基于EEMD和Bartlett检验的混合直流输电线路保护方法

Protection Method of Hybrid DC Transmission Lines Based on EEMD and Bartlett’s Test

混合直流输电系统克服了单一类型的传统直流输电系统和柔性直流输电系统各自存在的缺点,将两种输电系统通过不同的拓扑和连线结合在一起,在高压直流输电领域具有广阔的应用背景。因此,对于混合直流输电系统,如何快速可靠地识别线路故障成为电力系统安全稳定运行地重要研究内容之一。为了可靠且快速地识别线路故障,本文提出了一种基于集合经验模态分解(Ensemble Empirical Mode Decomposition,EEMD)和Bartlett检验的混合直流输电线路纵联保护新方法。本方法利用线路发生故障后首末两端电流变化趋势的差异性,首先采用EEMD算法提取故障电流的低频分量,随后对其变化趋势进行了Bartlett检验,识别区内外故障。在PSCAD/EMTDC仿真软件上搭建LCC-MMC混合双端直流输电系统模型,实验结果证明了本文保护方法的正确性,并验证了该保护方法具有较强的抗过渡电阻和抗噪声能力。

Hybrid DC transmission system overcomes the shortcomings of a single type such as traditional DC transmission system and flexible DC transmission system.It combines the two transmission systems through different topologies and connections.It has a broad application background in the field of HVDC power transmission.Therefore,how to find the line fault quickly and reliably has become one of the important research contents for the safe and stable operation of the power system for hybrid DC transmission system.A new method for pilot protection of hybrid DC transmission lines based on ensemble empirical mode decomposition(EEMD)and Bartlett test is proposed in this paper for Identifying line faults reliably and quickly.This method takes advantage of the differences of the changing trend of the current at both ends of the line after a fault occurs.Firstly,EEMD algorithm is used to extract the low-frequency part of the fault current,and then Bartlett test is conducted on its changing trend to show the faults in and out of the zone.The LCC-MMC hybrid double-terminal DC transmission system model is built on PSCAD/EMTDC simulation software.The experimental results prove the correctness of the protection method in this paper,but also verify that the protection method has strong anti-transition resistance and anti-noise ability.