中文摘要：

故障行波在故障点与线路终端之间来：回反射，所形成的固有频率与故障距离有明确的数学关系。通过分析固有频率的形成，直流线路故障誊电压源型换流器型（VSG）换流站故障及与VSC联接的交流系统故障情况下固有频率的区别，形成保护判据，对基于电压源型换流器的高压直流（VSC-HVDC）输电线路区内外保护进行研究。在PSCAD／EMTDC建立遗VSC—HVDG系统模型，并在不同故障工况下对该保护方案的适应性进行仿真，大量的仿真结果表明，该保护在不同故障工况下均能可靠、快速动作，具有较好的适应性和实用性。

英文摘要：

Traveling wave travels between fault point and the end of the line, forming natural frequencies which have mathematical relationship with fault distance. By analyzing how natural frequencies form and the difference of the natural frequencies among dc transmission line faults, VSC converter faults and ac system faults, this paper analyzes the internal and external faults of VSC- HVDC transmission line, and forms the protection scheme based on the natural frequencies. VSC-HVDC model is established in PSCAD/EMTDC and lots of simulations on different fault conditions are done with this model. The results show that this method can work precisely and quickly under different fauh conditions and has good adaptability and practical values.