An Empirical Method for Online Detection of Power Oscillations in Power Systems

Abstract

This paper presents an empirical method, which can quickly detect power oscillations in power system as they emerge. To detect growing oscillations and compute their magnitude, two algorithms are proposed in this paper; the first one is based on the wavelet transform, and the second one uses the outer boundary approach. When an oscillation arises and its magnitude is larger than a predefined threshold, a measurement window containing the oscillatory response is automatically captured. This provides suitable data for a Prony analysis to identify the dominant oscillation frequencies and corresponding damping ratios. The resulting information is valuable in order to increase situational awareness of system operators and consequently paves the way for timely countermeasures. An online prototype application has been implemented for testing the method with live stream PMU data from the Norwegian transmission system. The experience so far is that the proposed method works properly in a real-life power grid.