Dual-loop primary frequency regulation controller for VSC-HVDC system

This paper presents a frequency control mechanism for an AC system through the active and reactive power loops of a VSC-HVDC system. The proposed scheme makes use of the reactive power loop for inertia support by exploiting the voltage-power sensitivity of loads, and active power droop control has been used to provide governor-like support following the large-disturbance. The performance of the presented controller is evaluated through various simulation case studies in DIgSILENT Power Factory including small-perturbation to demonstrate the effect of the frequency controller in system electromechanical mode damping. From the set of case studies it can be found that the proposed dual-loop control has favorable effects on the frequency behaviour and the inter-area mode damping of the system.