An electric power distribution network consists of distribution substations, distribution feeders, circuit breakers, and interconnecting and sectionalizing switches, and have an extremely important role in delivering electrical power to the customers. Historically, the distribution feeders, e.g. 6.6 kV feeders in Japan, have been expanded radially from the distribution substations to supply power to spreading power consuming area. With the aim of enhancing reliability of the power supply, the distribution feeders are divided into several load sections by the sectionalizing switches, and then each of the load sections is connected to different feeders through the interconnecting switches. By the states of the circuit breakers and the switches, power flow in the distribution networks is controlled. This is called the multi-sectionalized and multi-connected distribution network. In this network structure, each load section can receive power from one or more distribution feeders even if one feeder has a