## 3 Key Contributions to Smart Grids
### Scheduling  
In a smart grid, an EV is characterized as both an energy consumer and an alternative energy storage unit, as well as a power load. EVs connected to the smart grid are integrated with charge/discharge modes. EVs, which can be integrated with the clean energy system and reduce the utilization of traditional energy sources, draw attention to a balance between the amounts of energy produced/consumed in a V2G system [84, 85]. Figure 4 presents a typical scheduling process for EVs integrated into smart grids. The  
Figure 3: The fundamental contributions of EV-smart grid integration regarding energy management. proper scheduling process is achieved using the charging information of EVSEs, road information, and vehicle information [86]. The smart grid operators have to plan smooth electrical energy management based on the information necessary to schedule the EV loads. Bidirectional communication information exchange between smart grid operators and EVs/aggregators should be realized. The scheduling process of the V2G system is also achieved using consumption and generation power profile information [87]. The smooth planning of EV integration can preserve grid stability and provide a balance between power generation and consumption [88]. Figure 5 summarizes the charging/discharging modes of EVs. The scheduling of EV charging/discharging can be classified under two headlines: control structure and mobility [89]. Figure 5 shows these scheduling types and their individual properties for the integration of EVs into the smart grid. Figure 4: The scheme of a typical scheduling process. Figure 5: The classification of the scheduling process in terms of control structure and mobility. As a control structure, centralized scheduling supervises the charging/discharging of EV fleets by taking information from the management center [90]. In the centralized programming method, EVs are optimized by controlling them over an EV aggregator according to the state of the grid and the charging demand. In order to determine the optimum loading/unloading strategy of the EVs, the aggregator is activated according to the loading demands and market behavior forecasts. EV aggregators charge their fleet of EVs according to the optimum load profile. In addition, each EV user is controlled by the aggregator through an online settlement system [91]. The control in which each region has its own planning and can cooperate with others and the main grid by exchanging electrical energy is called decentralized scheduling. Decentralized scheduling is more scalable and simple due to its lower computational and communication complexity compared to centralized scheduling [92]. EV owners can plan their charging according to their wishes in order to reduce the charging costs. Decentralized scheduling is an incentive approach in which the pricing behavior of EVs will be directly arranged by the electrical energy pricing program [93]. According to mobility, the scheduling process can be categorized as static and dynamic. Static scheduling refers to planning in which the mobility of EVs is neglected, assuming fixed loads, without the temporal characteristics of the mobility of EVs. Scheduling according to a natural vehicle entry-exit, where EVs come and go at any time, is expressed as dynamic scheduling. Dynamic scheduling is expressed as planning performed using different mobility features such as the trip histories of EVs and unplanned departures of EVs. For instance, charging demands can be predicted based on estimated arrival times at EVSEs; similarly, the unplanned departures of EVs and their effect on the smart grid can be investigated in dynamic scheduling. On the other hand, problem formulation in static planning is simpler than in dynamic planning [19]. A static schedule has constant daily planning that restricts the amount of electrical power for charging at different times of the day. In addition, it aims to reduce the load on a low-voltage grid by restricting the amount of power used to charge EVs [94].