PID controller design for micro gas turbines using experimental frequency-response data and a linear identification technique

Abstract

This paper discusses the identification process of engine dynamics and presents derived transfer function models including; thrust, shaft speed, compressor exit pressure and turbine exit temperature in relation to the fuel flow. Model identification approach, presented in this paper, is the first to consider frequency-sweep signals to excite dynamics, as well as to utilise windowing and smoothing techniques to reduce random errors in the spectral estimates. Here, frequency sweep provides a fairly uniform spectral excitation and chirp-z transform warrants the exact determination of the frequency responses that are robust to the uncertainties. The identified models are also validated with the engine responses to doublet input as well as the engine comprehensive thermodynamic model. In addition, a PID controller is designed based on the identified models to effectively control the non-linear system. The results show great performance of the controller, in simulation environment, implemented to the non-linear system.