Abstract-The paper presents a microcontroller-based power management system (PMS) designed for the online operation of an experimental low voltage microgrid equipped with a battery storage system and two power supplies: a kilowatt (kW)-class proton exchange membrane (PEM) fuel cell (FC) and a photovoltaic (PV) module emulator, both connected to a low voltage ac node. The connections of the energy sources to the common ac bus make use of power inverters with specific functionalities. The ac node feeds electric active and reactive load emulators able to reproduce programmable profiles. The automatic PMS provides the microgrid monitoring and the FC power scheduling in both grid-connected and islanded operating conditions. The paper describes the structure and functionalities of the PMS as well as a specific experimental investigation aimed at assessing the dynamic performance of the microgrid in islanded conditions. Index Terms-Battery, digital microcontroller, electrical microgrids, fuel cell (FC), photovoltaic (PV) emulator, power management system (PMS).

In this paper an investigation on the performance of a commercial Proton Exchange Membrane (PEM) fuel cell, tested at the laboratories of the University of Bologna, is carried out. The investigation takes into account the management of anodic exhaust and relevant effects on the flooding phenomenon. To address the problem of flooding, it is necessary to run periodically the purge process of the fuel cell (FC) resulting into an overall decrease of the efficiency of the transformation process. This operation is performed by opening the so-called Outlet Control Valve (OCV) located along the anodic exhaust line. The aim of this analysis is to optimize the purge process to: (i) increase the FC lifetime, (ii) reduce the amount of hydrogen that is discharged with water and (iii) increase the FC efficiency. An investigation on the benefits in terms of fuel utilization factor and costs, resulting from optimization of the FC purge process, has been analyzed.

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PEM (Proton Exchange Membrane) fuel cells show characteristics of high power density, low operating temperature and fast start-up capability, which make them potentially suitable to replace conventional power sources (e.g. internal combustion engines) as Auxiliary Power Units (APU) for on-board applications. This paper presents a methodology for a preliminary investigation on either sizing and operating management of the main components of an on-board power system composed by: i) PEM fuel cell, ii) hydrogen storage subsystem, iii) battery, iv) grid interface for the connection to an external electrical power source when available, and v) electrical appliances and auxiliaries installed on the vehicle.A model able to reproduce the typical profiles of electric power requests of on-board appliances and auxiliaries has been implemented in a computer program. The proposed methodology helps also to define the sizing of the various system components and to identify the fuel cell operating sequence, on the basis of the above mentioned load profiles.