Design, Implementation and Testing of an Automatic Power Management System for Residential Stand-alone Microgrids with Hybrid Power Supply

The paper presents an automatic power management system (PMS) designed for the on-line operation of an experimental low voltage microgrid equipped with two power supplies, a kW-class fuel cell (FC) and a photovoltaic (PV) module emulator, along with a 100-Ah battery storage system, all connected to a 230 VAC node. The connections of the various components to the common AC bus make use of power inverters with specific functionalities: the FC inverter controls the power production taking into account the FC limitations and requirements, the inverter of the PV emulator tracks its maximum power operating point, whilst, in islanded operating conditions, the bidirectional converter of the battery controls the voltage and frequency of the AC node. The AC node feeds electric active and reactive loads able to reproduce arbitrary and programmable profiles. The automatic PMS is implemented in a real time microcontroller and it is able to provide both the microgrid monitoring and supervisory control during grid-connected and islanded conditions and the FC power scheduling throughout various operating modes. The paper describes also the experimental investigation aimed at assessing the dynamic characteristics of the stand-alone microgrid equipped with the developed PMS.