Central Distance Theorem and Cable Fault Location

The precision of cable fault location of traveling wave method is subjected to the uncertainty of the traveling wave speed. To solve this problem, the central distance theorem is presented after three new concepts of scaling time, scaling speed and central distance are defined based on wavelet analysis and multiresolution analysis. The relationship between the central distance, the scaling speed, sampling frequency and the number of the first modulus maximum of wavelet reconstructing signals is described by the central distance theorem. The scaling times of a component of traveling wave can be found in the method of the central distance theorem. This eliminates the disturbances of the other frequency components in sampling signals. Finally, simulation example shows that the mean relative error is 0.1% in cable fault location based on the central distance theorem. They are remarkably less than that of the common used methods