smarter gridops with synchrophasors - chalmers · freq change means: sudden gen-load mw imbalance...
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Smarter Power Grid Operations with
Synchrophasors
Jay Giri [email protected]
March 29th, 2012
2012
The Next Generation Energy Management System (EMS)
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The Interconnected Power Grid… Thoughts to ponder..
“The interconnected electric power grid is one of the most complex real-time, 7x24, engineering machines in existence today!” Millions of equipment components need to work in concert, to get power from the source to the customer, around the clock!
“Operating the power grid is not rocket science…
It is much more than that!!“
Terry Boston, CEO PJM
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Greatest Engineering Achievements: Of the 20th Century
20. High-performance materials
19. Nuclear technologies
18. Laser and fiber optics
17. Petroleum and petrochemical technologies
16. Health technologies
15. Household appliances
14. Imaging
13. Internet
12. Spacecraft
11. Highways
10. Air conditioning and refrigeration
9. Telephone
8. Computers
7. Agricultural mechanization
6. Radio and television
5. Electronics
4. Water supply and distribution
3. Airplane
2. Automobile
As voted by the US National Academy of Engineers in 2001
#1. Electrification
“Electricity is a key Prime-mover which Drives Society ”
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L. Fink, K. Carlsen, IEEE Spectrum, March 1978
Secure
A-Secure
System not intact System intact
Reduction in reserve margins and/or increased probability of disturbance
Restorative Resynchronization
E I
Emergency Heroic Action
E I
System splitting and/or load loss
In extremis Cut losses, Protect Equipment
E I
Normal Objective: Load tracking, cost minimization, system coordination
E I
Insecure Alert Preventive Control
Violation of inequality constraints
E I
E = Demand is met
I = Constraints are met
Power System Grid Operating States
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Sources of Grid Vulnerability
• Natural calamities
• Component failures, communication link failures
• Protection and control failures
• Faults
• Human errors
• Inadequate security margin
• Gaming in the market
• Missing or uncertain information
• Sabotage or cyber-intrusion by external agents • http://www.digitalbond.com/2012/01/30/documenting-the-lost-decade-ics-vuln-analysis/#more-10966 • http://www.us-cert.gov/control_systems/pdf/ICS-ALERT-12-046-01.pdf
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The Reality We Face….
“Blackouts will occur again in the future”….
− Our power grids are too complex to make it fail-safe!
Our challenge is:
− To Prevent the Cascading, Uncontrolled Spread of an initiating blackout!
− And more importantly: To Restore power to affected customers ASAP!
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The Grid Operation Challenge!
1. Electricity as a Commodity Cannot be Stored!
2. Electricity Demand changes from instant to instant
3. Supply needs to change instantaneously to meet Demand… − Otherwise, Frequency goes off-normal (not 60Hz)…
resulting in:
• Protective relay trips of generating units, loads, etc.
• Potential trigger for a cascading blackout..
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Economics Reliability
9
Electric Utilities Goal – Balancing Reliability and Economics
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Automation Products ‘Meter to Market’
EMS Components
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EMS Views of the Grid
Asynchronous, Uncorrelated,
Telemetry view SCADA
System-wide, correlated
Existing system-wide view
Generation, Ties
Energy Balance (Freq) view
What is coming up next
Future system-wide view
AGC
SE & CA
DTS
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Control Center Operator
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The emerging, new power grid paradigm
Growth of Synchrophasor Measurements
From Phasor Measurement Unit (PMU) devices
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What is SynchroPhasor Technology?
− Next generation measurement
technology. (voltages, currents, frequency,
frequency rate-of-change, etc)
− Higher resolution scans (e.g. 30 samples/second). ─ Improved visibility into dynamic grid conditions. ─ Early warning detection alerts
− Precise GPS time stamping. ─ Wide-area Situational Awareness. ─ Faster Post-Event Analysis.
“MRI quality (3-D color) visibility of power
system, compared to X-ray (2-D b/w) quality
visibility of SCADA” – Terry Boston (PJM)
PMU Resolution
SCADA Resolution
Phasor Measurement Units (PMUs)
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Leverage Enabling Technologies… PMUs measure voltages & currents - magnitudes & angles
SCADA data
Refresh rate 2-5 seconds
Latency and skew
‘Older’ legacy communication
Responds to quasi-static behavior
Freq change means:
Sudden Gen-Load MW imbalance
somewhere in the grid
X-ray
Phasor data (PMU)
Refresh rate 30-60 samples/sec
Time tagged data, minimal latency
Compatible with modern communication
technology
Responds to system dynamic behavior
Angle-pair change means:
Sudden MW change in a
specific location of the grid
MRI
Courtesy EIPP, NASPI
Earlier Information for Better Decisions
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The changing US landscape
Synchrophasor measurement devices are being deployed aggressively in the US and globally − By 2012, will be a five-fold increase in PMUs across US –
over 1000 PMUs deployed − Each PMU provides 10-12 separate sub-second
measurements − Measurements include voltages, currents and frequencies − Augments traditional 2-4 second SCADA
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As PMUs grow relative to existing SCADA..
The utility industry will benefit with a:
• A time-synchronized snapshot of grid conditions at a sub-second rate
• Improved wide-area monitoring systems (WAMS) and future wide area control (WAC) – a self-healing grid!
The next SCADA frontier – “fast, sub-second measurements and fast, automated controls”
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Impact of Synchrophasors
on Grid Operations
An Unprecedented Transformational Change:
• to help operate the grid more efficiently & reliably
• to facilitate integration of Green energy resources with variable generation outputs
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Where in the grid should we deploy PMUs?
19
Key T
ie
Lin
es
Key P
ath
s
An
gu
lar
Sep
ara
tio
n
Majo
r
Gen
erati
on
or L
oad
Co
ng
esti
on
Man
ag
em
en
t
Win
d
Inte
grati
on
Oscilla
tio
ns
FA
CT
S
Co
ntr
ols
ENTER Business
Priority Weight for
Column Category
2 2 1 1 2 1 2 2 2 3 1
Data Rates
(samples/second)1 1 1 1 10 - 30 10 - 30 10 - 30 10 - 30 60 - 120
123 500.0 ABC ABC 2 1 1 3 7
455 500.0 XYZ ZYZ 2 1 1 2 3 9
Total 2 PMUs
PMU Siting Spreadsheet
Sta
te E
sti
mati
on
Situational Awareness PriorityBus KV level Station Name
Sta
tio
n A
lread
y
Netw
orked
SCORE
(Priority)
Sta
tio
n A
lread
y
CIP
Co
mp
lain
t
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Why PMU-based analysis?
Improve Security
EARLY WARNING OF
INSTABILITY
SITUATIONAL
AWARENESS
ISLANDING RECOVERY
BLACKSTART
SELF-HEALING GRID
Increase Transfer
RELIEVE DAMPING
CONSTRAINTS
STATE ESTIMATION &
CONTINGENCY ANALYSIS
IDENTIFY LINE
PARAMETERS
System Analysis
PSS TUNING
PLANT COMMISSIONING
POST-EVENT ANALYSIS
IMPACT OF RENEWABLES
IDENTIFY DYNAMICS
ISSUES
PSS
ENABLED
PSS
DISABLED
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Holistic Generalized Grid Security Analysis
Control Center -PDC
PMU
MEASUREMENT-BASED Analysis
(PhasorPoint)
Traditional
MODEL-BASED Analysis
(EMS)
SCADA
& Alarms WAMS
State
Estimator
State
Measurement
Other EMS
Applications
New
Applications
Small Signal
Stability
Oscillation
Monitoring
Transient
& Voltage
Stability
Stability
Monitoring
& Control
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e-terrastability
Dynamic Security Assessment
Transient Stability Analysis
Small Signal Stability Analysis
Voltage Stability Analysis
EMS Integrated with SynchroPhasor Solutions
G G
SynchroPhasor Applications
Framework (PhasorPoint) – Oscillatory Stability Monitoring
– Disturbance Detection
– Composite Events
– Islanding/Restoration/Blackstart
– Post-Event Analysis, Baselining
PMU Data
(30-60 per second)
PMUs
PMUs
PMUs
PMU Data
(1 per second)
Wid
e-Area A
dvan
ced V
isualizatio
n
e-te
rravis
ion
Energy Management System (EMS) – Improved State Estimation
–Grid Security Assessment
–SynchroPhasor State Estimator
e-terratransmission
SE snapshot (1 per min)
PMU based Information/Alerts (few seconds)
FACTS
Damping
control
IEC 61850
Real-Time
Controls
Phasor Data
Concentrator
PDC
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Integrated “measurement-based” &
“model-based” Stability Analysis….
A very nice marriage!
PMU Measurement-based analysis
PhasorPoint
PREDICT & MITIGATE
TRUE
LIMIT
GRID
OPERATING POINT
Model-based analysis:
Corrective actions based on ‘what-if’ analysis
EMS
Limit
NEW
Limit
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PMU Benefits to Grid Operations
Situational awareness tools
− Advanced visualization − Early warning detection alerts − Quick, reliable assessment of system during emergencies
Integration of PMU’s in State Estimator
− Voltage & current phasors as part of SE solution − State Estimator as a validation tool, as PMUs are deployed − Improved subsequent network analysis and optimization
Fast online stability solutions
− Small signal Oscillation Monitoring • Detection of poorly damped oscillations & control recommendations
− Voltage Stability margins − Transient Stability margins
Disturbance Locator
− Triangulate PMU and SCADA information to precisely locate where a disturbance originated
Identification of coherent groups of generators
− Recommendations for Online Adaptive islanding
Improved forensic analysis
− Post-event recreation − Improved restoration procedures
24
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New EMS applications – using only PMU data
Uses PMU data at the sub-second rate
Oscillation Monitoring
Grid-wide Disturbance Locator
Fast Stability Analysis & Control
25
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Oscillatory Stability Management
1/F MODE FREQUENCY
MODE AMPLITUDE
A
MODE DECAY TIME
EXP(-t/ )
MODE PHASE
Mode Frequency
Mode Amplitude
Mode decay time
Mode Phase
Exp(-t/)
Measured P / f /
Simultaneous multi-oscillation detection and characterisation direct from measurements
For each oscillation detected, alarm on:
mode damping and/or
mode amplitude for
Operations
Planning & Analysis, Plant Performance
Unlimited oscillation frequency sub-bands
Individual alarm profiles for each sub-band
Post-event analysis
Dynamic model validation
Damping controller performance assessment
Dynamic performance baselining
Early warning of poor damping (two level alarms)
Fast Modal Analysis: Alarms
Trend Modal Analysis: Analysis
Wide area mode alarms Mode locus plot with alarm thresholds
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Disturbance Location
Use PMU and to triangulate & precisely locate
the origin of the disturbance
A sudden disturbance causes a traveling wave that can be detected by PMU data across the grid:
Source: VirginiaTech FNET
Disturbance Location
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Visualization of dynamic clusters and frequency
28
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Dynamic Dashboard: Current area of interest
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PMU angle differences
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Contour: area Voltage
Query: station voltages
Flyout: SCADA 1-lines
Power flow animation
Integrated SCADA & GIS Displays
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Voltage Stability – Locations & Controls
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Where are the VAR sources?
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Oscillation Modes & Damping
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Weather Radar Overlay
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Today:
Protecting the Power System Grid
To “Keep the Lights On! “
Local, Device protection predominantly: − Transformers, lines, bus structures, generating units, etc
System-wide, Grid protection: − AGC: Automatic Generation Control
• A pioneering Smart-Grid application since the ‘70s!
• Automatically maintains system’s frequency and tie-flows
− Remedial action schemes (RAS), special protection schemes (SPS or SIPS), etc.
• Drawbacks are: − Logic is fixed and does not adapt to current conditions
− Are conservative by design; have to work for a wide range of 7/24 operating conditions
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Tomorrow:
Wide Area Monitoring & Control, too!
Grid Protection, In the Future: − Develop protective control schemes
that dynamically adapt to current power system conditions, to preserve the integrity of the “grid” as an entity.
− Tightly integrate fast sub-second measurements with fast sub-second controls (FACTS, HVDC, etc)
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Intelligent Decentralized Wide-area Grid Control
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Grid Control Devices
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Best
Adequate
Not
appropriate
J
L
K
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Thank you…