基于多分辨形态梯度的行波距离保护方案

为解决现有的行波距离保护方案无法有效识别正方向区内、外故障,利用超高压输电线路母线杂散电容及线路末端阻波器对高频暂态信号强烈的屏蔽作用而导致行波通过母线前后波前时间的差异,提出一种基于行波波前时间比较法的行波距离保护新方法,并使用多分辨形态梯度提取波前时间构成保护方案。理论分析与仿真研究证明,这种保护能正确识别正方向区内、外故障,有较高的准确性和可靠性。

New Scheme of Traveling Wave Distance Protection Based on Multi-resolution Morphological Gradient

High fault cutting speed with fault location are required for extra-high-voltage transmission line protection relay. Based on the fact, traveling wave distance protection was researched greatly by many people because of its integrated function including protection and fault location without communicating on transmission lines. For traveling wave distance protection existed now can not distinguish the internal and the external fault effectively when a forward fault occurred, it can be not used in practice rapidly. Lots of research recently years proved, stray capacitance exists on the bus of extra-high-voltage transmission line and it has great filtering function to high frequency transient signals, at the same time trap filter fitted on the terminal of the line also has great filtering effect to high frequency transient signals. The filtering function mentioned above make the great difference for traveling wave before and after it pass the bus, the gradient of traveling wave front is very high so the wave front time is quite short because the traveling wave has lots of high frequency signals before it pass the bus bar, on the contrary the wave front time become long because majority of high frequency signals are filtered after the traveling wave pass the bus bar. Basing on the fact above, the paper proposed a new traveling wave distance protection scheme by using the difference of traveling wave front time before and after its passing bus. At the same time, multi-resolution morphological gradient was used skillfully to abstranct the wave front time for protection scheme composing. The protection proposed in this paper can distinguish the internal and external fault correctly when a forward fault occurred which was proved by theory analysis and simulation research, and the conclusion was effective and reliable.