The type of fuel, ambient conditions and gas turbine engine variations are among many variables, which determine the amount of metered fuel required for efficient and reliable gas turbine start-up with minimized thermal stresses and without compressor instabilities. Hence, scheduling of fuel for gas turbine engine start-up without dynamic adjustments for unpredictable influencing variables cannot assure reliable start-up. To address this variability, implementation of the active compressor stability control for the start-up scheduling was considered in this study. Generic active control method has been proposed, and this method can be applied on both open and closed start-up scheduling loops. Active control philosophy is based on the control of stability margin using corrective action to avoid or recover engine from compressor instabilities. Active control method is designed to sense incipient stall using stall detection method and subsequently to initiate engine control system corrective action to avoid compressor instabilities by adjusting the fuel flow schedule. Centre casing dynamic pressure signal is used for synthesis of fast and reliable measure of compressor destabilization. When compressor instability is detected, engine control system initiates adjustment of fuel flow schedule defined by corrective function, which is based on the synthesized measure of compressor destabilization. To assess applicability of proposed control method, dynamic simulations of engine start-up have been carried out using generic gas turbine simulation tool GasTurboLib. Nonlinear mathematical model of transient compressor dynamics has been developed to describe instability behaviour of axial compressor. During simulation of start-up sequence, compressor instabilities have been induced to study respond of proposed active control method. Description of implemented compressor model and numerical simulation results are given in this paper
