This article presents a tool to calculate the three-phase unbalanced mode of the tension and the current in the North American distribution networks in the presence of integrated renewable energy system (RES). We examine firstly a test North America distribution network (the principal feeder is three-phase, the derivation is single-phase and the neutral is distributed and grounded regularly) including the point connected RES. Then a three-phase unbalanced power flow calculation, which is based on the configuration of the network and takes into account the point of single-phase power injection, is considered. This calculation shows the plan of tension and the passage of current through each phase and each node of the grid. Finally, an algorithm for the unbalance of the tension and the current based on an iterative loop and symmetrical components is coded and simulated in Matlab. The results obtained are tested and validated by comparing with those of the EMTP software which uses the traditional matrix method in his simulation