Simulation Study Of The Power Cable Fault Location

Off-line fault location for power cable and on-line fault location for overhead transmission line have been accomplished in the past several decades. Nowadays power cable systems are in great need of on-line fault location technologies. Before achieving this goal, several important and difficult problems should be thought of carefully. First, whether or not can effective traveling wave due to cable fault be found to locate the fault point in cable system whose transformer neutral point not directly grounded? Second, what's the characteristic of the traveling wave during its propagation? Third, will the fault point characteristic affect the traveling wave? Fourth, how will the traveling wave change at the measuring point? And the last but not the least, how to determine accurately the arrival time of the traveling wave?This paper created a sample power cable system model with a transient simulation tool PSCAD/EMTDC based on a 35kV XLPE power cable. Within this model, the characteristic of fault current is simulated in different grounding modes, and so to answer the question whether or not effective traveling wave can be found in cable system whose transformer neutral point not directly grounded. The characteristics of fault point and measuring point are simulated to determine their effect to traveling wave. Besides, a spectral analysis is made to the fault current traveling wave.The factors affecting the location accuracy is discussed and using wavelet transform and local module maximum method to find break point is adopted. As a case, on-line fault location is made to a sample power cable using two wavelets separately, and thus to validate the feasibility of on-line fault location.