Necessity and Impendency of Online Monitoring the Vibration of 800MW Generator Stator End Winding in Suizhong Power Plant

摘要

With the increase of generator unit capacity, more strict demands are put forward on the mechanical property of stator end winding support system. It is usually difficult to study these properties with calculating method, and the required precision can not be ensured. Moreover, calculation is sometimes hard to perform due to some unsteady parameters and many factors such as manufacturing technology, characteristics of the fixing materials, installation quality, inspection and repairing quality, operation and maintenance, and so on. Therefore, testing is the most popular and the only feasible method in the research of large generator mechanical property, i.e. the stability of its vibration characteristics. This paper demonstrates with a lot of facts and test data that the stator end winding structural design for the two 800MW generators manufactured in Russia are acceptable and it is not necessary to invest hundreds of million Yuan for its overall modernization by France Alstom company. Indeed, both generators had occurred some problems during the operation of more than a decade. Based on the operation experience of the worldwide large turbogenerators, we suggest that an optical on-line monitoring system for stator end winding vibration is installed in each of the generators, respectively, to realize real-time measuring of the vibration magnitude and thus giving early alarm for condition-based maintenance. In this way, huge economic losses resulted from emergent incidences and unnecessary retrofit due to mistake judgment can be avoided. This paper also stresses that the retrofit of generator stator end winding structure is very difficult. The existing technology can not ensure a hundred percent success. Therefore, vibration measurement before retrofit not only allows demonstrating the effectiveness of the retrofit, but is also indeed significant for reducing the risk of a failed retrofit.