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1. 1 ALSTOM © 20111 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
„

2. 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

3. 3 ALSTOM © 2011
Introduction to Grid Integration Issues

4. 4 ALSTOM © 2011
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

15. 15 ALSTOM © 2011
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

22. 22 ALSTOM © 2011
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 Forecast
Ramp Forecasting
Ensemble Forecast
Weather Situational Awareness
Ramp Risk Forecast
Short-Term Forecast
Source: Ref. 2

24. 24 ALSTOM © 2011
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 Analysis
Optimal Power Flow with Wind Forecast
Transients Stability Analysis
Optimization-Based Transmission Planning

25. 25 ALSTOM © 2011
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

34. 34 ALSTOM © 2011
Importance of Processes, Policies, and Procedures
Source: Ref. 2

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Bridging the gap between Forecast and Operations
Renewable Forecast
Management
Day Ahead
UC & Dispatch
Real Time
Control
Studies & Outage
Evaluation
Simulation
Performance
Analysis &
Reporting
Numerical
Weather
Prediction
Historical
Met & Power
Data
Future
Availability
& Outages
Wind / Solar
Description &
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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40
Notify Curtail Verify Restore
Demand
ResponseEvent
A basic concept – utilities provide incentives to electricity customers to
reduce their consumption during periods of peak demand.
Demand Side Response Scheduled Curtailments
August 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
CurtailedLoad(MW)
0
100
200
300
400
500
600
700
800
900
1000
PJMLMP($/MWh)
Economic Emergency PJM LMP
• To address the challenge of
peak demand, utilities typically
bring new generation assets
online, known as “peaker
plants.”
• Demand response offers a
faster and cheaper alternative
to peak generation.
• Utilities, grid operators, and
end users all have incentives
to 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

42. 42 ALSTOM © 2011
Instantaneous Wind Ramp in ERCOT on February 28,
2008
Source: Presentation by John Dumas, ERCOT

43. 43 ALSTOM © 2011
Conclusions

44. 44 ALSTOM © 2011
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.

45. 45 ALSTOM © 2011
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.

46. 46 ALSTOM © 2011
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.

47. 47 ALSTOM © 2011
Dr. Lawrence Jones
Alstom Grid
+1 (425) 241 0649
lawrence.jones@alstom.com
Thank You