To address the combined challenges of wind-solar power fluctuations and seasonal hydropower disparities in the Qinghai grid under high renewable energy penetration

this paper presents a bi-level optimization model for energy storage capacity planning. The model explicitly considers the patterns of hydropower output and its complementarity with renewable energy by incorporating time-dependent operational constraints that quantify these characteristics. For a typical year

the optimized storage configuration in the scenario under certain time-segmented hydropower constraints is 526 MW/1578 MWh with a 3-hour duration

achieving a 91% renewable energy utilization rate. This rate is higher than the ones of 84%

88%

and 86% achieved by the hydropower operations under no constraint

annual wide-constraint

and annual narrow-constraint

respectively. It verifies that our novel method that represents the hydropower features using quantified constraints enhances its rationality and applicability in practical applications of the storage configuration

thereby supporting higher renewable energy integration.