Abstract：In order to analyze the influence of the initial running speed of the variable speed pumped-storage unit on the load rejection transient process by adjusting the parameters of the guarantee, aiming at the operation characteristics of variable speed pumped storage unit, based on the theory of one-dimensional transient flow characteristic line method, the initial variable speed pumped-storage power station running speed calculation and transient process simulation model was established, combined with the engineering example, the influence of unit running speed on power generation efficiency under different head operating conditions, and the influence of variable speed pumped storage unit starting running speed on water hammer pressure and speed rising rate under the accident load rejection condition were studied, and the reasons for those were explained. The results show that when the variable speed pumped-storage unit is running at rated output under high water head and rated water head, with the decrease of initial operating speed, the maximum speed rising rate increases after the accident load rejection, and the water hammer pressure increases. The reason is that the change of initial speed of variable speed pumped-storage unit results in the change of torque and flow rate during the load rejection. The research results can provide reference for the selection of running speed and optimization of maintenance parameters in the transition process of load rejection in similar projects.
