Fixed low-order synchronized and non-synchronized wide-area damping controllers for inter-area oscillation in power system

Abstract

Low-frequency poorly damped oscillation is a major threat to bulk power transmission through a weak tie-line in the interconnected power system. A wide-area damping controller (WADC) can provide an adequate damping to these low-frequency modes to achieve secure operation of the large power system. In this work, a hybrid optimization algorithm based fixed low-order WADC is designed using wide-area feedback signal to improve the damping of poorly damped inter-area mode. Although wide-area signal can be used to improve the damping of the inter-area oscillations, the introduction of time delay in the wide-area signal can degrade the controller performance and even may lead to instability. Here, two types of delayed (synchronized and non-synchronized) feedback configurations are considered in case of wide-area signal transmission, and the controller is designed by optimizing the design functions such as H∞ norm, spectral abscissa and complex stability radius. The designed controllers enhanced the damping performance of the inter-area oscillations. A higher order mixed sensitivity based H∞ controller is also designed with additional pole placement constraints for comparison with the design functions. From the simulation studies of the Kundur’s two-area system and IEEE-39 bus test system, it is demonstrated that the fixed low-order controllers are effective to improve the damping of the inter-area oscillations and compensating the time delay effect in the wide-area signal.