Real-time monitoring of inter-area power oscillation using phasor measurement units

Abstract

The stability problem of inter-area power oscillation may cause system blackout. Due to continuously changing of power system operating condition, it makes such stability problem difficult to observe. Real-time monitoring of inter-area power oscillation will play an important role in maintaining the power system stability. This thesis proposes real-time monitoring system of inter-area power oscillation stability by identifying predominant modes of oscillation as well as the associated mode damping and mode shape. The identification process is based on PMU data with preprocessing technique consisting of detrending and downsampling. The Modified Yule-Walker (MYW) algorithm is utilized for identifying frequency of oscillation and mode damping while combined Power Spectral Density (PSD) and Cross Spectral Density (CSD) are used for mode shape identification. In addition, the real-time monitoring system is equipped with operational recommendation options to provide the operator with guidelines to improve Power Oscillation Damping (POD). The recommendation is established based on the concept of mode sensitivity analysis. These identification results are then displayed on GUI to assist the power system operator to monitor system condition in real-time. The simplified 17-machine Western North American power grid system is used to verify the monitoring system performance. The results show that the proposed real-time monitoring system is able to accurately track the predominant modes of oscillation as well as to provide the system operator with recommendation for to improve power system damping. The real-time monitoring system works well during both ambient and ringdown conditions.