# Case Study of Power Plants in the Slovak Republic and Construction of Microgrid and Smart Grid
### Literature Overview  
The issue of microgrid systems is addressed worldwide, in which several publications have been published so far. The design of the economic system for the microgrid was realized in the Yanbu area in Saudi Arabia, where they considered using photovoltaic stations (PV), battery energy storage systems, wind farm, diesel generators, and biomass systems [6]. They have a different approach to this issue in South Korea, where they have applied a microgrid model to a photovoltaic system using energy stored in a pumped hydropower plant [7]. The state of Rio de Janeiro in Brazil considered the appropriate choice of sources to supplement renewable energy sources for the high dependence of fossil fuel power plants, therefore these studies were conducted to evaluate the complementarity of renewable energy sources for hydropower plants, photovoltaic stations, and wind farms [8]. From another perspective, the specific mix of energy sources and their environmental impacts and carbon dioxide (CO\({}_{2}\)) production should also be considered, this issue has been evaluated in Malaysia for the small share of RES and provides a comparison with neighboring countries [9]. In Italy, a study has been carried out in the alpine region to compare combined heat and power (CHP) systems with renewable such as photovoltaic station and run-of-the-river (RoR) hydropower. The use of this combined source system will ensure the same energy satisfaction as in thinking only with only twice the number of RES they do not consider CHP [10]. For the Portuguese power energy system, a study has been carried out on the optimal combination of renewable energy production, specifically for photovoltaic stations, hydropower plants and wind farms based on temporal and spatial diversity. The study shows that to limit the reserve power, it is appropriate to consider the total power of photovoltaic stations and wind farms, which their sum will be lower than the installed capacity of hydropower plants [11]. The issue of the mix of energy sources,  
Figure 1: Comparison of the current power network with the smart grid [5].  
mainly affects fewer developing countries than Bangladesh, where so far, they mainly use gas and oil as energy sources, which does not contribute to reducing carbon dioxide. It is for this reason that it is necessary to solve the problem of microgrid systems and introduce the ready-made solution directly to less developing countries [12]. Compared to other countries, the issue of the energy network in Sudan is considerably complicated by the size and location of the communities. For this reason, it uses small island networks, where they use solar and wind energy with energy storage using compressed air, which, due to their geographical location, are ideally renewable energy sources [13].  
When compiling the energy mix of resources, it is necessary to consider several factors, the main role being played by the daily load diagram and the selection of energy sources in terms of CO\({}_{2}\) minimization, risk minimization, or levelized cost of energy [14].  
The issue of microgrid system analyzes various possibilities of electricity storage, for example, using compressed air energy storage (CAES) and power-to-gas (P2G). The advantage of this system is the possibility of storing any excess energy [15]. The issue of renewable energy sources and their dynamic changes depending on the weather is important to solve, which also results in new or modified control methods that improve the use of energy stored in the battery or another storage system [16].