Transcript MAPP_Wind_Presentation_08 16 07

Mid-Continent Area Power Pool
Wind Integration Studies
Edward P. Weber
August 16, 2007
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OVERVIEW
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Study Background
 MN Wind Development
 Dakotas Wind Development
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Key Issues
Operation Impacts
Reliability Impacts
Wind Modeling Challenges
Wind Impacts on Transmission Lines
Potential Use of New Technology
Summary
References
1. Study Background
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MN Wind Development
 In May of 2005 the MN Legislature adopted a requirement for a
Wind Integration Study of the impacts on reliability and costs
associated with increasing wind capacity to 20% of MN retail
electric energy sales by 2020.
 That’s approximately 4,500 MW more wind generation than
exists today
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Dakotas Wind Development
 Western to perform a “transmission study on the placement of
500 MW of wind energy in North Dakota and South Dakota”
 The Dakotas lead the nation in potential wind resources
 New WAPA study underway to consider wind-hydro integration
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Wind Power Resource
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152 proxy tower (wind
plant) locations
Modeled results
include wind speed,
air density, power
density, energy
production
Temporal and
geographic variations
are characterized
Benefits shown for
geographic diversity &
for a sophisticated
method of forecasting
wind power production
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2. Key Issues
Reliable power system operation requires
precise balance between load and generation.
Capacity value of power plants depends on their
contribution to system reliability.
Output of wind plants cannot be controlled and
scheduled with a high degree of accuracy.
Wind generation is becoming large enough to
have measurable impact on system operations
and planning.
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3. Operation Impacts
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Regulation: Does wind plants affect or
increase the area control error (ACE)?
Load following: What happens if wind plant
output decreases in the morning when the
load is increasing?
Scheduling: How can committed units be
scheduled for the day if wind plant output is
not predicted? What happens if the wind
forecast is inaccurate?
Committing generating units: Over several
days, how should wind plant production be
factored into planning what generation units
need to be available?
4. Reliability Impacts
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Reliability analysis
 Loss of Load Probability (GE MARS and NEA Marelli)
Wind generators capacity contribution is based on its influence on
overall system reliability
Effective Load Carrying Capability (ELCC), a common reliability
measure, is evaluated to determine wind generation reliability
impacts
The system’s hourly loads and generation are modeled with and
without the wind generators while maintaining a fixed reliability
level (one day in ten years)
Results show the ELCC values of approx 12% at 4600 MW
Significant inter-annual variability exists, more years of data
would increase confidence
5. Wind Modeling Challenges
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Capturing seasonal, diurnal characteristics of
wind generation in a “snapshot” model
Insuring that wind and load patterns correlated
 “wind doesn’t blow on hot humid days”
 “wind blows at night and in spring”
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Difficult to capture in a statistical model
 Can be addressed by treating wind generation as
load modifier
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Availability of dynamic wind models
 How do we model various control modes (power
factor versus voltage control)
 Improve wind model representation
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ND/SD FPLE Projects: 80 MW
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600
3000
500
2500
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2000
300
1500
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1000
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500
0
0
-100
-500
July18 - July 25, 2004
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Oahe gen
Big Bend gen
Hyde wind gen x 10
CA load
CA load in MW and wind generation
in 100's of kW
MW hydro generation
Oahe, Big Bend, and Hyde gen and CA load
6. Wind Impact on Transmission
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Wind Needs Transmission Lines
To deliver output from generation to market
Windiest areas are sparsely populated; little load
Most wind energy is off-peak
Off-peak, output has to travel further to serve load
To “hide” output fluctuations in a large system
Area Control Error (“ACE”)
Avoid need for higher spinning reserves
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6. Wind Impact on Transmission
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Fluctuations in generation output cause voltage
fluctuations that must be considered
 Turbine MW output: proportional to cube of wind speed
 Line & transformer loadings: proportional to generator output
(MW)
 Line & transformer reactive power consumptions: proportional to
the square of current
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Result: Transmission system reactive consumption is
proportional to sixth power of wind speed !!
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Example: if wind speed doubles, reactive power
requirement increases by factor of 64.
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6. Wind Impact on Transmission
Lines
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Reactive power supply must be fast enough to
keep up with wind generation output fluctuations,
(including trip out of wind farm).
FERC reactive power standard is of modest
magnitude (.95 pf) and does not require dynamic
response.
Prudent developers provide better reactive
output capability (.90 pf), and dynamic response
Concentration of wind farms means that future
years’ largest single generation contingency
could be trip of several wind farms due to a
single fault.
7. Potential Use of New
Technologies
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Study technology-based solutions that can
increase the use of existing transmission lines
Technologies studied include:
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Static Var compensation
Series compensation
Phase-shifting
Dynamic line ratings
Reconductoring with new conductor
8. Summary
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High voltages (345 & 765 kV) required to
 achieve reasonable efficiency;
 achieve good dynamic stability & voltage stability
performance;
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To achieve adequate voltage control, we’ll need
more
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Shunt capacitors
Series capacitors
Static VAR Systems (SVS or SVC)
Additional reactive capability from wind generators (.90
pf rather than .95 pf) would help significantly .90 pf was
achievable and proven in 2000. We should be able to do
better (lower pf) today.
References
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2006 Minnesota Wind Integration Study by
MN PUC
Dakotas Wind Transmission Study by
Western Area Power Administration
Transmission Needs for “20% Renewables”
Penetration of the Minnesota Electric Energy
Market by Excel Engineering
QUESTIONS ?
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