ABB Review Special Report - ABB - ABB Group

dents. This accurate identification providesa sound basis for the planning ofsystem expansions and future systemreinforcements.1Configuration of a wide area monitoring system with synchronized phasormeasurements from PMUs used as input for the system monitoring centerSystem platform overviewSystem monitoring centerGPS satellitePhasor measurement as basic technologyWide area monitoring systems are essentiallybased on new data acquisitiontechnology. Unlike conventional controlsystems, which use, for example, RTUsto acquire the rms values of currentsand voltages, a wide area monitoringsystem acquires GPS 1) -synchronized current,voltage and frequency phasor informationmeasured by PMUs at selectedlocations in the power system. Themeasured quantities include both magnitudesand phase angles, being timesynchronizedvia GPS receivers with anaccuracy of one microsecond. Untilnow, critical nodes in transmission gridshave usually been monitored using staticor quasi-dynamic data based on rmsmeasurements. Phasors, measured at thesame time, provide instant snapshots ofthe status of the monitored nodes. Bycomparing these snapshots, both thedynamicandsteadystate ofcriticalnodes intransmissionandsub-transmissionnetworkscan beobserved. The result is dynamic monitoringof the power systems.System architecture of the wide area1) GPS Global Positioning SystemPMUPMUmonitoring platformThe platform architecture for monitoringis made up of the following hardware:Phasor measurement unitsCommunication linksSystem monitoring centerPMUs are placed in the substations toallow the power system to be observedunder all the different operating conditions(network islanding, line or generatoroutage, etc). Some redundancy isprovided to secure this information inthe event of certain data being unavailable,forexampleWide area monitoring is essentiallybased on new data acquisitiontechnology, with GPS-synchronizedcurrent, voltage and frequencyphasor information measured byPMUs at selected locations.due toPMU outageorcommunicationfailure.The measureddataare sentvia dedicatedcommunication channels to thePSG 850’s system monitoring center(SMC) – a central computational unit inwhich the collected data are synchronizedand sorted 1 . This provides asnapshot of the power system’s status.In the case of meshed network topologies,the snapshot is then processedby the basic monitoring (BM) package,which is part of the SMC. BM denotesthe set of algorithms included in allinstallations of the wide area platformas the basis for different software applications.This solution package has thefollowing capabilities:PMUTransmission networkAbility to provide consistent inputdata for all PSG 850 applications.Fast execution, leaving sufficient timeto run additional applications withinthe sampling interval.Robustness – the system is resistant tothe poor quality of some of the inputdata (availability, range, synchronization)The reference phasor can be chosenfrom various points in the grid. Softwareapplications, which are linked to the BMoutput, address various dynamic phenomenaoccurring in power systems.They predict the state of the power systemand suggest appropriate action tobe taken by the system operators whenan emerging instability is detected. Anergonomic graphical user interface (GUI)2 displays the output information.Historical data can also be accessed,allowing phasor data to be retrieved forsubsequent analysis. A navigation facilityis provided for easy selection anddisplay of the required information.Implementation activities andadvanced software applicationsTo take full advantage of Inform IT WideArea Monitoring PSG 850, a step-wiseSpecial ReportABB Review35