# Assessment of the Impact of Electric Vehicle Batteries in the Non-Linear Control of DC Microgrids
## 1 Introduction  
Microgrids received beneficial interest a few years ago. They have significant benefits for the electrical grid and the energy users by using distributed generation (DG) and energy storage systems (ESSs). The benefits include enhancing electricity quality, decreasing pollution, congestion, reducing supply problems, and increasing the energy efficiency [1]. A microgrid could be described as a cluster of loads, DGs, and ESSs operated in conjunction to provide electricity securely and linked to the host power system at the distribution level at the Point of Common Coupling (PCC) [2]. Besides, microgrids can work independently, or they can be connected to a grid based on the voltage type: AC, DC, or hybrid [3]. Generally, microgrids incorporate DG units and energy storage technologies that are focused on renewable energy (RE). Some examples of DG units include PV panels, wind turbines, diesel generators, and microturbines. Some ESS examples include electric batteries, supercapacitors, thermal storage, and flywheels. These are the primary microgrid components, and the main answer for rural areas without primary grid connectivity is considered [4]. AC microgrids have been widely studied in the literature; however, growing attention has recently been devoted to DC microgrids due to their higher reliability, improved performance for various kinds of RE sources and ESS, as well as improved compliance with, among others, DC consumer electronics [5]. Furthermore, as components are linked along a DC bus, no issues exist with reactive power, energy efficiency, and frequency regulation, which leads to a notably less complicated control system [6]. However, various disadvantages must be overcome during the implementation of DC microgrids, like the commitment to construct DC distribution lines, and the safety of DC grids is more complicated [7]. Big cities suffer environmental issues due to internal combustion vehicles. Thus, it is expected that the purchasing of electric vehicles (EVs) would increase to mitigate theseenvironmental issues. Some papers have proposed the control, operation, and planning of DC microgrids with the incorporation of EVs [8; 9; 10]. Moreover, EVs own a key component, which is an electric battery that has recently received considerable attention since it is an energy storage system. Because many utilities and scientists use software simulation packages to model and analyze different problems in microgrid systems, grid components must be modeled in a sufficient way to accurately represent device behavior and performance. However, battery energy storage systems in microgrids have been less studied in the literature, since they are relatively new components [11]. Li-ion batteries are the most mature and commercial technologies used in power systems, such as DC microgrids. However, the integration of Li-ion batteries, like EV batteries, require formal modeling [12]. Different models of batteries have been carried out for a long time [13; 14; 15]. Nowadays, EVs typically own a Li-Ion battery. Some researchers have proposed different modeling for Li-Ion batteries. Some studies consider thermal modeling. For example, in [16], a generic electrothermal model for Li-ion battery is presented. The authors of [17] present the simulation a Li-ion battery pack for a lightweight commercial EV. In [18], an equivalent circuit model, which keeps a straight correlation between its parameters and the battery electrochemical principles, is presented. Some other works have focused on the optimal performance of batteries. For example, in [19], an optimal charging pattern for the high-performance multistage constant current charge method is studied. The authors of [20] presented a nondissipative equalization scheme that is based on fuzzy logic control to improve the inconsistency of series-connected Lithium-ion batteries. Other authors studied models of battery parameters. For example, in [21], the impedance spectra were modeled based on an equivalent circuit model for Li-Ion Batteries.