Linearized Model of Variable Speed Wind Turbines for Studying Power System Frequency Changes

An increased share of variable speed wind turbines reduces the inertia of the power system due to the decoupling of mechanical rotor frequency and grid frequency. In the recent years, a lot of research has been done about exploitation of the rotating mass of a wind turbine for participation in the primary frequency regulation of the power system. This paper proposes a linearized general variable speed wind turbine model for studying power system frequency changes. First, an overview of different types of wind turbines is given. Then, the mathematical model of frequency regulation capable variable speed wind turbine is linearized. Finally, a simple system frequency response (SFR) model of a power system is simulated in order to examine the influence of variable speed wind turbines on power system frequency.