说明：  In the past, distribution system load flow was the only tool used for planning or/and operational purposes [4- 121. Recently, with the growing interest in distribution automation systems (DAS), real-time control of the distribution system has become possible. DAS needs many meters to obtain real-time measurements, with which it is possible to develop algorithms to identify the network topology, and a distribution SE may soon be justified to provide the real-time power profile. Similar to EMS, SE should be executed after the network topology update. In a distribution