## 2 Power System Impacts of EVs
### Power Losses  
Power losses are defined as instantaneous losses, where the significant integration of EVs into the smart grid can result in significant efficiency reductions. Integrating a significant number of EVs into the smart grid requires enormous amounts of active power, leading to a poor performance in the electrical energy area [71]. With the integration of EVs into the grid, off-peak power losses increase to higher values. Researchers have explained that the uncoordinated charging of EVs leads to major increases in voltage deviation and power loss [72].  
A particularly high number of EVs integrated into a smart grid will result in an additional load demand that requires energy generation and supply. Existing interface parts are not planned for the additional load, which can lead to the surcharging of the components and affect the transformer life [73]. Various systems have been proposed to solve the problem of EVs' influence on the smart grid. Coordinated charging improves the load factor and reduces power loss in the smart grid system. Energy loss from the power grid can be reduced by intelligently selecting the best locations and energy-filling capacities for energy storage stations. In a smart grid, power system stability can be developed by properly managing vehicle-smart grid integration. An efficient method for mitigating this impact is to combine domestic energy production with charging infrastructure such as sustainable energy resources [72].  
In the smart grid connection, EVs generate current harmonics because they have several power electronic converter interfaces. According to the IEEE 519-2014 power quality standards, THD values have to be less than 5%. In several cases, individual THD levels are below 1% when the EVs are connected to the smart grid, but it may increase as the number of grid-connected EVs increases [74]. Many grid-integrated EVs require large amounts of active power, resulting in power losses in the energy area. Because EVs have non-linear load characteristics, they consume high amounts of active power in short time intervals, destabilizing the entire power grid [75]. With a large number of EVs integrated into the smart grid, the whole smart grid becomes very sensitive to interference, making it difficult to reach stability in a short time. Generally, the widespread adoption of EVs brings astonishing changes in the flow of electricity in the grid. At some point, the presence of a large number of EVs in a given area will peak the demand in the energy sector, increasing transmission line losses and reducing the voltage. In addition, voltage reduction can be tolerated up to a definite level, after which the grid will no longer supply electrical power [72].  
According to grid operators, power loss is an economic issue while EVs are connected to the system. These losses should be diminished significantly, and transformers/feeders have to be prevented from overloading. Not only the power loss but also the quality of the network (voltage sags, unbalances, harmonic problems, etc.) are of great importance to both smart grid operators and network customers. In addition, night-time network connection can also induce base-load power plant utilization, smoothing the daily cycle or avoiding supplementary generator initiations that reduce the entire performance. From the EV owner's perspective, the EV's battery needs to be charged at night to have a fully charged vehicle before departure. This offers smart integration opportunities. Grid integration can be adjusted from a distance to change the demand to periods of low energy consumption to avoid high power consumption peaks [76].