A digital computer system for EHV substations: Analysis and field tests

This paper describes the research and development work being done at the AEP Service Corp. on digital computer applications in EHV substations. Relaying of transmission lines and other power system equipment, station alarm monitoring and data logging, oscillography, and supervisory control functions are considered for possible computer implementation. A new algorithm for computing the impedance as seen from the terminals of a faulted transmission line is presented. Results obtained with the new algorithm for faults simulated with a model transmission line are included in the paper. Field experience obtained from operating a minicomputer in an EHV substation is also described.