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IEC61850: assessing the impact on substation developments

21st February 2013


Todayfor substation communicationsthere is a large variety of protocolsmaking it difficult for devices running on different protocols to communicate unless converters are used. This adds to costs and can create delays and errors in messages.

Since 1995about 60 experts from 14 countries have been tackling these issues in three IEC working groups. The result is IEC61850 and it covers all the devices that are capable of sending signals and all the information created in substations including GOOSE (Generic Object Orientated Substation Event) messageswhich transport binary status signals over the substation network and are also used for tripping and interlocking.

It is now ready and defines one globally applicable protocol for the entire substation. It fully supports all substation automation functions comprising controlprotection and monitoring and is future-proofso it easy to expand any system and so safeguard the initial investment. It also uses readily available industrial Ethernet and communication components.

The object-orientated data model of IEC61850 defines all objects in the substation that communicate with each other. These so-called Logical Nodes contain the data and attributes of the respective objects. The data model uses terminology familiar to any power system engineer. In additionthis part contains a device modelwhich describes the function allocation as well as the properties of each physical device.

The communication procedures are described by the seven-layer ISO/OSI model. The data model and the communication stack are linked by means of a standardised mappingwhich is the only item to be adapted in case changes in communication technology are implemented.

System integrators need to know the basic information of each device such as the

IP-addressand its capability such as the supported logical nodes and services. In IEC61850each device has a self-description file called the intelligent electronic device (IED) capability description (ICD). This can be read by any configuration tool supporting the standard.

The system integrator enters into the configuration tool the information about the substation automation system such as the primary equipmentthe automation functionscommunication methods of the devices. The configuration tool reads in all the ICD filesassigns the automation functions to the devices and lets each party know which and where its communication partners are. The configuration tool generates a file called substation configuration description (SCD). The information in this file is written back into the respective devices.

IEC’s international standards facilitate world trade by removing technical barriers to tradeleading to new markets and economic growth. Any product built to an IEC standard can be sold throughout the world.

Products

Kalki’s IEC61850 productssolutionsconsulting and substation SCADA and interface engineering enable customers to realise the benefits of IEC61850 in their existing substation and control systems with minimal modifications.

KSGL Gateway is a protocol converter and data concentratorthat can be deployed in existing substations automation systems. It can be used to integrate existing IED’s in a substation to the new standard although it supports many other protocols. Kalki also provides OEM specific hardware modules to enable OEMs to reduce their time to market for products.

Enterprise Integration using standards-based integration schemas and industry standards like CIM (IEC61968/61970)GID and SP-95 form the key platform for Kalki’s long term vision of a convergence of controlcommunication and computing. The company is working towards this goal by developing products and solutions such as the utility integration bus (UIB) which enables enterprise-wide integration. Kalki also provides protocol source code libraries and implementation services.

Sisco is a leader in IEC61850 implementation with many products that reduce system costs for end users and cut time to market for developers with field-proven

off-the-shelf technology.

Access for Manufacturing Message Specification (AX-S4 MMS) is an easy-to-use IEC61850 client application for real-time data integration in Microsoft Windows-based systems supporting OPC and DDE.

AX-S4 MMS supports variabledomainjournaland file services including unsolicited reporting and GOOSE/GSSE messaging. Included with AX-S4 MMS is the interactive MMS Object Explorer for intuitive access to IEC61850UCA2 and MMS device objects.

MMS-EASE Lite is a source code implementation supporting IEC61850 and MMS that has been optimised for use in IEDs such as remote terminalsreclosersPLCsmeters and other embedded applications.

Siemens Power Transmission and Distribution has just launched a process bus solution based on IEC61850. It enables an uninterrupted and redundant data flow synchronised to a time of less than one microsecond directly via the communications bus. A redundant ring in the fibre-optic linkin which the signals are transmitted in both directions simultaneouslyensures no messages are lost even if the communications route is interrupted.

There is also no need to allow for any reconfiguration time for real-time Ethernet. In the past the transmission of triggering signalsso-called tripsfor circuit-breakers as a form of intelligent local control was virtually inconceivablebut the new communications concept also makes this kind of control system possible.

Whereas in the past highly accurate time synchronisation was transmitted via an additional optic-optic link to the upstream recording units (merging units)according to the new concept synchronisation is now carried out over the real-time Ethernet process bus.

Tools

A free capture tool for IEC61850 protocol analysers will be included in the renewed Service Level Agreements for customers of Kema. It can be used to capture IP based traffic on an unlimited number of sites and store these in log files; can use the Cyclic Buffering functionalitysaving log filesfor exampleif specific and configurable situations occur; and it can remove old log files in order to prevent running out of disc space.

Existing customers just need to renew their Service Level Agreement for the analyser to enable this option. An unlimited number of free capture tools can be usedone running in every substationsfor example.

Omicron IEDScout is a software tool for engineers working with IEC61850 devices. It provides numerous useful functions needed in the substation or the laboratory including testingtroubleshooting and commissioning. The evaluation version has no time limit and can be installed on as many PCs as desired but some features are restricted or disabled.

Schweitzer Engineering Laboratories (SEL) has recently introduced a complete IEC61850 product family for station protectionautomationand control for distancecurrent differentialdistributiontransformerbusand bay control.

It includes AcSELerator Architect Software to import and export files directly to the protectionautomationor control devicewith no need for device firmware changes.

The SEL complete IEC61850 product family includes High-Speed Line ProtectionAutomationand Control; a Bay ControlAutomationand Protection System; Bus Protection and Breaker Failure; Line Current Differential Protection and Automation; and software enables the user to easily configure and document IEC 61850 communications among multiple suppliers' devices.


Modular design

Tamarack is a leader in the development of IEC61850and has supplied software and services to many vendors currently active in implementing and deploying devices utilising this standard. The modular approach to building high performance embedded implementations of IEC61850 typically requires very little customdevice-specific code.

It says its IEC 61850 Software is unique in that it was designed from the start for small device implementations. The code is written in ANSI standard C and has been used under LinuxWindowsVxWorkspSOS and a number of other operating systems as well as in stand-aloneOS-lessapplications.

The company’s IEC61850 Server is a compact unit for embedding in systems. The package includes MMS encodingdecodingand services for the IEC61850 subset of MMSalong with the required subsets of OSI SessionPresentationand ACSE. The object modelling and Object Dictionary generation software (ObjPREP)RFC 1006 interface softwareand the Tamarack generalized transport interface are shipped as part of the package.

The IEC61850 Client implements the standard’s client services. Applications range from devices requiring simple read/write access to peer devices in the network to complex gateway devices and remote terminals which must use self-description techniques and reporting models to access data from subordinate devices and which then serve the data acquired to other clients.

ABBthe leading power and automation technology companyhas just been recognised as a qualified test centre to certify products as compliant with IEC61850.

The certification authorises ABB’s System Verification and Validation Centre in BadenSwitzerlandto perform IEC61850 Conformance Testing in accordance with the group’s Quality Assurance Testing Program Procedures.

This new standard continues the principle of interoperability which first came on the automation scene probably a decade ago. Before thenmanufacturers built their own private standards into products to ensure that customers could not easily go to other suppliers. It took many years for manufacturers to realise that a more open approach would sell extra products for everyone and provide greater customer satisfaction. 

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