Bi-Level Optimal Configuration of Shared Energy Storage Considering Frequency Regulation Revenue and Degradation Cost Under High-Penetration Renewable Energy

Shared energy storage (SES) can mitigate the high investment cost and low utilization efficiency associated with independently configured energy storage in user-side integrated energy systems. This paper proposes a bi-level optimal configuration method for SES considering frequency regulation revenue and energy storage degradation costs. First, for a multi-park scenario in which several parks jointly construct and share an SES station, an upper-level investment and operation model is developed to minimize the comprehensive cost of the SES station, while considering its participation in the frequency regulation market and the degradation cost caused by charge–discharge cycling. A lower-level coordinated operation model is then established to optimize the joint operating economy of the parks. Second, the Karush–Kuhn–Tucker (KKT) conditions of the lower-level model and the Big-M method are used to reformulate the bi-level problem as a single-level mixed-integer linear programming (MILP) model. Third, a bilateral Shapley value method is introduced to fairly allocate the SES investment cost. Finally, case studies are conducted to verify the rationality and effectiveness of the proposed bi-level model. The results show that the optimal rated power and rated energy capacity of the SES are 22.00 MW and 44.00 MWh, respectively. Participation in frequency regulation increases the annual net profit of the SES operator by 7.31%, whereas ignoring the degradation cost increases the annual net profit to CNY 11.29 million, thereby overestimating the actual economic performance of the project. Compared with independently configured energy storage, the comprehensive cost of the three-park grand coalition is reduced by 16.96%. Overall, the proposed method can coordinate SES capacity configuration, frequency regulation revenue, and degradation cost, thereby reducing the comprehensive energy storage cost of multiple parks and improving project economics while providing a reference for the planning and operation of multi-park SES under high renewable energy penetration.