On-line coherency monitoring of power system oscillations

This paper presents the real-time FFT based online monitoring of power system oscillation modes. The monitoring system is set up by using a personal computer with a DSP board including an AD conversion interface. For the monitoring of oscillation modes, the real power flows on 500 kV trunk lines were measured at all the 500 kV substations in the Kyushu Electric Power System. The monitored power flows were utilized for the FFT analysis to identify the oscillation modes in real time. A coherency index, based on the FFT analysis, has been proposed to identify coherent areas in the study system. The efficiency of the proposed method has been demonstrated by using the real power flows measured on all the 500 kV trunk lines. The proposed coherency analysis is quite efficient to have better understanding of power system oscillations in the Kyushu Electric Power System.