A study of power electronic based stall and electromechanical yaw power control strategies in small-scale grid-connected wind turbines

The performance of two different control strategies for small-scale squirrel cage induction generator (SCIG) based variable speed wind turbines (WTs) are examined in this paper. The first is stall control, which uses power electronics to force the turbine blades to operate in a stall condition when the turbine is operating in above rated wind speed conditions. The second is yaw control, which rotates the wind turbine away from the direction of the wind to limit power when the turbine is operating above rated wind speed conditions. This paper analyses the performance of these two control strategies and their impact on the utility grid using a comprehensive model that considers electrical, mechanical and aerodynamic aspects of WT operation; the model is discussed in detail in the paper. The comparison shows that completely power electronic-based stall control is better than electromechanical yaw control in terms of power, voltage regulation, and flicker emission level.