Real-Time Voltage Stability Monitoring Voltage Stability... · Measurement-based indicators: ... o...
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Quanta Technology, LLC4020 Westchase Boulevard Suite 300Raleigh, NC 27607 USATel: +1 919-334-3000 www.quanta-technology.com Copyright © 2012. Quanta Technology, LLC Confidential & Proprietary
Smart Solutions, Practical Results
Real-Time Voltage Stability Monitoring
Damir NovoselPresident, Quanta Technology LLC
JSIS MeetingTempe, Arizona
January 15-17, 2013
Voltage Stability Assessmentx
Under‐voltage signal
#1
#2
r
Voltage instability region
#1: Inaccurate under‐voltage detection#2: Under‐voltage fails to detect
Dynamic, model-based simulation tools:• Voltage Stability Assessment (VSA) based on
State Estimation contingency analysis• Tracking the relative distance from voltage
instability continually in real-timeo Distance to the nose of the PV curve o State Estimation based stability boundary
• Important to validate model correctness
Measurement-based indicators:• Monitor available reactive power levels
(capacitor/reactor reserves, tap-changers)• Singular Value Decomposition (SVD)• Sensitivity analysis• Distance of the load's apparent impedance to
the Thevenin impedance - VIP, REI equivalent, Real-time Voltage Instability Indicator (RVII)Source: ABB
Accuracy Easy to Interpret Data Req. Comput.
BurdenLocal/ WA/
FIDVRRVII or VIP improved^ Low/Mod.* High Very low Very low L/WA/FID.
VIP^ Low Mod./High Very low Very low L/WA
REI^ Low Mod./High Low Low L/WA
SVD Mod./High Moderate Moderate Moderate WA
Sensitivity Moderate Moderate Low Low L/WA
Time Series Moderate Moderate Low Low/Mod. WA
* Low – far from stability boundary; Moderate – close to stability boundary^ Pilot or Product Installation WA – Wide Area
Model‐Free
High-Level Method Assessment
Accuracy Easy to Interpret Data Req. Comput.
BurdenLocal/
WA/ FIDVR
RT Nomogram**^ High High High Mod./High WA
Contingency VSA^ High High High High WA/FIDVR
Cont. Power Flow^ Mod./High High High High WA
Reactive Reserve^ Moderate Moderate Mod./High Moderate L/WA
Decision Trees High Moderate High High/Low** WA
Sensit./Eigenval. High Moderate High Mod./High WA
** Two dimensional, SCADA/SE updated or multi‐dimensional RT VSA *** High in offline training; Low in real‐time^ Pilot or Product Installation WA – Wide Area
Model‐Based
High-Level Method Assessment
RVII/VIP Improved Advantages• Model-free, fast real-time voltage instability detection
method*, independent of state estimation• Implementation in several variants: bus, load center,
transmission line, transmission corridor o Calculates Q-margin & other indices for proximity to collapseo Stability boundary
calculated with real-time PMU data refresh rate
• Easily combined with other methods/indices o Reactive power monitoring o Could initiate model-based
contingency analysis(e.g., by alarming the operator)
New Q‐Margin Loading margin
RVII/VIP Improved Advantages• Ability to process data from different sources (PMUs,
SCADA, simulation outputs (static and dynamic)o Takes immediate advantage of available PMUso Scales up well with increased number of PMUs
• Excellent results from actual system tests o Slowly changing system operating conditions (load ramp) o Tracking system dynamics after disturbances
• Able to distinguish FIDVR even if voltage is very low
• Simple implementation in Control Center tools and/or local IEDs for: o Operator tools to increase
situational awarenesso Local automated actions o Addition to SIPS
Source: BPA
Extracting More Information from RVII
Source: PG&E
• Increased observability improves accuracy• Managing loss of PMU data
Extracting More Information from RVII
• Flags indicating breaker status• Incorporate switching, e.g. bypassing capacitors
Source: PG&E
Test Result SummaryComprehensive tests using real-life PMU and SCADA measurements and off-line time-sequence simulation tools:• Performance improves with additional information
o Design consideration on where to install and what to measure
• Ability to detect instability even if voltage close to nominalo Load centers, transmission lines, and corridorso Highly-meshed high voltage systems more challenging
• Results comparable to detailed, model-based off-line QV analysis; very accurate closer to instability boundary
• Discriminates between FIDVR and fast voltage instability• No false alarms
• Customized visualization tool for monitoring voltage instability running at the SCE's Advanced Technologies Center
• Using real-time phasor streaming data
Source: SCE
SCE Pilot Installation
• Deployment efforts as part of comprehensive WAMPAC o At PG&E integration with Alstom e-terravisiono With BPA - Pilot installation with Space Time Insight STAS
• Design monitoring and control strategies
Present & Future Activities
NewMEASUREMENT-BASEDVOLTAGE STABILITYRVII Methodology
Other Indices
TraditionalMODEL-BASED
VOLTAGE STABILITYAnalysis
(EMS)
SCADA& Alarms WAMS
State Estimator
StateMeasurement
Other EMSApplications
New Applications
Small SignalStability
OscillationMonitoring
Transient & Voltage Stability
StabilityMonitoring& Control
IslandManagement
Island Detection, Resynchronization,
& Blackstart
New Real-time Voltage Instability Indicator Solution
Alstom e-terravision
approach with RVII
• Different methods have different advantages and users should select methods optimal for their systemo None is suitable for all systems and all possible
manifestations of instability, measurement configurations, etc.
• Real-time, model-free methods are faster but generally less accurate – Good for trend and status monitoring
• Combination of selected methods provides comprehensive solution for voltage stability issues
• Real-Time Voltage Instability monitoring technology is needed as a part of the overall solution
• Importance of integration and coordination at WECC
Summary