尾水支管长短对相继甩负荷尾水管进口最小压力的影响

Influence of Length of Tailrace Branch Pipe on Minimum Pressure at Draft Tube Inlet with Load Successive Rejection

抽水蓄能电站相继甩负荷过程中两台机组的流量相互影响,尾水支管长短对尾水管进口压力的影响很大。通过理论推导结合对实际工程的数值模拟,分析了后甩机组尾水支管长短对相继甩负荷后甩机组尾水管进口最小压力的影响。结果表明,机组流量变化率大小决定尾水支管长短对自身机组尾水管进口最小压力的影响程度,与同时甩负荷相比,相继甩负荷后甩机组的尾水管进口最小压力对自身机组尾水支管长短更敏感;固定上、下游岔点位置,移动机组使其靠近下游岔点,可减小尾水支管水流惯性、增大相继甩负荷尾水管进口最小压力,该措施可代替降低机组安装高程的方法。

The flow of two turbines influences each other during the load successive rejection of pumped-storage station,the length of the tailrace branch pipe has a great impacte on the pressure at draft tube inlet.This paper analyzed the influence of the length of the tailrace pipe of the latter load rejection unit on the minimum pressure at draft tube inlet of load successive rejection through theoretical derivation and engineering data analysis.It is revealed that the degree of the influence which the length of the tailrace pipe has on the minimum pressure at draft tube inlet depends on the change rate of the turbines＇ flow;compared with the load simultaneous rejection,the minimum pressure at draft tube inlet of the latter load rejection unit is more sensitive to the length of the tailrace branch pipe;anchoring the upstream and downstream bifurcation points,and moving the turbine to make it be close to the downstream bifurcation point,water inertia in the tailrace branch pipe reduced,and the minimum pressure at draft tube inlet in the load successive rejection increased,which can replace reduction of unit installation elevation method.