Utilization of windpower is considerably increasing in many countries around of the world. However, it produces an unreliable output due to the vagaries of the wind profile. To solve the problem, wind energy should be supported by local conventional sources. The requirements concerning the reliability and quality of electric energy supply can be most satisfactorily fulfilled when a windfarm is connected to a large electric power system. Then any electric power fluctuations, resulting either from wind turbulence or power demand variation, provoke system frequency variations. They should be damped by applying an appropriate control system of such a large power system. In this paper, the problem of control of a separate electric power system composed of windpower farm and supported by a gas turbine plant or a combined cycle has been investigated. First, the impact of wind turbulence on gas turbine plant control system has been modeled and simulated. This is carried out for different amplitudes and frequencies of wind speed. Next, the structure of gas turbine plant control system and its parameters have been adapted to limit the power and frequency fluctuations resulting from wind turbulence. Then the design is further developed by considering a combined cycle instead of a single gas turbine.