Wind Experience in SPP and Potential
Areas of Improvement
Brian Gedrich
Director, Regulatory Affairs
May 30, 2013
With well over 10,000 MWs, NextEra Energy Resources, is
the largest wind and solar generator in North America
Over 1,300 MWs of Wind Generation in SPP
•Need Mp
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The extent and impact of the Spring 2013 curtailments were
a surprise
NextEra’s Experiences
• Wind curtailments were chronic, unexpected and
unpredictable
– Generation interconnection studies did not indicate curtailment
issues
– There were a significant number of transmission outages
– Loop flows and distant wind farms contributed to the constraints
• It was difficult to recreate the curtailments through
modeling
– Operational system information is difficult to obtain
– Actual line flows are not public
– Real-time sub-regional wind totals are not available
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NextEra is concerned about Fall 2013 when outage season
begins again, but with even more wind operational
Potential Areas for Improvement
1. Improve coordination of transmission outages
2. Constraint/flow-gate forecasting
3. Potential switching to limit loop flow and remote wind
contributions to congestion
4. Improve wind assumptions used in generator
interconnection studies
5. Increase transparency of operational transmission
information
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Potential Areas for Improvement – continued
1. Improve coordination of transmission outages
– Increase the forward view of transmission outages
TOs should attempt to increase scheduling lead time
– Currently, minimum lead time for “planned "outages is 7 days and
“discretionary” is 2 days
SPP should not only show approved outages, but also outages
that are in the review/approval process
Facility de-ratings should also be made public
– In high wind concentrations areas, consider moving transmission
maintenance outages to peak
May improve scheduling and maintenance costs for TOs
– Allow SPP to consider economics, not just reliability, when
coordinating transmission outages
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Potential Areas for Improvement – continued
2. Constraint/flow-gate forecasting
– SPP should provide transmission constraint/flow-gate forecasts and
should attempt to identify seasonal areas of congestion
Allows stakeholders to prepare and better manage congestion
exposure
Transmission constraint forecast will allow stakeholders time to
bring forward ideas to mitigate congestion
– Temporary Special Protective Schemes (SPS), or re-configurations,
should be considered to reduce congestion
SPS process needs to be shortened to allow for seasonal
implementation
Pre-emptive actions should be identified and considered
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Potential Areas for Improvement – continued
3. Potential switching to limit loop flow and remote wind
contributions to congestion
– SPP should study ways to maximize SPP wind production
Configurations to limit the impacts of wind on lower voltage
transmission
– Attempt to limit flows through lower voltage systems
– Keep flows on the bulk system
– SPP should attempt to identify configurations that could limit MISO
and remote wind impacts
Identify configurations that limit MISO’s loop flows
– MISO wind is contributing to SPP’s congestion
Identify configurations that will limit SPP wind impacts on SPP
congested areas
– Reduce impacts of remote wind on congestion
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Potential Areas for Improvement – continued
4. Improve wind assumptions used in generator
interconnection studies
– The amount of wind modeled needs to be more realistic
Currently:
– Wind generator under study is modeled at 100%
– Neighboring wind generators in the same area are modeled at
80%
– Wind generators in other areas are modeled at 20%
– Additional analysis should be performed with all wind at 80%
– The higher wind results should be used for informational purposes
and not result in additional upgrades
– Wind generators and transmission owners need to fully understand
the curtailment risk
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Potential Areas for Improvement – continued
5. Increase transparency of operational transmission
information
– SPP should consider making additional operational data public:
Key internal line flows
Tie-line flows with SPP neighbors
Sub-regional wind generation
– SPP should provide after-the-fact operational load flow cases
Provides transparency to the stakeholders
Will help stakeholders understand the operational issues
Due to the lack of operation data, it is difficult to understand what is
happening and/or what is going to happen
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This conference is a great first step – we need to build on
this effort, plan and implement next steps, and make the
necessary improvments
Next Steps
• We hope today’s workshop is the first step in the
process, not the last
– The issues identified today are not trivial and will take time to
resolve
– NextEra would request a stakeholder task force be formed to
focus on the wind related issues identified today and in future
issues which confront SPP
• NextEra is committed to working with SPP and the
stakeholders on developing and implementing new,
better processes to mitigate curtailments
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