A Robust H∞ Controller Based Gain-scheduled Approach for the Power Smoothing of Wind Turbine Generator with a Battery Energy Storage System

Abstract

Output power fluctuation of the wind turbine generator is a serious issue for power systems. The battery energy storage system is installed to the power system to solve this problem. However, the large battery energy storage system can increase the capital cost of the wind turbine generator system. Hence, the capacity of the battery should be reduced as much as possible. This article presents an H∞ based control method for the output power smoothing method of the wind turbine generator by using a battery energy storage system. The output power fluctuation of the wind turbine generator is considered in the frequency domain. Low-frequency fluctuations are smoothed by pitch angle control of the wind turbine generator, while high-frequency variations are smoothed by charge or discharge of the battery energy storage system, respectively. The battery energy storage system’s capacity and mechanical stress of wind turbine blades can be reduced by the proposed method. In addition, the gain-scheduled control theory is applied to the pitch angle control system of the wind turbine generator. Therefore, the robust control performance for high non-linearities of the wind turbine generator model can be achieved. The effectiveness of the proposed method is validated by numerical simulations.