Battery energy storage systems (BESSs) are at high cost, thus it brings challenges in gaining revenue when working independently. But when BESS provides assistance for wind power and participates in frequency modulation (FM) and energy markets together, it can bring significant benefits. This paper puts forward a BESS and wind farm cooperation scheme in a bidding problem. The BESS model uses the traditional depth of discharge (DoD) model. After the optimization, the rainflow counting method (RCM) is used to evaluate the accuracy of the BESS loss calculated in the optimization, which verifies the feasibility of the bidding model. And the economy and feasibility can be confirmed when the BESS provides assistance for wind power and participates in the market.