Network frequency control function is incorporated into a grid-connected wind farm-dual battery energy storage system (BESS) scheme. The design of the scheme takes advantage of the rapid response characteristics of the BESS and the in-built short-term over loading capability of the associated power conversion devices. Acontrol strategy to regulate the BESS output power is then proposed. It is shown that the frequency control actionoffered by the BESS complements amicably with that of conventional generators in enhancing the frequency regu-lation attribute of the grid system.