I. Introduction
It is well known that the power delivered by the wind turbines fluctuates intensely due to the wind variability. Additionally, many of these generating sources will operate as distributed generators. When the power system grid connection is not available, these uncontrollable sources may operate in an island mode. In this case, disturbances such as wind fluctuation and load perturbation have adverse effects on grid frequency and voltage in completely isolated and relatively small power systems with significant penetration of wind generation [1]–[3]. As a solution, the battery storage technologies can play a vital role in improving the power quality against voltage depressions and power interruptions and reliability of the power system [4]–[6].