Insights Into Dissipating Energy-Based Source/Sink Characterization of TCSC and STATCOM for Low-Frequency Oscillations
Kaustav Chatterjee, Sayan Samanta, Nilanjan Ray Chaudhuri
Abstract
Determination of the sources of oscillations in the power system helps operators take appropriate preventive actions. In recent years, the dissipating energy flow (DEF) method has emerged as a promising tool for the online localization of low-frequency oscillation sources. In literature, the mathematical foundation of the DEF method is well-studied for networks with synchronous generators. In this paper, we extend the analysis to flexible AC transmission systems (FACTS). We derive the DEF-expressions for a thyristor controlled series capacitor (TCSC) and a static synchronous compensator (STATCOM) operating with conventional control strategies. Specifically, TCSC with both fixed and variable compensation, and STATCOM in grid-following mode with dc-link voltage and ac voltage-reactive power droop control are considered. Analyzing their respective DEFs, we obtain the conditions for which these FACTS devices could appear as the sources of low-frequency oscillations. Our findings are structured into propositions and are supported through numerical case studies on IEEE test systems.