To address the competitive disadvantage of renewable energy units in capacity markets due to their low capacity credibility

this study proposes an optimal capacity allocation method for hybrid pumped storage systems within a wind-solar-hydro-energy storage alliance. The proposed approach leverages cascade hydropower resources and their integration with pumped storage to form regulatory resources. A bi-level optimization model is developed that simultaneously considers both capacity markets and spot markets. The upper-level model optimizes the capacity allocation of hybrid pumped storage to maximize the alliance's overall benefits. The lower-level model employs a two-stage market-clearing mechanism. Stage 1 (Capacity Market): The alliance's capacity credit is determined and submitted for capacity market bidding based on production simulation. Market clearing is performed to maximize social welfare. Stage 2 (Spot Market): Typical daily scenarios are generated through clustering

and a spot market clearing model is established to minimize power procurement costs. The clearing results from both markets are fed back to the upper-level model

and the bi-level optimization iteratively determines the optimal capacity allocation for hybrid pumped storage. Case studies demonstrate that the proposed method effectively enhances the additional capacity credit of the wind-solar-hydro-energy storage alliance

facilitating the absorption of renewable energy while boosting profitability for members of the alliance.