Abstract

Electrical power systems have been experiencing significant changes in the latest years. The increasing insertion of energy through renewable sources tends to change the energy matrix, introducing new concepts such as active grids and microgrids.The use of renewable sources is widespread in those grids that can operate connected or islanded. In the islanded condition, the grid is weaker, i.e., has a low short-circuit level and frequency variation, which leads to higher sensitivity to contingencies. For this reason, the monitoring of its operational conditions is essential to understand.This chapter focuses in the concepts of islanded microgrid and its power quality impacts. The monitoring of those power quality phenomena can be used to detect islanding on the grid. It was also cited as the definition of the total harmonic distortion, as well as voltage unbalance and frequency variation. This allows an automated diagnosis which evaluates whether the grid is operating under acceptable conditions or not. Also, this chapter introduces a brief analysis of hosting capacity and related concepts as applied to distribution network systems. Furthermore, it addresses the applicability of hosting capacity study methodologies to harmonic voltage distortion caused by GD and connected to distributions systems.