This paper proposes three-phase steady-state models for distributed generators (DGs) with different negative control strategies. An augmented rectangular load flow method is used for three-phase distribution systems. For two types of DGs with power electronic devices: photovoltaic power generators and doubly-fed induction generators, the nodal voltage equations and output power equations are derived. Moreover, under unbalanced conditions, the strategies for mitigating the effects caused by negative sequence components are formulated as functions of the nodal voltage and the injected current. Furthermore, the models are incorporated into an augmented rectangular load flow method with nodal voltage and injected current as state variables in three-phase systems. Case studies are conducted to verify the correctness and accuracy of the proposed models by comparing the results obtained from MATLAB and PSCAD.