Mechanism of Extreme Pressure Generation of Pumped Storage Station

This paper presents a simulation study of the hydraulic transient process under extreme conditions for a pumped power station with a two-machine one-cave layout, based on the method of characteristics. The focus is on analyzing the impact of the unit operating trajectory on the minimum pressure at the tailrace tunnel inlet. The results indicate that when the load rejection time of the two units is at the most unfavorable moment, the asynchrony in the time derivative of the first wave flow of the two units reaches its peak. At this moment, the pressure at the tailrace tunnel inlet reaches the minimum value among all conditions. The operating trajectory of the unit that first rejects load bends at the upper part of the characteristic curve S region, while the operating trajectory of the unit that rejects load later bends at the lower part of the characteristic curve S region.