Contribution Factors Based Optimal Selection of Wide-area Signals for Power System Damping Control

Abstract

—Common wide-area signal selection methods hardly guarantee the control effect of a closed-loop system. In addition, signals selected by these methods could not adapt to different types of controllers and have poor robustness against system uncertainty. Addressing these problems, an optimal signal selection method based on the contribution factor is proposed in this article to improve the damping effect of feedback signals. First, the damping effect of different feedback signals on eigenvalues of closed loops is quantified by the interval extension theory and perturbation theory. On this basis, the concepts of the contribution factor and contribution factor sum are proposed. Then optimal signals are chosen due to the contribution factor sum, which indicate the overall damping effect. Time-domain and frequency-domain simulation results of an IEEE 4-machine 11-bus test system and an IEEE 16-machine 68-bus test system demonstrate that the proposed optimal signal selection method is capable of coordinating different supplementary controllers and different control laws. Furthermore, the damping ratio of the system is significantly improved using the selected feedback signals with the similar effect of using all signals. Meanwhile, the proposed method is verified to show robustness against uncertainties in the system operation mode.