Robust damping of inter-area oscillations through controllable phase shifters using global signals

This paper demonstrates a robust damping control design for multiple swing modes damping using global stabilizing signals. A multiple-input, single-output (MISO) controller is designed for a controllable phase shifter (CPS) to improve the damping of the critical inter-area modes. The stabilizing signals are obtained from remote locations based on the observability of the critical modes. A H_∞ damping control design based on the mixed-sensitivity formulation in linear matrix inequality (LMI) framework is carried out. The damping performance of the centralized controller is examined in the frequency and the time domain for various operating scenarios. The controllers are found to be robust against varying power-flow patterns, nature of loads, tie-line strengths and system non-linearities, including saturations.