某水电站某机组异常振动试验分析及检修

Abnormal Vibration Test Analysis and Maintenance of Unit 1 in a Hydropower Station

某水电站一号机因水轮机部件磨蚀损坏严重进行了检修,检修后启动时出现了异常振动,机组只能带1/3额定负荷勉强运行。针对该机组在某一工况运行时出现的异常振动现象,进行了一系列稳定性试验。通过试验分析,得知该机组旋转体动平衡特性和电磁力平衡特性良好,该异常振动是由水轮机迷宫不均衡压力激发转动体产生的自激振动,并提出了解决该问题的对策,即通过改变转动体固有频率或改变水轮机流态及其迷宫压力分布消除此振动。通过提出的建议方案检修处理后,机组各负荷工况下运行正常,异常振动消除。

Unit 1 of a hydropower station was overhauled due to serious abrasion and damage of turbine components.Abnormal vibration occurred during startup after overhaul,and the unit can only operate reluctantly with one-third of the rated load.In view of the abnormal vibration of the unit under a certain working condition,a series of stability tests were carried out.Through the test and analysis,it is found that the dynamic balance and the electromagnetic force balance of the rotator of the unit are good.It is also found that the abnormal vibration is the self-excited vibration generated by the rotator excited by the unbalanced pressure of the turbine labyrinth.The countermeasure is to eliminate this vibration by changing the natural frequency of the rotator or changing the flow pattern and labyrinth pressure distribution of the hydraulic turbine.After the maintenance treatment proposed by the countermeasures,the unit operates normally under various load conditions and the abnormal vibration is eliminated.