A dynamic model was developed for long-term simulation of a heavy duty gas turbine. The model includes the essential control algorithm of the gas turbine as well as the most common outputs and other important intermediate variables. Control algorithm details, such as wind up protection and load limiter algorithm which have large effect on gas turbine transient behavior, are included. The model parameters are identified by applying genetic algorithm and least squares algorithm on regular operational data from a real plant to better match the model response to the real plant. The simulation results have been validated with real plant data and shown to have valid accuracy for many engineering applications.