The electric power generation using renewable energy sources like wind, solar and/or fuel cells is the need of the hour. The renewable energy system can be used either in grid connected or in standalone mode of operation. Both of the modes require voltage and frequency control to maintain them within the specified limits as per the standards. This paper gives one such control technique to maintain the voltage and frequency in prescribed limits. This paper discusses various control strategies which includes iterative learning controller, model predictive controller and adaptive voltage controller. Among these, the adaptive voltage controller figure out the superior performance. The performance of the controller is verified and presented using the simulation results for various load conditions