Prediction of Corrosion Fatigue Damages for Turbine Blades Subjecting to Randomly Distributed Power System Unbalance

Abstract

In this paper, a fatigue damage estimation procedure is implemented by integrating the results of an EPRI and a GE testing reports as well as a shareware developed by the Oslo University, which is incorporated with a verified transient simulation program developed by the Aberdeen University to study the effects of power system unbalance on turbine blade damaging. Based on the Weibull distribution in the negative sequence current (I₂) and the operational environment containing 22% NaCl, the probability level of fatigue life as well as the reliability against fatigue failure for the long blades of low-pressure (LP) turbine are evaluated. It is shown that even though the blades could withstand the most serious impact arising from three-phase-to-ground fault, still it cannot guarantee adequate long-term reliability in the normal operational condition.