Electrical networks fed by fuel-cells for uninterruptible electrical supply

For customer satisfaction a reliable and stable supply is required. Electric loads characteristics often make it a necessity to adopt back-tip energy sources, which, coupled with the main one, are able to satisfy load requirements in terms of continuity and quality. For special applications, which require a high continuity source, it is necessary to combine the main electric energy source with UPS sources, which consist of a DC battery and a rotating electric generator, which supports the finite capacity of the battery pack. The research is actually devolved to study electric power systems, which, characterised by high reliability and low maintenance costs, present also low pollution and noise level: in particular, it is already carrying out tests to use UPS, which are equipped with fuel-cell systems. When the duration of power outage/requirement is uncertain, the fuel-cell system is an ideal power source, which keeps generating power required by the loads, as long as a sufficient quantity of hydrogen and oxygen is provided. In the paper, the design for a fuel-cell-based inverter system is discussed. The defined fuel-cell characteristics are, in particular, focused on the possibility of selecting between battery or ultracapacitor-based energy storage device with reference to their features in terms of electrical and reliability aspects.