Neutral-point shifting and voltage unbalance due to single-phase DG units in low voltage distribution networks

Abstract

When distributed generation (DG) units are connected to a low voltage (LV) single-phase distribution network the voltage profile will change. The connection of single-phase DG units to three-phase distribution networks will not only alter the voltage profile in the connected phase, but also the two other phase voltages will be influenced due to neutral-point shifting and voltage unbalance. The purpose of this paper is to examine the influence of single-phase DG units on the phase voltages, in different circumstances. This will be investigated by performing several simulations. In order to make these detailed simulations, an unbalanced multiphase harmonic power flow method, considering the neutral wire, will be proposed. The presented model uses the iterative forward/backward method. Furthermore, the network is solved by using symmetrical components and the prevalent convergence problems will be tackled in this paper.