Investigation of the Impacts of a Multiple-DG Microgrid on the Short-Circuit Levels of a Distribution System

This paper presents an impact analysis of distributed generation high insertion in a microgrid connected to an electric power distribution system, focusing on the short-circuit levels. The study is conducted considering four distributed generator technologies: DFIG, photovoltaic generator, synchronous generator, and induction generator. The investigation was carried out by applying solid three-phase faults in different system buses and considering different scenarios of generators connection, allowing to evaluate the increase of network short-circuit levels due to the individual and collective operation of the distributed generators. The influence of the generators in voltage sags in the system is also analyzed. Simulations were carried out in Simulink® software using a distribution system based on a real feeder. Only the grid-connected mode of the microgrid was considered. The results allowed to evaluate key factors related to the different contributions of each type of distributed generator in the system short-circuit levels and the possible impacts caused by the massive insertion of such technologies.