Formulation of a Power Quality Index of a Radial Distribution Network with Distributed Generation

This paper presents the formulation of a unified power quality index applied to radial distribution networks. The index focuses on voltage sags and total harmonic distortion of voltage, and allows quantifying the impact of connecting photovoltaic sources and nonlinear loads. The formulation is achieved from a sensitivity analysis of the network voltages facing the variations of the feeder and load resistances, and the location and level of penetration of photovoltaic sources and nonlinear loads. The index is applied to case studies on the IEEE 33-node test system. The variation of load and feeder resistances, the connection of a photovoltaic source with a specific harmonic injection, and a motor variable speed drive are considered in the case studies. For those connections, the level of penetration can reduce the power quality, and the connection of the nonlinear load causes its greatest reduction. The index classifies the nodes according to their power quality.