Abstract:The vibration frequent mutation of high and medium pressure rotors of a certain supercritical 660MW steam turbine occurred. The frequency spectrum analysis shows that the vibration mutation is mainly represented by the semi-frequency components, and the vibration mutation is closely related to the load of the unit. According to the vibration in different load, optimize the valve opening and the main stream parameters, examine the bearing oil film pressure and gland steam system, the cause of fault diagnosis is steam-flow exciting vibration. Through the further analysis of the characteristics and mechanism of the vibration, it is pointed out that the excitation force of the steam flow mainly comes from the exciting force of the seal and the gap between the top of the blade. Then, the full stroke characteristic of the high-pressure governing valve is tested, the vibration trend of every valve is studied in the whole trip, and the opening sequence of the high-pressure governing valve is adjusted according to the test results, from the actual situation of several test valve sequence, the optimal opening sequence of high pressure governing valve is found, and successfully eliminates the vibration fault, and provides reference for similar vibration failure processing.