Recently, dispersed generators have been installed in distribution network to supply power to commercial facilities. Renewable energy generation contains output power fluctuations and distributed generator produces sluggish response for power demand. In order to overcome these problems, an ultra capacitor energy storage system is used for compensating the instantaneous power imbalance. However, use of a large capacity ultra capacitor energy system increases system cost. In addition, PPSs (Power Producer and Supplier) that own these generators are supposed to achieve 30-min balancing control for stable supply of electric power. This paper proposes a control system to achieve both 30-min balancing control and interconnection point power flow control by using a fuel cell and an ultra capacitor based on the H-infinity control theory. Besides, remaining storage energy of the ultra capacitor is controlled to be constant to maintain compensation capability. Effectiveness of the proposed control system is verified by using simulation results. (c) 2010 Elsevier Ltd. All rights reserved.