Fault position relay based on current travelling waves and wavelets

The current travelling wave is utilized to detect the fault position in the transmission lines in this paper. How to identify the incident travelling waves and reflected ones from the fault point when noises exist is discussed and resolved. A fault position relay based on current travelling waves and wavelets theory is designed. The relay's principle is mainly on wavelet theory and modulus maxima of the wavelet transform. By analyzing the distribution of the modulus maxima, different components in the current travelling waves can be distinguished and then the incident and reflected travelling waves are identified and finally useless components are filtered. The incident and reflected travelling wave's time difference arrival time difference indicates the fault position. An EMTP simulation example is illustrated. The relay is been proved correct and effective.