Although the value of V2G-based grid services is potentially greater than that of V1G, realising those benefits may not be a straightforward task. There are a set of major technological requirements that could potentially impact the onground implementation and the possibility of scale-up in the near future.
4.2 Key techno-economic factors for VGI implementation The study has identified the following three important technological aspects of VGI that impact its commercial attractiveness, as detailed below: 1.
THE CHARGING TECHNOLOGY USED FOR V1G, OR SMART CHARGING, IS VERY DIFFERENT FROM THAT REQUIRED FOR V2G, BECAUSE OF THE FUNDAMENTAL DIFFERENCE IN ENERGY FLOW IN THE TWO SYSTEMS.
Advanced charging technologies: Charging infrastructure plays a critical role in VGI. Not only is it the backbone of e-mobility, but it also closely binds mobility to the electricity sector and has the potential to bring about major transformations in the power system. VGI requires sophisticated charging technology to enable EV participation in grid services. The charging technology used for V1G, or smart charging, is very different from that required for V2G, because of the fundamental difference in energy flow in the two systems. V1G entails the usual unidirectional energy flow, from the EVSE to the battery inside an EV, as seen in any EV charging system. Furthermore, similar to a simple charger, the smart charger can be either AC or DC. However, considering that DC fast charging has greater impact on the load on the grid, it makes sense to make DC fast chargers “smart”. The basic difference between a simple EVSE and an EVSE used in V1G is that the latter shares a data connection with an EV, as well as with the charging point operator. As opposed to a simple charging device that is not connected to the cloud, smart charging allows the charging service provider to monitor, manage, and restrict the use of chargers remotely to optimise energy consumption. Moreover, smart chargers can be enabled to respond to price signals on their own (based on the applied algorithms). Smart charging is powered by an intelligent back-end solution that enables real-time data sharing between the EV, EVSE, and charging point operator, called the Central Management System (CMS). A major operational advantage of smart chargers is that their functions can be modified at any point in time; it is easy to add and remove features and design a system to meet one’s needs. Hence, the costs of smart chargers vary depending on the features. Smart chargers are widely available in advanced EV markets and are becoming a mainstream solution. Such EVSEs are also available on the Indian market, and many of the existing installed chargers already have smart features of varying degree, but currently, these features are often disabled due to lack of use. On the other hand, V2G goes one step further and enables the feeding back of energy stored in the EV battery into the grid, apart from the usual energy flow during EV charging to the EV battery. V2G requires additional electrical equipment compared to standard or smart charging, such as a bidirectional inverter to convert the DC output power from the on-board EV battery to AC. This conversion equipment is normally integrated into the EVSE, although some manufacturers are considering integrating the bidirectional equipment within the vehicle. Currently, the J1772 connector and IEC 62196 connector are capable of AC discharging (provided the EV is equipped with a bidirectional inverter), whereas a CHAdeMo connector is suitable for DC discharging (again, if the EVSE has a bidirectional inverter). Control units are also required for efficient, reliable, and safe battery
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