Life Analysis of Industrial Gas Turbines Used As a Back-Up to Renewable Energy Sources

The estimated life of gas turbines is expected to diminish over time when compared to the manufacturers' estimated life, particularly when used as a back-up to Renewable Energy Sources (RES). As RES are been introduced into the grid, the gas turbines used in conjunction with them are operated in “Load-Following” modes to these RES which includes wind, thermal, solar, etc. As back-up plants, the start/stop and power settings are expected to be dictated by the response to grid requirements and need to compensate for the load shortfall attributable to unpredictable nature of RES. This mode of operation results in Gas turbine high pressure turbine blades experiencing low cycle fatigue and creep life failure over time. It is therefore of great importance to estimate the life consumed during this mode of operation to enable appropriate maintenance planning/repair action. In order to estimate the life consumed during adverse/cyclic operating regimes, a tool has been developed wherein different scenarios can be simulated and analyzed to obtain engine life consumption factors. The tool is capable of estimating life consumption based on seasonal power demand. For the purpose of study, an aero derivative power plant of 100MW power output was used as a reference engine. The paper provides an in-depth analysis of the study undertaken and it arrives at the conclusion that the operation of engine during summer contributes to a higher degree of LCF and creep life consumption in comparison to operations during other seasons.