Research on characteristic of shut-down process of ring valve in extra-long water conveyance system of hydropower station

Influenced by the surge in chamber in front of the units of extra-long water conveyance system of hydropower station, the largest transient speed of the unit in runaway is higher than the maximum speed of the unit in steady runaway state, and the transient time is long. Under different shut-down process, the influence on the water hammer and maximum transient speed of unit is researched by adopting the flow coefficient of ring valve calibrated by original flow. The research can provide reference for study of runaway case in the extra-long water conveyance system and the shut-down process of ring valve.