具有直流故障阻断能力的电流主动转移型MMC

具有直流故障阻断能力的模块化多电平换流器(MMC)是柔性直流输配电技术的重要支撑设备.针对传统半桥型MMC无法阻断直流短路故障的问题,通过结合现有的故障阻断方案,提出了具有直流故障阻断能力的电流主动转移型MMC.该拓扑增加了断流支路、桥臂阻断支路以及能量吸收支路.直流故障发生后,通过断开断流支路,一方面主动转移故障电流...

Active Current-transferring Modular Multilevel Converter with DC Fault Blocking Capability

Modular multilevel converter (MMC) with DC fault blocking capability is the key equipment for the flexible DC transmission and distribution technology. Aiming at the problem that traditional half-bridge MMC cannot block DC short-circuit fault, an active current transferring MMC with DC fault blocking capability is proposed by combining the existing fault blocking schemes. The current breaking branch, the bridge arm blocking branch and the energy absorbing branch are added to the topology. Once a DC fault occurs, the current breaking branch is disconnected to transfer the fault current actively and reverse the arm current simultaneously, and then the fault energy in MMC can be absorbed with half-bridge submodules. Meanwhile, capacitors also operate to absorb the fault energy on the line side during the blocking process of full-bridge submodules in the energy absorbing branch. Thus the short-circuit fault is blocked quickly. The fault blocking mechanism is analyzed in detail by establishing the active current transferring MMC model, and a single-end 100 kV/25-level simulation model is built in MATLAB/Simulink to verify the feasibility and effectiveness of the proposed topology.