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Overcoming Challenges To
Integrating Renewable Energy
Resources
Paul Roberti, Commissioner
Rhode Island Public Utilities Commission
May 16, 2013
Renewable Integration Challenges in New
England Are Regional In Nature
• Independent System Operator
of New England (ISO-NE)
• Responsible for:
– Ensuring regional reliability
– Administering electricity
markets
• Regulated by Federal Energy
Regulatory Commission
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New England’s Electric Power Grid at a Glance
•
6.5 million households and businesses;
population 14 million
•
350+ generators
•
8,000+ miles of high-voltage
transmission lines (115 kV and above)
•
32,000 megawatts of total supply and
2,000+ megawatts of demand resources
•
28,130 megawatts all-time peak demand,
set on August 2, 2006
•
500 participants in the marketplace
•
$5 billion total energy market value in
2012
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Fuel Mix for New England – 2012
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Generator Proposals in the ISO Queue
Approximately 5,000 MW looking to connect to the New England
system – Greater than 50 Percent are Renewable Energy Resources
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Challenges Posed by Greater Levels of Variable Resources
• The region’s aging generation fleet and uncertain performance of
demand response resources has increased the need for system
operations flexibility – both system wide and locationally
• As traditional units retire or are too expensive to run, and variable
resources increase on the system, the system operator will need
more resources that have quick-start capability, fast ramp rates,
and are dispatchable across seasons
• Wide spectrum of solutions available, some already underway,
each with unique costs and complexities. For example:
–
–
–
–
Increase system reserves
Enhance performance incentives and penalties in wholesale markets
Negative pricing for energy market offers
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Integrate wind forecasting into commitment and dispatch
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Today, MA accounts for
46% of the region’s total
electricity consumption; CT
25%; RI 6%
With passive demand
response forecasts (11.6%
energy reduction in 2021),
LSEs would need
renewables to provide
20.2% of projected electric
energy use to meet existing
targets.
By 2021, 31.8% of region’s
projected electric energy
consumption could be met
by EE, RPS targets, and
related renewable goals.
% of LSE Electric Energy Supplied by Renewables
New England Renewable Energy Targets, 2021
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20
16
15
14
12
10
10
5
0
ME
NH
RI
State
Source: ISO-NE RSP 2012, p. 135, 138-139.
MA
CT
New England Generator Interconnection Proposals
Approximately 6,000 MW proposed; over a third are wind projects
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Challenges for Wind Development
• Population and electricity
demand concentrated in
southern New England
• No overlap between wind
resources and high
energy demand areas
• Transmission investment
would be required for
large-scale wind
integration
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New England Wind Integration Study (NEWIS)
New England-focused wind integration analysis
• Large-scale wind integration in
New England is technically
feasible
• Regional requirements:
– Maintaining flexible resources to
manage variability
– Transmission upgrades
– Increasing regulation service and
operating reserves
– Developing wind forecasting tools
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Challenges of Wind Integration
• The ISO is unable to dispatch wind resources today.
– Unit dispatch software is unable to send dispatch instructions.
– Non-dispatchable resources (which includes wind) are ineligible to
set price.
– Market/operations protocol used to determine curtailment priority
generally results in wind being curtailed before other resources.
– Inability to submit negative energy offers gives competing
resources little incentive to reduce output when congestion occurs.
– System operators must rely on manual actions to ensure reliability.
• Improved short, medium, and long-term forecasting tools
are needed.
• Full integration of wind resources into automated market
and dispatch systems is needed.
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Addressing the Challenges of Wind Integration
• The ISO is developing market and infrastructure
improvements:
– Allow negative energy offers
– Make wind resources dispatchable and eligible to set price
– Calculate and send out a do-not-exceed (DNE) limit to each wind
plant on dispatch
• The DNE limits will reflect several characteristics of each
plant:
–
–
–
–
–
Economic offer curve
Maximum output under ideal weather conditions
Short-term wind output forecast
Transmission constraints
Telemetered physical status for the next dispatch interval
• A wind plant will be free to operate anywhere between 0 MW
and the DNE limit
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Addressing the Challenges of Wind Integration cont.
• A centralized, regional wind power forecasting system is scheduled
to be in service in early 2013.
• All wind resources will be required to provide real-time telemetry
indicating current output and weather conditions.
– Improves system operator’s situational awareness
– Enable ISO’s real-time automated communication of dispatch
instructions
– Enhances the quality of the centralized forecast
• More flexible structure for hourly day-ahead energy offers and
intraday reoffers is being developed.
– Reduces the desire to self-schedule, giving system operators
more flexibility to integrate renewable energy resources
– Increases the percentage of resources dispatched economically
– Better for efficient system operation as a whole
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Addressing the Challenges of Wind Integration cont.
• Potential increase in regulation requirements as more
wind resources interconnect to the grid
– Current hourly requirement averages ~60 MW
– Could increase to ~300 MW if wind penetration increases to 20%
of annual energy
– New England currently has 800+ MW of regulation capable
resources
• Forward Capacity Market issues under consideration
– Pay-for-performance incentives
– Identification of operational needs of resources to be acquired in
the capacity auction
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Current Situation
• Wind resources and other Intermittent resources are “nondispatchable”
– Unit Dispatch Software (UDS) is unable to manage congestion by
sending dispatch instructions
– Wind resources not eligible to set price in LMP calculator
– System operators must manually curtail resources if necessary to
ensure reliable operation of the grid
• Anticipated wind production generally not reflected in unit
commitment for real-time
• Manually curtailing non-dispatchable resources when required
to manage congestion does not result in price separation
– Non-dispatchable resources are effectively zero-priced
– Resulting LMPs are inconsistent with “dispatch” decisions to curtail
zero-price resources
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Existing RT Curtailment Procedure
• When economic dispatch is insufficient to manage
congestion, priority goes to resources that cleared or
self-scheduled in Day-Ahead.
• As a practical matter, this leads to economically
inefficient outcomes
– Renewable energy credits and production tax credits result
in wind plants having a negative energy price
– Interconnections on weaker portions of the grid, and fast
ramp rates mean wind plants are typically curtailed more
frequently than other resource types
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Existing Manual Procedure Will Not Be Adequate
Going Forward
• Lack of real-time telemetry and uncertainty about anticipated
wind output lead to:
– More conservative operating practices and limits
– Less optimal resource commitment
• Suboptimal dispatch and inappropriate pricing
– Low cost resources may be curtailed before higher cost
resources
– Manual curtailments to manage congestion don’t result in
price separation
• With higher wind penetration, system operators with only
manual dispatch & curtailment procedures will be overloaded
during dynamic weather conditions
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Near Term Improvements
• Wind short-term forecast – early 2013
– An accurate forecast is critically dependent on wind
resources providing detailed plant data ASAP
• OP-14 & OP-18 – real-time telemetry from wind
plants
• Both of these:
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–
–
–
Greatly improve operator situational awareness
Reduce uncertainty
Improve commitment and dispatch of all resources
Make possible a real-time “Do Not Exceed” (DNE) dispatch
of wind resources
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Wind RT DNE Dispatch - Objectives
• Secure, reliable, and efficient operation of the system
through normal economic dispatch of the system.
• Reduced need for manual curtailments of nondispatchable resources.
– Improved opportunities for wind production
• Allow wind resources to impact energy prices in a
manner consistent with their economic value and
energy market offers.
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How Will Wind RT DNE Dispatch Work?
• UDS will calculate and send out a Do Not Exceed limit to
each wind plant on dispatch
• The DNE limits will reflect
–
–
–
–
Economics
Constraints
plant status (RTHOL and persistence)
high-confidence “next 5 minutes” wind output forecasts
• Will consider both energy balance (i.e. gen = load) and
reliability
• Will allow price-based congestion management based on
offer parameters
– Contemplates the eventual introduction of negative energy offers
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How Will Wind RT DNE Dispatch Work? (cont.)
• Wind plants will be considered “following dispatch” if operating
between 0 MW and the DNE limit and not exceeding ramping
limits.
– Output can vary with changing weather conditions
– Downward ramps due to plant emergencies and/or decreasing
wind not counted for “following dispatch”
• Will allow wind plants on dispatch to be eligible to set price
• Accurate forecasts and frequent telemetry should reduce
curtailments and provide greater opportunity to maximize
output.
• Will prevent “manual procedure” overload for system operators
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Who is Affected and When?
• No one is affected until the DNE dispatch software can be
implemented (estimated for 2014)
– ISO efforts have been unable to identify a feasible way to dispatch wind
manually
• Once software is in place, DNE dispatch may be optionally selected by
wind plants through their offer data
• DNE dispatch is planned to become mandatory when negative energy
offers are implemented, for wind plants that meet one or more of the
following conditions:
– Interconnect to a transmission facility or a FERC jurisdictional distribution
facility
– Has a Capacity Supply Obligation
– Is a Capacity Network Resource
– Has a total nameplate capacity at the point of interconnection of >= 5 MW
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How Will a Wind Plant Participate
• Submit an economic offer curve into the Day-Ahead or Real-Time
Energy Markets
• Must be providing all weather and plant data required by recent OP14 & OP-18 changes
– This data supports the forthcoming real-time wind forecast system
– Accurate real-time wind production forecasts are critical to effective operation of
the DNE dispatch
• No requirement to offer into Day-Ahead
• Self-scheduling will continue to be permissible while Wind RT
Dispatch is voluntary.
• Assuming a dispatchable wind plant offers $0 commitment costs, it
will be treated as “committed” whenever available (i.e. RTHOL > 0)
– Otherwise, must offer & clear in DA, or self-schedule in RT
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New England’s Current Implementation Plan
• Voluntary Wind RT DNE Dispatch – mid-2014
– Market rules being presented today address only voluntary DNE
dispatch
• Implementation on a voluntary basis provides some early
operational/reliability benefits, but will not fully resolve
pricing and congestion management issues until all wind
plants are responding to DNE dispatch instructions
• Becomes mandatory when negative offers are
implemented.
– Likely not until 2014 or 2015
– Will require a separate rule change at that time
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THANK YOU
Paul Roberti, Commissioner
Rhode Island Public Utilities Commission
89 Jefferson Blvd.
Warwick, RI 02888
Tel: (401) 780-2147
Email: [email protected]
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