Damping of inter-area power oscillations in hybrid AC-DC power systems based on supervisory control scheme utilizing FACTS and HVDC

Scope of this paper is to present a design process of a supervisory control scheme that optimally coordinates a parallel operation of FACTS devices and an HVDC link to synchronously counteract inter-area oscillations in a power system. The control system is based on Linear Quadratic Gaussian (LQG) optimal control theory. The scheme provides coordinating control signals to the power electronic devices to coherently damp electromechanical oscillations inherent in the system. The scenarios considered involve transient disturbances, signal time delays and reduced system inertia. The feasibility of the proposed scheme is validated on a two-area network incorporating HVDC link, TCSC and SVC devices. The modelling was performed in MATLAB and DIgSILENT simulation environments. Main outcome from this research is the demonstration of improved performance and robustness measures achieved by the novel control scheme, utilizing flexible transmission assets to effectively damp power oscillations in inter-connected power systems.