This paper considers a future electric power system that is based on renewable energy resources and storage batteries. It proposes a control method of an inverter for the storage battery that adjusts the supply-and-demand balance of the future power system. A large overcurrent occurs when a short circuit fault happens on the power system side. The authors propose the strategy that control so as not to stop the inverter by the overcurrent. And it is verified by simulations. The authors also examines the influence on protection relay from the analysis of the fault current when a system fault occurred.