Control Strategy Research of VSC Based Multiterminal HVDC System

The control strategy of VSC based multi-terminal HVDC system is investigated in this paper. DC voltage feed-forward compensation and the controller configuration of double closed loops based on linearized feedback of the input and the output are applied in the controller design of the converter. By this approach the decoupled control of the active and the reactive power can be realized. Meanwhile, the voltage and the current waveforms at the AC sides of the converters can be improved. Also, multi point DC voltage control strategy is proposed in this paper, which can improve the ability of the MTDC system to balance the power and enhance the reliability and economics of system operation. Simulation is performed on a VSC-MTDC system with five terminals and the results show that the proposed control strategy has satisfactory dynamic characteristics and the VSC-MTDC system can persist in supplying AC voltage of good quality to sensitive loads during the disturbances