Communication is necessary in the electric vehicle (EV) ecosystem for key purposes such as: user authentication, to communicate the maximum allowable charging current, control start/end of charging session, billing, smart charging and provision of roaming facilities.
As explained in the second article of this series, communication includes the exchange of information between the EV and electric vehicle supply equipment (EVSE), between EVSE and charge point operator (CPO), between CPO and electric Mobility Service Provider (eMSP), between eMSP and the distribution system operator (DSO). Seamless charging operation at any geographic location is achieved using roaming interoperability of the EV charging environment. Basically, it allows the EV user to charge from any public charging station irrespective of whether the EV user is a subscriber of the CPO managing that station.
The flow of information between different entities in the EV ecosystem is depicted in the illustration given below.
Figure: Flow of information in the EV environment
Source: IIT Bombay and GIZ India – Report 1 – ‘Fundamentals of Electric Vehicle Charging Technology and its Grid Integration’
The flow of information passing from EV to DSO is shown in the figure. It is a cyclic process to perform real-time charging every time. For initiating the charging between EV and the EVSE, several steps of connections are followed for EVSE to regulate the voltage of the control pin. Therefore communication plays a key role in every stage of the complete EV charging process.
If the roaming feature is enabled, ideally it is possible for an EV user to find information of all public charging stations in the country on a single app/web platform and also be able to book/reserve any available charger using this app. Presently in India, an EV user needs to sign up individually for each CPO/network service provider (NSP) which makes it a cumbersome and unattractive process. If I am an EV user, why do I need to sign up for different CPOs? For example, if I have signed up for an EV charging subscription from A, then my app will only show those charging stations that are managed by A. Therefore, even if B’s charging station, with a compatible EV charger available, is just 1 km away from me, I will only be able to see A’s nearest charging station (on my app). It could be possible that A’s charging station is 10 km away without a compatible charger available for reservation at that instance.
When the CPOs and NSPs use their own proprietary communication protocols, it could hinder interoperability and grid integration of EV charging infrastructure. Open protocols are also important for optimising the utilisation of EV load to provide flexibility in grid management. The open-source protocols for EV smart environment have four major functionalities: (a) Smart Charging, (b) Roaming, (c) Communication between EV and charge point, (d) Communication between the Charging Station Management System (CSMS) and charge point.
In India, the Bureau of Indian Standards (BIS) is the national standard body of India established for the development of standardisation, marking and quality certification of goods. BIS set up the sectional committee EDT-51 in 2017 as the national committee for IEC Technical Committees on EV charging standards. BIS took the International Electrotechnical Commission (IEC) standards as a base for developing the Indian EV standards (DST, 2021). BIS has been active in issuing several standards related to EVs, chargers, sockets, connectors, and other EV related components. For various types of energy transfer viz, conductive and inductive, the standards for EV charger, connectors, and EVSE are covered in BIS standards (BIS, 2018). Additional to the already published several standards, BIS is developing standards for a few more categories of chargers, which will be published soon.
Some of the communication protocols specified by the EV standards in India as of January 15, 2022, are presented in the following section.
Status quo on communication protocols applicable in India
To cater to the immediate need of electric 2-wheelers (e-2W), electric 3- wheelers (e-3W) and electric passenger cars (e-cars) with a battery voltage of less than 100 V, the Bharat EV charger specification namely, AC001 and DC001 were released in 2017 by the Department of Heavy Industry (DHI). The communication protocol between the public metered AC outlet (PMAO) and the central management system (here it refers to the CSMS) is defined to be open charge point protocol (OCPP) 1.5. It was also specified that if a higher version of OCPP was used then it should be compatible with OCPP 1.5. This is an independent and open protocol that facilitates interoperability between the EVSE and the CPO. The functions intended to be performed by OCPP 1.5 are authentication, reservation of charger, start and end of charging, share information on the state of charge (SoC) level, depth of discharge (DoD) level of the battery, maximum allowable current limits, parking time, type of connector, and charging type. The other Indian standards for EV charging were notified by BIS in November 2021 and the relevant communication protocols specified between the EV and EVSE are as given below:
Table: Indian standards for EV charging notified by BIS on November 1, 2021
|Sl. No.||Type of charge point||Power capacity||EV – EVSE communication|
|1.||Light EV AC (LEV AC) Charge Point||Level 1 – up to 7 kW||Bluetooth Low Energy|
|2.||Light EV DC (LEV DC) Charge Point||Level 1 – up to 7 kW||IS-17017-25 [CAN*]|
|3.||Parkbay AC Charge Point||Level 2 –
~11kW/ 22 kW
for Smart Charging
|4.||Parkbay DC Charge Point||Level 2 –
~11kW/ 22 kW
|5.||DC Charging Protocol||Level 3 –
50 kW to 250 kW
|6.||e-Bus Charging Station
· Dual Gun Charging Station
· Automated Pantograph Charging Station
|Level 4 –
250 kW to 500 kW
*CAN: Controller Area Network; PLC: Power Line Carrier
Source: Ministry of Power – Charging Infrastructure for Electric Vehicles (EV) – the revised consolidated Guidelines and Standards (January 14, 2022)
As the communication would be via Bluetooth between the LEV AC charger and the EV user mobile, if the EV user does not possess a mobile with Bluetooth facility, the user will not be able to charge the vehicle. The standard IS-15118 defines communication interface for bi-directional charging/ discharging of EV and can be used for both AC and DC charging for EVs. It is indeed appreciable that BIS has specified IS-15118 between EV and EVSE for some of the proposed EV standards. The key relevant feature of IS-15118 is the use of digital certificates for security and enabling secure exchange of tariff and metering data (Maarten Venselaar, 2019).
Ministry of Power (MoP) released the “Charging Infrastructure for Electric Vehicles (EV) – the revised consolidated Guidelines and Standards” on January 14, 2022, while the first version of these guidelines was published in December 2018. Back from the very first version, it was mentioned that every public charging station (PCS) should have collaborated with an NSP to enable features such as reservation of charger (online booking) and also to provide information to the users on the location of the charger, types of chargers, availability of chargers and the cost of charging. Except for the data on the availability of chargers, all other required data is static data. To obtain the availability of chargers and to activate the feature of reservation of chargers, OCPP 1.5 or above communication protocol is necessary and the EV chargers must be compatible with this protocol.
Under the MoP guidelines, the Central Electricity Authority (CEA) was entrusted with the responsibility to create and maintain the database of all PCS in the country. In June 2019, the CEA formulated the format to collect the information from the distribution companies (DISCOMs) on PCS (CEA, 2019). The DISCOMs were requested to send the following details to CEA over email on a monthly basis. As per the given format, the data requested includes the location of the charger, circle/zonal details of the respective DISCOM, type of charging station (public/restricted/captive), operation time, payment methods, date of commissioning, type of connector, number of level 1, level 2 and DC fast chargers, connection voltage and the DC output from the charger. The second category of data aims at recording the electricity consumption from the EV charging stations under the jurisdiction of the DISCOM and it includes data on total number of charging stations, number of EVs charged and the total electricity consumption. All the data points requested by CEA is static data and does not necessitate the implementation of any EV related communication protocol.
The way forward for India
Presently, the vehicle market in India is dominated by 2-wheelers and amongst the different vehicle segments, public buses, taxi fleets, 2-wheelers and three-wheelers are expected to be the first adopters of EVs. Most of the EV users charge their e-2W and e-3W at home using the 15 A socket or the proprietary chargers provided along with the EVs. As the number of EVs begins to grow, the management of the charging process will be an uphill task for the DISCOMs in the absence of communication protocols. Mandating OCPP 1.5 is one of the first steps towards harmonisation of communication protocols across the country. But in the absence of guidelines/standards for minimum communication requirements among other entities, the CPOs and NSPs are using their own proprietary software for sharing data with the consumers. As of today, the DISCOMs are only receiving the data of electrical consumption from the EV chargers, if the consumer has availed EV tariff and installed a separate meter for the EV charging load.
Some of the key measures could include harmonisation of standards, implementation of minimum standards for interoperability and integration of smart grid infrastructure of DISCOMs with ICT (Information and Communications Technology) infrastructure. To create awareness and encourage CPOs, NSPs and charger OEMs to adopt communication protocols, certain guidelines from the government could be released. These are some basic communication requirements that are crucial for interoperability and the use of proprietary protocols would certainly create problems for DISCOMs as well as the EV users. Some of the communication protocols that could be mentioned in the guidelines are:
- Between EV and EVSE: IEC 61851 and ISO 15118
- Between EVSE and CSMS/CPO: Open charge point protocol (OCPP 1.6 or higher)
- Between any two CPOs/NSPs to enable e-roaming: Open charge point interface (OCPI)
- Between CSMS and DISCOM for smart charging: Open smart charging protocol (OSCP)
- Between CSMS and DISCOM for communicating demand response (DR) signals: Open Automated Demand Response (OpenADR)
Beyond communication standards, there is also the need to specify the details of data that needs to be exchanged between different entities in the EV stakeholder chain. For example, which parameters (voltage, power factor, current etc.) a CPO needs to communicate to the DISCOM and what should be the time resolution of the data (rms value, instantaneous value, real-time etc.). Load forecasting for EVs is complicated because it depends on the consumer’s behaviour and needs which could change rapidly. In this scenario, the availability of data from EV chargers will be crucial for the DISCOMs for planning grid augmentation, forecasting EV load and management of EV chargers under its jurisdiction. Along with communication, smart charging can be utilised to charge EVs optimally and intelligently in a coordinated and controlled manner. Various aspects of smart charging coordination strategies will be discussed in our upcoming articles.
This article is the third in the series of articles related to various aspects of grid integration of EVs in India. The next article of this series will be focused on the smart charging of EVs.