Draft IEC 61850-8-2 SCSM – Mapping to XER and XMPP

Some 20 years after the first draft IEC 61850-8-2 SCSM (Mapping to Profibus FMS) we could expect the real IEC 61850-8-2 to be available by end of 2015.

The draft 8-2 provides an additional mapping of the messages of MMS by XER (XML Encoding Rule) and XMPP.

The MMS messages for IEC 61850-8-2 (above TCP/TLS/XMPP) are just differently encoded as in IEC 61850-8-1, as can be seen by the following example:

ASN.1 BER uses a binary encoding that produces less overhead compared to XER. But there will be many benefits provided by IEC 61850-8-2.

According to a presentation by Siemens during the Hanover Fair 2015, these are the main conclusions:

1. It provides a secure and powerful communication for public networks considering end-to-middle and end-to-end security relations
2. IEC 61850-8-2 is intended to use for power management and demand response of DER (distributed energy resources)
3. In 2015 the IEC TC57 working group WG17 will finalize and publish this new specification

Click HERE for the full presentation [pdf, 3 MB]

Tissue Database for IEC 62351 just opened

The Tissue Database for IEC 62351:

Power systems management and associated information exchange – Data and communications security

has been opened for immediate access. Nine parts have been published so far. You may post your feedback (bug reports, …) now.

Access the Tissue Database for IEC 62351.

How to Secure the Smart Grid Network Infrastructure?

Andrew K. Wright, Paul Kalv, and Rodrick Sibery have published an excellent paper with the title "Interoperability and Security for Converged Smart Grid Networks".

The conclude: " While modern computing and technologies are now widely used throughout control centers and utility enterprise environments, field communications equipment largely uses outdated technologies. By deploying a converged smart grid network, utilities like ... can modernize their communications infrastructure, deploy new applications such as AMI and Distribution Automation, and adopt an architecture that is based on standards and supports interoperability based on Internet Protocol. Interoperability will allow them to replace individual subsystems that become out of date as technology evolves, without requiring forklift upgrades. Converged smart grid networks will require strong logical separation of traffic to ensure security of smart grid applications, and this will be best provided by a defense-in-depth architecture that considers security across all layers of the IP stack."

Click HERE for downloading the excellent paper [pdf, 1.5MB]

Recall the following statement I posted the other day "NAMUR expects that this clear statement and the requirements formulated will enable all those involved in the standardisation process to work together constructively with a view to achieving a converged [added by Karlheinz - Wireless Fieldbus] standard.")

Click HERE for the discussion of the Wireless Fieldbus (NAMUR, ...).

From the view point of information models, configuration Language, information exchange services and (IP-based) protocols we have reached a very high level of convergence with IEC 61850 - including the security measures as defined in IEC 62351.

Wireless Sensor Networks: Users Want ONE and ONLY ONE Standard

Some 20 (!) years after the publication of the first field bus standards, the acceptance of field busses in the process industry is still behind expectations! The current IEC Field Bus Standards comprise about 100 (!) parts - specifying some 50 solutions under one Standard number: IEC 61158. No wonder that the users are still looking for a convergent solution.

The German Association NAMUR (representing some 120 users and vendors involved in process automation) has published a very strong requirement document on the convergence of wireless sensor networks: NE 133 "Wireless Sensor Networks - Requirements for the convergence of existing standards" ("Wireless Sensor Netzwerke: Anforderungen an die Konvergenz der verfügbaren Standards")

NAMUR requires to get coexistence, interoperability and Interchangeability for wireless based technologies.

The press release states that NAMUR is expecting to get ONE International Wireless Standard for the process automation domain. ("Die NAMUR erwartet, dass diese klare Meinungsäußerung und die formulierten Anforderungen alle am Standardisierungsprozess Beteiligten zu einer konstruktiven Zusammenarbeit mit dem Ziel eines konvergierten Standards bringt." / "NAMUR expects that this clear statement and the requirements formulated will enable all those involved in the standardisation process to work together constructively with a view to achieving a converged standard.")

Click HERE for some details listed in the press release of the annual conference of NAMUR (Nov 2010) [pdf, German].

Click HERE for the abstract (Zusammenfassung) of NE 133. [Word, de/en]

Click HERE for the order form to order a free of charge copy of the requirements document NE 133 [order form, de/en] ... you will get a free copy sent to your email address.

Click HERE for a list of IEC 61158 standards (Edition 2).

The far too many IEC standardized protocol stacks of the Field Busses (comprising some 12.000 pages) are causing still a lot of headaches and pain.

IEC 61850 provides JUST ONE Client/Server and two Publisher/Subscriber protocol stack solutions - This is what the Utility domain appreciates very much all over! Many vendors of industrial automation systems have already or will soon implement IEC 61850 - especially for their need to communicate over TCP/IP.

The Protocol stack defined in IEC 61850-8-1 using ISO 9506 (MMS) is not the crucial focus of IEC 61850 at all - BUT when it comes to interoperability at device level, then this is very crucial! IEC 61850 has more than protocols: information models and a configuration language ...

Updated FERC Smart Grid Policy and Interoperability

The US Federal Energy Regulators Commission (FERC) has published recently an updated Smart Grid Policy (Docket No. PL09-4-000, Issued July 16, 2009).

Excerpt from the summary of the report: "This Policy Statement provides guidance regarding the development of a smart grid for the nation’s electric transmission system, focusing on the development of key standards to achieve interoperability and functionality of smart grid systems and devices. In response to the need for urgent action on potential challenges to the bulk-power system, in this Policy Statement the Commission provides additional guidance on standards to help to realize a smart grid. ...".

The essential term used is "Interoperability" (Interoperability is described as exchanging meaningful information between two or more systems and achieving an agreed expectation for the response to the information exchange while maintaining reliability, accuracy, and security; according to GridWise). The term "Interoperability" is used 89 times throughout the policy statement.

One of the crucial standards that supports interoperability in power system automation, protection and control is the standard IEC 61850 ... also referred to in the policy statement: "The Commission stated that IEC Standards 61970 and 61968 (together, Common Information Model), along with IEC 61850 (Communications Networks and Systems in Substations), could provide a basis for addressing this issue."

Interoperability is impacted by many aspects (standard definition, implementation, subsetting, resources available in a device, ...). Two IEDs that are fully compliant may not be able to talk together, because of resource restrictions. A Server IED may support 3 TCP connections. A fourth client that wants to retrieve some information from that server cannot even open a TCP connection - due to the resource restriction. From an application point of view the two devices cannot interoperate.

There is a crucial difference in the use of TCP for general web applications and IEC 61850 (and other close to real-time applications). Usually a client opens a TCP connection posts a request, gets some responses, and closes the TCP connection.  Web browsers, in their simplest mode of operation, would just connect to download a page and then disconnect. This simple transactions use very little resources. The resources are free after each transaction. But connecting and disconnecting repeatedly to the same server does carry an overhead and slows the communication down.

To allow close to real-time information exchange over TCP requires to keep the connection open all time. This has the drawback that the server needs to reserve resources for each client - independent if there is little or high traffic. For that reason IEDs in power systems (often with very limited resources) have a limited number of clients that can communicate with them at the same time. Once resources are consumed, there is no interoperation with one additional client possible at all.

This kind of limited resources in automation devices makes interoperability a challenge. If two devices do not operate: please do not start to blame it to the standard or to the implementation ... A system integrator needs to know many details on limitations. Be aware: Everything is limited!

The discussed challenge is independent of the upper layer protocols like DNP3, IEC 60870-5, IEC 60870-6, IEC 61850, ... it is typical for all protocols in the automation domain that use TCP.

Click HERE for the complete FERC Smart Grid Policy.