中文摘要：

由于柔性直流输电系统调节方式和自身结构的特殊性,直流线路的故障电流具有上升速度快、峰值大的特点,极易损坏换流器件和设备绝缘,且柔性直流系统无法通过调节触发角实现故障自清除。因此,对直流线路故障处理和保护提出了更高要求。对于柔性直流线路故障,不仅需要快速且可靠的线路保护对故障进行识别,也需要相应的处理措施和手段对故障后的电流进行有效限制,以减少故障冲击电流对换流器件、直流线路自身以及系统的损害。基于柔性直流输电线路的故障特征,从直流线路故障电流抑制、减少故障影响、线路保护原理等方面,系统地介绍了国内、国外柔性直流输电线路故障处理与保护技术的现状和发展。重点分析了几种辅助电路、新型换流器拓扑和直流输电结构,以及直流断路器在处理直流线路故障方面的性能。探讨了目前柔性直流输电线路故障处理和保护亟须解决的关键问题以及未来进一步的研究方向。

英文摘要：

Owing to the specific mode of regulation and structure of the voltage source converter-high voltage direct current (VSC-HVDC) transmission system,the DC line fault current is characterized by high increasing speed and great peak value. This is extremely susceptible to destruction of converter devices and damage to insulation of equipment.VSC-HVDC system cannot realize fault self-clearing by adjusting the firing angle.Therefore,higher requirements are made on protection and fault handling of DC transmission lines.For DC line faults,not only is reliable and fast protection needed for fault identification,but also corresponding control measures and circuit should be taken to limit the fault current and reduce the damage of the current to converter devices,the DC line itself and system.Based on the fault characteristics of VSC-HVDC transmission lines,the state of the art of DC line protection technology and prospects for application at home and abroad are described.Protection and fault handling technologies of DC lines are summarized and analyzed with respect to fault current limiting,reducing fault impact,and protection principle. The fault handling capability of several protection circuits, converter topologies, DC transmission structures and DC breakers are focused on.Finally,several key issues about protection and fault handling of VSC-HVDC transmission lines and future directions for further research demanding prompt solution are discussed.