An integrated model- and rule-based approach to design of automatic switching for subtransmission lines

Automatic switching is the protective scheme installed on subtransmission lines to maintain service to distribution substations along each line after faults. At present, control engineers design the automatic switching for the new/modified subtransmission lines using a manual, time-consuming process. Not only is this process laborious, but many solutions are possible. The designer needs to select the one which yields maximum service restoration subject to constraints based on priority of loads and probable fault locations. This paper presents a new knowledge-based approach to design of automatic switching. This methodology uses model-based reasoning to incorporate information of the substation loads, segment lengths, fault probabilities, and protective devices as well as the relative priorities of the substations. This model is used in conjunction with design constraints, analytical criteria, and heuristic rules to guide the designer through the process of identifying the placement of automatic switches, the functions to be used, and the time setting(s) for each. Further, this approach can explain the detailed reasoning process and provide evaluation information in a causal/temporal network format