Connection between dispersed power sources and utility distribution systems: TEPCO´s technical challenges

The use of dispersed power sources is spreading, including renewable sources such as solar and wind power. Increasingly, utilities in Japan are seeking to connect these sources within their distribution systems. However, uncontrolled or nonregulated connections to these power sources may compromise the supply reliability, quality of utility power, and even public safety. To promote the spread of dispersed power sources and maintain the reliability and quality of utility distribution systems in Japan, the Ministry of Economy and Industry published Technical Requirements for System Interconnection, a guideline designed to facilitate the standardization of technologies for source-to-system interconnection, with the ultimate objection of protecting the systems and maintaining the quality of power. Tokyo Electric Power Company (TEPCO) is making efforts to develop various devices and systems, including an independent operation detecting system and new voltage regulator. These new systems may facilitate harmonious and safer connection to dispersed power sources, which in turn may contribute to the spread of dispersed power sources in a sound manner.