A novel control of VSC-HVDC for improving power quality of an industrial plant

In this paper a novel control system for the VSC-HVDC supply of an industrial plant is proposed. The dynamic performance of the system is investigated during unbalanced faults. The control system of the VSC-HVDC consists of an outer controller and a vector current controller through phase reactors, an ac filter and a transformer. The impact of the current limit of the VSC-HVDC converters is also studied. The modified inner current controller is proposed to avoid overcurrent. Simulation results of the studied system, using PSCAD/EMTDC, show that the proposed control strategy can fulfill the objective of controlling the dc voltage on the dc link, the ac voltage and the frequency at the point of common coupling. A comparison between a pure ac supply and a VSC-HVDC supply shows that the use of a VSC-HVDC supply significantly enhances the quality of power supply to the industrial plant.