World Electric Vehicle Journal Vol. 6 - ISSN 2032-6653 - © 2013 WEVA Page Page 0863 EVS27 Barcelona, Spain, November 17 - 20, 2013 Evaluation of OCPP and IEC 61850 for Smart Charging Electric Vehicles Jens Schmutzler1, Claus Amtrup Andersen2, Christian Wietfeld1 1Dortmund University of Technology, Communication Networks Institute, Dortmund, Germany, EMails: [email protected], [email protected] 2EURISCO Research & Development, Odense, Denmark, EMails: [email protected] Abstract Interoperability of charging infrastructures is a key success factor for E-Mobility. Standards like ISO/IEC 15118 and IEC 61851-1 are developed to ensure base level interoperability of front-end com- munication and signaling processes for smart charging between electric vehicles and charge spots. With the Open Charge Point Protocol (OCPP) a forum of European industry members also moves towards a common back-end protocol for charge spots intending to reduce and secure overall investment costs. However, in the current form OCPP lacks means for enabling grid services based on smart charging. In this paper the authors provide a review of today’s state of the art in ISO/IEC standardization of the V2G Interface and furthermore detail how OCPP could leverage existing standardization efforts for grid automation from IEC 61850 in order to overcome its shortcomings. Keywords: Smart Charging, OCPP, IEC 61850, ISO/IEC 15118, Vehicle-to-Grid Communication Interface, V2G 1 Introduction beneficial to standardize back-end integration as- pects of charging infrastructures in the long term. With the introduction of EVs certain challenges According to the European Commission’s cli- arise for the power grid since it was deployed mate and energy targets set in 2007 as well as at times, when such additional loads were not following directives like 2009/28/EC [1] on the yet considered. Assuming mass market adop- use of energy from renewable sources, EVs are tion of EVs this inevitably comes along with high considered to provide their share reducing CO2 chances for concurrent charging processes and emissions in the transport sector. Being shiftable therefore overload of low voltage grid segments. loads as well as regularly available energy stor- In order to address these issues and ensure inter- ages in the low-voltage grid, they are furthermore operability between charging infrastructures of supposed to provide a certain benefit to grid sta- various vendors, standardization bodies like ISO bility in conjunction with increased penetration and IEC are busy defining corresponding stan- of renewable energy sources. In that sense the dards for E-Mobility. As of today, core efforts integration of EVs and charging infrastructures were spent in front-end issues of E-Mobility, like need to be extended beyond the current scope plugs, in- & outlets, electrical and safety require- of purely operational aspects being covered by ments, as well as the front-end communication today’s solutions. In order to integrate seam- interface in order to ensure common access to EV lessly in tomorrow’s grid infrastructures a look charging infrastructures. Back-end and grid inte- into the IEC standardization roadmap [2] is nec- gration approaches were developed individually essary. They define IEC 61850 as core standard as part of research and pilot projects leading to for grid automation and consider it as the core proprietary solutions reflecting the situation on driver of Smart Grid development in the mid- and today’s market. However, in terms of operational long-term. aspects as well as for securing the industry’s in- Hence this work analyzes the alignment of the vestments in charging infrastructures it may be Open Charge Point Protocol (OCPP) - today’s EVS27 International Battery, Hybrid and Fuel Cell Electric Vehicle Symposium 1 World Electric Vehicle Journal Vol. 6 - ISSN 2032-6653 - © 2013 WEVA Page Page 0864 most commonly used and openly available back- 2.1 Plugs (in- & outlets) end communication protocol for charging infras- tructures - and IEC 61850 in order to overcome The IEC 62196 standards series is defined in today’s lack of grid integration for charging in- TC23/SC23 and currently comprises three parts. frastructures of EVs. In sections 3 and 4 both The first part defines general requirements for approaches for back-end integration are evalu- dedicated plugs, socket outlets, vehicle connec- ated and differentiated from each other. In sec- tors and vehicle inlets for interfacing a dedicated tion 5 the authors summarize the lessons learned charging equipment with an EV. The current ver- and provide an outlook on smart charging us- sion was released end of 2011 and represents ing OCPP and IEC 61850. But before go- the second edition of this standard. However, ing into such detail, some background on op- work on the third edition has already started in erational aspects of charging infrastructures and the meantime. The second part defines the di- how plugged-in EVs can be characterized as grid mensional compatibility and interchangeability assets is needed. Hence, the following section requirements for AC plugs (in- & outlets). The provides an overview on current state of the art standards defines three different types of connec- considering the E-Mobility V2G Interface. tors, type 1 for single phase charging supporting charging rates of up to 7.4kW. Whereas type 2 supports single and three phase charging, the lat- ter with rates of up to 44kW. In January 2013 the 2 Standardization Landscape of European Commission declared the type 2 con- nector as a common basis for charging infras- the E-Mobility V2G Interface tructures and EVs in the European Union. Part three of the standard defines dimensional com- Standardization for the V2G Interface in E- patibility and interchangeability requirements for Mobility already has a long history which lately DC plugs (in- & outlets) as well as Combo Plugs experienced major increase of interest and de- (combined AC & DC plugs and in- & outlets). velopment. The global interest in reducing CO2 Until today this part is still work in progress and emissions in the transport sector and its result- not yet published as an international standard. ing economical interests impacting two of the The relevance of IEC 62196 regarding interoper- worlds largest industrial domains (utilities and ability of the V2G interface is limited to physical automotive) led to extensive industrial support in specifications in terms of signaling pins and con- research and development. The resulting stan- nector compatibility (physical layout & dimen- dardization landscape of E-Mobility can be clas- sions). sified in the following four domains: 1. Plugs (in- & outlets) 2.2 Charging Topologies Different charging topologies need to be con- 2. Charging Topologies sidered for conductive AC- and DC-based ded- icated charging equipments. Such EV charg- 3. Communication ing equipments are defined in the IEC 61851 standards series. The first part describes gen- 4. Security eral requirements for conductive charging sys- tems. It applies to on-board and off-board AC 5. Safety and DC charging equipment and also to any ad- ditional services on the vehicle which may re- The remainder of this section will walk quire electrical power when connected to the through each domain highlighting corresponding supply network. It defines four different charg- ISO/IEC standardization work. An overview of ing modes starting from slow charging using the landscape is shown in Figure 1. household-type socket outlets to fast charging us- ing an external charger. It also defines char- acteristics and operating conditions of the sup- Security 4 ISO/IEC 27000 ply device and the connection to the vehicle as Communication 3 well as the operator’s and third party’s electri- ISO/IEC 15118 IEC 61850 cal safety. IEC 61851-1 specifically defines a IEC 62351 Charging Topology safety-related low level signalling process based 2 on a Pulse Width Modulation (PWM) signal in- IEC 61439-1 1 Plugs, In- & Outlets IEC 61439-7 dicating various EV connection states, supported Electric Vehicle IEC 62196-1 charge currents and communication means. The IEC 62196-2 IEC 61851-1 5 IEC 62196-3 PWM signal provides means for handling time- Safety IEC 61851-23 critical state changes, some of them even with IEC 61140 IEC 61851-21 IEC 61980-1 IEC 61851-22 IEC 62040 respect to individual safety. Hence, IEC 61851-1 IEC 61980-3 IEC 60529 IEC 61851-24 IEC 60364-7-722 IEC 61980-2 ISO 6469-3 is a cross-cutting standard in terms of the pre- ISO 17409 viously mentioned domains, dealing with charg- ing topologies, safety and communication (on a Figure 1: Digest of main ISO/IEC standards for the signalling level). The second edition was re- scope of the E-Mobility V2G Interface based on [3] leased end of 2010 but work is already ongoing for the third edition of this standard. The second part IEC 61851-21 describes technical require- EVS27 International Battery, Hybrid and Fuel Cell Electric Vehicle Symposium 2 World Electric Vehicle Journal Vol. 6 - ISSN 2032-6653 - © 2013 WEVA Page Page 0865 ments relevant for EVs being connected to AC or communication controllers in EVs (EVCC) and DC EVSEs. Two further sub-parts of this stan- charge spots (SECC) as shown in Figure 2. Part dard detail the EMC requirements of on-board 3 defines the physical and data link layer require- (IEC 61851-21-1) or off-board (IEC 61851-21-2) ments of the powerline communication based chargers. The following parts IEC 61851-22 and carrier technology including the association pro- IEC 61851-23 detail specific requirements for cess. The envisioned high level communication AC- or DC-based EVSEs, respectively. Part 24 protocol will allow for advanced interaction be- of IEC 61851 is described in section 2.3. tween the grid and connected EVs for authenti- The charging topologies and relevant technical cation & authorization, accounting, load level- requirements for inductive charging equipments ing management and further added-value ser- are defined in IEC 61980-1 where specific re- vices.