Gas turbines are used as main engines to convert fuel energy into mechanical energy used to move the generator and thus produce electrical power at the power plants. When you use a gas turbine in the power plants, it must maintain a constant speed of the turbine and thus fixed frequency output of the current also must maintain the parameters of the turbine such as pressures and temperatures at the limits and thus extend the life of the turbine components and increased efficiency. there was a need for the design of control systems maintain a constant speed of the turbine and to avoid operating at others and allowed values. In this research, we modeled the gas turbine and solving the model using MATLAB/ SIMULINK program, and then design a proportional integral differential controller for gas turbine operating In Gandar Station