中文摘要：

VSC—HVDC（voltage source converterHVDC）控制系统复杂，故障承受能力差，研究适用于VSC．HVDC系统的高性能保护十分必要。对VSC．HVDC直流输电系统结构及边界特性的分析发现，输电线路两侧的大电容，因其对高频信号呈现低阻抗的特性，使得输电线路区内、外故障时，直流线路两端保护安装处感受到的电流信号频率成分存在差异。利用此特点，提出一种仅利用单端电流量的VSC．HVDC输电线路全线速动保护新原理，该原理采用高、低频电流的幅值比来区分直流线路的区内、外故障，该比值在区外故障时小，区内故障时大。本原理能够实现区内、外故障的判别，对采样频率要求不高，动作速度快，受过渡电阻影响小。利用PSCAD进行故障分析，大量仿真结果表明，该原理能可靠区分直流输电线路的区内、外故障。

英文摘要：

It is discovered and boundary characteristic system that large capacitors VSC-HVDC transmission line in the research on the structure of VSC-HVDC transmission configured at both ends of appear as low impedances for high-frequency signals, and it affects the protections installed at both ends of HVDC transmission line so that there are frequency differences among the current components sensed by the protections. Using such a feature a new single-end current based quick-action protective principle to protect the whole length of VSC-HVDC transmission line is proposed： the amplitude ratio of high-frequency component of fault current to its low-frequency component amplitude is used to distinguish the fault occurred inside the protection zone from the fault occurred outside the protection zone. The value of this amplitude ratio is smaller for the fault occurred outside the protection zone and lager for the fault occurred inside the protection zone. Using the proposed protective principle, whether the fault is inside or outside the protection zone can be effectively recognized and there is no strict requirement on sampling frequency. The PSCAD based simulation of the proposed protection is performed and simulation results show that the proposed protection is quick-action and slightly affected by transition resistance.