ASSESSING THE CAPACITY VALUE OF WIND POWER Lennart S

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• ASSESSING THE CAPACITY VALUE OF WIND POWER
  Lennart SöderKungliga Tekniska Högskolan (KTH),
  Sweden
• Hannele Holttinen, Michael Milligan, Andrew
  Keane, Mark OMalley

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Wind Power Capacity Value Basics
How much can the consumption increase when
the amount of wind power increases and the risk
of power deficit is kept constant?
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Wind power capacity value - 1
No wind power
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Wind power capacity value - 2
With wind power
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Wind power capacity value - 3
With wind power, load 300 MW
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Estimating capacity value of wind power

• Input data is crucial
• Data from many years are needed to capture the
  behaviour of wind during high load hours.
  Synchronous data wind/load
• Data to represent wind power production from
  larger areas, data from several sites
• There are several ways to make estimates using
  average wind power during high load situations
  can give a first estimate for low penetration
  levels but a thorough study will take into
  account the failure probabilities of conventional
  generators and wind power probabilities during
  high load situations and calculates the loss of
  load probabilities LOLP for the system
• Taking into account the interconnection
  possibilities to neighbouring countries also
  relevant for many systems

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How to calculate and what it is ELCC method

• Start with target reliability level (1 day in 10
  years LOLE, loss of load expectation, is common)
• Add wind generation to the model
• Increase load until the target reliability level
  is again attained
• The increase in load is the capacity value of the
  wind plant
• Recommended method by IEEE, NERC in U.S.

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Approximation methods

• Approximation methods are sometimes used
• These methods often calculate the wind capacity
  factor (ratio of average wind output to rated
  output) during the time of system peak
• Example PJM in the U.S. Uses June-August,
  1500-1800
• Approximation methods are not based on
  reliability and therefore cant inform about risk

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Capacity value declines with more wind

• Wind capacity value decreases faster for smaller
  areas.
• There can be large differences in capacity value
  for different systems wind resource at peak
  loads, reliability level, methodology

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Impact on system
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Transmission affecting LOLP (US NY)
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Numbers of years of data 8 years of data
required
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Number of stations required for wind input data
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Capacity value key points

• Wind power has a considerable impact on
  generation adequacy
• Highlights the need for transmission
• Approximations not wise - a full effective load
  carrying capability (ELCC) calculation is the
  preferred method
• Data needed
• Synchronised
• Multi year
• High resolution
• We do not recommend using the lower capacity
  value of wind to calculate a capacity cost as
  has been done in some studies. The meaning of
  this is the cost for the difference between
  capacity credit for wind power and capacity
  credit for a conventional power plant. It is then
  important to consider the lowest realistic cost
  compensation in order not to overestimate this
  cost