Damping subsynchronous resonance using a novel excitation controller

A novel supplementary subsynchronous damping controller (SSDC) is proposed for the generator excitation system which is capable of damping out subsynchronous oscillations in power systems with series compensated transmission lines. The offered SSDC uses a filtered feedback from generator acceleration power signal and after passing through a proportional gain it is added to automatic voltage regulator (AVR) output. Two filters are used and the cut off frequencies are specified intelligently in order to affect only the modes that are critical to damping capability of the system. The IEEE second benchmark problem is considered as the studying system. The simulation results proved that the designed controller can be successfully used in damping the oscillations for the all series compensation ratios even when small and large disturbances influence the system. Simplicity, practicality and high performance of the offered controller are other advantages of the proposed controller.