Wind Turbine Participation in Primary Frequency Control

Abstract

Wind energy is a clean and desirable power source, but wind turbines can potentially operate to the detriment of grid stability. As wind turbine penetration increases, concerns grow regarding power intermittency and frequency regulation. These factors motivate a need for control methodologies that enable a wind turbine to support grid frequency regulation. In this paper, a control design is proposed for a wind turbine to operate in conjunction with a backup synchronous generator for primary frequency control in a microgrid. The proposed design capitalizes on the idea that the wind turbine has a significant amount of rotational inertia in its rotor, and so the power output of the wind turbine can be rapidly adjusted for frequency support via power electronic commands. A novel torque controller is proposed to quickly track the commanded power output without causing wind turbine instability, and an H2 gain-scheduled pitch controller has been developed to optimally track the commanded power output while avoiding turbine overspeeding. The proposed design may be used for either un-deloaded or deloaded wind turbine operation, depending on the available wind power. Simulation results show that the proposed wind turbine frequency control effectively enhances the grid frequency response by reducing the frequency deviation from its nominal value following a power imbalance event.