BLADE VIBRATION MONITORING IN A LOW-PRESSURE STEAM TURBINE

A tip-timing system is used in a coal power station to investigate and mitigate excessive blade vibrations in the exit stage of the low-pressure steam turbine. There are presented hardware and software solutions used to monitor blade responses as well as the analyses of amplitude and frequency trends observed during the 5-year collaborative project, including operation at the nominal speed and during the shutdowns and start-ups. The transition from data acquisition to the embedded system with the partial reuse of tip-timing algorithms and Lab View code is demonstrated. The proposed system processes the data coming from the turbine blades in real time and operates autonomously or under the supervision of the PC-based client program connected to the network. Acquired data are stored in a cyclic buffer and can be transferred to the host. The stack pattern is used to distinguish blades and calculate rotating reference. Tip deflection is analysed statistically and evaluated against defined reference patterns.