A computer-aided technique for generating substation interlocking schemes

The continuity of power supply is maintained by reconfiguring a power system as its operating state changes. The reconfiguration is done by opening and closing circuit breakers and isolators. An improper operation of a switch can damage equipment and/or adversely affect the quality of the supply to the customers. Switching operations are performed by operators (as well as by substation controllers) using pre-defined guidelines including interlocking of switches. A major obstacle in using computerized switching schemes is that interlocking logic has to be designed specifically for each substation. This paper describes the design of a software application that can be used to automatically generate interlocking schemes for substations. The software has two components, one to generate the interlocking scheme from the substation data and the other to generate switching instructions and implement them. Three examples of interlocking schemes are included in the paper.