Transient Analysis for Ground Fault Distance Estimation in ElectricalDistribution Networks

摘要

The report discusses post fault transient analysis for single phase to groundfault distance estimation in electrical distribution networks. The networks are assumed to be radially operated, and the neutral either isolated or compensated. The composition of ground fault transients, i.e. charge, discharge and interline compensating components, is first discussed. For transient analysis, a new two frequency model is introduced, which takes into account the interdependence of charge and discharge components. According to the theory, the charge transient, which is primarily due to the voltage rise of the two fault free phases, is most suitable for fault location, since it is the lowest in frequency and in most cases also the largest in amplitude. Of the various factors affecting the transients, fault resistance and loads were found to be the most important ones. Also errors of measurement transformers are discussed, and models proposed for the analysis of their transient response. From the other error sources, the effect of fault arc nonlinearity was studied using a simulation model.