AC Grids Characteristics Oriented Multi-Point Voltage Coordinated Control Strategy for VSC-MTDC

Meshed dc grid technology is an attractive solution to improve the operational reliability of a voltage source converter-based multi-terminal HVDC transmission (VSC-MTDC) system; in addition, the VSC-MTDC becomes widely accepted for the integration of large-scale renewable energy and power supply to passive ac grids. Hence, the performance requirements of the dc voltage control and the power control of the VSC-MTDC system become higher, and this is the key issue of coordinated control strategies for the VSC-MTDC system. Considering that the mainstream coordinated control under the above new situations is facing challenges in terms of dc voltage dynamic control performance or dynamic power deviation, this paper proposes an ac grids characteristic-oriented multi-point voltage coordinated control strategy for the VSC-MTDC system to provide satisfactory dynamic dc voltage control performance with minimized dynamic and steady state power deviations of the converter stations. The theoretical analysis and the simulations results based on PSCAD/EMTDC are to verify the effectiveness of the proposed control strategy.