An intelligent approach to generate switching sequences for 500kv Shuanglong substation is presented in this paper. A method for developing an practical expert system is presented, which uses the technologies of facility modeling, network topology, SCADA information, special expert knowledge database, hierarchical inference engine and so on. To solve the main problem of " State Recognition" and "State Change", an online network topology analysis algorithm is used to replace inefficient special rule. So the proposed expert system has a higher intelligence and a good recognition ability to run mode of facility. The node-model and bus-model for primary device and the incident-model for secondary device are created. The real time SCADA information is utilized. A multi-production system is used to implement the knowledge expression for expert system. Having designed an explanation engine, the inference process and the used rules can be explained in details. This system has been used at 500kv Shuanglong substation, Jinhua, Zhejiang, since May 1999.
