Transient Process inversion calculation and extreme condition prediction of large pump turbine based on field test

Abstract An innovative closing law, blocked for a while and then one segment linear closing, was investigated in a pump storage power station. It can mitigate the maximum pressure of the spiral case and the minimum pressure of the draft tube during load rejection. Problems also exist such as long load rejection process, intense unit vibration, large amplitude of the fluctuating pressure, large noise in the field. Considering the fluctuating pressure is significant in pump turbine, segmental correction method was proposed in order to guarantee the pressure inversion accurate. Field test under load rejection and hydraulic disturbance condition were conducted, proving that the fluctuating pressure is larger. The changing law of the fluctuating pressure was also obtained. The numerical result under the same condition agreed well with the test value, verifying the reliability of the numerical calculation. Numerical calculation was analysed under the extreme condition which is not suitable for field test. The result was corrected and then compared with the design value, checking the safety of the water conveyance system. The study provides reference for other pump storage power station.