基于平波电抗器压差特性的直流输电线路保护研究

A Study on the DC Transmission Line Protection Based on Differential Pressures and Features of the Flat Wave Reactor

柔性直流输电技术的发展使得大规模远距离输电损耗较小、更加经济,但输电线路发生双极故障时对系统破坏性极强,需要保护快速识别故障类型并动作。据此对直流输电线路两端的平波电抗器特性及在不同故障类型时两端压差进行分析,得到了区内故障平波电抗器压差与区外故障时的变化趋势差别,并利用斯皮尔曼相关系数构造保护判据。最后利用Matlab/Simulink搭建光伏中压直流输电并网系统进行仿真,验证了该保护判据的有效性。

The development of flexible DC transmission technology can reduce the loss of large-scale and long-distance transmission and make it more economical.However,double-pole faults of the transmission line can cause serious damage to the system,so quick recognition of the types of faults and action of the protection are needed.This paper analyzes the features of the flat wave reactors at the two ends of the DC transmission line as well as the differential pressures at the two ends in different faults,gains the difference of the variation trends of the differential pressures of the flat wave reactors in internal and external faults,and establishes the protection criterion by means of Spearman's rank correlation coefficient.Finally,the photovoltaic medium voltage DC transmission grid-connection system is established for simulation with the help of the Matlab/Simulink,to verify the effectiveness of the protection criterion.