I synthesized a Robust MIMO controller to reduce the frequency deviations in a smart microgrid system which enjoys attached storage. Frequency deviations are associated with load fluctuations and also the renewable energy sources because of their inherent variability. This project considered a microgrid where fossil fuel generators and renewable energy sources are combined with a battery-based storage system. A controller which guarantees Robust stability and performance is synthesized using D-K iteration method. Robustness of the perturbed system is analyzed via investigation of the structured singular values.