水电站输水系统相继甩负荷下调压室涌浪叠加研究

水电站调压室高度取决于调压室内的涌浪极值,其大小与计算工况密切相关,相对于同时甩负荷产生的涌浪极值,人们往往忽略了相继甩负荷事故工况。本文从调压室基本方程出发,通过理论分析,推导并得到了反映相继甩负荷危险时间间隔点特征的理论计算公式,进行了水电站输水系统相继甩负荷工况下的调压室涌浪叠加特性研究。结果表明:对于简单式调压室,同时甩负荷产生的涌浪极值必然大于相继甩负荷;而对于阻抗式调压室,同一水力单元机组发生相继甩负荷事故时,存在一个最危险的间隔时刻点,该时刻较同时甩负荷产生的调压室涌浪极值更危险。结合具体电站进行的相继甩负荷实例计算验证了理论分析的正确性,且进一步的分析表明,调压室底部阻抗越大,二者差别越明显。如不慎重考虑,将为工程运行带来极大的安全隐患。

Surge superposition following successive load rejection in hydropower stations

In the calculation of extreme values of tank surge in hydropower stations, the engineers mainly concern on accident condition of simultaneous load rejection, whereas successive load rejection is usually neglected. This present study deals with the tank surge following successive load rejection. Based on the fundamental equations for a surge chamber, the formula that can embody the hydraulic characteristic of maximum upsurge has been derived theoretically when successive load rejection occurs at the worst instant. Besides, case studies regarding the tank surge following successive load rejection were conducted and verified the correctness and accuracy of the formula. The results show that, for throttled surge tank, it is the successive load rejection that can induce much higher upsurge than simultaneous load rejection. Additionally, the larger the head loss across the restricted orifice in the surge tank is, the larger the difference in maximum upsurge between successive load rejection and simultaneous load rejection will be. And the difference may exceed the safety margin regulated in the current surge chamber specification, so there is no doubt to take it into consideration in advance.