Feasibility Study of Energy Storage Technologies for Remote Microgrid’s Energy Management System

Energy storage systems (ESSs) play a significant role in remote microgrids energy management system (EMS) with the large penetration rate of renewable energy which is intermittent in nature. Energy storage improves system reliability and efficiency in remote microgrids by optimizing the power demand and generation to reduce operational costs. Moreover, it increases the dispatch ability of the energy sources in remote microgrid systems. Lead acid battery (PbA) can be used as an energy storage device in remote microgrids due to its low cost; however, the response rate, short life cycle, and depth of discharge (DoD) lead to high operational costs. Ultracapacitor has a considerably longer life cycle, its energy density is low, and the initial cost is very high. Lithium-ion (Li-ion) and hybrid ion batteries may have comparatively better economical prospects in terms of DoD, life cycle, and operational cost. In this thesis, different energy storage technologies are considered for remote microgrids energy management systems. In addition, the Schiffer weighted Ah throughput model introduces two weight factors to describe that a battery degrades faster in real time operation than the standard test conditions due to different stress factors. These weight factors virtually increase the battery throughput, and accelerate the degradation. To mitigate this problem, different periodical and auto cycling strategies were investigated in this thesis. However, the results demonstrated that frequent full charging prevents the battery from over degradation. Auto cycling strategy was found more cost effective than the periodical cycling. Applying this cycling strategy, the yearly total operational cost of a microgrid system with a 142 kWh PbA battery bank was reduced by 0.62% ($826). Results also showed that the wear cost is an important factor to consider while designing the energy management system. Li-ion and hybrid-ion batteries had lower wear costs and showed great potentiality, although the EMS with a Li-ion battery was found to be 2.55% more cost effective and 1.5% more fuel efficient than hybrid ion batteries. The reduction in operational cost ensures the access to low cost electricity for the people in remote areas. It will accelerate the development of industries, communications, technologies, and the standard of living including the remote health clinics in those areas. Furthermore, the reduction in generators fuel consumption will reduce CO2 emission which will lower the global warming and the greenhouse effect. In this thesis, one of the objectives was to prolong the battery lifetime by preventing the degradation, that may lower the number of yearly battery disposals which are hazardous to the human health and the environment