A novel protection method for VSC-MTDC cable based on the transient DC current using the S transform
A novel protection method for VSC-MTDC cable based on the transient DC current using the S transform
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DOI：
10.1016/j.ijepes.2017.11.007
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发表时间：
2018-04
影响因子：
5.2
通讯作者：
Pu Zhao;Qing Chen;Kongming Sun
中科院分区：
文献类型：
--
作者：
Pu Zhao;Qing Chen;Kongming Sun
基于电压型换流器的多端高压直流输电技术正受到越来越多的研究。本文提出了一种双极型直流电缆的相模变换方法来实现电缆电流的解耦，并分析了故障后暂态直流电流的特点。在此基础上，提出了一种新的直流电缆保护方法。首先，通过S变换提取模式电流的频率分量，并提取高频分量的突变点进行故障检测，确定故障时刻。然后利用零频分量的大小来忽略干扰。最后通过直流电缆两端故障电流分量的极性来识别内部故障和外部故障。在PSCAD/EMTDC中对一个三端VSC-MTDC系统进行了建模，并对各种故障进行了仿真，验证了该方法的有效性。仿真结果表明，该保护方法能快速有效地识别不同故障电阻和距离条件下的内部故障。
Voltage source converter based multi-terminal high voltage DC (VSC-MTDC) transmission technology is attracting more and more research. In this paper, a phase-mode transform method for bipolar DC cable is proposed to decouple the currents in the cables and the characteristic of the transient DC currents after faults are analyzed. Based on the analysis, a novel DC cable protection method is proposed. Firstly, the frequency components of the mode currents are extracted by the S transforms, and the sudden change points of the high frequency components are extracted to detect the fault and determine the fault time. Then the magnitudes of the zero frequency components are employed to ignore the disturbances. Finally, the internal faults are identified from the external faults by the polarities of the fault current components at the two terminals of the DC cable. A three-terminal VSC-MTDC system is modeled in PSCAD/EMTDC, and various faults are simulated to verify the proposed method. The simulation results show that this protection method can recognize the internal faults under different fault resistance and distance conditions rapidly and effectively.