Recently, solar energy generation and wind power generation have been introduced to electric power system. But, as for this natural energy, influence such as frequency fluctuation is exerted on electric power system, which is a fundamental problem in operation of a small grid system such as micro-grid. These systems should provide appropriate power quality compared to a large grid. However, using the telecommunication line for monitoring and controlling the system devices is costly, as an alternative method, autonomous distribution control which enables local power supply and demand control is also required in design and operational stage. This paper discusses benefits of these methods conducting cost evaluation.