# Virtual Power Plant Optimization in Smart Grids: A Narrative Review
## 4 VPP Applications in Smart Grids
### Energy Communities' Sustainability  
Fundamental for increasing the adoption of VPPs are the customer engagement strategies and underlying measures for voluntary participation [93]. Decentralized renewable energy and digitalization allow new ways for engagement through energy cooperatives and citizen energy communities [111]. The EU energy regulation provides an enabling framework for citizen energy communities as well as renewable energy communities [112]. VPPs are keys to ensuring that the prosumers and local communities take the front seat and co-create innovations that are aligned with their values and expectations (e.g., comfort, well-being, prices, etc.) [52]. These developments further provide opportunities for support of additional values and VPP management and optimization. A concrete example is a VPP of electric vehicle sharing within the local community, powered by their electricity, and used for storage, with multiple users such as citizens, companies, volunteer organizations, municipality personnel, etc. [102] (see Figure 6). The engagement of citizens and communities in such a local energy system increases the trust, identity, and the sense of community [101]. \begin{table}
\begin{tabular}{c c c} \hline \hline \multicolumn{2}{c}{**Resources Integration in VPPs**} & \multicolumn{1}{c}{**Approach**} \\ \hline \multirow{4}{*}{Controllable loads} & Energy Storage & [78; 79; 80; 81; 89; 92; 94] \\  & Renewable & Hydro & [79; 80; 85] \\  & Energy & PV & [5; 36; 44; 75; 79; 81; 82; 83; 84; 85; 86; 87; 88; 89; 93] \\  & Wind farms & [5; 44; 75; 81; 82; 83; 85; 86; 88] \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Energy resources coordination in VPP for energy autonomy. Figure 6: VPP for energy communities. For smaller communities, the costs to use services from other suppliers of VPPs can represent an impediment in obtaining the energy needed [80]. Therefore, the concept of a VPP for the energy community was studied and applied in multiple communities where the needs of the population were the focus, but at the same time the costs must remain affordable, and the system had to offer stability, balance, and high availability [103]. In a VPP that provides energy for communities, the consumers can decouple from the grid and still function as needed using local resources [103]. This scenario was embraced especially by communities where the distribution of energy from raw materials is problematic or implies costs that cannot be supported. Even inside the community, the distribution of that energy is important, and in this type of architecture, the storage resources play a big part in the distribution system [104]. The authors of [96] investigate how VPPs can be used to provide energy for communities and services to the grid. The approach proposes to use an energy storage distributed to energy prosumers so that the energy storage devices are aggregated into a VPP. The daily optimization considers the battery state to improve its lifetime. In [95], the authors propose the use of VPPs that coordinates a set of distributed energy resources to improve the quality and reliability of the power supply. The model described offers a solution for increasing the production of energy and sustainability while, in turn, decreasing the carbon footprint. In [97], a VPP community in Poland is studied. It contains hydropower plants and energy storage systems and addresses the power quality issues. The research considers the frequency of the energy, voltage, and the asymmetry factor. The VPP is formed by two types of voltages of the distribution of energy in the network. The system was tested with real data and is helping the community from Poland to generate energy from renewable resources. Community VPPs have become one of the most promising solutions to integrate intermittent renewable while considering the local socioeconomic context [51]. In [98], an array of optimization solutions are developed and applied for a community-oriented VPP aggregating renewable energy generation units.