Investigation of voltage stability in unbalanced distribution systems with DG using three-phase current injection based CPF

Because of slow expansion of unbalanced distribution systems and fast growth of load, as well as the increased DG penetration level, voltage stability becomes an important issue for the proper operation of distribution systems. In this work, a three-phase current injection based continuation power flow was proposed and implemented to compute the three-phase PV curve of distribution systems. Different load models and load connections were considered, as well as DG in PQ or PV control mode with reactive power limit. Detailed implementation of the proposed method was described. IEEE 13-node test feeder was modeled and several case studies were performed to investigate the impact of various factors on the voltage stability of the unbalanced distribution system.