In the wind farm expansion stage, installing battery energy storage systems (BESSs) assists in mitigating the time of overloading the connected transmission systems by peak shaving. Applying dynamic thermal rating (DTR) improves the utilization of the transmission systems based on monitoring real-time environmental conditions. DTR and BESS are combined in this paper to maximize power dispatch of an expanded wind farm without expanding the transmission system. The novelty of this paper lies in considering DTR of transformer and degradation cost of the batteries in the proposed optimization framework. Results show that the utilization of DTR and BESS mitigates wind power curtailment and applying DTR reduces degradation costs of the batteries. The findings also indicate the importance of carefully planning the size and control strategy of BESSs in order to minimize operational costs, especially for expanded wind farms and the connected transmission systems applying DTR.