STUDY ON PRINCIPLE OF POWER SYSTEM SEPARATION DEVICE BASED ON LOCAL ELECTRICAL PARAMETER

A power system separation device based on local electrical parameter hasbeen introduced in this article.Through the analyses to out of step status of power system,one system separation criterion is proposed. When the impedance angle goes through a preset area,at the same time,if the magnitude of the voltage falls down to the lowest value when the line real power changes direction,out of step is detected. If the minimum magnitude of impedance measured less than the predetermined threshold,separation will start, the cooperation of different devices are also proposed according to the number of swing.The simplified flow chart of separation device is given out .At the end of the article,an actual case is described to show the validity and correction of this method.