A New Adaptive DC Voltage Droop Control for Hybrid Cascaded HVDC Transmission System

Abstract

Hybrid cascaded multi-terminal HVDC transmission technology is a research hotspot in the field of DC transmission. The system topology adopts line commutated converter (LCC) converters at the sending end and high-end LCC converters at the receiving end in series with multiple low-end MMC converters. When the modular multilevel converter (MMC) occur an AC side failure or a blocking failure, the surplus power in the system will cause DC voltage overvoltage, which will endanger the safe and stable operation of the system. This paper proposes a master-slave control with adaptive droop characteristics, which can fully absorb the unbalanced power in the system under the premise of ensuring that the converter is not overloaded. Finally, a simulation example is used to verify the effectiveness of the proposed control strategy.