Analysis of the torsional modes of the turbine-synchronous generator group

Series compensation of long transmission lines is widely used in electrical power systems in order to reduce losses and increase the transmission line capacity. However, for certain values of compensation, the series connected capacitors interact with the mechanical elements of the turbine-generator group leading to sub-synchronous resonance, which could damage or destroy the generation unit. Due to the severity and undesirable consequences for the generation unit when it is operated under these conditions, it is important to investigate this phenomenon and to determine the series compensation levels that lead to sub-synchronous resonance. This work is dedicated to the mathematical modeling and simulation of the turbine-generator-transmission line group with series compensation for the analysis of the torsional modes, in order to determine the compensating reactance values that can cause the sub-synchronous resonance phenomenon.