Topology-Based Interlocking of Electrical Substations

Conventional interlocking of substations is usually expressed by Boolean expressions and realized by electro-mechanical relays. Since these expressions are generated by applying verbally stated interlocking rules to a specific substation configuration, any change of the substation or of the operational philosophy affects them in such a complex way that the problem has to be tackled again in most cases from the very beginning. The proposed topology-based approach suited for microprocessors decouples knowledge-base and implementation, i.e. interlocking rules, and substation configuration. It results in interlocking rules that are independent of a single line diagram and can be applied to all known substation configurations. The rules are divided into mandatory and dependent on operational philosophy. The modularity allows for applying exactly those rules specified in the special project. Any new substation does not require new programming. The inherently fault-tolerant implementation in a 765 kV GIS is briefly described.