A New Improved Coordination Control Strategy for MMC Based Multi-terminal HVDC Systems

For MMC based multi-terminal HVDC systems, ensuring steady operation of the system, the system control strategy is the prior problem. The basic require of the system control strategy is to re-establish voltage and power balance of dc grid when a converter is tripped and suppress the oscillations and transients. A new improved coordination control strategy is proposed in this paper which combines the improved voltage margin control scheme and power deviation control method. Simulations done with an five-terminal HVDC system in PSCAD/EMTDC are exploited to discuss and assess the advantages of it. The simulation results prove that the re-established power and dc voltage balanced is close to origin reference value. And the strategy can also suppress the oscillation of dc voltage and power…