Environmental awareness and the need to reduce greenhouse gas emissions have promoted the use of green energy sources such as Wind Energy Conversion Systems (WECS). The Type 4 Permanent Magnet Synchronous Generator (PMSG) with a Full-Scale Converter has grown to be a preferred choice among WECS. Conventionally these WECS are modeled as fixed PQ injections in distribution system analysis studies and for that reason they are not accurately represented. This inaccuracy is accentuated given the large-scale of integration of WECS. To overcome this limitation, this thesis proposes to develop a steady-state model for the Type 4 PMSG WECS to be used in unbalanced three-phase distribution load flow programs. The proposed model is derived from the analytical representation of its six main components: (1) the wind turbine, (2) the synchronous generator, (3) the diode-bridge rectifier, (4) voltage source inverter, (5) the dc-link with a boost converter that connects them, and (6) control mode action. This proposed model is validated through mathematical analysis and by comparing with a Matlab/Simulink model. Subsequently, the proposed model is integrated into a three-phase unbalanced load flow program. The IEEE 37-bus test system data is used to benchmark the results of the power flow method.