Protocol communication or what is OCPP?

OCPP stands for Open Charge Point Protocol. This protocol is completely free and does not depend on the equipment used.

OCPP provides communication between the server software and the electric vehicle chargers. It sends start/stop information, charging session status, and firmware update messages to the server. 

Ideally, this data is transmitted independent of additional equipment, such as EV charging cable extensions or adapters. The wireless induction charging of an electric vehicle uses a similar principle of data exchange.

What charging stations can OCPP use?

With OCPP you can use any network with any charging station. It is more relevant for owners of public charging stations than for best NEMA 14-50 home EV chargers. Before this protocol was introduced, owners of electric charging networks had to change their equipment completely if there was a need to change the network provider.

Old and new OCPP 1.6 and 2.0.1 protocols

OCPP version 1.6 is the most commonly used protocol. It provides intelligent charging, makes it possible to set limits on the power level or set time limits for individual stations. It provides real-time information about the performance of the charging stations. It also manages charging status, processes payments and instantly detects faults.

Load balancing is also available for stations that support the OCPP protocol. It allows the available power to be evenly distributed between the charging stations and other electrical devices. Thus, the grid is not overloaded during the rush hour. By the way, knowing the grid power, it is easy to use the EV charging time calculator to determine the waiting time and price.

OCPP version 2.0.1 includes all of the above features and many more. Such as improved transaction processing, enhanced security, and Plug and Charge functionality.

The station recognizes the owner from the electric car 

Plug and Charge simplifies the process of charging an electric car. Now car owners do not need to use a credit card, show an RFID tag with a mobile app. All they have to do is plug their car into the charging station. All access and billing transactions are done between the charger and the car. No information about the electric car or its owner is shared with third parties. The security of this process is guaranteed by the ISO 15118 standard, which allows the electric car to be automatically identified and authorized on behalf of the owner. The same principle is applied to Tesla charging stations. Even the use of a J1772 to Tesla adapter does not interfere with the process of identifying the electric car during charging.

With the OCPP protocol, you can be sure that your equipment will be up to date for many years to come and that your chargers have the best control system.

How common is the protocol in the United States?

Although a center aimed at harmonizing electric transportation was established in 2013, the OCPP is less widespread in the U.S. than in Europe. It is the Center for Electric Vehicle and Smart Grid Interoperability, located in the United States.

Consider in detail the processes of data exchange?

The Open Point of Presence Protocol (OCPP) allows you to change hardware and software providers without losing the specification. It is as easy as changing the SIM card in your iPhone. The goal of OCPP is to provide a truly interoperable framework for electric vehicle charging, a versatile and easy-to-use framework for both electric vehicle drivers and system operators. OCPP allows customers to integrate charging stations from different vendors into a similar internal IT framework. They are also free to choose the most suitable charging station vendor(s) and the most suitable server IT service provider. OCPP was developed by the Open Charge Alliance and has become an inevitably familiar agreement and a true standard for more than 50 countries and more than 10,000 charging stations. Unlike restrictive matching agreements, the OCPP is open and free of license fees or conditions, making it easy to obtain. With support from many charging station vendors and major platform providers, OCPP consistency is becoming an “absolute necessity” for speculators. They see it as a way to maintain the fairness of their trading fund and reduce costs.  

The Open Charge Alliance has developed another type of agreement called OSCP (Open Smart Charging Protocol). This contract can be used to send the charging point operator a 24-hour forecast of available capacity in the area. The service provider will adapt the charging profiles for electric vehicles within the available limit. This is a protocol between the charging point management system and the site owner’s energy management system.  

Charging infrastructure  

The charging infrastructure usually consists of the electric vehicle, the charging station and the charging station management system (CSMS). 

A charging station is a physical structure in which an electric vehicle can be charged. The charging station shall have at least one electric vehicle supply equipment (EVSE). The EVSE is considered to operate autonomously and is part of the charging station under control, which can at any time transfer viability to an electric vehicle. The EVSE will communicate with the battery management system (BMS) of the electric vehicle so that the battery can be charged at the correct rate to maintain the SOH of the battery. The physical layer of this compliance can be Power Line Communication (PLC) or Controller Area Network (CAN); CAN is commonly used by automakers in India. Different countries have different connectivity standards for electric vehicles.

What versions of OCPP do we know?

Since the first version, there are basically three different versions of OCPP. They are, respectively, OCPP 1.5, OCPP 1.6 and OCPP 2.0.  

OCPP 1.2  

This version of OCPP is similar to OCPP 1.5, but with fewer features.  

OCPP 1.5  

OCPP 1.5 describes 25 operations, of which 10 are initiated by the charging station and 15 by the central control system. Authorization, Charging message, Data transmission, Diagnostic status message, Firmware status message, Control message, Counter values, Transaction initiation, Status message, Suspension of transaction initiated by charging station and cancellation of reservation, Change of availability, Change of configuration, Memory clear, Data transmission, Configuration retrieval, Diagnostics retrieval, Local list version retrieval, Remote charging start, Remote charging suspend, Reserve now, Reset, Local list send, Socket open, Central system initiated firmware update.    

OCPP 1.6 

This OCPP configuration uses the SOAP framework to send messages between partitions over the Internet. The advantage of SOAP is that the commands for sending and receiving messages are standard [6]. This allows it to be used quickly. The core of a SOAP message is written according to the XML standard. XML messages can contain images and executable code as well as composite content. The big advantage is that the message is sent with decodable content.  

OCPP 2.0  

OCPP 2.0 is the latest customisation, released in April 2018, and includes a number of updates, which are covered in the 116 user manuals.OCPP 2.0 simply supports JSON. It includes many features, such as device management, enhanced transaction management, additional security, additional smart charging features, 15118 support, screen and information support, and many additional updates requested by electric vehicle charging networks.

Implementation of OCPP 2.0  

The OCPP protocol describes a variety of use cases and messages: there are 16 functional blocks, each block containing one or more use cases. Only a few of them are necessary for the implementation of a basic load station or CSMS. Table III lists the messages that are typically implemented to provide the basic functions of an OCPP controlled load station. 

Loading, configuration and resetting of the load station  

The loading, configuration and reset of the load station functions shall be performed in the OCPP 2.0 initialisation function block. This functional block describes all the functions that allow the CSO to organise the load stations and allows the CSO to verify certificates and to restore the configuration data of these load stations through the system. It also includes a function to change the configuration of the loading system. The function blocks are Cold Load Station, Cold Load Station – Standby, Cold Load Station – Reject, Standby Standalone Load Station, Configure Variables, Accept Variables. For the basic execution of OCPP 2.0, the use cases are “Reset – without current transaction” and “Reset – with current transaction”. Transactions are mandatory use cases. 

Authorisation options  

This function is part of the OCPP 2.0 authorisation function block. This feature block contains all the functions related to authorization, including different methods of user authorization (online or offline), processing of AuthorizeRequest messages, and the Authorization Cache function. When a user wants to disconnect an EV from the charging station, the charging station shall verify that the user is the one who initiated the charging or that he is a member of the same group and therefore eligible to suspend the charging. If the charging station is approved, it shall inform the CSMS that charging has been suspended. There are 16 use cases for this function block, one of which is mandatory for the basic application: authentication of the electric vehicle driver by RFID, authentication by start button or authentication by PIN.   

Transaction mechanism  

This function is part of the OCPP 2.0 Transaction Function Block, which describes the functions related to OCPP transactions. A transaction can be initiated or terminated at the loading station and only one active transaction is possible at a time on the EVSE. There are 15 possible uses in this function block. Transaction start parameter, Transaction start – when the cable is connected for the first time, Transaction start – first transaction ID, Transaction start – when no ID is received, Transaction suspend parameter, Transaction suspend locally with IdToken, Transaction suspend when the charging station is offline. If cable is disconnected on the EV side: transaction stopped, if cable is disconnected on the EV side: transaction stopped, disconnected during transaction, transaction stopped locally with IdToken, transaction stopped if the charging station is offline. reporting to CSMS of transactions that are offline and messages related to a transaction not accepted by CSMS are mandatory for the core technologies.   

Availability  

This feature refers to the OCPP 2.0 Availability feature block. It indicates how the charging station informs the CSMS about the current availability to initiate a new exchange: it is important for the CSO to know if the charging station is available to charge the EV and to inform the EV driver. Therefore, charging stations need to continuously send their status and EVSE changes to CSMS.   

This transaction status is very useful if EV drivers encounter problems during charging. As soon as the charging station recognises the authorised person, the authorised person can make a specific notification and inform the CSMS of the failure; the CSO can change the availability at the moment when the charging station is needed in order not to restart the exchange. For example, the charging station does not need to be used because it needs to be serviced; the CSO may also change the availability of at least one EVSE. For example, if the customer informs us that the EVSE is broken. 

This transaction status is very useful when electric vehicle drivers experience problems while charging. Once the authorized person is recognized by the charging station, he can make a specific notification and inform the CSMS of the malfunction; the CSMS can change the availability of the charging station at the time needed to avoid starting an exchange again. For example, a charging station may not need to be used because it needs to be serviced; the CSO may also change the availability of at least one EVSE. For example, if a customer calls to say that an EVSE at a charging station is broken, the CSO can make that outlet unavailable so that the EV rider cannot use it. Similarly, it is clear that charging stations and sockets can be made available again if the CSMS instructs.   

There are five uses for this function block, four of which are mandatory. They are status notifications, change of EVSE availability, change of charging station availability, and lockout failure. 

Transmission of counter values related to a transaction. 

This function is part of the measurement function block of OCPP 2.0. It describes a function that enables the charging station to send counter values periodically (possibly synchronously with the clock). A wide range of transaction-related measurement data can be recorded and transmitted in different ways, depending on the purpose. There are three use cases for this function block and the transmission of transaction-related counter values is a MUST use case for the implementation of the OCPP 2.0 basic protocol.   

Interface Content  

The OCPP protocol provides standardized communication between a central control system (CSMS) and a charging station. The user interface is designed to make it easy for the user to operate this protocol, which runs on the server. Figure II shows the possible user interfaces that the CSO can use in the CSMS while the user is charging an electric vehicle at the charging station. 

One implementation of the OCPP 2.0 protocol was developed using the Java programming language; the concepts provided by the Java language, such as object-oriented programming and web sockets, make it easy to meet the requirements of this protocol. For the design of the external interface, a graphical user interface (GUI) was created using JavaFX. 

This post describes the Open Charge Point Protocol (OCPP), which can be used as a standard for internal communication between electric vehicle charging stations and the central control system. Different versions of the protocol and improvements to its functionality were discussed.