Hydraulic optimization design framework for enhancing transient safety of pumped storage hydropower systems

The construction of pumped-storage hydropower systems (PSHS) is critical for enhancing grid integration of renewable energy, as they provide peak shaving and frequency regulation making transient safety a key concern. Existing PSHSs are designed to meet national safety limits with practice focused on threshold compliance, yet a comprehensive hydraulic optimization framework that addresses all hydraulic transient safety evaluation indicators (HTSEIs) remains lacking. In this paper, a transient simulation model of a PSHS was first established. Three HTSEIs for units (the maximum unit speed rise rate φmax, the maximum spiral case pressure HΔSCP-max, and the minimum draft tube inlet pressure HDTP-min) and three HTSEIs for the water conveyance system (the maximum surge tank level Zmax, the minimum surge tank level Zmin, and the water conveyance system minimum pressure Hsys-min), along with their corresponding governing conditions, were proposed. Subsequently, the effects of 17 water conveyance system parameters on the six HTSEIs were investigated, and six key impact parameters were identified using the elasticity sensitivity index (ESI). Pareto fronts for the unit and water conveyance system HTSEIs were determined, and the optimal hydraulic configuration was determined using the CRITIC-TOPSIS multi-criteria decision-making method. The results showed that, compared with the baseline water conveyance system parameter scheme, the optimized configuration achieved comprehensive improvements in the HTSEI: φmax, HΔSCP-max, and Zmax were reduced by 1.64%, 16.15m, and 5.75 m, respectively. Meanwhile, HDTP-min, Zmin, and Hsys-min were improved by 6.67 m, 6.87 m, and 9.67 m, respectively.