AI in design: searching for differential relay protection

A generic design process that uses computer-aided, constraint-directed searches is outlined. The process is described as a search over a state space that holds all possible combinations of values of state variables representing facets of the design process; i.e. it holds all complete designs. The use of intelligent search to reduce the amount of effort and the role of the human navigator are discussed. By combination of directed iteration and pruning, the designer reduces the number of complete designs that must be evaluated. Differential relay setting is then considered as a computerized constraint-directed search problem. The differential relay setter algorithm attempts to limit the number of improvements available at each node of the search tree, reduce the difficulty in finding the best node in a large tree, eliminate loops, and allow more than one acceptable design to be found and cataloged. An application of the algorithm is described.<>