Dynamic Modeling and Control of Regenerative Gas Turbines

A non linear dynamic model has been developed in order to simulate the dynamic behavior of single-shaft or multi-shaft regenerative gas turbines. The aim of the work is to provide a fast and reliable model for the synthesis of the controllers and the study of critical dynamic situations. Some significant features characterize the proposed model: - an efficient one-dimensional model is used in order to properly model a stationary counter-flow regenerator; - a stage by stage model is provided for the air cooled turbine expansion in order to take into account the blade thermal transients. The mathematical model and the numerical methodology are described in the paper. A single-shaft regenerative cycle gas turbine is analyzed. In order to design a multivariable controller for this plant, a linearized model is developed from the non-linear model. The gas turbine is described by the transfer functions that relate the input variables (fuel rate and variable inlet guide vanes) to the state variables (shaft speed and turbine output temperature). Accuracy and effects of non-linearities are described.