相继甩负荷间隔时间与尾水管进口压力最小值的内在联系研究

Study on Relationship Between Interval Time of Successive Load Shedding and Minimum Pressure of Draft Tube Inlet

为探求相继甩负荷间隔时间与尾水管进口压力最小值之间的内在联系,针对双机一洞布置型式的抽水蓄能电站,基于瞬变流理论和特征线法对相继甩负荷工况水力过渡过程开展数值模拟,分析了相继甩负荷工况下机组流量变化率和运行轨迹与尾水管进口压力最小值之间的联系。结果表明,存在某一最不利相继甩间隔时间使得两台机组第一波流量变化率的时域不同步程度达到最大,则对应的尾水管进口压力达到最小,且此时先甩和后甩机组运行轨迹点分别在特性曲线反S区上弯点和下弯点。研究结果可为抽水蓄能电站尾水管进口压力极值计算提供参考。

The purpose of the paper is to explore connection mechanism between interval time and pressure at draft tube inlet in successive load shedding case.Based on transient flow theory and method of characteristics,numerical simulation calculation of transition process in the successive load shedding case for pumped storage power station with layout of two turbines and one tunnel was carried out.The relationship between flow rate,running track of turbines and minimum pressure at draft tube inlet was analyzed.The result shows that there is a certain most unfavorable interval time making the time-domain asynchronous degree of first wave flow rate in two turbines maximized and the pressure at draft tube inlet is the minimum.At the same time,running track point of the first load shedding turbine is near the upper bending point in the inverse S-region of characteristic curve and running track point of the last one is near the lower bending point.The conclusion can provide a reference for calculation of extreme value of pressure at draft tube inlet in the pumped storage power station.