Runner modification optimization design method for pump-turbine runner considering hydraulic transient guarantee parameter constraints

Pump-turbine runner, as a critical component for energy conversion of pumped storage power stations, can pose significant risks in transient processes if mismatched with the water conveyance system. Current studies on runner optimization primarily focus on improving efficiency, suppressing cavitation, and controlling pressure pulsations, with relatively limited attention to the interaction between the runners and water conveyance systems. To address this gap, this paper proposes a runner modification optimization method that incorporates hydraulic transient guarantee parameter constraints. First, a direct correlation model linking blade geometric parameters with transient parameters is developed using characteristic curves as an intermediate medium. Second, the influence of runner blade geometric parameters on characteristic curves and transient parameters is systematically analyzed. Based on these findings, targeted modification methods are formulated to optimize transient parameters. The results demonstrate that to improve transient parameter quality—specifically the maximum pressure at the spiral case inlet, maximum speed rise rate, and minimum pressure at the draft tube inlet—appropriate increases in blade inlet angle and inlet height or reductions in blade inlet diameter could be considered. The runner modification design case study demonstrates that increasing blade inlet height yields the most favorable outcomes, significantly improving the minimum pressure at the draft tube inlet and reducing maximum spiral case pressure while minimizing adverse effects on bidirectional efficiency. This work establishes a theoretical analysis framework and provides practical design recommendations for runner modification to improve transient parameters, offering valuable insights for the integrated design of pump-turbine runners and the water conveyance systems of power station.