter) is mainly considered in this paper. By using the proposed method, wind turbine power, generated power, generator losses, gearbox loss, power converter losses and energy efficiency can be calculated quickly. Moreover, annual energy production and capacity factor of the wind farm can be obtained by using the wind speed characteristic expressed by Weibull distribution function. Therefore, if the Weibull distribution function of wind speed is available, we can calculate the annual energy production without using real annual wind speed data. Using the data of Weibull distribution function of some different areas, capacity factor of each area is calculated and compared with those of other types of WTGSs such as Permanent Magnet Synchronous Generator (PMSG) and Squirrel-Cage Induction Generator (IG).