Patent ID: 6212446
Filing Date: 2001-04-03
Classification: H02J

Abstract:
A method for detecting an out-of-step in an electric power system in which two power sub-systems are connected at both sides of a transmission line, said method comprising the steps of:taking in a voltage and a current of said electric power system at regular measuring intervals;computing a phase angle difference between said voltage and said current taken by said voltage and current taking step; andjudging an out-of-step condition by receiving said phase angle difference, obtaining a change amount in phase angle differences at every measuring interval, and judging that an out-of-step occurs between said two power sub-systems in said electric power system when said change amount in said phase angle differences is below a predetermined threshold value for detecting a sudden change in phase angle and said phase angle difference is above a preset out-of-step judging phase angle difference.