For guaranteeing future energy supply, researches on reforming conventional power systems have been done widely. As the next-generation power system utilizes the advance of ICT technologies toward a huge evolution, Smart grid has been becoming an attractive research topic recently. By real-time control of peak power consumption and effective power allocation, which can be supported by ICT functions of Smart grid, the power system is expected to become reliable and be able to avoid black-out in large area. In this paper, we report a developed demonstration of small-scale power control system functionally suppressing the power consumption with high reliability. Furthermore, toward the application to large-scale power control systems, a distributed control algorithm between small-scale systems is proposed and its effectiveness is shown through simulation results.