Load Flow Analysis of Unbalanced Distribution Networks using Symmetrical Components Based Software

Abstract

This paper presents the algorithm and the main features of a Matlab (R2014a)-based software conceived by the authors for analysis of the asymmetrical operation of the three-phase distribution networks. The software’s algorithm is based on an iterative procedure of Newton-Raphson type. This algorithm is independently applied on three equivalent sequence networks and includes an equivalent model for the unbalanced loads supplied from the analysed distribution grid. In order to outline the capabilities of this software tool named PFASYM and illustrate the key concepts a comprehensive case study was considered. This one summarizes the results of a three-phase load flow analysis performed for a real representative 110/20 kV distribution network supplying industrial unbalanced loads. The PFASYM’s results are validated by comparison with those generated by a proprietary software package. The analysis methodology used in this illustrative case study and the results generated for different grid configurations could assist the grid operator in conducting the power flow studies of operational areas of interest. This work is part of an overall energy systems modelling and analysis project developed by the authors, in collaboration with the local power distribution operator. This one has as objective to facilitate the understanding of the power flow concepts for the present distribution networks operating in asymmetry conditions and to assist the grid operator in applying optimal mitigation measures. images