The Power Ministry aims to create a mechanism where electric vehicles (EVs), with the use of bi-directional vehicle-2-grid (V2G) technologies, will not just manage charging loads, but also aid in grid balancing with variable renewable energy (VRE) sources. To this effect, the Central Electricity Authority (CEA) has released a report on reverse charging of the grid from EV batteries. EVs can act as decentralised storage resources, capable of providing additional flexibility to support power system operations.
Smart charging is a way of optimising the charging process according to distribution grid constraints, utilising distributed RE sources, and customer preferences. It can help mitigate voltage fluctuations in girds having high penetration of VRE sources.
Smart charging includes bidirectional V2G, which for EVs, is the key to unleash synergies between clean transport and low-carbon economy. Car batteries could be instrumental in integrating a high share of renewables into the grid.
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Nangia & Co partner (Government and Public Sector Power Advisory), Arindam Ghosh, said V2G technology offers several benefits for both EV owners and power sector. V2G and reverse charging options present a promising solution to address challenges such as grid balancing, peak demand management, and intermittent renewable energy integration.
The CEA report said that V2G smart charging can help reduce costs by complementing the EV charging load and distribution load profile. For instance, if a high number of EVs are concentrated in a region in an uncontrolled charging environment, the local grid can be impacted. Besides, additional EV charging load would require infusion of additional generation capacity, the report noted.
Generally, EVs spend about 80-90 per cent of their lifetime in parking zones. These idle periods combined with battery storage could make EVs an attractive flexibility solution for power systems.
V2G charging may not only mitigate EV caused demand peaks mainly at the local grid level, but also adjust the load curve to integrate VRE, it added.
Incremental benefits of V2G will be particularly significant in solar-based systems. By shifting charging to better coincide with solar PV generation and by implementing V2G, increased share of solar can be integrated at the system level and the local grid level, thereby mitigating the need for investments in the distribution grid.
Ghosh pointed out that there is a technical standpoint in mass implementation of this technology option. First, continuous commitment by the EV owner is unlikely. A dedicated generation resource has a minimum level of availability/ commitment defined, V2G option has the basic issue of commitment, as use of vehicle and charging time of vehicle is inversely proportional.
“Therefore, innovative regulatory sandboxes will be required to be implemented on a test-case basis to define the commitment level for EV owners to act as generators thus facilitating and supporting the grid operations. Secondly, technology options and compensation mechanisms for existing distribution companies need to be defined,” he added.
It is well known that reverse charging from Vehicle to Grid may induce harmonics, thus hampering the asset life of Discoms, Ghosh said adding “We have to also consider such reduction of useful life of network assets under a compensatory mechanism In summary, allowing V2G integration and treating such integrated EV as storage requires clarity on commercial settlement and regulatory provisions.”
A senior government official said that the success of V2G smart charging will depend on host of factors, including bidirectional communications, interoperability, customer incentives, integrated planning of power and transport among others.
For instance, he explained that V2G requires a bidirectional system to deliver electricity from the grid to EV batteries and vice versa. This mechanism can be used through double unidirectional or single bi-directional converters, but double uni-directional converters, or simply chargers, have high initial costs, more weight and require larger space to install. Here, bi-directional converters can offer more benefits.
Another is that bi-directional charging aids in voltage regulation, but constant charging and discharging of the EV battery causes degradation impacting battery life, he added.