Mathematical model of a steam turbine for the thermal diagnostics system

Current operation control systems require advanced analytical tools, including mathematical models. A mathematical model can be developed either as an analytical model or as an empirical model. Compared to analytical models, the empirical ones are easier to formulate, however their applicability range is limited to the operating parameters, for which a particular model has been calibrated. Good results are obtained by combining analytical and empirical models. This paper discusses the mathematical model of a steam turbine working in a gas turbine combined cycle power plant. The steam turbine model contains substance and energy balance equations and the model of steam expansion line in the turbine. Leaks from valve stems and glands have been taken into account. The mathematical model of steam expansion lines contains a steam flow capacity equation and internal efficiency equation. The empirical parameters appearing in this equation have been estimated using the operating data. The computation algorithm and exemplary results are demonstrated.