基于不对称双子模块的混合MMC及其直流故障自清除能力

摘要

柔性直流输电技术及能源互联网的迅速发展,大大拓展了电力电子变流技术在电力系统输配电领域的应用.由于柔性直流输电架空线路较常出现瞬时性故障,研究了具有直流故障自清除能力的不对称双子模块结构.首先,详细阐述不对称双子模块的拓扑结构、工作原理和控制方法.在此基础上,详细分析不对称双子模块的直流故障自清除能力,并具体分析计算了不对称双子模块的损耗.然后,针对不对称双子模块损耗高于半桥型模块化多电平换流器(MMC)的问题,提出不对称双子模块和半桥子模块组成的混合MMC系统结构,并给出了两类模块个数的配置原则.最后,利用MATLAB/Simulink仿真软件给出直流侧瞬时故障情况下混合MMC系统的仿真波形,验证了混合MMC系统的直流故障自清除能力.%The rapid development of voltage source converter based high voltage direct current transmission (VSC-HVDC) technology and Energy Internet have greatly expanded the application of power electronic conversion technique in the field of transmission and distribution of the power system.Because of the frequent appearance of instantaneous fault on overhead lines of VSC-HVDC, the structure of asymmetrical double commutated cells (ADCC) with DC fault clearance capability is studied.First, the topology, operating principle and the control algorithm of the ADCC are given, the loss of ADCC is analyzed and calculated.Faced with the higher loss in the ADCC based multi-modular converter than that in the half bridge multi-modular converter, the structure of hybrid multi-modular converter with ADCC and half-bridge cell combined is proposed.Furthermore, the design principle of the hybrid multi-modular converter is also proposed.Finally, the DC fault clearance capability of the hybrid multi-modular converter is verified by simulation waveforms of the hybrid multi-modular converter in transient fault at DC side in MATLAB/Simulink software.