Remaining Useful Life Estimation Using Hybrid Monte-Carlo Simulation and Proportional Hazard Model

PS PLUS software offers power providers the ability to implement intelligent gas turbine life cycle management processes. Operators wish to achieve higher availability by reducing unnecessary scheduled outages for either inspection or repair. PS-PLUS is a SPAR-based application that uses the MonteCarlo (MC) method to estimate machinery remaining useful life. The method predicts the scope and schedule of maintenance associated with important failure modes. Other works have explored the Proportional Hazard Model (PHM), using EXAKT software to accurately forecast the probability of failure of gas turbine components. A PHM quantitatively measures the relative importance of each influential risk factor (covariate) that affects life estimation. The propensities for failure are modeled as a function of both time dependent covariates and an item’s working age. The hybrid PHM-MC prototype application demonstrates Remaining Useful Life Estimation in conjunction with time dependent covariates such as (a) key operational duty cycle profile factors i.e. load, fuel type, starts, trips, etc, (b) sensor readings, and (c) borescope inspection data indicative of component health and state. This paper presents a conceptual design, data requirements and analysis techniques needed to fuse PHM and MonteCarlo simulation techniques. The hybrid system should generate accurate remaining useful life predictions. Those predictions form the basis of cost-effective condition-based maintenance (CBM) of gas turbines. Effective CBM, in contrast to time-based maintenance (TBM), profoundly improves life cycle performance and cost. The paper demonstrates the superiority of PHM analysis compared to traditional Weibull analysis in predicting lower-end failure probabilities, for example B1 and B5 lives. Because of the serious economic consequences of critical failures, such reliability estimates must be considered in business decisions related to gas turbine operation and warranty management.