斯里兰卡M坝水电站转轮裂纹成因分析及修复措施

Analysis on cause of runner cracks of Moragahakanda Dam in Sri Lanka and corresponding restoration measures

转轮作为水电站水轮发电机组的核心部件,其性能的优劣,对水电站机组运行,保证电网可靠性等方面都有着巨大的影响.2018年上半年,斯里兰卡M坝水电站在机组30 d试运行考核结束后,打开尾水管进人门对水轮机转轮进行检查,发现2台7.5 MW机组转轮在叶片与上冠、下环交汇焊缝处出现多处裂纹.非最优工况运行及卡门涡引发的叶片共振等因素是裂纹产生的主要原因.本文结合机组运行数据及期间出现的一些现象对转轮叶片裂纹产生的原因进行了分析,并介绍了叶片裂纹的修复措施.

A runner is the core component of hydrogenerator set of a hydropower station and its performance has great influence on the operation of hydrogenerator set and the reliability of power grid. In the first half of 2018, the units of the Moragahakanda Dam in Sri Lanka were put into 30-day trial operation. Upon the completion of trial operation, the access door of the draft tube was opened for inspection of turbine runners. It was found that the runners of two 7.5MW units had multiple cracks at the weld joints between the blades and the crowns and skirts. Non-optimal operation and resonant vibration of blades caused by Karman vortex are the main causes of the cracks. Based on unit operation data and some phenomena occurring during operation, this paper analyzes the causes of the runner blade cracks and introduces corresponding restoration measures of the blade cracks.