百龙滩电站4号水轮机技术改造

Technological Modification of No.4 Hydroturbine in Bailongtan Power Station

百龙滩电站建成投产以来,运行近20年,受下游乐滩电站水位顶托,百龙滩电站正常尾水位抬高了约1.4 m,最低尾水位抬高了约4.2 m,最大水头由原来的18 m降低为16 m;运行条件改变后,机组在额定水头9.7m时,难以达到额定出力,导叶开度超过80%时机组振动较大,噪音大,因不能再加大开度,造成机组容量受阻严重;当电站水头低于5 m以下时,机组运行振动较大,基本不能发电;由于机组长期处于低水头振动区运行,诱发大量的缺陷及事故,安全生产隐患较多;电站正常的安全生产已无法保障,且低水头段电量损失严重,电站经济效益降低,为了保证电站安全生产,必需进行水轮机技术改造。经过改造,各项运行指标达到要求,机组在改造设计工况下稳定运行,达到水轮机技术改造预期目的。

Since Bailongtan Hydropower Station was completed and put into operation for nearly 20 years, due to water level backwater effect of downstream Letan Hydropower Station, the normal tailwater level of the Bailongtan Hydropower Station has been raised by about 1.4m, the lowest tailwater level has been raised by about 4.2m, and the maximum head has been reduced from 18m to 16m. After the operation conditions have been changed, when the rated head is 9.7m, it is difficult to reach the rated output, when the guide vane opening is more than 80%, the vibration and noise of the unit will be greater, and the capacity of the unit will be seriously hindered because the opening can not be increased; when the power station head is below 5m, the vibration of the unit is very large, and it can not generate electricity; because the unit is operating in low-head vibration area for a long time, a large number of defects and accidents are induced, and there are many hidden dangers in safety production; the normal safety production of the power station can not be guaranteed, and the power loss in the low head section is serious, and the economic benefit of the power station is reduced. In order to ensure the safety production of power station, it is necessary to carry out technical modifications of the hydroturbines. After the modifications, the operation indexes meet the requirements, the unit runs stably under the design conditions, and achieves the expected purpose of the technological modifications of the hydroturbine.