# Planning of High-Power Charging Stations for Electric Vehicles: A Review
## 2 Target Identification
### Charging Technologies  
#### 2.3.1 Plug-in Charging  
Plug-in charging is the most mature charging technology and the most present in global CI, with more than 5 million units between private and publicly available chargers [76]. Chargers are characterized by:  
* Level: the power output of the outlet. There are three commercially widespread levels. Level 1 (up to 3.7 kW) and Level 2 (up to 22 kW) exploit AC current, whereas Level 3 can be either AC or DC. Level 3 chargers are referred to as fast chargers, and the power outputs range from up to 43.5 kW for AC 3-phase technology to up to 400 kW for DC [77; 78]. Currently, standards for high-power chargers have been developed up to 600 kW, with a growing interest in so-called _mega-chargers_ up to 1 MW [76] for HDVs. * Type: socket, connector, and standards. Charging stations are developed based on different standards and defined by the Society of Automotive Engineers (SAE), a U.S. based professional association, which develops standards for engineering bodies in different industries. The International Electro Technical Commission IEC 61851 and American standard SAEJ1772 represent the two main standards defining the communication protocol and electrical and physical parameters [79]. A brief selection of important standards for charging stations is reported in Table 3. For further relevant standards, see [79,80]. Types of sockets and connectors adopted in the different countries may vary. The European Union mostly follows the Type 2 IEC 62196-2 and Type 2 IEC 62196-3 standards, also commercially called Combined Charging System Combo 2. The most common DC fast charger plugs in the global market are the CHAdeMO (accepted by IEC 62196-3), the Tesla supercharger, and the Guobiao recommended-standard 20234 [76]. * Mode: the communication protocol. Different chargers host different types of communication protocols. Whereas AC slow-chargers have no direct communication in their cables, it is possible to regulate the charging speed of AC fast-chargers, but it still require external controls for communication. In contrast, DC fast-charging CCS is coupled with power line communication (PLC), whereas CHAdeMO, Tesla, and Guobiao use a controller area network (CAN). PLC and CAN protocols allow for smart charging strategies such as V2G [76]. In the reviewed literature, authors do not always specify the complete characteristics of their chargers, and some of them describe chargers depending on the nominal power output or the time taken to complete a full charge of an average BEV [81]. A fair amount of research investigates infrastructure planning, taking into account both fast and slow charging. Study [82] analyzes the effect of implementing Level 1 (1.9 kW), Level 2 (4 kW), and Level 3 (up to 100 kW) chargers on the voltage profile of a power system. The authors verify that the critical voltage drop in commercial feeders can be remarkably reduced through the optimization described in the paper, even with a high penetration of Level 3 chargers. A similar range of charging powers is included in [50,81]. In [50], technologies compete against each other in a Bayesian game model, each of them implementing one different charging technology. The overall consumer satisfaction is finally characterized to prioritize EV user satisfaction. Results indicate a small presence of DC FCSs in the optimal solution (ca. half of Level 1). In [51], the authors