Application of STATCOM for Reducing Stresses due to Torsional Oscillations in Turbine-Generator Shaft

This paper presents the results of a study on the application of the recently developed Flexible AC Transmission Systems (FACTs) device, Static Compensator (STATCOM), for the damping of torsional oscillations that occur in series compensated ac system and its effect on stresses developed at couplings of the Turbine- Generator (T-G) set. The IEEE first benchmark System is considered for this study. In order to suppress unstable torsional mode oscillations, STATCOM with Proportional Integrator (PI) controller to regulate the bus voltage and with an auxiliary signal derived from the generator speed deviation is employed at the generator terminal. In addition, dynamic performance of the non-linear system with optimized STATCOM Controller is evaluated under a three-phase fault in digital time simulation. The Matlab -Simulink is employed to simulate the effect on stresses of T-G shaft. The simulation results also show the reduced stresses of T-G shaft with the application of STATCOM controller.