Abstract: Considering the important role of Distributed Generation (DG) in the future distribution networks there is a need for effective algorithms and models to integrate DGs in distribution system power flow analysis. The forward/backward method is a relatively simple and efficient method that has been widely used for distribution system load flow. This study integrates a more detailed model of DGs in forward/backward power flow formulation. DGs, operating as remote voltage controller or partial unbalance compensator are modeled in this power flow formulation. Also, the conventional operation mode of DGs as constant voltage source and constant power factor system is modeled. The proposed unbalanced power flow algorithm is capable of switching between DG’s different operation modes. The developed software is verified by comparing the results of the distribution system which does not have any DG with the result of IEEE 37 bus test system. Then, the power flow is carried out in various cases to demonstrate the different features incorporated in the developed algorithm and study the impact of different operation modes of DGs on the voltage profile.