基于行波波形相关性分析的直流输电线路纵联保护方案

直流输电线路差动保护易受故障暂态影响,动作速度慢,有必要研究性能更为优越的纵联保护方案。通过对线路区内、区外故障行波传输过程的分析可知:区外故障时,故障侧前行波与非故障侧反行波为同一行波,波形呈现很强的相似性;区内故障时,一侧的前行波与另一侧反行波为不同行波,波形相似度很小。根据此特征差异,提出了一种基于行波波形相关性分析的快速纵联保护方案。仿真结果表明,所提出的纵联保护方案能够快速识别区内、区外故障,准确检测高阻接地故障,正确判别故障极,适用于不同电压等级直流输电工程,且对数据同步性要求不高。

A Novel Pilot Protection Scheme for HVDC Transmission Lines Based on Waveform Correlation Analysis of Traveling Wave

The differential protection of HVDC transmission lines is easily influenced during fault transient process, which limits its speed of action. Thus, research on a novel pilot protection scheme of better performance is needed. The traveling wave spreading processes in internal and external faults are analyzed. For the external fault, the forward traveling wave on the faulty side and the backward traveling wave on the non-faulty side are the same traveling wave with a strong similarity in waveform. In the case of the internal fault, the forward traveling wave on one side is different from the backward traveling wave on the other with a weak similarity in waveform. According to this feature, a novel high-speed pilot protection scheme based on the waveform correlation analysis of traveling wave is proposed. Simulation results show that the protection scheme proposed is able to rapidly distinguish the internal fault from the external fault, accurately detect the high impedance fault, and correctly identify the faulty pole. The proposed protection is suitable for HVDC systems of different voltage levels and has no high requirements on data synchronization.