Smoothing of wind power using flywheel energy storage system

Flywheel systems are quick acting energy storage that enable smoothing of a wind turbine output to ensure a controllable power dispatch. The effectiveness of a flywheel depends on how well it can be controlled to respond to fluctuating power output from intermittent sources. A quadratic Lyapunov function based non-linear controller is proposed which is designed based on an implicit understanding of the system including its inherent nonlinearities. Two different configurations of flywheel designs have been studied. The controller ensures asymptotic stability of the system as well as obtaining a better and more reliable performance than linear proportional–integral controllers in tracking rapid changes in power references. A further benefit is that the tuning of the proposed controller remains unaffected by changes in the system parameter and operating conditions. The efficacy of the algorithm is verified using non-linear time-domain simulation in MATLAB.