Unbalanced three-phase continuation power flow for distribution networks with distributed generation

Continuation power flow is an important tool for assessing power system voltage stability. A continuation power flow method for distribution networks is proposed in view of unbalanced three-phase lines and loads in distribution networks with distributed generations (DG). The proposed method consists of tangent predictor and Newton corrector. A local geometric parameterization technique is utilized for the characteristics of the P-V curves of unbalanced three-phase systems. A double-switching logic is proposed for handling the capability constraints of DGs which modeled as PV and PQ buses. A scheme for identifying the type of bifurcation is also given. Simulation results on IEEE 33-bus distribution system show that the proposed method is effective in tracing the P-V curves of three-phase distribution systems and computing the voltage stability critical point as well as identifying the type of bifurcation.