特高压多端混合直流线路经验模式分解单端保护

Single-end Protection for UHV Multi-terminal Hybrid DC Transmission Line Based onEmpirical Mode Decomposition

针对特高压多端混合直流输电线路T区边界不明显,现有保护难以实现线路全线速动保护,本文提出一种特高压多端混合直流输电线路单端保护方案。首先分析整流侧边界和线路末端逆变侧边界频率特性,根据T区两侧线路电流线模分量突变量极性的差异,提出故障方向判据;然后,利用Teager能量算子计算故障电流线模第1个固有模态分量的瞬时能量,通过该分量瞬时能量的最大值与整定值比较,判断线路首端整流侧及线路末端逆变侧区内外故障,提出特高压多端混合直流输电线路保护方案。最后,搭建昆柳龙特高压多端混合直流输电系统仿真模型并对所提保护方案进行验证,仿真结果表明,该保护方案能准确判断故障位置,实现特高压多端混合直流输电线路全线速动保护。

For the T-zone boundary of an ultra high voltage(UHV)multi-terminal hybrid DC transmission line is not ob⁃vious,it is difficult to achieve a full-line quick protection under the existing protection.In this paper,a single-end pro⁃tection scheme for UHV multi-terminal hybrid DC transmission line is proposed.First,the frequency characteristics of the rectifier-side boundary and the inverter-side boundary at the end of the line are analyzed.Second,a fault direction criterion is put forward according to the polarity difference between the abrupt changes in the line-mode component of current on both sides of the T-zone.Third,the instantaneous energy of line-mode the first intrinsic modal component of fault current is calculated by the Teager energy operator,the inside and outside faults which are on the rectifier-side and at the head of the line or on the inverter-side and at the end of the line are judged by comparing the maximum value of the component instantaneous energy with the setting value,and the protection scheme for UHV multi-terminal hybrid DC transmission line is formulated.Finally,a simulation model of Kunliulong UHV multi-terminal hybrid DC transmis⁃sion system is built,and the proposed protection scheme is verified.Simulation results show that this protection scheme can accurately judge the fault location and realize the full-line quick protection of UHV multi-terminal hybrid DC trans⁃mission line.