Electricity Today Issue 4, 200310

SCADA integration has historicallybeen a costly and complex venturefor many utilities. The need forsimplified amalgamation has becomeincreasingly pressing as the industrymoves to the establishment of open,worldwide accepted standards to sharedata seamlessly throughout the organiza-tion. While the establishment of theseprotocols is an important catalyst in thesuccessful evolution of todays SCADAenvironments, there is the ongoing chal-lenge of ensuring that substation equip-ment is optimized in order to leverage allthe technology and economic benefitsthat these standards bring to the equation.

Now more than ever, utilities needflexible, microprocessor-based hardwareand software tools to truly realize thesebenefits. Without them, SCADA systemswill continue to be restricted by the com-plexities of working with proprietaryequipment, software and communica-tions protocols. Among other challenges,equipment having different proprietaryprotocols cannot be integrated withoutthe installation of Remote Terminal Units(RTUs) to perform the translation work,which is both expensive and labour-intensive.

The move to international standardshas been evolving over many years, andled to the widespread acceptance of theUCA/MMS Version 2.0 protocol. Thiswas established by Electric PowerResearch Institute (EPRI) under thesponsorship of utilities around the worldand has been steadily gaining in popular-ity. More recently, the InternationalElectrotechnical Commission (IEC) hasbeen moving towards the establishmentof the IEC 61850 CommunicationNetworks and Systems in Substationsstandard communication protocol. Thisnew standard, which is scheduled forfinal approval later this year, representsan enhanced version of EPRIsUCA/MMS.

The new IEC standard incorporates

the following features:- Complete communication profile

based on existing IEC/IEEE/ISO/OSI communication standards

- Uses existing standards and com-monly accepted communicationprinciples, open protocols and self-descriptive devices that allow one toadd new functionality.

- Self-descriptive data objects relatedto the needs of the electric powerindustry.

THE NEED FOR GLOBALCOMMUNICATIONS PROTOCOLS

Industry experience has demonstrat-ed the need and the opportunity fordeveloping standard communication pro-tocols, which would support interoper-ability of IEDs from different manufac-turers. Interoperability in this case is theability to operate on the same network orcommunication path sharing informationand commands. There is also a desire tohave IED interchangeability i.e. theability to replace a device supplied byone manufacturer with a device suppliedby another manufacturer withoutmaking changes to the other elements inthe system. Interoperability is a commongoal for electric utilities, equipment ven-dors and standardization bodies.

With open, standard protocols, it isunderstood that utilities can more easily and affordably benefit fromadvanced high-speed, peer-to-peer com-munications as well as device interoper-ability for substation automation withoutthe need of high cost for integration.Standards-compliant hardware and soft-ware from different vendors can belinked and progressively integrated overtime, thereby providing a means to cost-effectively upgrade as needs and technol-ogy develops.

The flexibility provided by theIEC850/UCA-MMS protocols has thepotential for saving millions of dollars indevelopment costs for utilities and man-

ufacturers, since it eliminates the needfor protocol converters and lengthy, com-plex database mapping when integratingdevices from different manufacturers. Inaddition, the possibility of exchangingprotection/control signals in real timeover a high-speed LAN in a peer-to-peerrelationship means that a great deal ofinter-device control wiring can be elimi-nated by performing inter-device controlsignaling over the LAN. New protocolsalso provide an easy, clear path forexpansions and future upgrading toSCADA systems.

This communications flexibility ofsubstation devices represents significantadvantages to SCADA environments ona number of fronts. With microprocessor-based hardware based on an open plat-form, utilities can perform upgradesmore cost-effectively, preserve their ini-tial technology investment, and substan-tially reduce long-term implementationcosts. Gateways may still be required atthe substation as data concentratorsand/or protocol translation for legacydevices.

The new standards offer the connec-tivity that older SCADA systems havedifficulty providing. Any authorized userwithin the utility enterprise can easilyaccess information from devices on thenetwork from their desktop, without theusual complexity and expense of build-ing SCADA extensions to engineering,accounting, planning and other depart-ments that need the information.

THE CONCEPT OF THE UNIVERSAL RELAY

GE Multilin recognized the industryneeds for a modular, IntelligentElectronic Device (IED) platform usingopen communication protocols at thebeginning of the development of theUniversal Relay (UR) several years ago.The UR platform provides modularityand flexibility to adapt and support sev-eral communication protocols includ-

SYSTEM CONTROL

MICROPROCESSOR-BASED RELAYS AN ENABLER TO SCADA INTEGRATION

By Gustavo Brunello

13470_ET 04_03 6/26/03 2:52 AM Page 10

Industry Restructuring, Continued from page 9cism of those involved in opening of Ontarios electricity market.Moving to an open market was a large undertaking which was car-ried out with adherence to sound electricity rate-making princi-ples.

By adopting the above recommendations, Ontario electricityconsumers will benefit in the following four key ways:- Clear information will be provided on electricity bills, with

detailed information available for consumers who wish toverify calculations.

- The terminology, definitions, and basis of calculating chargeson bills will be consistent across the Province. Comparisonsamong different LDCs will be easier to perform.

- Consumers will know that bill charges have been developedusing sound rate-making principles.

- Cost savings and long-term energy conservation can be pur-sued through the use of new technologies, such as intervalmeters.The fact that Ontario consumers have become increasingly

interested in the local electricity market is to be welcomed, as thisinterest will result in a greater degree of accountability for allinvolved. In the end, consumers and industry will benefit.

Note that the full Electricity Bill Review report and a sum-mary brochure can be downloaded from the Ontario Ministry ofEnergy website: www.energy.gov.on.ca.

The contributor also wishes to acknowledge the followingpeople who participated in preparing the Electricity Bill Reviewreport: Jane Allen, Principal; Sal Badali, Senior Manager; andRouhan Coutinho, Consultant, all from the Toronto office ofDeloitte Consulting. ET

ing those that have yet to be established. In order to achievethis end, it relied on the same concepts and technologies thathave driven the desktop PC to becoming a general-purposetool and engine of the information age.

Whereas traditionally, manufacturers of protective relaydevices produced different products specific to the protectionof generation, transmission, distribution and industrial equip-ment, the UR provides utilities with a common, microproces-sor-based tool for protection, metering, monitoring and con-trol, across the entire power system. In essence, its purpose isto serve as a universal platform for substation automation.

As a microprocessor-based relay, the UR comprises a coreset of software and hardware building blocks that can encom-pass a number of functions, including: algorithmic and controllogic processing; power system current and voltage acquisi-tion; digital inputs and outputs for control interfaces; analoginputs and outputs for interfacing to transducer and SCADAsystems; communications to station computers and/or SCADAsystems; local Human Machine Interface (HMI) and powersupply circuitry for control power.

The architecture accommodates these functional blocks ina modular manner to allow for cost-effective scalability, flexi-bility and upgradeability. Much of the cost savings is achievedthrough the use of common components such as CTs and VTsmodules, single identical CPU cards, power supplies and net-work/communication cards. Modularity is achieved through aplug-in card system similar to that found in programmablelogic controllers (PLCs) as well as PCs. A high-speed parallelbus provides the modules with a common power connectionand high-speed data interface to the master processor as wellas to each other.

SCALABILITY, UPGRADEABILITYScalability is found in the ability to configure the relay

from minimum to maximum I/O capability according to par-ticular requirements. Users can add modules configured withthe desired I/O for maximum flexibility.

Upgradeability requires the simple replacement or addi-tion of modules. For example, users can upgrade from a twist-ed pair copper wire communications interface to high-speedfibre-optics communications or enhance a transformer pro-tection application by adding an Analog I/O module for RTDs among other enhancements.

Modular, field programmable software can be configuredto support a number of functions. These can include protectionelements, programmable logic and I/O control, metering, dataand event capture/storage, digital signal processing, HMI con-trol and communications.

One advancement in engineering that is an integral part ofUR development is Object Oriented Programming and Design.By using this concept, users can create a protection class andobjects of the class. These software modules can be complete-ly self-contained or encapsulated.

While not all utilities have made the move to new stan-dards, gaining international acceptance, this advanced level ofcommunications promises to play a critical role in the evolu-tion of the SCADA environment. As the industry continues toseek out ways to migrate to more efficient operations, it standsto reason that the more flexible and upgradeable the elementsare on the system, the easier and less costly the integrationrequirements.

Gustavo Brunello is a Senior Application Engineer withGE Multilin. For more information, visit the Web site athttp://www.geindustrial.com/Multilin. ET

11Electricity Today Issue 4, 2003

13470_ET 04_03 6/26/03 3:48 AM Page 11

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