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Imagination at work
WAMS as Core Smart Grid Technology
London12/2015
GE Proprietary Information—Class III (Confidential) Export Controlled—U.S. Government approval is required prior to export from the U.S., re-export from a third country, or release to a foreign national wherever located.
Oleg Bagleybter, PhD
V4V1
Wide Area Measurement System -Synchrophasors
Full per-cycle detail
GPS
Timestamp
Phase
V4, V1
Magnitude
1 2 3 4
Synchrophasors: Key FeaturesSynchrophasors: Key Features
� Synchronised V, I & Frq measurements
� 50/60Hz data captures dynamics
� 3-phase measurements
� Real-time streaming
Time
Phasor
format
Phasor
format
Angle Difference increases with
• Power flow
• Impedance (weakened network)
V4V1
Voltage phase angle as an indicator of transmission capacity usage or stress
GPS
Timestamp
Phase
V4, V1
Magnitude
1 2 3 4Time
Phasor
format
Phasor
format
1 2 3 4
• Next generation measurement technology
− Voltages, currents, frequency, frequency rate-of-change, etc.
• Higher resolution scans (example: 50 samples/second)
− Improved visibility into dynamic grid conditions− Early warning detection alerts
• Precise GPS time-stamping
− Wide-area situational awareness− Faster post-event analysis
• Data integration - C37.118 Standard
Phasor Measurement Units (PMUs)
WAMS vs. SCADA
SCADASCADA
WAMSWAMS
SCADA data (@ 4 FPS)
showed a small change in
the system frequency
PMU data (@ 60FPS) showed a
much larger frequency swing
associated with the event where
frequency oscillations lasted several
seconds
Using phasors: gaining small-signal detectability
6
Source: Terna
SCADA measurementsSynchrophasors
measurements
Control Center - PDC
Copyright Alstom Grid 2013
New
Applications
Other EMS Applications
SCADA & Alarms WAMS Alarms
State Estimator State Measurement
Small Signal Stability Oscillation Monitoring
Transient & Voltage Stability Stability Monitoring & Control
Island Management Island Detection, Resync, & Blackstart
EMS
MODEL-BASED
Analysis
PhasorPointPMU MEASUREMENT-
BASED Analysis
Complementing EMS with WAMS: Earlier “Dynamic” Information for Better Decisions
The Next Generation Energy Management System!
Transitioning from traditional “steady-state” view to enhanced “dynamic” situational awareness.
Network Operational Challenges
Security
• Cascading disturbances
• System stability issues
• Security co-ordination
Constraint Relief
• Conservative margins used for dynamic constraints
• Real-time limits not known
• Interacting Controls
Sustainability
• Balancing with intermittent resources
• Impact of renewables on stability
• Smart Grid complexity
Enabling New Grid Solutions
WAMS
Generator
& ISO Compliance
Offline Analysis
Modelling
Root Cause
Analysis
Post-Event
New Smart Grid
Applications
Real-time toolsRestoration
Constraint relief
Dynamics -
early warning
Wide Area
Controls
EMS
Substation
Automation
Synchrophasor
Analytics
Distributed
Controls
State Estimation
Contingency
Analysis
Dynamic Security
Assessment
Reduce Congestion Improve Resilience System Analysis
Smart Grid Challenges
WIDE-AREA
CONTROL
Early Warnings
• Angles diverge
• Oscillation alarms
• Precursor events
Faster Restoration
• Situational awareness
• Island reconnection
• Stabilisation
• Stress reduction
What is WAMS useful for?
EVENT
PRE-EVENT POST-EVENT
Reduce Probability Reduce Impact
Control Design
• PSS/POD tuning
• GOV tuning
• Cause analysis
• Auto-action design
• OPS Procedures
LONG-TERM
Improve Performance
Real-TimeControl Room
PhasorPoint Summary
Oscillation
Management
Separation
Management
Disturbance
Monitoring
Angle
Constraints
Situational
Awareness
HistoricAnalysis & Design
Post-event
analysis
Control Design
& Test
Stability Risk
Assessment
Renewable
Connection
Operator
SupportProven Scalable Flexible
WAMS – from Small Pilot to Large Scale
Small Pilot Systems Large Enterprise-Class Systems
Supports 5,000+ phasors @ 50/60Hz
Enterprise-class reliability, security, inter-operability
Pilot installation ≤ 5 locations
Simple implementation
• High Availability & Co-Location Options
• Fully Scalable (locations, phasors, etc.)
• Fully Extensible (applications, etc.)
• Efficient & Flexible Archiving
• Flexible Display Building
• High Availability & Co-Location Options
• Fully Scalable (locations, phasors, etc.)
• Fully Extensible (applications, etc.)
• Efficient & Flexible Archiving
• Flexible Display Building
CONTROL ROOM PROCESSES
System Separation: Islanding Management
Island Detection
Algorithm (Angle & frequency
coherency)
Stabilise frequency
by balancing islands
Select reconnect
boundary
Match frequency,
voltage across
boundary
Arm CheckSync
Relay
Observe Resync
Confirm success,
close other lines
If unsuccessful,
retry with closer
frequency
Overview, Alarm �
EMS or audible
alarm
Island visualisation
Situational Awareness Operational Response
PROBLEM
IDENTIFICATION
Measurement &
Analytics
RECTIFICATION
NOTIFICATION
Feedback on
problem resolved
OPERATIONAL
WARNINGS
Alarms &
Visualisation
OPERATIONAL
GUIDANCE
Procedure to
accompany alarm
System Disturbance Management
Situational Awareness Operational Response
PROBLEM
IDENTIFICATION
Measurement &
Analytics
PROBLEM
IDENTIFICATION
Measurement &
Analytics
RECTIFICATION
NOTIFICATION
Feedback on
problem resolved
RECTIFICATION
NOTIFICATION
Feedback on
problem resolved
OPERATIONAL
WARNINGS
Alarms &
Visualisation
OPERATIONAL
WARNINGS
Alarms &
Visualisation
OPERATIONAL
GUIDANCE
Procedure to
accompany alarm
OPERATIONAL
GUIDANCE
Procedure to
accompany alarm
Detect disturbance
Locate trigger point
Detect event type
(load/gen/line loss)
Estimate impact
Num. events & impact justify
action
(re-dispatch or load shed)
Locate effective action
Decide level of action
Confirm freq restored
Identify any grid
bottleneck
Check oscillations
Display trigger location
Show sequence
(multi events � high risk)
Log impact
Oscillatory Stability Monitoring
Oscillation
Indicator
Since 1999
• 0.5Hz Mode Poor Damping
− Reduce Scotland-England Flow
• Other Mode Instability
− Broadcast alert to generators, affected units reduce output
Situational Awareness Operational Response
PROBLEM
IDENTIFICATION
Measurement &
Analytics
PROBLEM
IDENTIFICATION
Measurement &
Analytics
RECTIFICATION
NOTIFICATION
Feedback on
problem resolved
RECTIFICATION
NOTIFICATION
Feedback on
problem resolved
OPERATIONAL
WARNINGS
Alarms &
Visualisation
OPERATIONAL
WARNINGS
Alarms &
Visualisation
OPERATIONAL
GUIDANCE
Procedure to
accompany alarm
OPERATIONAL
GUIDANCE
Procedure to
accompany alarm
Oscillatory Stability Monitoring: Problem Identification
PROBLEM
IDENTIFICATION
Measurement &
Analytics
PROBLEM
IDENTIFICATION
Measurement &
Analytics
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/τ)
Measured P / f / δ
Simultaneous multi-oscillation detection and
characterisation direct from measurements
(no modelling required)
Fast Modal
Analysis:
Alarms
Trend Modal
Analysis:
Analysis
Oscillations
0.005-0.1Hz Governor / frequency
0.1-4.0Hz Electromechanical
0.1 – 1Hz Inter-area
1 – 2Hz Local
2 – 3Hz Interplant
4.0-45Hz Sub-synchronous
Early warning of poor damping
Source Location of contributions
Guidance for real-time & planning
CASE STUDIES
National Grid UK & AEMO Australia
Constraint Relief
Australia3 Oscillation Constraints
Great BritainScotland – England
Interconnector
Transmission Corridor Net Transfer Capacity
+128MW
Model limit
with margin
Limit with
measured
damping
Thermal limitAREA 1
AREA 2
+160MW+200MW
Damping Measurement for Real-Time Constraints
• Modelling uncertainty requires large margin
• Use margin as long as observed damping is good
• Reduce transfer if poor inter-area mode damping occurs
AEMO, Australia
Security
• 150MW Oscillations, high risk of separation leading to blackout
• Alarm flood in EMS
• PhasorPoint shows damping issue begins with generator start
• Operators able to take action to avoid separation
• Root cause was generator control fault
• Similar instability 2010; other cases avoided by early warning
ACAM ProjectAngle Constraint based Active network Management
ACAM Principle:• Measure angle difference
between wind generators
and key grid sites
• Network studies � max
angle between PMUs for
all load / generation and
outage scenarios
• Angle acts as proxy for
thermal, reverse power
flow & voltage excursions
• Control algorithms to
curtail generation based
on angles
ACAM ProjectAngle Constraint based Active network Management
ACAM Pilot Network:
• 33kV network on Anglesey
• High wind penetration,
>33MVA connected
• Several connection requests
for wind, hydro & large PV
• Voltage, thermal & reverse
power constraints limit BaU
connections
• ACAM minimises the
monitoring & comms
channels required
• Adaptable to network
changes
HVDC
Sub-Synchronous Oscillation (SSO) Monitoring - Ongoing
Sub-Synchronous OscillationsCapacitors in series with inductance � natural frequency.
Natural frequency coinciding with torsional or control mode � resonanceCan involve series caps, thermal generators, windfarms, HVDC
Novel Analysis & Early Warning
Determine effective LC natural frequency (no resonance) � understand
variabilityReal-time detect near-resonance � raised amplitude, modes interacting
� Address by changing effective L (by dispatch) AVOID TRIPPING
SSO Outstation and Applications
New 200Hz waveform streaming from integrated DFR/PMU/SSO
Outstation4-45Hz Frequency, amplitude, damping analysis
<80Hz Spectrum (2nd phase)
RA33x
Acquisition Unit
RPV311
Central Unit
Installed & Operational by Fixed
Series Capacitor Installation March
2015
Series Capacitors
Thermal GeneratorsWindfarms
Sub-Synchronous Resonance - Ongoing
Torsional frequencies fixed
Effective L varies with
system condition
Series capacitance may
be fixed or controlled
� Some uncertainty in
SSR behaviour
SSR Typically ~10-40Hz
Derive SSR components from Waveforms (not phasors);
WAMS infrastructure for Control Room Alerts & Analysis
Transient stability limits based on ANGLE information
δ
(δ)
δP
B6 (Cheviot) Boundary
~ 3.5GW Transient Stability Limit (P)
~ 1.5GW Wind Capacity in Corridor
���� Volatility in corridor capability
Expressing Limit as Angle
• Transient stability closely related
to angle difference
• Define limits by Angle, not MW
alone
• Possible future use of angle in
new HVDC control
Energinet, Short Circuit Capacity
• Alert and Alarm on low SCC due to HVDC issues
• Action taken to increase SCC if in Alert state
• HVDC protected in case of low SCC
• Future work in relating system conditions to SCC
• Flexible SCC trending
Security Constraint Relief
Short Circuit Capacity from PMUs
Concept
• Calculate RoC of V&I due to “downstream” event (not changing source V & Z)
• Filter switching events are downstream. SCADA switching event sent to PhasorPoint to initiate SCC calculation.
ZI
V=
∆
∆−
&
&
Benefits
• Ensure SCC large enough at connection to HVDC
• Address uncertainties in model based SCC with high renewable generation
• Relax generation dispatch constraints
• Filter switching can be initiated manually when SCC value needed
• Historical SCC for planning
Landsnet, Iceland Control Centre
Overview Islanding
Selected Freq, Voltage,
Boundary & Key Unit P Islanding
Selected Freq, Voltage,
Boundary & Key Unit P
PhasorPoint used in operational procedures for:
Islanding & ResynchronisationResolving instability in disturbances
Dynamics Issues in Iceland
Problem Solutions
Inter-area oscillations Power System Stabilisers (PSS)
Wide Area PSS
SVC Power Oscillation Damper
Very low frequency oscillations Governor tuning
Angle stability Wide Area Defence
Controlled Separation
Island stability Secure transitions
Reduce exposure time
Governor control
Landsnet Control Project
Gen Fast Ramp
Fast trigger
Smelter 1 Control
Down&Up - fast
action Smelter 2 Ramp
Down action
Wide Area POD
Adaptive damping
East Load Shed
Triggered load
shedMicrogrid
Island operation
Adaptive Islanding
Choosing split-line
KRA Gov Mode
Enable speed modeTrial Active NowInitial scheme operational
Planned1-4 year timeframe
Deploy PSS parameters
• Dynamic performance review
− After ~ 2-4 weeks
• Acceptance or review
− Performance improvement− No increased risks
• Before PSS tuning
• After PSS tuning2.0Hz Mode
Mode Decay Time Constant (sec)
Mode Amplitude (MW)
• Before PSS tuning
• After PSS tuning1.2Hz Mode
Mode Decay Time Constant (sec)
Mode Amplitude (MW)
• Before PSS tuning
• After PSS tuning0.8Hz Mode
Mode Decay Time Constant (sec)
Mode Amplitude (MW)
National Grid Frequency Control NIC
• National Grid projects Frequency Reserve Cost increase £60M now � £250M by 2024 due to reduced inertia
• Wind, storage, PV, DSR etc. can provide useful non-conventional Frequency Response
• Enhanced Frequency Control Capability (EFCC) accelerates response and co-ordinates diverse resources
• Target reserve response deployed 0.5-2s(at present 2-10s)
• Facilitates a Frequency Response Aggregation Service for diverse resources, thus an enabler for a Fast Frequency Response Market
Target (Alstom):Develop new monitoring and control system (MCS) and
demonstrate viability of obtaining rapid frequency
response from new resources (including renewables and
demand side response)
Reducing Inertia with Increasing Share of Wind
• Large high wind N�S power flow
• Major constraint Scotland-England
• Inertia reducing, esp in Scotland
− Wind power - no inertia− Interconnectors – no inertia− Synchronous plant closed or constrained off
Large Wind
Resources
Largest
Load
Inter-
connectors
Wide-Area Control
Measured Frequency response to generator loss
RoCoF varies across system depending on event proximity
• Wide-area observability required for this behaviour
• Use of Angles information
• Used to prioritise action closer to event
• No visualisation can lead to separation
System Splits
Risk of blind control
GE WAMS Centre of Excellence – Edinburgh(former Psymetrix)
Advanced Phasor
Framework
• Data Management
• Analysis Tools
• Visualisation
Advanced Phasor
Framework
• Data Management
• Analysis Tools
• Visualisation
Phasor Applications
• Reliability
• Constraint Relief
• Dynamic Performance
• Renewables Integration
• Wide-Area Control &
Protection
Phasor Applications
• Reliability
• Constraint Relief
• Dynamic Performance
• Renewables Integration
• Wide-Area Control &
Protection
Consulting Services
• WAMS Deployment
• Dynamics & Control
• Operations & Planning
Guidance
• Power System Analysis
Consulting Services
• WAMS Deployment
• Dynamics & Control
• Operations & Planning
Guidance
• Power System Analysis