Dynamic modeling and robust nonlinear control of a laboratory gas turbine engine

In this paper, a physics-based mathematical model of a mini SR-30 gas turbine engine (GTE) is presented using a state variable modeling method. This model is developed by utilizing approximated maps of the engine components and generic governing equations that describe the engine's behavior. The mathematical model captures both the steady-state and transient behavior of the engine. Using the developed model, a modern control system design approach is proposed to satisfy the stability and performance of the GTE. The objective of this control design is to adjust the required fuel flow rate to the combustion chamber such that the shaft speed of the engine tracks its command signal as closely as possible. The proposed robust nonlinear fuel flow controller is developed based on the nonlinear dynamic inversion (NDI) technique, augmented with a dual extended Kalman filter (DEKF) estimation design. DEKF-based state and parameter estimation are used here to ensure robustness against model inaccuracies due to not accurately known component maps, as well as process and measurement noises. To validate the developed mathematical model, the realistic data extracted from the SR-30 GTE are utilized. The simulation results of the proposed control design approach indicate that it is effective in achieving satisfactory performance of the engine. Also, the proposed NDI controller is compared with the well-established proportional-integral-derivative (PID) controller to illustrate its superiority.