两机一洞抽蓄系统水力短路运行对发电机组压力脉动的影响OA

The hydraulic short-circuit(HSC)mode in Pumped Storage Systems(PSSs)can achieve overall adjust-able input through coordinated control of the output/input of multiple units.However,the system's water flow in this mode deviates from the design conditions,which may induce intense pressure pulsations and threaten the stable opera-tion of the units.To explore the impact of HSC on pressure pulsations within the generating unit,a validated three-dimensional computational fluid dynamics model was employed to simulate the branch pipe and pump-turbine of a prototype two-unit one-tunnel PSS.Using conventional dual-unit generation mode as a control case,comparative analysis reveals that the HSC mode amplifies pressure pulsations,particularly the low-frequency components near the bifurcation,with less impact on high-frequency components or areas further away.The Q-criterion and entropy pro-duction analysis indicate that intensive water impact at the bifurcation under the HSC mode triggers large-scale flow separations and massive vortices.These vortices migrate into the pump-turbine,intensifying energy dissipation and ultimately amplifying pressure pulsations.This study elucidates the amplification mechanism of pressure pulsations in the HSC mode,providing a basis for investigating the risks and the corresponding mitigation strategies of this mode.