To resolve the impact of transient high frequency signals induced by lightning stroke on the travelling wave protection of transmission line, a novel identification algorithm is proposed. Using the characteristics of ...To resolve the impact of transient high frequency signals induced by lightning stroke on the travelling wave protection of transmission line, a novel identification algorithm is proposed. Using the characteristics of symmetric current wave-form induced by lightning stroke without causing fault and that of asymmetric current waveform generated by fault within a very short time interval, the waveform of transient current above and below time-axes are integrated respec-tively. First, through comparing the relative ratio of them with threshold value, the primary criterion identifying fault and lightning stroke is constructed;Secondly, to improve the reliability of discrimination between lightning stroke with and without causing fault, according to the difference of them, the secondary criterion is also defined. The simulation results and analysis demonstrate that the proposed integral criterions are valid and correct.展开更多
针对目前柔性直流(voltage source converter-based high voltage DC,VSC-HVDC)电网的线路保护中存在的问题,提出一种基于双端初始电流行波(Initial current traveling wave,ICTW)时频矩阵相似度的柔性直流输电线路保护原理。首先,对柔...针对目前柔性直流(voltage source converter-based high voltage DC,VSC-HVDC)电网的线路保护中存在的问题,提出一种基于双端初始电流行波(Initial current traveling wave,ICTW)时频矩阵相似度的柔性直流输电线路保护原理。首先,对柔性直流电网在线路区内外故障下两端保护所在处ICTW的故障特性进行分析,总结出在特定时间窗内,区内故障下两端ICTW的频域相似度远高于区外故障。在此基础上,利用S变换对双端ICTW进行时频分析,建立时频矩阵,并对其做奇异值分解(singular value decomposition,SVD)。然后根据特征矩阵构造双端ICTW的相似度计算公式,以该相似度的大小判别线路区内外故障。另外,根据线路两端ICTW的高低频能量比识别雷击干扰。最后,各种故障情况下的仿真结果表明,该保护原理不依赖线路边界元件,可以保护不同长度线路的全长,具有更高的耐过渡电阻和抗噪声能力,并且能够满足柔性直流电网主保护的速动性要求。展开更多
针对目前直流输电线路行波保护耐受过渡电阻能力差的问题,在系统地分析±800 k V直流线路不同故障暂态特性的基础上,提出了一种利用电压比自适应调整保护定值的极线行波保护新原理及其定值整定原则。采用应用于±800 k V云广直...针对目前直流输电线路行波保护耐受过渡电阻能力差的问题,在系统地分析±800 k V直流线路不同故障暂态特性的基础上,提出了一种利用电压比自适应调整保护定值的极线行波保护新原理及其定值整定原则。采用应用于±800 k V云广直流实际工程运维分析的PSCAD/EMTDC详细仿真模型对保护新原理进行验证,结果表明所提保护原理能有效地提高目前行波保护耐受过渡电阻能力和抗干扰能力,且可在现有行波保护软硬件平台上实现,工程实用性强。展开更多
文摘To resolve the impact of transient high frequency signals induced by lightning stroke on the travelling wave protection of transmission line, a novel identification algorithm is proposed. Using the characteristics of symmetric current wave-form induced by lightning stroke without causing fault and that of asymmetric current waveform generated by fault within a very short time interval, the waveform of transient current above and below time-axes are integrated respec-tively. First, through comparing the relative ratio of them with threshold value, the primary criterion identifying fault and lightning stroke is constructed;Secondly, to improve the reliability of discrimination between lightning stroke with and without causing fault, according to the difference of them, the secondary criterion is also defined. The simulation results and analysis demonstrate that the proposed integral criterions are valid and correct.
文摘针对目前柔性直流(voltage source converter-based high voltage DC,VSC-HVDC)电网的线路保护中存在的问题,提出一种基于双端初始电流行波(Initial current traveling wave,ICTW)时频矩阵相似度的柔性直流输电线路保护原理。首先,对柔性直流电网在线路区内外故障下两端保护所在处ICTW的故障特性进行分析,总结出在特定时间窗内,区内故障下两端ICTW的频域相似度远高于区外故障。在此基础上,利用S变换对双端ICTW进行时频分析,建立时频矩阵,并对其做奇异值分解(singular value decomposition,SVD)。然后根据特征矩阵构造双端ICTW的相似度计算公式,以该相似度的大小判别线路区内外故障。另外,根据线路两端ICTW的高低频能量比识别雷击干扰。最后,各种故障情况下的仿真结果表明,该保护原理不依赖线路边界元件,可以保护不同长度线路的全长,具有更高的耐过渡电阻和抗噪声能力,并且能够满足柔性直流电网主保护的速动性要求。
文摘针对目前直流输电线路行波保护耐受过渡电阻能力差的问题,在系统地分析±800 k V直流线路不同故障暂态特性的基础上,提出了一种利用电压比自适应调整保护定值的极线行波保护新原理及其定值整定原则。采用应用于±800 k V云广直流实际工程运维分析的PSCAD/EMTDC详细仿真模型对保护新原理进行验证,结果表明所提保护原理能有效地提高目前行波保护耐受过渡电阻能力和抗干扰能力,且可在现有行波保护软硬件平台上实现,工程实用性强。