# Virtual Power Plant Optimization in Smart Grids: A Narrative Review
## 4 VPP Applications in Smart Grids
### Energy Services Delivery  
In modern smart grids, one important problem is system stability [2]. The grid can benefit from energy services as a solution to keep the power supply stable [109]. The services can be used to ensure that the energy demand, flexibility, or storage capabilities are used efficiently. The main role of a VPP in this context is to facilitate the prediction of the energy demand and generation of power from renewable sources such as wind, sun, etc. [22; 35]. Using these estimations, the VPP coordinates the remote control of the spread devices that are dealing with these issues to offer energy services [5]. Different services may be provided by the VPPs depending on the market type [73] (see Figure 4). A VPP may interact with the energy market to buy energy when the prices are low and charge energy storage systems and sell the energy surplus when prices are high by adjusting the demand and discharging energy from the batteries [65]. The VPP will act as an intermediary between the energy resources in its portfolio and the energy market while addressing market or policy barriers. In the balancing market, the VPP can provide capacity for power plants that cannot meet their original commitment [65]. In the ancillary services market, the VPP may provide near real-time services such as frequency regulation [65]. At the same time, a VPP can provide energy management towards the DSO, and the constraints of the members need to be satisfied while the stability of the entire system is considered the main objective [74]. The goal of VPPs is to manage the energy assets that are virtually aggregated to provide energy services to the DSO while optimizing the profit [64]. Such a scenario was embraced especially by the markets where the distribution of energy from raw materials is problematic or implies costs that cannot be supported [63]. The distribution of that energy is also important, and in this type of architecture, the storage resources are taking a big part in the distribution system. The focus is on the balance that efficient coordination can offer, and the costs associated that are kept as low as possible using management tools [38]. The delivery of energy service using VPPs was studied in the past decade. The Toshiba VPP offers energy services for multiple storage batteries from 2019 [66] and the focus is to facilitate the demand response based on the storage batteries and the status of the power network. Some of the services offered to consumers are imbalance prevention, storage for excess power, peak-cuts, etc. Multiple elementary and junior high schools will receive energy from the virtual storage battery group and will demonstrate that distributed power supply can be achieved at a low cost [67]. Others allow consumers to create their VPPs featuring infrastructure and services such as energy trading with live data, dispatching software to help the scheduling, load management, and at the same time demand response to control the supply and to ensure balanced services [68]. The customers are helped to aggregate different types of renewables in their VPP and to control the load. Tesla created a VPP that is designed to help the energy consumption in California [69]. Its involvement will facilitate the energy demand during the summer when the temperatures are high, but the consumers must participate voluntarily, without compensation. The beta version is offering services to predict the need for energy and ways to store the remaining energy when it is not used at full capacity. Other providers such as Sonnen invested in VPP energy services delivery for specific areas such as communities from New York [70]. They focus only on solar renewable energy that can supply 200 houses at a lower price. Sonnen provided services to 50 residents with limited income in Los Angeles to use solar energy power in California. Swell created a VPP that offers services in California, Hawaii, and New York focused on solar power energy.