基于母线关联出线暂态频谱信息的UPFC线路纵联保护

统一潮流控制器(UPFC)作为新一代柔性交流输电系统元件在输电线路中逐渐应用,需要对含UPFC线路的保护原理进行深入研究。通过分析UPFC对线路故障暂态影响,得出高频分量经其串联侧时发生严重衰减,使仅利用单端暂态量的保护可靠性下降。分析母线关联出线的故障暂态特征可知,同一母线的故障侧线路与非故障侧线路的电流频谱分布存在明显差异。通过采用小波能量熵提取母线各出线暂态信息,提出一种适用于含UPFC线路的方向纵联保护方案。仿真结果表明,该方案可准确识别区内、外故障及母线故障,在不同过渡电阻、故障初始角等故障情况下,均具有较好的灵敏性和可靠性。

Pilot Protection of UPFC Line Based on Transient Spectrum Information of Busbar-connected Outgoing Lines

With the gradual application of unified power flow controller (UPFC) as new generation components of flexible AC transmission systems in transmission lines, it is necessary to study the protection principle of the line with UPFC in deep. By analyzing the transient influence of UPFC on fault line, it is concluded that the series side of UPFC has a serious attenuation effect on the high frequency components, and the reliability of non-unit transient protection is reduced. The analysis of the fault transient characteristics of busbar-connected outgoing lines shows that there is a significant difference in the current spectrum distribution between the fault side line and the non-fault side lines for the same busbar. By using the wavelet energy entropy to extract the transient information of each outgoing line of the busbar, a directional pilot protection scheme for the line with UPFC is proposed. The simulation results show that the scheme can accurately identify the internal faults, external faults and bus faults. The scheme also has good sensitivity and reliability under fault conditions such as different transition resistances and fault inception angles.