Fault location for radial distribution systems using fault generated high-frequency transients and wavelet analysis

Fault location in radial distribution Systems can be divided into two important steps. The first is to identify the fault branch and the second one is to determine the location of the fault in the faulty branch. It is rarely less papers in the field of faulty branch identification. In this paper a new method based on previous works is presented for identifying the faulted branch in distribution system. The proposed method takes advantage of the special properties of wavelet transform to differentiate between faults occurring along different laterals of the same main feeder, with equal distance away form the main substation. The advantages of the method comparing with the previous ones are; a) JMarti line model simulation improvement, b) using a specified rang for s factor instead of a fixed number for a branch of network depend on it's topology c) generalizing the method for untransposed lines and deriving modal matrix for them. The algorithm of this method has been tested for a test radial distribution network. Simulation results obtained by using ATP/EMTP for the sample distribution system are included for demonstration of the proposed method. Faults in distribution systems effect power system reliability, security and quality. Accurate fault location minimize the time needs to restore power and will reduce the costs. The application of traditional fault location techniques that use fundamental voltages and currents at line terminals for distribution lines with tapped load is difficult. In recent years they have been used in conjunction with the concept of traveling ware and wavelet transform [8] In distribution systems, fault location method based on the information provided by DFR is not so common. Usually the fault location is estimated based on the information provided by the customer and is verified by the experienced dispatcher who sends the crew to the suspected location. If the initial estimation is incorrect, the dispatcher will have to make another guess and redirect the crew to the newly suspected location. This procedure may be repeated several times before successful location of the fault, for systems with several laterals emanating from the same feeder. Several new techniques have been proposed in the recent years to address this problem. In [1] a fault location technique for radial transmission lines with multiple loads taps data available only at the source side of the line is presented. A technique based on the high frequency measurement is proposed in [2]. Reference [3] proposed a fault location technique for rural distribution systems based on the apparent impedance method approach. Another technique based on the concept of super imposed components of the voltages and currents rather than total quantities are presented in [4]. Nevertheless, the case of a feeder having multilateral, with measurement normally available only at the substation where multiple possibilities of fault location exist for a given recording has not been fully resolved. The essential problem of such a case is that a number of possible locations by the same electrical distance from the substation can be found for a specified recorded signal at the substation end. Some attempts to address the problem of multiple solutions have been made using knowledge based approaches [5]. They are based on not only the information provided by the measurements but also that information presented in [7] integrated the information available from a substation DFR with the known feeder configuration as well as the protective coordination scheme used for the feeder. This data may not be accurate or even not available at all at the substations.