Online oscillatory stability estimation of power system using DSI Toolbox

Abstract

Electric power systems around the world are experiencing increased power transfer over the long interconnected transmission systems, and hence they become increasingly stressed in terms of oscillatory stability as the system damping capabilities have reduced. This paper investigates the potential utilization of the dynamic system identification (DSI) Toolbox, the open source software, for an online oscillatory stability monitoring purposes. Actual measured data based on two oscillation events occurred in Thailand power grid have been used to validate the correctness and effectiveness of the oscillatory frequency mode estimation. Different sliding window lengths to process the measured data along the time window to continuously estimate the oscillatory mode parameters were investigated, and the reasonable window length was then recommended. In addition, the study verified the effectiveness of the damping ratio estimates obtained from the DSI Toolbox and compared against those estimates obtained using the commercial software tool. The results indicates that the DSI Toolbox offers fairly accurate estimation of the oscillation mode information for both ambient noise and forced oscillation periods, and thus its algorithms could be adopted for online oscillatory stability monitoring tool to enhance the system operational capability.