This chapter presents the fundamentals to build a monitoring system of an electrical distribution network to detect areas that are operating out of the acceptable limits, established by the international power quality standards. To calculate the power quality (PQ) indices, signal model-based harmonic estimation is carried out using the Prony method, and the PQ indices are employed as inputs to the Petri net (PN). In this context, this document proposes a Petri net-based monitoring system for distribution systems, where different power quality disturbances are analyzed. First, the fundamentals of monitoring will be discussed, such as trends, new challenges, and application by the compliance of existing grid codes. Then, harmonic estimation of the monitored signals will be discussed to estimate the signal parameters according to the Prony method. Finally, the fundamentals of Petri nets are presented, and an application in a distribution network will be considered.
