Wind Power Smoothing Using Flywheel Energy Storage System with Nonlinear Controller

Wind power generation is gaining popularity due to technological advancements and issues related to fossil fuel depletion. High wind penetration poses challenges in grid operation in terms of power balancing due to the intermittent nature of wind speed. Flywheel energy storage system (FESS) with high cycle efficiency and power density is a suitable option for smoothing wind turbine power output. FESS consists of a spinning disc connected to a rotating electric machine which stores energy in the form of rotational kinetic energy thereby ensures controllable power dispatch between Wind Energy Conversion System (WECS) and grid. This paper proposes an integral sliding mode controller for DC machine based FESS model to ensure smooth power output. A non-linear controller is used to track non-linear power output, which assures asymptotic stability of the closed-loop system. The proposed robust control method is compared with Lyapunov based control implemented in an existing literature. Better performance in tracking and disturbance rejection is obtained and certain limitations in the existing work are clarified with proper justifications.