Wide Area Monitoring with Phasor Measurement Data

Energy Sector© Siemens AG 2010

Wide Area Monitoring with Phasor Measurement Data

Dr. Markus WacheSiemens E D EA, Nuremberg, Germany

Energy SectorEnergy AutomationPage 2 March 2010© Siemens AG 2010

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Basics of PhasorMeasurementRealization of PMUsPower System StabilityStandard IEEE C37.118Structure of Wide AreaMonitoring System Application and referencesof WAMSummary


SIGUARD Phasor Data Processor Why should we measure phasors?

Xs

U1 U2)sin(212 δ

XsUUP ⋅

=

This equation means that active power flow is proportional to the phase angle difference between U1 and U2.

Thus it is possible to measure power flow withoutcomplicated algorithms as state estimator, power flow etc.


PMU Calculation of Total Vector Error

Both amplitude and phase angle errorhave to be considered forsynchrophasor accuracy.


Influence of CT accuracy on TVE

TVE = Abs Value of VdiffCT accuracy is defined in IEC 60044-1

CT 0,5S:Angle error ϕ = max 0,5 degAmplitude error = max 0,5%Abs(Vdiff) = 0,010038

TVE = 1%

CT 10PAngle error ϕ = max 3 degAmplitude error = max 3%Abs(Vdiff) = 0,05234

TVE > 5%

Conclusion: To fulfill TVE requirements of standard IEEE C37.118, measurement current transducer should be used.

CT 5PAngle error ϕ = max 1 degAmplitude error = max. 1%Abs(Vdiff) = 0,02004

TVE = 2%


SIGUARD Phasor Data Processor How to measure phasors

GPS Signal

IEEE C37.118

VdtdffI ,,,

Requirement time accuracy:

at 60Hz: 1ms means 21,7° !

required: < 10μs GPS-Sync. necessary


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Realization types of PMUs

Currently, three different realizations of PMUs are offered:

1) Standalone PMU Mainly based on protection relay technology

2) PMU functionality integrated in fault recorders

reasonable for transmission systems

3) PMU functionality integrated in protection devices

reasonable for distribution systems


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Why Phasor Measurement Units?

Inter - AreaOscillations

1V

2VLoss of

Synchronization

LineTrip

f

t

Cascadingoutages

P

V

Voltagecollapse

Reactivepower

shortage

Transmissioncorridor

congestion

HeavyLoad

Loss ofGeneration

Frequencydeviation

LocalOscillations


Overview: Power System Security and Blackout Prevention

Monitoring

SiGuard®

Measuring

1-5sec20ms-200ms1-100ms

Signal-

Transmission Steps

IAP

Metered Valuesof

Transducers

Swit

chin

gSt

ate

Met. Values Results

State estimatorShort-Circuit

LoadflowContingency

.......

Rel

aySe

ttin

gs

Analysis, Location SIMEAS SAFIR

Metered Valuesof

Relays / Recoders

Fault RecordsFault Protocols

Evaluation locally IEEE C37.118, 2006

Metered Valuesof

PMUs

Met. ValuesWAMS

ResultsOperat. Instructions

WAPC

Phasor Data Processing

System

Expertsystem

ScalableAcc. to

no. Of PMUs

ResultsOperat. InstructionsOperator-Training

PredictingDSA – PSSTMNETOMAC PSA – PSSTMSINCAL

Expertsystem


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PMU The standard IEEE C37.118

At present, IEEE C37.118 is worldwide the only standard in electric energy systems for the measurement of synchrophasors.

Specifications for the measurement and assignment of synchrophasors:Time reference= UTC (Universal Time Coordinated)Angle reference = cos (0° if maximum at PPS-puls)Reporting rate = 10Hz or 25Hz for nominal frequenzy 50Hz Measuring error max. 1% TVE (Total Vector Error)Communication model (structure of telegramms)

No specification for:Speed of measuringMeasuring accuracy under transient conditionsHardware / software of meterAlgorithm of measuring

The fixed specifications make a simple processing of synchrophasors of different measuring systems possible, both in real time and offline.


Future development of the standard

Dynamic requirements for measuring in PMUHarmonization with IEC61850

PMU The standard IEEE C37.118


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Basics of PhasorMeasurementRealization of PMUsPower System StabilityStandard IEEE C37.118Structure of Wide AreaMonitoring SystemApplication and referencesof WAMSummary


Possible structure of Wide Area Monitoring System (1/2)

1) Decentralized StructureOne PDC in each substation

Central PDC at Control Center

PMU1 PMU2

PDC

Substation 1

PMU1

PDC

Substation 2

PMU1 PMU2

PDC

Substation n

….

PDC Control Center LevelSCADA

Pro:• Local PDC as data storage

in case of telecomm. FaultCon:• Recall of information after

telecomm.fault is not standardizedproprietary solutions only

• Only few PMUs per substation (mostly one is sufficient)

High amount of PDCs required


Possible structure of Wide Area Monitoring System (2/2)

2) Centralized StructurePDC on control center level only

Regional control center may haveown PDC

PMU1 PMU2

PDC

Substation 1

PMU1

Substation 2

PMU1 PMU2

Substation n

….

PDC Main Control Center

Pro:• Better balance betwen number of

PDCs and number of PMUsLess Costs

• Flexible Concept: PDCs to be placed where Phasor information is needed

Con:• No storage for telecomm. fault

below „lowest“ PDC

Remark: Local fault recorder functionality may serve as independent archive.

Regional Control Center


Scope ofSIGUARD

Phasor DataProcessing System

Interfaces of a Wide Area Phasor Measurement System

PMU PMU PMU PMU PMU

PDC

Phasor Data Concentrator (PDC), System Monitor (PMU Errors, Communications, PDC Operations)

Substation Measurements

Data Collection

DISPLAYPhase Angle,

Stability Analysis,Monitoring

CONTROLReal Time Controls

WACS

PROTECTIONProtection Schemes

WAPS

SCADAPhase Angle,

Voltage, Frequency,Alarms

State Estimation

PhasorData

Applications

IEEE C37.118

IEEE C37.118

IEEE C37.118


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Application of Wide Area Monitoring

Support analysis of critical system status by control center expertsDuring disturbance: Fast and precise measurement display

After disturbance: Use PMU measurements to understand the dynamicbehaviour of the system to be able to improve it; create report.

Load monitoring (stress) of lines based on angle differencesSynchrophasors give a clear picture without the need of using systemtopology data

Reference Phasor provides the view for the relevant differenceClear indication of system separation

Example disturbance Nov 4th 2006, Europe: System separation was notrecognised by all TSOs immediately

Optimal loading of transmission corridors with Voltage-Power-CurveGives an actual picture of load situation and reserves

Check results of state estimation with real measurements


Future applications

Synchrophasors as base for Wide Area Control SystemControl of HVDC, FACTS as fast reaction to power swings based on synchrophasor measurement

Algorithms will have a strong project specific componentSynchrophasors as base for Wide Area Protection System

Direct transmission of phasors between protection devices

Could improve reaction of protection device

PDC will probably not be involved


Reference: transpower stromübertragungs gmbh (TPS) (former E.ON Netz TSO), Germany

Description:7 SIMEAS-R PMUs on 400kV Level in all parts of TPS-grid in GermanyOne central SIGUARD PDP Monitoring system in BayreuthPMU-data sent via existing fast communication network fromtranspowerRunning in a test-configuration sinceMarch 2009Reporting rate 10/s, nominal frequency= 50 Hz


Experiences: Several power swings could be observed in real time with damping and frequencyMonitoring of change of power flow, caused by wind power infeed,in real time without using any topology information. Changing phase angles between different parts of thegrid could be observed.




Example: Generation loss in southern europe

FrequencyPMU NorthPMU South

VoltagePMU NorthPMU South



Example: Strong Windpower in the North

Voltage PhasorPMU North1PMU North 2PMU South (reference)

Phase Angle reaches 60 Degree


Application: ewz (city supplier of Zurich), switzerland

Description:18 SIMEAS-R PMUs on distribution and transmission level in greater Zurich areaOne central SIGUARD PDP Monitoring system in ewz officePMU-data sent via existing fast communication network from ewzRunning since May 2009Reporting rate 25/s, nominal frequency = 50 HzPDP server functionality to SAFIR (data aquisition tool)

Goals:Fast Fault location in distribution networkSynchrophasors used as additional information source for disturbance locationMonitoring of the complete distribution network, especially at the interfacesto transmission network

Experiences: PDP server functionality (sending out PMU data in IEEE C37.118 protocol) is implemented for the first time


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Wide Area Monitoring with Synchrophasors Summary

Increased network load, thus it is necessary to understand the mid term dynamics (100ms…10s) by online observation and offline disturbance analysis of

Voltage stability

Frequency stability

Power oscillations

Loadability

Phasor measurement is base technology for future smart grid features

System integrity protection schemes (SIPS)

Power oscillation damping devices (FACTS, fast valving)

Real time state estimator


Wide Area Monitoring with Synchrophasors Summary

Using the complete capacity of transmission lines without loosing stabilityTransmission corridor supervision with „nose curve“ (U-P-curve)

Support for Blackout Prevention

Fast Analysis of Power SwingsReports after disturbances can be quickly prepared

Closes the gap between fast, local measurements (protection) and slow, large area measurements (control center)


Thank you!


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Overview User InterfaceApplicationRoadmapOnline Demo


SIGUARD Phasor Data ProcessorMonitoring of - Online view or - Historic view (selectable) Power System Status Curve

Geographical View (Google Earth based)

Time charts

Phasor diagrams


SIGUARD Phasor Data Processor

Calculation with Formulas

Voltage stability curve


SIGUARD Phasor Data Processor

Online limit editing

Measurement system health


SIGUARD Phasor Data Processing System User Interface / Example Limits Editor


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SIGUARD Phasor Data Processing System Application

Phasor Data Concentrator: Collecting Phasor Measurement Data via IEEE C37.118 Protocol. PDP-Server: IEEE C37.118 Data Provider for other PDCsMonitoring- Online View or- View of history (selectable)- Phasor View or Time-based diagramCalculating and displaying of Status Value for the Power SystemIndication of measurement system healthGeographical View (Google Earth based)Charts View and Measurement List (CSV-Export, configurable), forreportingFormula Editor for specific analysisLimits Editor for online adaptation of limitsTransmission Corridor monitoring (Voltage-Power-Curve)


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Thank you!

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Wide Area Monitoring with Phasor Measurement Data