At the recent COP26 summit at Glasgow, India has set a target to reach net zero emissions by 2070, which shows that it has come a long way from its first Nationally Determined Contributions under the Paris Agreement. In less than 10 years, by 2030, India aims to meet 50 per cent of its energy requirements from non-fossil fuel energy, which is indeed an ambitious, but much-needed target. According to the International Energy Agency, 13.5 per cent of India’s energy-related CO2 emissions is contributed by the transport sector, and road transport accounts for 90 per cent of the transport sector’s total energy consumption. Previously, it was expected that India could achieve an electric vehicle (EV) sales penetration of 70 per cent for commercial cars, 30 per cent for private cars, 40 per cent for buses and 80 per cent for two- and three-wheelers by 2030 if Phase II of the Faster Adoption and Manufacturing of Hybrid and Electric Vehicle (FAME) scheme and other supporting schemes and policies are successful (NITI Aayog and Rocky Mountain Institute, 2019). Now, in light of the new focus on NDCs and its effect on the decarbonisation of the Indian transport sector, it is obvious that EVs and charging infrastructure will become even more important.
Efficient charging infrastructure is a prerequisite for the mass adoption of EVs. As of 2019, the total number of public chargers in India stood at 1,827, with the majority of them being slow chargers with power ratings of less than 22 kW (IEA, 2020). Seamless grid integration of EVs is essential for accelerating EV adoption. An increase in EV penetration will inevitably demand an increase in the number of EV charging stations. In this context, India needs timely deployment of effective EV charging infrastructure, along with secure and efficient integration of EVs into the power system.
This gives an opportunity for stronger sector coupling between the energy and transport subsectors, making e-mobility a central element in the necessary green transition of the economy. In the overall aim to make the transition in mobility, the importance of energy transition in transport, that is, fuel shifts, needs to be emphasised.
Forecasting EV load is difficult since it depends on the travel behaviour of EV users, and the charging load demand is different for residential and public charging stations. The charging power of an EV is dependent on various other factors including AC/DC charging (1), the state of charge (SoC), the level of the battery (2), the rated charging capacity of the EV on-board charger (if AC charging) and the rated charging capacity of the EV supply equipment (EVSE). Owing to the inconsistency in EV load demand and the nature of EV load, there are some key challenges in integrating EVs into the grid.
Typically, EV charging entails higher power demand compared to other residential loads, and a high penetration of EVs will significantly increase the power demand in low voltage grids, which can potentially lead to undervoltage issues. When the EV charging load coincides with other loads during peak demand periods, it will further aggravate the voltage sag issue. Non-uniform distribution of single-phase chargers (mostly used for charging electric two-wheelers) among the phases of a distribution network may lead to unbalanced phase voltages and current loading. With uncontrolled and uncoordinated EV charging, there is the risk of feeder congestion and potential overloading of the transmission system and distribution network assets such as transformers and cables. Such overloading can significantly reduce the lifespan of the equipment while simultaneously reducing the efficiency of the energy transmission system. EV chargers are power electronic converter-based devices that introduce voltage and current harmonic distortions into the supply, and the level of distortion is proportional to the number of EV chargers operating simultaneously in the distribution network. Detailed information on grid integration of EVs and its impact can be obtained from Chapter 6 (Page 87) of Report 1 – ‘Fundamentals of Electric Vehicle Charging Technology and its Grid Integration’.
The primary function of an EV is to satisfy the EV user’s transportation needs, but it must be noted that most of the time vehicles are parked, and this presents opportunities to EVs to provide grid support services by controlling the charging of EVs or by allowing bidirectional flow of power. From the perspectives of transmission system operators and distribution operators, EVs can be utilised as a mobile storage unit to benefit different grid operators. The controllable nature of EV charging makes them ideal for providing ancillary services. Ancillary service markets generally have a minimum bid volume, so an EV as a single entity cannot participate in these markets. An aggregator must group a fleet of EVs for participation in ancillary service markets to maintain the minimum bid volume. The different applications of an EV charger have been categorised in Fig. 1.
Controlled and coordinated EV charging can help provide different solutions to mitigate the challenges presented by EV integration into the grid. Smart charging controls the charging power or shifts the time of charging. It is performed using different strategies, which are a combination of information flow and decision-taking ability between the aggregator and the EV owner. One way of incentivising EV users to shift their charging needs to off-peak periods is to implement time-based EV tariffs such as time-of-use (ToU) tariffs, which is the simplest way of smart charging. Enabling time-based tariffs such as ToU is limited by the smart meter proliferation in the country. Although smart meter deployment has grown in recent years, these smart meters have to be installed in private residential households in order to facilitate passive control over EV charging using time-based tariffs. For the commercial sector, different state electricity regulators have issued ToU tariffs for commercial chargers based on the power capacity.
In light of having 21 of the world’s 30 most polluted cities (World AQ Report, 2019), India is striving for a cleaner mode of transport. Meanwhile, India has recently set goals to reduce the total projected carbon emissions by 1 billion tonnes from the present to 2030, and to reduce the carbon intensity of its economy to less than 45 per cent. These targets increase the importance of faster adoption of EVs to bring down carbon emissions. Even if a significant portion of India’s electricity is generated from coal, the well-to-wheel CO2 emissions of electric cars are lower as compared to their internal combustion engine counterparts (International Council on Clean Transportation, 2021). Across the globe, the energy and transport sectors are on the path to becoming sustainable by incorporating renewable energy-based fuels. EVs and their charging infrastructure, if used judiciously, can act as a great source of flexibility in the energy as well as transport systems. Both these sectors could complement each other through efficient sector coupling. Smart charging and bidirectional charging of EVs present opportunities to tap the synergies between the transport and energy systems.
To mitigate congestion in the grid, it is necessary to upgrade the grid infrastructure, which entails significant capital investments. In India, most distribution companies are state run and have a poor financial status, making it difficult for discoms to justify grid upgradation to cater to the EV load. While smart meters could facilitate data transfer between the metered point of connection and the discom, there is a need for fast, reliable and secure communication between entities in an EV ecosystem for efficient management of the charging process. To effectively manage EV charging and exploit the grid support opportunities from EVs, exchange of information is crucial between the key entities, such as: between the EV and EVSE, between the EVSE and the charge point operator (CPO), between the CPO and the electric mobility service provider (eMSP), between the eMSP and the distribution system operator (DSO), and between the eMSP, the CPO and the DSO.
- Even though the vehicle may have DC charging capability, the charger that the EV is connected to may be an AC charger. So, having an EV with DC charging capability does not guarantee that charging would always be DC and vice-versa. Also, as AC and DC charging would both have different charging power in the same EV, so by charging the EV in either mode would add a different amount of load in the network.
- Generally, the charging in the EV models is designed such that higher amount of charging current is drawn at low SoC levels and vice-versa.
This article is the first in a series of articles related to various aspects of grid integration of EVs in India. The next article of this series will encapsulate the functions and roles of EV related communication protocols and the status quo on communication protocols applicable in India.