白鹤滩尾水隧洞明满流对水电站稳定性的影响

白鹤滩水电站单机容量为1 000 MW，规模居世界第二。对于水电站而言，引水发电系统的稳定性尤为重要，而该水电站的尾水隧洞存在着明满流现象，严重影响到了引水发电系统的稳定性。为此，采用特征隐格式下的虚拟狭缝法，分析了尾水隧洞内不同流态对机组稳定性及尾水调压室水位波动的影响。分析结果表明：当明满流段流态为明流时，可以加速调压室水位波动收敛，有利于输水系统的稳定；当流态为明满过渡流时，其压力脉动现象会导致机组调节品质变差，不利于输水系统的稳定。此外，明满流段的长度对机组调节品质影响很小，长度的选取不受输水系统稳定性限制。研究成果可为类似输水系统设计和研究提供参考。

Influence of free -pressure transition flow in tailrace tunnel on operation stability of Baihetan Hydropower Station

Baihetan Hydropower Station is the world′s second largest hydropower station with installation capacity of 16000 MW. The stability of the diversion and power generation system is very important for the operation of the whole power station. The free-pressure transition flow in the tailrace tunnel influences the stability of the diversion and power generation system seriously. In this paper, the effects of different flow states in the tailrace tunnel on the unit stability and water level fluctuation in the tailrace surge chamber are studied by the characteristic implicit scheme virtual slit method. The results show that the open channel flow in the tailrace tunnel can accelerate the stability of water level fluctuation in surge tank, which is conducive to the diversion system stability; however, for the free-pressure transition flow, the pressure fluctuation will worse the unit′s stable regulation quality, which is unfavorable to the diversion system stability; the length of the free-pressure flow section has little effect on the regulation quality of the unit and the length selection is not limited by the diversion system stability. The results may provide reference for the design and research of similar water diversion system.