Using industrial gas turbines is on the rise because of their flexibility and structural diversity in different conditions and different industries. One of the multi-axial turbines produced in Iran is MGT-30 and there is an extensive program for their use in power generation and oil and gas industries. In this paper, dynamic modeling and analysis of the behavior of this type of turbines in the loading and unloading conditions are considered. Modeling was done by combining the thermodynamic equations and the equations derived from the values of some key parameters in two scenarios. In the first one, modeling was done based on the plant performance line and the model outputs were set according to the input disturbance to the system. In the second scenario, off-design conditions were achieved by adjustable parameters based on the system's physical condition. In addition, the application of the disturbances' effect of changing the type of fuel and ambient temperature on the ideal system's performance was investigated. Validation of the model for LPT exhaust temperature, PT's power and adaption of compressor's operation line was also carried out. Furthermore, the results of the model adaptation with Qeshm power plant on actual system conditions were provided. (C) 2016 Elsevier Ltd. All rights reserved.