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Getting there:

Smart metering standardization in Europe By Gyozo Kmethy

Metering International 3 / 2011 “Smart meter standardization – Challenges in Europe” by Daniel Hec, David Johnson and Catherine Vigneron provided an insight into European smart metering standardization under the Mandate M/441. This article provides an update especially as regards electricity metering, and focuses on some key issues, like use cases, openness, interoperability, data security, privacy and safety.

THE M/441 MANDATE

Standardization is carried out under the Mandate issued by the European Commission in March 2009. It tasks the European Standardization Organizations (ESOs), CEN, CENELEC and ETSI to develop European Standards for an open architecture for utility meters that is capable to support applications of any complexity, can use current and future communication media, and allows secure interfacing with the protected metrological block. It also requires the development of standards for additional functionalities within an interoperable framework. The work is coordinated by the Smart Metering Coordination Group (SM-CG).

The objective is to ensure that all needs of European Member States – with very different energy market structures – regarding smart metering are covered by suitable European Standards, i.e. the standards should be seen as a toolbox from which the necessary tools for a given project can be selected.

CAPTURING THE REQUIREMENTS: USE CASES

Use cases describe how users interact with a system to achieve a particular goal. They are widely used to capture requirements in software and systems engineering. M/441 Mandate participants – as well as M/490 Smart Grid Mandate participants – agreed to use this methodology to identify, clarify and organize system requirements. The work is carried out by the TCs and coordinated by the SM-CG. Use cases have been grouped into six clusters:

Energy market events, describing the interactions when a consumer moves house or changes supplier;

Billing, describing the interactions to parameterize the billing function, collection of billing data and managing (pre)payment;

Configure events, statuses and actions, describing the interactions needed to act on events and statuses that may occur in the system;

Supply quality, describing the interactions needed to monitor power quality;

Consumer information provision, describing how information is provided to energy consumers;

Installation and configuration, describing the interactions needed to install, configure, monitor and maintain elements of the smart metering system.

The use cases are currently out for comments to SM-CG members.

Use cases can be used by NCs to formulate project requirements and by the TCs to validate existing standards, to identify gaps and in the development of new standards. During this process, use cases will be mapped to the elements of the standards to ensure that all use cases and requirements can be supported. The use cases developed will be made available in a public repository, coordinated with the M/490 Mandate and IEC TC 8.

OPENNESS AND INTEROPERABILITY

Openness for our purposes means that the functional architecture specified shall be capable to meet current and future needs, integrate new communication technologies, and be implemented in a range of physical embodiments, including fully integrated, modular and multi-part equipment. In particular, it means that the standards developed should provide a framework readily accommodating new functionalities and communication technologies.

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Interoperability is another requirement emphasized by the Mandate. The Smart Metering Technical Report TR 50572 defines interoperability as the ability of a system to exchange data with other systems of different types and/or from different manufacturers.

For the sake of both openness and interoperability, it is essential in the development of standards to de-couple application modelling from communication technology. This allows protecting the investment in application development while benefiting from the never-ending technology evolution. This also enables efficient migration.

Interoperability has two aspects: semantic and syntactic interoperability. Semantic interoperability refers to the ability of system elements to exchange data with unambiguous, shared meaning. This is accomplished by adding data about the data (metadata) linking each element to a controlled, shared vocabulary. Metadata may be transferred with the data itself, or may be known from an agreed context. Syntactic interoperability is a pre-requisite for semantic interoperability. This refers to structuring, packaging and transporting the data.

DATA SECURITY, DATA PROTECTION AND PRIVACY

The Mandate also lays great emphasis on these aspects. First, experience with smart meter rollouts show that consumers are concerned with privacy. They will not accept smart meters unless sufficient assurances and controls are given. Second, using public networks and open standards makes smart metering systems vulnerable unless strong security policies and solutions are applied to prevent successful cyber-attacks. Third, the legal metrology block must be protected from undue influence from other functions.

The key security services to be provided by the standards are:

Authentication: The assurance to one entity that another entity is who it claims to be;

Integrity: The assurance to an entity that data has not been altered (intentionally or unintentionally) between "there" and "here," or between "then" and "now";

Confidentiality: The assurance to an entity that no one can read a particular piece of data except the receiver(s) explicitly intended.

Note here that the Scope of the Mandate does stops at the HES1, therefore protection of data and privacy beyond the HES is out of the Scope of the standards developed.

Entities operating the smart metering system should use these and other appropriate tools in such a way that their security targets are achieved.

TC13 identified the following key security requirements based on NISTIR 76282:

Only approved crypto algorithms may be used;

It should be possible to upgrade the set of crypto algorithms used;

Tools for cryptographic key management shall be provided;

It shall be possible to identify and authenticate parties exchanging data;

Role based access control shall be provided (due to market differences, the definition of the roles is left to specific projects);

Authenticity and confidentiality of critical messages during transport and data during transport and storage shall be ensured (judgement of “criticality” is left to the projects);

Digital signature of critical commands and data shall be ensured;

Security event logs and alerts shall be provided;

Secure firmware upgrade shall be supported;

Physical security shall be ensured.

Peer authentication and role based access control are part of DLMS/COSEM from the outset and are supported by Application Associations (AAs) established between DLMS/COSEM servers (meters or logical parts of meters) and clients (data collection systems). Several AAs may be defined as needed. Each AA determines the contexts, access rights and the security policy used.

————————— 1 HES: Head End System

2 NISTIR 7628: Guidelines for Smart Grid Cyber Security: a National Institute of Standards and Technology Interagency Report

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DLMS UA Blue Book Edition 10 and Green Book Edition 7 specify security suite 0, providing authenticated encryption using the AES-GCM-128 algorithm – NIST SP 800-38D – and key transport using AES key wrap (RFC 3394). Security suite 0 is also part of the new edition of the IEC 62056 series.

To meet all the requirements listed above, the security solutions provided by DLMS/COSEM are being extended. To achieve interoperability also in this area, the work is using the NSA Suite B, a set of cryptographic algorithms promulgated by the National Security Agency (of the US), that consists of the following NIST-approved techniques:

Encryption. Advanced Encryption Standard – FIPS PUB 197 (with keys sizes of 128 and 256 bits);

Key Exchange. The Ephemeral Unified Model and the One-Pass Diffie-Hellman key agreement schemes (two of several ECDH schemes) – NIST SP 800-56A (using the curves with 256- and 384-bit prime moduli);

Digital Signature. Elliptic Curve Digital Signature Algorithm (ECDSA) – FIPS PUB 186-3 (using the curves with 256 and 384-bit prime moduli);

Hashing. Secure Hash Algorithm (SHA) – FIPS PUB 180-3 (using SHA-256 and SHA-384).

The work on data security is coordinated with the Smart Grid Mandate.

SAFETY

Safety probably received less emphasis in the Mandate. However, higher rated currents “one size fits all approach” and the presence of supply control and load control switches in the meters require a careful approach to this problem. That’s why IEC TC 13 is developing a product safety standard. IEC 62056-31 Safety of electricity metering equipment will reach the CDV stage by end of 2012.

SM-CG DELIVERABLES

An initial report has been produced in December 2009. It provides an overview of the standardization landscape as regards smart metering, identifies standardisation requirements, determines additional functionalities, makes recommendations for the standardization process and allocates responsibilities among the TCs.

The next deliverable, CEN/CLC/ETSI/TR 50572 Functional reference architecture for communications in smart metering systems has been published in December 2011. See

ftp://ftp.cen.eu/cen/Sectors/List/Measurement/Smartmeters/CENCLCETSI_TR50572.pdf

First, the Report sets the Scope then it puts the work into the context of the European legislative framework. It provides a glossary of terms, describes the approach to standardization using existing standards where possible and being open to new proposals. Further, it determines additional smart metering functionalities and places smart metering in the context of smart grids. It addresses data security and privacy then presents the functional architecture, the functional elements and the interfaces between them and allocates responsibilities to the TCs for developing standards for those interfaces. Finally, it discourses interoperability, provides implementation examples and gives an initial list of use cases.

A consolidated work programme of the TCs has also been produced. This is a living document regularly updated thus it facilitates managing the work and provides visibility to stakeholders.

The SM-CG works now on a final report, to be published by the end of 2012. This document will present the work accomplished, the standards developed and the outstanding work.

TECHNICAL COMMITTEES

Standards already available or to be developed involve a large number of TCs from the three ESOs. To ensure a co-ordinated approach, co-ordinating TCs have been identified:

CEN TC 294 Communications systems for meters and remote reading of meters is responsible for data exchange with meters other than electricity. It co-ordinates its activities with TC 237 Gas meters, TC 92 Water meters and TC 176 Heat meters;

CENELEC TC 13 Equipment for electrical energy measurement and load control is responsible for electricity metering and control. It co-ordinates its activities with TC 57, Power systems management and associated information exchange and SC 205A Mains communicating systems. The mandated work is carried out by WG02, in cooperation with IEC TC13 and the DLMS UA;

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CENELEC TC 205 Home and Building Electronic Systems (HBES). It co-ordinates its activities with CEN TC 247, Building Automation, Controls and Building Management;

ETSI M2M Machine to Machine Communications. It co-ordinates its activities with a number of other ETSI TCs.

TC 294 and TC 13 share responsibility for the data model and upper layers standards for the C, M, G1 and G2 interfaces (see Figure 2). ETSI M2M and TC 13 share responsibility for the upper layers standards for the G2 interface. ETSI M2M is responsible for the lower layer standards for the G1 and G2 interfaces and for the L and N interfaces. TC 205 is responsible for the H1, H2 and H3 interfaces.

IEC TC 13 WG 14 and CENELEC TC 13 WG 02

The mandated work is shared between these two committees. WG 14 maintains and develops IEC 62056. WG 02 develops the use cases and handles the results of the OPEN meter project – www.openmeter.com – as well as new proposals.

In Q4 2012, a new edition of IEC 62056 will be published under the general title Electricity metering data exchange – The DLMS/COSEM suite. The new parts and main changes are:

IEC 62056-3-1, Use of local area networks on twisted pair with carrier signalling (Euridis) specifies a new DLMS/COSEM profile for this medium;

IEC 62056-5-3, DLMS/COSEM Application layer specifies the symmetric key cryptographic algorithms and amends the DLMS service and protocol specifications;

IEC 62056-6-1, Object Identification System (OBIS) specifies a number of new OBIS codes for smart metering applications;

IEC 62056-6-2, COSEM interface classes specifies new ICs supporting new smart metering applications and communication media, including Image transfer, Security setup, Disconnect control, Limiter, M-Bus setup ICs and S-FSK PLC setup ICs;

IEC 62056-7-6, The 3-layer, connection-oriented HDLC based communication profile specifies data exchange over the local port, or remote data exchange using PSTN / GSM modems (was previously part of IEC 62056-53.);

IEC 62056-8-3, PLC S-FSK profile for neighbourhood networks is based on IEC 61334-5-1, IEC 61334-4-511 and -4-512 with enhancements for improved performance. It specifies data exchange on the NN via the C interface;

IEC 62056-9-7, Communication profile for TCP-UDP/IP networks specifies data exchange over IP enabled WANs via the G1 interface (was previously part of IEC 62056-53).

Recently, a Korean proposal for a DLMS/COSEM BPL communication profile using ISO/IEC 12139-1 has been accepted by WG14.

WG14 also works on a standardization framework, to be IEC 62056-1-0. IEC 62056 is part of the IEC Smart Grid Standards portfolio.

DLMS/COSEM has been designed to provide an open and interoperable standardization framework as described above, with:

The COSEM objects modelling the various smart metering functions. The objects provide both the data of interest e.g. register values, tariffs, schedules, and meta-data e.g. scalers, units, data types and most importantly the meaning carried by the OBIS codes thus providing semantic interoperability. Cryptographic protection can be applied to the data stored in the objects;

The DLMS services provide secure access to the objects and the resulting messages can be cryptographically protected. They are specified in ASN.1 ensuring syntactic interoperability. The services are encoded in A-XDR (IEC 61334-6, a simpler version of BER). XML encoding is being specified;

Communication profiles define how application messages are transported over various media.

These three elements are fully de-coupled facilitating the addition of new application functions by extending the COSEM model, addition of new messaging methods (SML3, proposed by Germany, is an approved WG 14 work item) and adopting new communication technologies.

————————— 3 SML: Smart Metering Language, future IEC 62056-5-3-8.

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CENELEC TC 13 WG02 received three results from the OPEN meter project:

PRIME PLC (stemming from Spain and supported by the PRIME Alliance) using OFDM modulation with an IEC 61334-4 LLC layer or IPv4 or IPv6 and DLMS/COSEM on top;

G3 PLC (stemming from France and supported by the G3-PLC Alliance) using another kind of OFDM modulation with 6LoWPAN and IPv6 and DLMS/COSEM on top;

Meters&More PLC (stemming from Italy and supported by the Meters&More Association), using B-PSK modulation and a table oriented data representation.

Later, two further technologies have been proposed:

OSGP (Open Smart Grid Protocol) proposed by Finland and promoted by ESNA4, a companion specification to EN 14908 PLC using B-PSK PLC and a table oriented data representation similar to ANSI C12.19. (It has been published by ETSI as GS OSG 001, an Industry Group Specification);

CX1, proposed by Austria, using a fast frequency-hopping spread spectrum technique combined with Differential Phase Shift Keying (DPSK) and error-correcting block coding, an adaptive cellular network layer with DLMS/COSEM on top.

PRIME PLC, G3 PLC and CX1 use DLMS/COSEM. Therefore, they can be readily integrated to the DLMS/COSEM suite to achieve semantic interoperability; see Figure 1.

The following Technical Specifications are ready for approval after final editing:

prTS 52056-8-4, The PLC Orthogonal Frequency Division Multiplexing (OFDM Type 1, AKA PRIME PLC) profile;

prTS 52056-8-5, The PLC Orthogonal Frequency Division Multiplexing (OFDM Type 2, AKA G3 PLC) profile.

The lower layers of these profiles are specified in ITU-T G.9955 and G.9956 Annex B and A respectively.

It is noted that the different PLC technologies are not interoperable, but chips supporting multiple PLC technologies are available. G3 PLC can co-exist with S-FSK PLC.

Concerning Meters&More and OSGP there were different views in WG02 if they should be published as proposed, or should be integrated into IEC 62056 by replacing their data model with COSEM. A questionnaire sent to the National Committees has shown that they do not want a proliferation of data models and asked WG02 to treat all proposals such that the resulting Technical Specifications or standards support the common DLMS/COSEM data representation. Consequently, the Meters&More Association decided to withdraw its data model from standardization and use COSEM instead. ESNA agreed to provide a mapping between the OSGP tables and COSEM. The technical solutions are being worked out.

DLMS USER ASSOCIATION

A new edition of the DLMS UA Books is planned for Q4 2012, significantly extending the Scope and improving the performance and security of DLMS/COSEM:

New elements in Blue Book Edition 11, describing the COSEM data model and the OBIS Object identification system include:

New versions of the Association and Security setup classes to support public key cryptography and new security policies for message and / or data protection;

Modelling of push operation;

Modelling of payment metering;

A Parameter monitor class allowing to build an audit trail of parameter changes;

Setup classes for OFDM Type 1 / PRIME PLC, OFDM Type 2 / G3 PLC and IPv6;

A new version of the M-Bus client setup class;

A number of new OBIS codes.

————————— 4 ESNA: Energy Services Network Association

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New elements in Green Book Edition 8, describing the DLMS protocol and the DLMS/COSEM communication profiles include:

New security suites using elliptic curve public key cryptographic algorithms for protecting either application layer messages or application data (object level security);

A new unified ACCESS service for accessing attributes and methods of COSEM objects;

An improved block transfer algorithm;

Data exchange via transparent gateways.

INTERFACES, TECHNOLOGIES AND STANDARDS

Figure 2 shows the M/441 functional architecture together with the communication technologies available for use on the various interfaces. This architecture divides the communication infrastructure from the HES and the meters to three sections:

Wide Area Network (WAN). The most widely used technology on the WAN is GPRS;

The Neighbourhood Network (NN) covering a number of premises. The entry point to the NN is the Neighbourhood Area Access Point (NNAP). For the NN a number of PLC technologies are standardized;

The Local Network (LN), within the same premises. The entry point to the NN is the Neighbourhood Area Access Point (NNAP). For the NN, both wireless and wired technologies are standardized.

IMPLEMENTATION EXAMPLES

Figure 3 shows implementation examples of the functional architecture and the relevant standards. In each case, the HES acts as a DLMS/COSEM Client and the meters – that may be electricity, gas, water or heat meters – act as Servers (except in the sixth).

1st example: the HES exchanges data directly with the meters over the WAN, using the G1 interface. IEC 62056-9-7 (currently in FDIS5 stage), the DLMS/COSEM TCP-UDP / IP profile is used over the GPRS network;

2nd example: an LNAP is present, acting as a transparent gateway. Messages sent over the WAN using the G1 interface are forwarded to the meter(s) over the LN using the M interface and vice versa. For this interface, the IEC 62056-3-1 (FDIS) DLMS/COSEM profile can be used. Alternatively, DLMS/COSEM messages may be transported over wired or wireless M-Bus specified in the EN 13757 series. The DLMS/COSEM M-Bus profiles are yet to be developed. Another possibility is to use Zigbee on the LN;

3rd example: it is similar to the 2nd, except that the LNAP acts as a DLMS/COSEM Client towards the meters and as a Server towards the HES;

4th example: an NNAP is present. Data exchange between the HES and the NNAP takes place over the WAN, using the G2 interface. This interface is not yet standardized; but it will probably use web services to access and transport metering applications modelled with COSEM. Data exchange between the NNAP and the meters takes place over the NN using the C interface and various PLC technologies including:

IEC 62056-8-3 (FDIS), the DLMS/COSEM S-FSK PLC profile;

prTS 52056-8-4, the DLMS/COSEM PRIME PLC profile;

prTS 52056-8-5, the DLMS/COSEM G3 PLC profile;

A DLMS/COSEM profile for B-PSK PLC (Meters&More) is being developed;

For OSGP, mapping between COSEM objects and OSGP tables will be provided.

5th example: it is the combination of the 3rd and 4th example;

6th example: it is similar to the 5th, except that the LNAP is integrated with an electricity meter, acting as a DLMS/COSEM Server towards the NNAP and as an M-Bus master towards non-electricity meters. It provides COSEM container objects for M-Bus information and may map this information to proper COSEM objects.

————————— 5 FDIS: Final Draft International Standard (IEC)

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COMPANION SPECIFICATIONS

IEC 62056 DLMS/COSEM provides a rich data model leaving several options to product designers. These options may be limited for a given project, largely simplifying the complexity of implementations and closing any interoperability gaps. There are also some elements, on which no international agreement can be reached (for example tariff structures). These are the subjects of companion specifications. Some examples:

The Dutch DSMR specification;

The French Linky specification;

The Spanish T5 specification;

The UK SSWG specification;

The German BSI gateway protection profile; and many more, also outside of Europe.

LINK BETWEEN SMART METERING AND SMART GRIDS

IEC TC 13 and TC 57 are working together to create the link between smart metering and smart grids. A project to map the IEC 61968-9 CIM model and DLMS/COSEM has been launched in TC 13; this will be the future IEC TS 62056-6-9. A similar project, mapping IEC 61850 and COSEM will be launched by IEC TC 57.

SUMMARY

Work under the M/441 mandate has produced significant results. Standards supporting additional functionalities and data exchange on the various interfaces are being published. With the publication of the final SM-CG report the mandated work will be completed, but the TCs will continue working on outstanding items and new proposals and the SM-CG will continue as a coordinating body.

ABOUT THE AUTHOR

Gyozo Kmethy – gyozo.kmethy@dlms.com – is the President of the DLMS UA and he leads the DLMS UA Maintenance Working Group. He is also Secretary of IEC TC 13 and Convenor of CENELEC TC 13 WG 02. He represents TC 13 in the SM-CG Use Case Task Force.

ABOUT THE ORGANIZATION

The DLMS User Association is a non-profit organization established in 1997 registered in Zug, Switzerland. It promotes and supports the DLMS/COSEM specification, internationally standardized as IEC 62056 for electricity metering and adopted in EN 13757-1 for non-electricity metering. Its membership is growing fast and exceeds now 250. The DLMS UA operates a conformance certification scheme. To date, more than 260 meter types have been certified to be DLMS/COSEM compliant. The DLMS UA is liaised with IEC TC 13, CEN TC 294, CENELEC and several other organizations. See www.dlms.com.

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Figure 1: Integration of new technologies

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Figure 2: Smart metering functional architecture

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Figure 3: Implementation examples