This paper presents the study on the integration of battery energy storage system (BESS) to STATCOM for smoothing out the intermittent output power of a wind farm. Lead-acid battery type is considered as the energy storage system for availability and comparably simpler management system. Reviewed several modeling approaches indicating their advantages and drawbacks; particularly, appropriate for high power applicationspsila time-frames, current-based third order model is developed. The experimental tests are conducted to identify the parameters and consequently, to construct the battery model. The performance of the proposed system is analyzed by introducing the state-of-charge (SOC) controller implemented for this type of battery integrated to a proposed 10 MVA STATCOM for a 50 MW wind farm.