Historical Trends and Interactive Relationship in Establishment of the Method of Symmetrical Coordinates and AC Network Analyzer

Abstract

This paper reviews historical trends of electric power system simulation technology focusing on the method of symmetrical coordinates and ac network analyzer. The method of symmetrical coordinates was proposed by C. L. Fortescue in 1918. The method of symmetrical coordinates was refined from the original usage and became very easy application form for ac network analyses by S. Bekku in Japan. The origin of ac network analyzer was invented in 1925. Ac network analyzer was improved greatly in its operation by applying the method of symmetrical coordinates particularly in analyses of power networks under unsymmetrical conditions. On the other hand, the method of symmetrical coordinates was improved by the idea of equivalent circuit which was born from application of the method to ac network analyzer. This paper describes historical interactive relationship in establishment of the method of symmetrical coordinates and ac network analyzer.