Transient Protection of EHV AC Line Based on Wavelet Packet Entropy

With the ultra/extra high voltage lines put into operation in the power system, the traditional protection principle is challenged and the research of transient volume protection is paid more and more attention. In the fault transient process, the fault traveling wave will pass through the line boundary with obvious transverse reflection phenomenon. Therefore, this paper extracts the local energy characteristics and overall singularity characteristics of the line fault current for k-means clustering analysis. The difference in the wavelet entropy information of the internal and external fault is used to construct the transient protection criterion, which avoids the difficulty of transient protection settings and realizes the fast and correct action of protection. The results of PSCAD/EMTDC simulation show that the protection method can correctly perform fast fault detection and is little affected by fault location, fault type, transition resistance and line length factors.