Nonlinear Zero Dynamics Analysis and Control of a Low Power Gas Turbine

Background. Gas turbines are highly nonlinear systems, where the widely applied linear controllers based on locally linearized models are of limited use. Method of approach. A simple nonlinear dynamic model is developed that is in a quasi-polynomial form. Nonlinear stability and zero dynamics analysis is applied to find a controller structure for input-output linearization. Results. The estimated stability neighborhood of the system with turbine inlet pressure held constant is 30-35% of the operating domain of the turbine. The servo controller for the rotational speed is asyptotically stable and robust against disturbances in the operating domain. Conclusions. The proposed servo controller has better qualitative and quantitative properties than a servo controller based on a locally linearized model.