Study on power fluctuation characteristics of wind energy converters with fluctuating turbine torque

In recent years the installed capacity of wind power generation has significantly increased in countries including Japan. This increase has given rise to growing concerns over the power quality of a power system with large penetration of wind power because fluctuation of its output power is significantly larger than that of conventional power sources. Tower shadow effects, the fluctuation frequency of which is determined by rotating speed of wind turbine, considerably contribute to the fluctuation. While a power fluctuation due to tower shadow effects can cause flicker and thereby deteriorate power quality, its amplitude varies with constants of induction generators and impedance of the distribution/transmission system connected to the generators. This paper examines the relationship between the amplitude of the power fluctuation in the input torque of induction generators while making machine constants or back impedance at the connection point parameters. The study derives a transfer function describing the relationship by linearizing related differential equations and verifies its validity through a simulation study with MATLAB/Simulink. Implication of the results on amplitude of 3p components of wind power output is discussed. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 153(4): 1–11, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20221