AN IMPROVED FAULT ANALYSIS ALGORITHM FOR UNBALANCED MULTIPHASE POWER DISTRIBUTION-SYSTEMS

The results of an improved method for fault calculations in unbalanced multi-phase power distribution systems containing non-utility generat ors and large induction motor loads are presented in this paper. The m ethod utilizes a combined time- and frequency-domain analysis approach to produce results that are superior to those obtained in ''classical '' fault analysis without demanding the large increase in computer tim e associated with complete time-domain solutions. Sources and loads ca n be represented by either classical frequency-domain models or detail ed differential equation models. The potentially unbalanced power dist ribution system is represented by an admittance matrix formed using a linear graph-based application of ac circuit theory. The time-domain d ifferential equation source and load models are interfaced with the fr equency-domain distribution system model using time series analyses to estimate equivalent voltage and current phasors from discrete data se ts.