MODEL-BASED CONTROL AND DIAGNOSTIC TECHNIQUES FOR OPERATIONAL IMPROVEMENTS OF GAS TURBINE ENGINES

Gas turbines operational requirements continue to become more demanding in response to the need for extended component life, increased reliability and improved overall efficiency. To support these requirements, new model-based gas turbine control and diagnostics concepts have been introduced. Traditionally gas turbine control system transforms real engine limits, into limits which are based on measured engine variables. As a result of that, engines operate with increased safety margins and thus with non-optimal performance. To overcome this problem model based control concepts have been proposed. Model based control approach exploits real-time on-line engine models to estimate control feedback signals, enabling the implementation of novel control methods. Model-based diagnostics employs engine models tuned to match the observed engine state in the same manner as model-based control. The residual deviations between predicted and sensed parameters are modelled, again usually as variations in component losses and flow capacity, and the best match is used to identify likely component degradation modes and faults. The use of model based techniques to diagnose and adaptively manage degradation of engine component characteristics is crucial for operational effectiveness of gas turbines. This paper gives overview of current and evolving model-based techniques and discusses benefits of these concepts in operational management of the gas turbines.