Evaluation of thermo-mechanical fatigue stresses and residual life: An implemented procedure for on-line monitoring of a gas-steam power

In a context of free energy market, it is very important to find proper management optimization methods, taking into account plant part-load and time-dependent operation performances, to avoid that short-term “optimum” strategies can result in increased long-term running costs, reduced profits and increased unavailability and failure rates. This paper presents a procedure aimed at forecasting the cumulative damage of each component or of the whole power plant as a function of the selected management strategy. The final objective is to assist the management decision and suggest actions for power plant on-line monitoring, control, production and maintenance scheduling, considering short- and long-term economic performance targets. The implemented procedure is based on an original calculation model of the cumulative fatigue damage in the critical components of a plant and of their residual life, as a function of the management strategies of the plants. It also helps determine the load history of the plant components and forecast the residual life for the management applied to the whole plant. These results can act as a feedback in the optimization of plant operation and can be included in the mathematical functions which describe the short-time management objectives, with the aim of extending the analysis over longer periods of time.