Abstract The traditional current differential protections for HVDC transmission lines are easily affected by distributed capacitive current. Although some improved differential principles have been presented in literatures, they still risk maloperation caused by synchronization error, noise or parameter errors. To overcome the problems above, this paper proposes a novel pilot protection scheme based on waveform matching. After the electrical quantities on both sides are low-pass filtered, the HVDC line is simplified to two PI models from the midpoint, which can eliminate the effect of distributed capacitive current and has simple computation as well as satisfying precision. The midpoint currents, which can be calculated based on the simplified DC line model with the information of either side, will be matched under external faults while have opposite trend under internal faults. The improved Pearson correlation coefficient (IPCC) is proposed to measure the similarity between the waveforms of the calculated midpoint currents and establish the protection criterion. A ± 800 kV HVDC test system is modeled in PSCAD/EMTDC. Extensive simulations of various fault situations indicate that the new protection has absolute selectivity, great reliability and strong fault resistance withstand ability. Sensitivity analysis and comparisons with other pilot protections further demonstrate that the proposed protection stands out for high accuracy and strong robustness to many non-ideal factors.

中文翻译：

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基于波形匹配的高压直流线路导频保护新方案

摘要 传统的高压直流输电线路电流差动保护容易受到分布容性电流的影响。尽管文献中已经提出了一些改进的差分原理，但它们仍然存在由同步错误、噪声或参数错误引起的误操作的风险。针对上述问题，本文提出了一种基于波形匹配的导频保护方案。对两侧电量进行低通滤波后，HVDC线路从中点简化为两个PI模型，可以消除分布容性电流的影响，计算简单，精度满足。中点电流，可基于简化的直流线路模型计算，其中包含任一侧的信息，外部故障时匹配，内部故障时趋势相反。提出了改进的皮尔逊相关系数(IPCC)来衡量计算出的中点电流波形之间的相似性并建立保护标准。± 800 kV HVDC 测试系统在 PSCAD/EMTDC 中建模。对各种故障情况的大量模拟表明，新型保护具有绝对的选择性、可靠性和抗故障能力强。敏感性分析和与其他飞行员保护的比较进一步表明，所提出的保护具有对许多非理想因素的高精度和强鲁棒性的突出优势。提出改进的皮尔逊相关系数(IPCC)来衡量计算出的中点电流波形之间的相似性并建立保护准则。± 800 kV HVDC 测试系统在 PSCAD/EMTDC 中建模。对各种故障情况的大量模拟表明，新型保护具有绝对的选择性、可靠性和抗故障能力强。敏感性分析和与其他飞行员保护的比较进一步表明，所提出的保护具有对许多非理想因素的高精度和强鲁棒性的突出优势。提出改进的皮尔逊相关系数(IPCC)来衡量计算出的中点电流波形之间的相似性并建立保护准则。± 800 kV HVDC 测试系统在 PSCAD/EMTDC 中建模。对各种故障情况的大量模拟表明，新型保护具有绝对的选择性、可靠性和抗故障能力强。灵敏度分析和与其他飞行员保护的比较进一步表明，所提出的保护对许多非理想因素具有高精度和强鲁棒性。可靠性高，抗故障能力强。灵敏度分析和与其他飞行员保护的比较进一步表明，所提出的保护对许多非理想因素具有高精度和强鲁棒性。可靠性高，抗故障能力强。灵敏度分析和与其他飞行员保护的比较进一步表明，所提出的保护对许多非理想因素具有高精度和强鲁棒性。