基于测量波阻抗豪斯多夫距离的三端柔性直流线路纵联保护

Pilot Protection for Three-terminal Flexible DC Line Based on Measuring Wave Impedance Hausdorff Distance

针对大规模新能源场站并入多端柔性直流电网所突显的直流输电线路故障问题,为了使线路保护的可靠性能够得到保障,提出了一种基于测量波阻抗豪斯多夫距离的三端柔性直流线路纵联保护方法。首先分析了所搭建模型中线路在发生区外故障与区内故障时其波阻抗幅值的变化趋势与不同,然后使用改进完全集合经验模态分解提取实验所需测量波阻抗,再利用豪斯多夫距离公式计算出提取出的测量波阻抗之间的距离。通过对此距离的分析,可以区分故障发生区域为区内还是区外。在仿真软件中进行大量故障仿真实验。结果表明,该方法能够使保护非常灵敏且准确地进行动作,从而使直流线路更加可靠地运行。

Aiming at the DC transmission line fault problems highlighted by the integration of large-scale new energy stations into multi-terminal flexible DC grids,a three-terminal flexible DC line pilot protection method based on measuring wave impedance Hausdorff distance is proposed to ensure the reliability of line protection to be guaranteed.Firstly,the variation trend and difference of wave impedance amplitude when the line in the constructed model has an out-of-area fault and an in-area fault are analyzed.Secondly,the measured wave impedance required by the experiment is extracted by using the improved complete ensemble empirical mode decomposition,and then the distance between the extracted measured wave impedance is calculated by using the Hausdorff distance formula.By analyzing the distance,it is possible to distinguish whether the fault occurs is in-area or out-of area.A large number of fault simulation experiments are carried out in simulation software.The results show that the method enables the protection to be very sensitively and accurately,so that the DC line can run more reliably.