Wind-solar integration with energy storage is an available strategy for facilitating the grid synthesis of large-scale renewable energy sources generation. Currently, the huge expenses of energy storage is a significant constraint on the economic viability of wind-solar integration. This paper aims to optimize the net profit of a wind-solar energy storage station operating under the tie-line adjustment mode of scheduling over a specific time period. The optimization objective is to maximize net profit, considering three economic indicators: revenue from selling electricity generated by the wind-solar energy storage station, costs associated with energy storage construction and losses, and scheduling deviation assessment cost. Establishing a model to optimize energy storage capacity based on these indicators. The model is utilized to identify the optimal energy storage capacity setup for maximizing net profit. Finally, sensitivity analysis of the scheduling deviation assessment cost is conducted to explore the impact of variations in scheduling deviation assessment cost on the economic viability and electrical output quality of wind-solar energy storage stations.