Using energy storage systems (ESS) for regulating wind farm power output variation is a promising application. It is known that wind farm output variation has negative impact on load following and grid voltage stability. ESS can be used to store certain amount of wind power and re-dispatch it appropriately. In this way ESS can reduce the wind farm output variation and the adverse stability-related impact. The concept is simple but comprehensive investigation is required to develop the ESS-based application and measure its effectiveness. This paper presents a study into this area. First, the ESS-based application settings are developed. Then, the ESS effects on wind power integration, voltage stability, and load-demand mismatch reduction is quantified and analyzed. The results show that ESS of certain ratings can make the wind farm output a better match for the load-demand while raising the grid voltage stability significantly. The ESS typically needs to perform only a few charge-discharge cycles per day. This is advantageous in preserving the ESS life.