输水系统布置对抽水蓄能电站相继甩负荷水力过渡过程影晌

The influence of layout of water conveyance system on the hydraulic transients of pump-turbines load successive rejection in pumped storage station

在抽水蓄能电站输水系统水力过渡过程计算中,系统布置对水锤压力影响显著,在相继甩负荷时尤为突出,将导致输水系统出现新的压力控制值。本文针对输水系统的不同布置在理论上分析了相继甩负荷工况出现压力控制值的原因以及可能发生的危险时刻。计算表明:同一水力单元的可逆机组相继甩负荷时,不同的输水系统布置得到的尾水管进口压力差别较大,随着相继甩负荷发生时间的不同,尾水管进口压力将出现较大幅度的降低,严重时将危及输水系统安全,须引起工程设计与建设单位重视;同时,根据可逆机组实际运行情况和计算分析,发生相继甩负荷时,最危险组合时间点应控制在同一水力单元先甩机组流量过零时刻附近。

During the calculation of hydraulic transients in pumped storage station, the layout arrangement of water conveyance system has great influence on the water-hammer pressure especially under the combined conditions of load successive rejection and the new minimum or maximum pressure of water conveyance system occurred. Based on the different layout arrangement of water conveyance system, the reason why the pressure occurs under the combined conditions of load successive rejection and the dangerous interval time is analyzed. The research indicates that when the reversible turbines in the same hydraulic unit reject the load successively, the difference of pressure at draft tube inlet of different water conveyance system layout is great, and the change of pressure drop at draft tube inlet is also great in the different interval time, which endangers the water conveyance system, so should be pay great attention on it. Combining the practical operation of pump-turbine and calculation in theory, it would be the dangerous interval time of load successive rejection of pump-turbines after the first pump-turbines reject load and its flow achieve zero, the pressure of draft tube inlet would drop to the minimum, the other set in the same hydraulic unit also rejects the load at the moment.