# On Hybrid Nanogrids Energy Management Systems--An Insight into Embedded Systems
## 1 Introduction  
Between 2009 and 2019, global energy consumption witnessed a 21% increase and is expected to grow by over 50% by 2050 [1]. To meet this escalating demand, the world's energy production in 2018 reached 14,421 million tons of oil equivalent (Moe), with fossil fuels accounting for more than 81% of the total production [2]. However, the adverse environmental impacts, including greenhouse gas emissions, have led the international community to address climate change, resulting in the signing of the Paris Agreement in 2016. The objective of this agreement is to significantly reduce global warming and the associated risks of climate change. In this context, renewable energy sources are expected to play an important role in achieving the objectives outlined in the COP21 agreement for a sustainable and decarbonized future [3]. To ensure a consistent power supply, it is essential to manage energy flows (including production, consumption, and storage) in an optimal manner. An energy management system (EMS) is necessary to effectively manage the distribution of energy to different loads and storage systems. This is especially important for renewable energy sources, as their intermittency requires advanced prediction of production, storage capacity, and consumption needs. By integrating these various constraints, an EMS can help minimize energy losses and ensure efficient energy usage. In the context of modern energy management, a nanogrid emerges as a small-scale power grid that can operate independently or in parallelwith a larger grid. Hybrid nanogrids particularly highlight the incorporation of various energy sources, enhancing the adaptability and robustness of the energy management system. In the context of applications of nanogrids, an embedded context refers to situations where nanogrids are integrated into or used as part of other systems or devices to enhance local power distribution and management. A nanogrid is similar to a microgrid, but it is a scaled-down version of it and often has lower power and less complexity than microgrids [1; 2; 3; 4; 5]. According to [6], a distributed island resource system (considered a microgrid) meets four requirements: (i) integrate DERs and loads; (ii) have the capability of being disconnected (in parallel) from the electric power system; (iii) contain the local electric power system; and (iv) be purposely planned [7]. While microgrids have undergone significant standardization efforts due to their relatively large size and impact on the overall grid, nanogrids, despite their popularity, lack a clearly defined standard to the same extent [8]. Some references provided a definition for the term nanogrid using the following statements:  
* \"a single domain for voltage, price, reliability, quality, and administration\" [9]. * \"a small power system that uses a combination of renewable and non-renewable energy sources to supply power to small local loads\" [10]. Additional definitions are cited in [11]. Nanogrids are characterized by their compact size and flexible functionality. This complex system includes diverse types of electrical equipment, along with a combination of renewable and non-renewable energy production sources. Additionally, nanogrids are integrated with energy storage systems, further enhancing their capacity to deliver reliable and sustainable power solutions [11; 12; 13; 14; 15; 16; 17; 18; 19; 20; 21; 22]. Despite being a relatively new area of research in the field of power systems, nanogrids are gaining interest from both small and large research groups worldwide [23]. This is evident from the keyword searches for \"microgrid\" or \"nanogrid\" and \"energy management\" in the Elsevier and IEEE databases shown in Figure 1.  
Despite the promising potential of renewable energy sources such as solar, wind, and tidal power, their intermittent nature presents many challenges. As a result, energy storage systems (ESS) have emerged as an essential component of renewable power plants, improving their reliability and dispatchability.