A novel method of fault identification for dc line based on the correlation of transient current is proposed to improve the fault-handling ability of VSC-HVDC transmission system.The difference of the transient current at parallel capacitor branch and dc line entrance is significant between the internal and external fault of dc line.Pearson correlation coefficient is used to measure the difference between the transient currents,by which the fault identification can be achieved easily by calculating the correlation coefficients at both ends of the faulted line.The proposed method is able to eliminate the influence of the contribution from non-faulted line and it is suitable for two-terminal and multi-terminal VSC-HVDC system.The results of the analysis and the simulations show that the proposed method is able to identify the internal and external faults of dc line and select the fault line accurately without the influence of high-frequency component,data synchronization,fault types and fault location,noise interference and the control mode of VSC-HVDC system.%为提高柔性直流(VSC-HVDC)输电系统的直流线路故障处理能力,提出了一种基于暂态电流相关性的直流线路故障判别方法.直流线路发生区内、外故障时,直流线路两端的电容支路暂态电流与直流线路入口处暂态电流特征差异明显;利用Pearson相关系数来描述电容支路与线路入口处暂态电流的差异程度,直流线路故障的判别仅通过线路两端计算的暂态电流Pearson相关系数即可实现.该故障判别方法可克服非故障线路馈入电流的影响,适用于两端以及多端柔性直流输电系统.分析和仿真结果表明,该故障判别方法不受高频分量、数据同步、故障位置与类型、噪声干扰以及控制方式等因素的影响,能准确地识别直流线路区内、外故障,实现故障线路的选择.
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