1 ALSTOM © 2011 1 ALSTOM © 2011 Grid Impacts of Variable Generation at High Penetration Levels Dr. Lawrence Jones Vice President Regulatory Affairs, Policy & Industry Relations Alstom Grid, North America ESMAP Training Program The World Bank Group Washington, DC October 22, 2012 „
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1 ALSTOM © 2011 1 ALSTOM © 2011
Grid Impacts of Variable Generation at
High Penetration Levels
Dr. Lawrence JonesVice President
Regulatory Affairs, Policy & Industry RelationsAlstom Grid, North America
ESMAP Training ProgramThe World Bank Group
Washington, DCOctober 22, 2012
„
2 ALSTOM © 2011
Outline
Four Coupled Dimensions of Integrating Variable Generation Slide 12
Highlights from Global Study of Variable Generation Integration Slide 16
Conclusions Slide 43
Introduction to Grid Integration Issues Slide 3
Strategies, Solutions and Decision Support Systems Slide 25
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Introduction to Grid Integration Issues
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Power System Operation
Supply Demand
Maintaining the Balance between Supply and Demand
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Key Grid Operation Issues
Stability
Balancing
Adequacy
Variability
Uncertainty
Net Load
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Two Common Characteristics of all Power Systems: Variability and Uncertainty
Supply
Demand
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Balancing Challenge - Simultaneous Variation of Generation and Load, Subject to Uncertainty
• Load varies by seconds, minutes, hours, by day, weather etc
• Variable generation vary based on fuel availability
• Dispatchable generation may not be available
Variability
• System operational decision is made by using the best available forecasts (load, generation, etc)
• Forecast error is common – there is no perfect forecast
• Dispatchable resources may deviate from scheduled set points
Uncertainty
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Power System Operations – Time Frames Matter
Source: Ref. 1
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Variability in Demand and Net Load
Source: WWIS, NREL, 2010
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Interaction of Variable Generation with Power Grid Operations - Time Scales Matter
Graphic Illustration – Courtesy of Russ Philbrick . See Ref. 2
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Impacts of Variable Generation on Grid Operations
• Procuring the flexible resources necessary to cope with increased system variability
• Managing congestion
• Forecasting to cope with ramp events.
• Efficient electricity markets
• Determining adequate operating reserves and transmission capacity
• Unit commitment and economic dispatch that takes into account the transmission network
• Managing new operational constraints, e.g., inertia, fault currents, unusual power flow limit
• Controlling system voltages
• Maintaining dynamic performance – Transient and Small signal stability (voltage, frequency and rotor angle)
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Four Coupled Dimensions of Integrating Variable Generation
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Four Dimensions of Integration
Physics Operation
Economics Information
Variable Generation Integration
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Physical, Operational, and Informational
• Physical• How wind and solar plants are connected to
the T&D grids
• Operational• Considers the system conditions and
performance goals, and also operational requirements and guidelines for the physical grid and electricity markets
• Informational• How information is managed and used by
assets and human operators
Physical
Informational
Operational
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What is the cost of balancing power systems with high penetration of variable generation?
Operational
Physical
Informational
Perform operational impact studies accounting for various costs factors
Cost
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Highlights from Global Study of Variable Generation Integration
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Global Survey on Variable Generation Integration
• DoE‟s goals for this ground-breaking global research project were to establish a central source for information on:• Wind integration trends• Global best practices• Examples of excellence• Lessons learned• Recommendations for
tomorrow
Available at: http://energy.gov/articles/new-report-integrating-variable-wind-energy-grid.
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Three Complimentary Research Methods
Questionnaire for Grid Operators
6 In-Depth Control Center Visits
Survey of Existing Literature
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Unprecedented Gathering of Global Data
Power Grids
represented in this
survey account for
72% of worldwide wind capacity
• 33 grid operators • 18 countries• Combined wind generation of 141 GW
Source: Ref. 2
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Wind Generation Capacity Distribution by Country & Region
*AKNZSA: Australia, Korea, New Zealand, South Africa
MW
Source: Ref. 2
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Wind Generation Capacity Penetration Level
• Large operators do not necessarily have the most experience with wind
• Smaller operators with higher penetration have valuable insights
Source: Ref. 2
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Five Elements for Successful Variable Generation Integration
1. Accurate Forecasting
2. Decision Support
3. Policy/Regulation
4. Flexibility
5. Workforce
Source: Ref. 2
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Forecasting is Vital to Successful Integration
The need for short-term forecast (5-10 minutes) will be increasingly
important as wind penetration increases
Key Forecasting Tools (Cited by at Least 40% of Respondents)
Next-Hour ForecastRamp ForecastingEnsemble Forecast
Weather Situational AwarenessRamp Risk ForecastShort-Term Forecast
Source: Ref. 2
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Decision Support Systems Are Essential
Forecast and uncertainty information must be incorporated into
real-time decision support systems and planning tools
Key Decision Support Tools (Cited by at Least 50% of Respondents)
Voltage Stability AnalysisOptimal Power Flow with Wind Forecast
Transients Stability AnalysisOptimization-Based Transmission Planning
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Strategies, Solutions and Decision Support Systems
•The role of system flexibility • Advanced transmission and distribution systems applications• Market design and mechanisms• Demand response
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System Flexibility
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Power System Flexibility
Power system flexibility expresses the extent to which a power system can increase/decrease electricity production or consumption in response to variability, expected or otherwise.
± MW / time
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Flexibility Needs and Resources
Existing and new flexibility needs can be met by a range of resources in the electricity system – facilitated by power system markets, operation and hardware.
Source: Ref. 1
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Understanding the Unique System Attributes that Affect Flexibility
Source: Ref. 1, Case Studies
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Flexibility Assessment Method (FAST) – IEA Method to Identify a Power System‟s Balancing Capacity
Source: Ref.1
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Smarter T&D Electricity Grids Increase Flexibility
Source: Ref. 2
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Advanced Transmission and Distribution Systems Applications
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Implement Advanced Decision Support Systems to Support Wind Integration
Grid operators are at different stages of deploying advanced decision
support tools in control center
Source: Ref. 2
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Importance of Processes, Policies, and Procedures
Source: Ref. 2
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Bridging the gap between Forecast and Operations
Renewable ForecastManagement
Day AheadUC & Dispatch
Real Time Control
Studies & Outage Evaluation Simulation
Performance Analysis & Reporting
Numerical Weather
Prediction
HistoricalMet & Power
Data
Future Availability& Outages
Wind / SolarDescription &
Location
• Market or Regulated env• Wind Integration Policies• Reserve Adequacy
• Network security (current and look ahead)
• Load-following power balancing
• Wind Generation Monitoring and control
• Reserve Monitoring• Real time curtailment• Archiving
• Steady State• Dynamic Stability• Look-ahead• What-if scenarios• Transmission Planning• Generation Adequacy
• Operator Training• Realistic wind simulation• Scenario creation• Event replay
• Centralized forecast• Public publishing• Market participants• Wind plant operators• Researchers
Load Forecast
Managing and Mitigating Operational Uncertainty
Source: Alstom Grid
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Deploy Smarter Technologies and Applications
Integration of smart applications with wind power forecast improves real-
time operations, but some smart technologies must become more efficient
and cost competitive for benefits to be fully-realized.
Source: Ref. 2
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Market Design and Mechanisms
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Market Design and Mechanisms
• Market should be designed to support the frequent scheduling (e.g., sub-hourly) and dispatching of generation and transmission resources.
• Ancillary services markets (e.g., efficient procurement of more flexible resources).
• Greater coupling and harmonization between national and regional electricity markets (e.g., reserve sharing and transmission scheduling).
• Congestion management
• Regulatory policies should be designed and implemented to support the development of multi-regional markets for ancillary services and reserves..
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Demand Response
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Notify
The CSP initiates a load curtailment by sending a signal to its customers to reduce their loads by a specified amount.
Curtail
1:00pm – Clients manually shut off lights and other devices, or use an Energy Management System (“EMS”).
Verify
The CSP verifies the status of the load reduction among all customers until it meets the level required by the grid operator.
Restore
3:00pm – Clients return systems to normal operation.
Demand Response Event
During a period of peak capacity, the grid operator initiates a demand response event and calls the CSP.
A basic concept – utilities provide incentives to electricity customers toreduce their consumption during periods of peak demand.
Demand Side Response Scheduled CurtailmentsAugust 8, 2007
0
200
400
600
800
1000
1200
1400
1600
1800
2000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour Ending
Curta
iled
Load
(MW
)
0
100
200
300
400
500
600
700
800
900
1000
PJM
LM
P ($
/MW
h)
Economic Emergency PJM LMP
• To address the challenge ofpeak demand, utilities typicallybring new generation assetsonline, known as “peakerplants.”
• Demand response offers afaster and cheaper alternativeto peak generation.
• Utilities, grid operators, andend users all have incentivesto adopt demand response.
Demand Response (DR): A Smart Grid Technology
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Smart Applications Currently Implemented or Will be Implemented
Respondents who have implemented DR programs
are in systems with competitive electricity markets,
and Storage has huge growth potential
Source: Ref. 2
Source: Ref. 2
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Instantaneous Wind Ramp in ERCOT on February 28, 2008
Source: Presentation by John Dumas, ERCOT
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Conclusions
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Conclusion (1)
More and more grid operators are interested in
applying industry best practices and examples of
excellence as the starting point for deploying their
own decision support systems built specifically to
address wind energy integration at the control
center level.
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Conclusion (2)
Efficient integration of wind and solar energy requires
grid operators to have access to a proper mix
of flexible resources ranging on the supply-side,
delivery-side and demand-side.
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References
1. International Energy Agency. Harnessing Variable Renewables: A Guide to the Balancing Challenging, 2011. www.iea.org/publications
2. Lawrence E. Jones, Strategies and Decision Support Systems for Integrating Variable Energy Resources in Control Centers for Reliable Grid Operations. 2011. Download at: http://energy.gov/articles/new-report-integrating-variable-wind-energy-grid.
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