天荒坪机组突甩负荷试验工况蜗壳进口压力的统计特性剖析

本文从天荒坪抽水蓄能电站水轮机突甩负荷工况蜗壳进口压力的真机测试资料统计结果着手，利用特征线原理对其双峰特性进行分析和理论上的延伸，最终得出如下结论：(1)当机组采用先快后慢的两段折线式导叶关闭规律，且其拐点位置没有进入机组特性曲线的反“s”区域，蜗壳进口压力将呈双峰现象：第一峰对应于导叶关闭规律的拐点位置，第二峰出现在当机组单位转速为反水泵区域内的第一个最小值的瞬时，且其值大于第一个峰值。若机组关闭规律不变而拐点位置已经进入反“s”区域，蜗壳进口压力将呈现为单峰形态。(2)当机组采用先慢后快的两段折线式导叶关闭规律时，蜗壳进口压力只有单峰。

Theoretical analysis of statistical characteristics of casing pressure at turbine load rejection in Tianhuangping pumped storage station

Based on the statistic results of spiral case inlet pressure under turbine load rejection testing in Tianhuangping pumped storage plant, the method of characteristics is presented in this paper for analyzing and explaining the statistical characteristics of two pressure peaks,which are shown as follows.First,when the chengeover point of the two-segment closing law,the guide vanes close fast first and then slower,is turning point is not located in the S-shape zone of the discharge characteristic of the unit,there exist two pressure peaks along the curve of spiral case inlet pressure within the total closing time of the guide vane,the second happens at the instant when the unit reaches its first minimum specific speed in reverse pump mode,moreover,its value is greater than the first one.If the changeover point of the above closing law is located in the S-shape effect zone,there is only one pressure peak.Secondly,if the two-segment closing law,the guide vanes close slowly first and then faster,only one pressure peak will be left.