基于时域电压比的高压直流输电线路暂态保护方案

针对传统行波保护在高压直流输电线路中耐受过渡电阻能力不足、T区两侧故障线路定位依赖边界元件等问题，以最具代表性的多端混合高压直流系统为例，从数学层面上分别明晰了高压直流输电线路区内外故障和T区故障下的行波特征，进而构造了不同采样周期下的时域暂态电压比判据，以削弱T区和过渡电阻的影响，实现区内外故障识别；利用时域电压比判据，提出了基于单端量保护配合的高压直流输电线路暂态保护方案，实现了高压直流输电线路故障的快速判别以及T区两侧故障线路的准确定位；最后，利用实际工程的电磁暂态仿真模型对所提方法进行详细验证，结果表明，所提保护方案可行且具有较高的灵敏性和可靠性。

Transient Protection Scheme of HVDC Transmission Line Based on Time-domain Voltage Ratio

To address the issues about the application of traditional traveling-wave protection on high-voltage direct current (HVDC) transmission lines, such as the insufficient endurance of fault resistance and the dependence of faulty line location around the T zone on the boundary elements, this paper takes the most representative multi-terminal hybrid HVDC system as an example, and mathematically clarifies the traveling wave characteristics of internal faults, external faults and T-zone faults on HVDC transmission lines. Then the time-domain transient voltage ratios with different sampling periods are constructed to reduce the impact of T zone and high fault resistance, thus realizing the internal and external fault identification. Using the time-domain voltage ratio criterion, a transient protection scheme of the HVDC transmission line based on the coordination of single-end protections is proposed to realize the fast fault identification of the HVDC transmission line and the accurate faulty line location on both sides of the T zone. Finally, this paper adopts the electromagnetic transient simulation model based on an actual project to verify the proposed method in detail. The results show that the proposed scheme is feasible with high sensitivity and reliability.