Reliability evaluation of power systems with WTGs and energy storage

Renewable energy is increasingly being treated as a promising solution to the global warming and other environment issues. Due to the intermittent and uncertain nature of these energy resources, energy storage is required to provide certain wind generation capacity. An analytical method is presented in this paper to evaluate the reliability of power systems with wind turbine generators (WTGs) and energy storage. The Expected Energy Not Supplied (EENS) index is used to investigate the impacts of the rated capacity of energy storage and charging/discharging rate, and the wind speed on system reliability. Expected Energy Not Used (EENU) index is defined to represent the wind energy produced but not used to serve system load.