长管道小型水电站的调压阀选型计算

Pressure regulating valve model selection calculation in long pipeline small hydropower station

当水轮发电机组甩负荷时,调速器控制水轮机活动关闭导叶,压力管道内产生压力,机组转速上升。对于压力引水管道较长的电站,改变导叶关闭时间,就不一定能同时使压力和转速上升都控制在允许的范围之内。使用调压阀的作用在于:在机组甩负荷、导叶快速关闭的同时相应地打开泄流通道,从而降低水锤压力上升,待导叶全关后,再缓慢关闭,使引水管道的流量变化缓慢,防止引水管道水压升高及机组转速过高。导叶关闭时间T_w≤12s的中小型电站采用调压阀代替调压井后,不但能够节省投资、缩短工期,而且调压阀的布置还不易受地质、地形等条件限制。

When hydro-generating set occurs load rejection,speed governors can be used for controlling the activities of turbines and closing guide vane. Pressure is produced in pressure pipeline. The set rotation speed is increased. If guide vane closing time is changed in power station with longer pressure water diversion pipeline,pressure and rotation speed increase cannot be necessarily controlled within an allowable scope. The functions of pressure regulating valve include the follows： spillway channel can be correspondingly opened when the set occurs load rejection and guide vane is rapidly closed,thereby reducing water hammer pressure increase. After the guide vane is fully closed,the spillway channel can be slowly closed,thereby slowly changing the flow capacity in the water diversion pipeline,and preventing water pressure increase in water diversion pipeline and too high rotation speed of the set. After water regulating valve is adopted to replace water regulating well in medium and small power station with guide vane closing time Tw≤12s. Such method can save investment and shorten construction duration,and the layout of pressure regulating valves cannot be easily limited by geology,terrain and other conditions.