The transition to sustainable mode of transport has been accelerated driven by the imperatives to meet global targets for reduction in greenhouse gas emissions. The accelerated growth of electric vehicles (EVs) results in corresponding increase in the energy demand. This increase in the energy demand is a serious concern for the energy providers as it will overwhelm the existing grid infrastructure. To accommodate the increase in the peak demand, the grid infrastructure will need an upgrade in its capacity. However, this is not a viable solution, economically and technically, as the infrastructure cannot keep adding capacity with the increase in adoption of electric mobility. To address these concerns, we can reduce the peak increase by levelling the energy demand throughout the day. This can be facilitated by nudging the EV users to shift their charging time through incentives such as price mechanisms or by allowing the energy providers to have a control in the rate and time of charging the EVs. This method of “controlled/managed” charging is known as smart charging.
What is smart charging?
The definition of smart charging is rather broad with different sources having different definitions of smart charging. According to International Renewable Energy Agency (IRENA 2019), “Smart charging means adapting the charging cycle of EVs to both the conditions of the power system and the needs of vehicle users. This facilitates the integration of EVs while meeting mobility needs.” As per ElaadNL (ElaadNL, 2020), “Smart Charging is essentially a control signal that indicates when and at what speed an electric car is charged. Smart technology ensures that it is charged at the best time and at an optimum speed.”
Generally, smart charging is a means of managing the EV load to reduce the impact of EV integration on the distribution network and may also incorporate grid support services. It can be achieved by customers responding to price signals, electric vehicle supply equipment (EVSE) responding to control signals from the distribution company (discom) or a Central Management System (CMS) while at the same time retaining enough charge in the battery to fulfil the EV users travel requirements.
There are several control strategies in smart charging that introduce flexibility in the charging process such that EV users can incentivise by deferring their charging time to reduce stress on the grid. Consequently, instead of immediately charging when an EV is plugged to the charger, smart charging technology ensures that the EV is charged at the best time and at an optimum speed. Therefore, by controlling the time and rate of charging, smart charging ensures a better distribution of the power demand. This helps avoid peak demand stress and reduces cost associated with reinforcing electricity infrastructure. It therefore plays a vital role in achieving different objectives, such as cost minimisation, loss minimisation, congestion management, grid support and grid stability depending on the type, preferences, and required infrastructural and computational capabilities of consumers.
Levels of smart charging
The levels of smart charging can start from a simple shifting of charging time by the EV users to more sophisticated charging methods where the EVs provide services to the grid (V2X). As the smart charging levels increase, so does the control methods and the participation from various stakeholders.
Figure 1: Levels of Smart Charging
Source: IRENA (2019), Innovation outlook: Smart charging for electric vehicles
The table below shows the levels of smart charging. It addresses the control required, its uses and maturity. Advanced smart charging approaches, such as direct control mechanisms, will be necessary as a long-term solution at higher penetration levels and for the delivery of close-to-real-time balancing and ancillary services. Vehicle-to-home (V2H) and vehicle-to-building (V2B) are forms of bidirectional charging where EVs are used as a residential back-up power supply during periods of power outage or for increasing self-consumption of energy produced on-site (demand charge avoidance). Further, smart charging with dynamic pricing and automated control will be difficult to materialise without the support of policymakers and regulators. (IRENA Innovation Outlook: Smart charging for electric vehicles, 2019)
Table: Levels of smart charging
|Smart Charging Level||Control||Possible uses||Maturity|
|Uncontrolled charging with Time of Use (ToU) tariffs||None||Peak-shaving||High|
|Basic Control||On/off||Grid congestion management||Partial market deployment|
|Unidirectional controlled (V1G)||Controls the time of charging and the rate of charging power in real time||· Grid congestion management
· Renewable energy (RE) integration
· Ancillary service
|Partial market deployment|
|Bidirectional Control (V2X)
– Vehicle-to-home (V2H)
– Vehicle-to-building (V2B)
|Instant reaction to grid conditions; allows the EV to provide services to the grid in the discharge mode||· Grid congestion management
· Ancillary services
· RE integration and reduction in RE curtailment
· Micro-grid optimisation
|Advanced testing and pilot stage|
|Dynamic Pricing||EVSE embedded meter and close to real time communication between vehicle, EVSE, and grid||· Load following
· RE integration
|Partial market deployment|
Source: IRENA 2019
Standards for enabling smart charging
The standards IEC 62196, SAE J1772, GB/T 20234, CHAdeMO, and CCS define different modes of conductive charging depending on how the power is transferred to the vehicle and the technical specifications required for the design of plugs, socket outlets, vehicle connectors, and vehicle inlets. In the context of smart charging, the connector should have a control pilot (CP) pin. The CP is important and is used for communication (exchange of control signals) between the EVSE and the EV. The connectors as specified by IEC 62196 or type 2 or Mennekes, Tesla, CHAdeMO, CCS, and GB/T all have control pins and thus has the capability to perform smart charging. IEC 60309 is an AC connector with three pins without a control pin and thus it cannot perform smart charging. Most two-wheeler and three-wheelers use the IEC 60309 industrial plug for slow charging and thus cannot participate in V1G or V2X.
Communication is a crucial component for enabling smart charging. Communication protocols provide a set of rules and guidelines to facilitate communication and data exchange between two or more entities. For communication in the EV ecosystem, the standards ISO15118, IEC 61851, IEC 63110, SAE J2847, GB/T 27930, CCS, CHAdeMo, DIN SPEC 70121 and DIN SPEC 70122 are used. These standards specify the charging communication and ensure correct data exchange before and during the actual charging process. The pulse width modulation (PWM) is used for low-level communication between EV and EVSE. High-level communication includes Power Line Communication (PLC), Signal Level Attenuation Characterisation (SLAC), and Controller Area Network (CAN). PLC is used in combined charging system (CCS) and CAN is used in DC GB/T and DC CHAdeMO.
Figure 3: Data exchanged in the different communication levels
Smart charging entails active communication between EV and EVSE, and between EVSE and the back end. Communication protocols linking various entities in the EV ecosystem can be divided into front-end and back-end protocols. Front-end protocols define the link between car and charge point and specify requirements for plugs, charging topologies (on-board/off-board charging equipment; conductive/inductive charging), communication, safety and cyber-security. Back-end protocols, emphasising communication and cyber-security requirements, define the link between charge point and a third-party operator. Communication protocols can be proprietary- developed by private consortia such as Tesla or they can be open- developed by public standard development organisations, or open alliances such as open charge point protocol (OCPP). The OCPP 1.6 onwards supports smart charging.
Figure 3: Information and control flow in the EV ecosystem
Source: Myriam Neaimeh, 2020
Learnings from global best practices: pilot projects and case studies
Several projects have been conducted across countries to gain more insights into the aspect of smart charging. The Electric Nation Smart Charging Project was conducted in the UK with an aim to study the effect of EV in the low voltage distribution grid and investigate the feasibility of smart charging in mitigating the adverse effect of EVs. The project analysis validated the importance and benefits of smart charging. It concluded that a well-defined EV tariff structure improved customer satisfaction to participate and more importantly it was a cost-effective alternative to expensive grid upgradation. The results stated that the early evening peak in EV charging demand disappeared, confirming that smart charging is highly effective in mitigating excessive demand. Over 60 per cent of the consumers changed their charging preference from the default “optimise time” to “minimise cost” option.
The feasibility of more advanced type of smart charging, V2G, has also been documented in the Parker Project. The Parker Project was conducted in Denmark from 2016-2018 with the aim to demonstrate frequency support services from EVs. The analysis concluded that V2G can offer a significant support to the grid by providing active power support, reactive power support, frequency support and also facilitates renewable energy integration. Chen and Wu (L Chen, 2018) simulated a huge study case for the Guangzhou region in China for 1 million EVs. An increase of 15 per cent in the peak load of the grid was observed without charging control. However, with the time of use control strategy, a reduction of 43 per cent from peak load was observed while 50 per cent reduction was possible with V2G. Similarly, a study conducted in Turkey (Değer Saygın, 2019) to assess the impact of 10 per cent penetration level of the total stock, viz 2.5 million EVs, concluded that the increase in the peak load by 12.5 per cent with uncontrolled charging can be mitigated using smart charging. The peak load saw an increase of only 3.5 per cent with smart charging.
In the Indian context with regards to smart charging, some provisions have been given in the states’ EV policies. These include special EV time based (Time-of-use) tariff structure, encouragement of use of CMS, payment via online modes, database of historic and real-time information of charging stations, mention of V2G and ancillary services from EV and encouragement of RE integration.
Incorporating the necessary requirements of smart charging from the initial transitional phase to electrified mode of transport is highly crucial in making the transition a success. The learnings from the various projects mentioned in this article prove the usefulness and viability of incorporating smart charging approaches. Smart charging ensures that the EV uptake is not constrained by grid capacity as it helps reduce peak demand, RE curtailment, and the cost associated with grid infrastructure upgradation. Several interventions can be implemented to enable a smarter, efficient, and sustainable way of scaling up the adoption of EVs globally and in India.
This article is fourth in the series that introduces the concept of smart charging, the standards enabling smart charging, followed by few case studies highlighting the advantages of adopting smart charging to the EV ecosystem. The next article of this series will focus on various strategies that enable smart charging.
Değer Saygın, O. B. T. S. T. M. K., 2019. Transport sector transformation: integrating electric vehicles into Turkey’s distribution grids, Istanbul: SHURA Enerji Dönüşümü Merkezi.
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