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An energy management system for a hybrid reversible fuel cell/supercapacitor in a 100% renewable power system
Luta, Doudou Nanitamo
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Hydrogen is likely to play a significant role in the concept of low-carbon power generation in support to renewable power systems. It is abundant, eco-friendly, highly efficient and have the potential to be more cost-effective than fossil fuels provided that the engineering challenges associated with its safe infrastructure development, economical extraction and storage are solved. In the concept 100% renewable power system, a hydrogen production system may be used in conjunction with a fuel cell to form an energy storage system for power balancing and energy shifting to hinder any mismatch caused by potential variation of renewable resources. However, one of the drawbacks of a typical fuel cell is the slow response which may shorten its lifetime in case of several occurrences of sudden load variations above the fuel cell acceptable load. To avoid this issue, a complementary energy storage device with fast power response may be used to deal with sudden load fluctuations and transient regimes. In this research, a renewable power system containing a photovoltaic system and a hybrid energy storage-based fuel cell and supercapacitors is considered. The challenge when dealing with such a system is a proper energy management to coordinate the operation of the overall entity. On the other hand, a well-designed renewable power system implies a technically and economically reliable system. The aim of this research is to develop an energy management algorithm able to maintain the balance between the renewable power system and load and manage sudden load variations. The load considered in this research consists of a three kilowatts variable DC load and a seven kilowatts non-variable AC load. Based on the solar radiation of the selected location, the results of the best possible system to satisfy such a load show a combined set of components consisting of a 29 kW photovoltaic array, a 15 kW electrolyser, a 10 kW fuel cell, a 7 kg hydrogen tank and a 7.6 kW power converter. On the other hand, mathematical models of the components involved into the proposed renewable power system and the energy management algorithm employing rules are developed. A system integrating models of components and the energy management algorithm is simulated using Matlab/Simulink environment. Due to high computing performance requirements, the obtained Simulink model is simulated for a short duration to evaluate the effectiveness of the developed energy management algorithm. The results are presented in four scenarios demonstrating the ability of the system to maintain the balance between the supply and the demand and to manage sudden peak power occurrences.