H∞ based fixed order controller for low frequency oscillation in power system

Low-damping inter-area oscillation is a critical issue in power systems. The power transfer capabilities through the tie lines between different areas are significantly reduced due to these oscillations. The power system may lose its stability due to the presence of these oscillations. Inter area modes are better observable from different areas and controllable from one location. Therefore, a wide-area damping controller (WADC) is preferable to enhance the damping of these low-frequency oscillations with the help of a wide-area signal. In this work, a lower-order $H_{\infty}$ WADC is proposed by using the hybrid optimization algorithm-based technique. The feedback signal of the WADC is determined by calculating the controllability index, and the optimal location of the controller is determined by calculating the observability index. A robust PI controller is also proposed for comparison. The effectiveness of the proposed controllers is verified in the New England 10-machine system. It is observed from the obtained results that the proposed secondorder $H_{\infty}$ controller provides better damping performance than a robust proportional integral (PI) controller.