摘要 |
<p>A method for detecting an out-of-step in an electric power system in which two power systems (11,12) are connected at both sides of a transmission line (3). The method includes the steps of, a voltage and current taking step for taking in a voltage and a current of the electric power system at regular intervals, a phase angle difference computing step for computing a phase angle difference between the voltage and the current taken by the voltage and current taking step, and an out-of-step judging step for receiving the phase angle difference, for obtaining a change amount in the phase angle differences at every measuring interval and for judging that an out-of-step occurs between the two power systems in the electric power system when the change amount in the phase angle difference is below a predetermined threshold value for detecting sudden change in phase angle and the phase angle difference is above a preset out-of-step judging phase angle difference. <IMAGE></p> |