PMU based identification of low frequency oscillations — A case study

Abstract

The Indian electrical grid is one of the largest & complex networks in the world. Such complex system is subjected to stress or disturbances which manifest in the form of low frequency oscillations. Monitoring of these oscillations is necessary as they can disrupt the system if they are sustained for a longer period of time with significant magnitude. This paper presents the analysis of low frequency oscillation modes using the data from Phasor measurement units located at two extreme parts in Western region. It reports a case study of an event that occurred in the Western & Eastern regions of Indian power grid. The modes with low frequency oscillations were observed in Western region of the Indian grid. The Prony & Matrix Pencil techniques were used to identify the oscillatory modes in system during the occurrence of the event. The importance of identifying dominant mode, computation of non-dominant oscillatory modes & the role played by phasor measurement unit & their locations has been brought out in this paper.