Wide Area Monitoring Network Stability & Synchrophasors

Wide Area MonitoringNetwork Stability & Synchrophasors

GE Consumer & IndustrialMultilin

2GE Consumer & Industrial

MultilinApril 10th, 2005

A New Concept?• Hardly…. wide area monitoring is an integral part of power

system operation today:– Telemetry

– Alarming and status

– State estimation

• What is new?– High-speed, reliable & affordable digital communication means

– Coverage through broad deployment of IEDs

– Real-time metering and communication capabilities of modern IEDs

– Affordable time-synchronized measurements

– Processing and visualization capabilities

Time-synchronized measurements and response time are key



August 14, 2003Imagine all operators having access to real-time visualization tools like this ….

Pre-Blackout Ohio Region 115-230 kV Voltage Contour



August 14, 2003Real-time tool relying on direct measurements rather than on state estimation …

Northeast Ohio Voltage Contour at 15:05 EDT



August 14, 2003With automated processing and alarming features to identify problems and pinpoint locations …

Northeast Ohio Voltage Contour at 15:51 EDT



August 14, 2003Turned into an automated, or semi-automated closed-loop mitigation system …

Never-to-be Northeast Ohio Voltage Contour at 16:15 EDT



Wide Area Schemes - Drivers• Operating the grid is not going to get easier:

– Insufficient stability margins

– Generation and load centers displaced even more

– Environmental and cost constraints on new transmission

– Deregulations and pressure on asset utilization

– No recognition for maintaining system security and margins

• Logical response:– With limited capabilities to strengthen generation and

transmission (natural stability) need to rely more on active controls (forced stability)

– Better visualization and assistance tools for operators

– Closed-loop control for events beyond response time of manual control:

• fight to stay together

• island controllably

• restore quickly



Is the situation really new?

• Large systems require monitoring and control capabilities even under good natural margins

• Margins maintained by a balance between the “muscle” (generation, transmission) and “brain” (controls)

• Dramatic erosion of natural stability margins

• Added generation solves one problem but adds new ones

• Relatively shallow penetration of IEDs and modern communications

• Downsized engineering force having difficulties catching up with the amount of required upgrades

• Deregulation and market forces not aligned with best technical solutions

• Fast-paced society and economy are less forgiving

Always true … Somewhat new ….



Erosion of natural stability margins

Problems are not unique, but the scale is alarming



Is the situation really new?

• Large systems require monitoring and control capabilities even under good natural margins

• Margins maintained by a balance between the “muscle” (generation, transmission) and “brain” (controls)

• Dramatic erosion of natural stability margins

• Added generation solves one problem but adds new ones

• Relatively shallow penetration of IEDs and modern communications

• Downsized engineering force having difficulties catching up with the amount of required upgrades

• Deregulation and market forces not aligned with best technical solutions

• Fast-paced society and economy are less forgiving

Always true … Somewhat new ….



Applications• Wide Area Monitoring and

Warning Systems

• Telemetry & Inter-utility Data Exchange

• Load/Generation Shedding

• Angular Instability Detection

• Wide-area Voltage Regulation

• Remedial Action & Power System Protection Schemes

• System Back-up Protection & Related Applications

• Coordinated Restoration

• Self Recovering Systems

Theoretically-founded opportunities, limited practical experience



Wide Area Schemes - Issues

Inception System studies Design:

Investment Local measurement

Ownership Communications

Deployment Data concentration

Testing Redundancy

Maintenance Fail-safe and self-monitoring

Security of data Data archiving

Market viable data

Application:

Visualization

Operator assistance algorithms

Unpopular manual controls Automated control algorithms

Coordination & Arming

Multi-disciplinary effort

Organizational Technical



UR N60”Swiss Army Knife” for Special

Protection Schemes



Local measurements• Major measurement points:

– Status of transmission paths

– Active & reactive power

– Voltages & currents

– Temperature & wind

– Synchrophasors and synchronized measurements

• Principles:– Specialized devices vs hardened but general-purpose

platforms

– Redundant devices vs redundant measurement points

– Flexible and redundant communication capabilities

– Degree of separation from both SCADA and asset protection

Modern relay platforms are a good choice (N60!)



Major areas of functionality

PowerfulData Acquisition

Capabilities(V,I,P,oC,pf)

PowerfulCommunication

Capabilities(GOOSE,

Direct I/O)

SystemOrientedFeatures

(PSB, OST,Open Pole,

f, df/dt)

Flexible, Universal,

High-densityI/O

FlexLogic & Simple MATH

functions



N60 Features

Out-of-step tripping Sensitive Directional Power

Peer-to-peer via Ethernet

Power Swing Blocking Open pole detection Peer-to-peer via SONET

Under- & over-frequency VT Fuse Failure G.704, RS422, C37.94, fiber

Rate of change of frequency

Overcurrent Flexible comms. architectures

Synchrocheck Under- & over-voltage Telemetry with 8-bit resolution

FlexLogic LEDs, Latching outputs Add, subtract, compare, select

dP/dt, dV/dt via FlexElements

Weather data & actions Respond to remote & local data



Wide-area Schemes



Flexible peer-to-peer communications



Architecture with JMUXes and URs

DataConcentrator

Applications



SynchrophasorsThe Next Major Step in UR

offering



Concept and definitionAfter a major system blackout … Imagine a team of reporter photographers with flash cameras dispatched to take a “snapshot” of the power system state …

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VA

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VBVC

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VBVC



Concept and definitionNeed an arbitrary angle reference …

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Concept and definition

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After a major system blackout … Imagine a team of reporter photographers with flash cameras dispatched to take a “snapshot” of the power system state …



Concept and definitionImagine an automated system with strobe lights synched via GPS and communicating results via digital network…

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GPS Clock

GPS Clock

GPS

Modem

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GPS Clock



Synchrophasors – Strobe Light Analogy

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Strobe Light Analogy

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Phasors• Rotating rotors = alternate currents / voltages

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VBVC

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• Phasors are well established means of representing ac circuits Charles Proteus Steinmetz (1865-1923)

Complex Quantities and their use in Electrical Engineering; Charles Proteus Steinmetz; Proceedings of the International Electrical Congress, Chicago, IL; AIEE Proceedings, 1893; pp.33-74.



Measuring Synchrophasors



Strobe Light Analogy



IEEE Synchrophasor Standard (PC37.118)• Original standard C37.1344 was released in 1995, reaffirmed

in 2001

• The new standard PC37.118 IEEE Standard for Synchrophasors for Power Systems in balloting

• Strong desire to release it in order to advance the field

• No IEC standard at the moment; most likely the IEEE will become IEC (similar to the COMTRADE standard)

• Key items agreed upon:– Time reference = UTC (Universal Time Coordinated)

– Measuring rates = (10,25 / sec @ 50Hz; 10,12,15,20,30 / sec @ 60Hz starting at the top of a second)

– Angle reference = cosine (0 deg at positive waveform peak)

– Communication model (standard frames and data types, interoperability)

Documents

Wide Area Monitoring Network Stability & Synchrophasors