MMC-HVDC Testing and Simulation Based on Physical Simulation System

For the ever increasing power rating and voltage level of modular multilevel converter (MMC) based HVDC, it becomes more and more difficult for digital simulation system to reflect the energy fluctuation and control characteristic, as well as the valve based controller (VBC) full function testing. This paper developed a 200-level, 1200 sub-modules (SM) physical simulation system based on similarity theory for MMC-HVDC control and protection device test and project simulation. Taking the ±320kV/1000MW MMC-HVDC project in Xiamen, China as the study case, the control and protection device full-function test and project simulations are performed. An improved SM capacitor voltage balancing control is proposed for large-scale MMC-HVDC project. The physical simulation experiments and digital simulation results verify the correction of the proposed control strategy.