21-05-2013, 04:38 PM
Power System Requirements for Wind Power
Abstract – list of contents
Description of the functioning of the power system
• Different production units in an interconnected system, system operation including
active power and reactive power balance control
• Varying load with predictions
• Unit commitment/scheduling. Behaviour in electricity market similar, production with
low marginal costs run first
• Technical reserves: Regulation and load following: Frequency control /Primary
control, Secondary regulation (15 min…1 hour)
• Adequacy of power system: Enough capacity for all peak load situations: Reserves
(slow) (tertiary regulation)
What production form wind power replaces?
• Wind power is renewable, CO2 emissions (from the manufacturing and construction)
of the order of 10 gCO2/kWh
• When wind power replaces fossil fuels, CO2 emissions of the system will be decreased
• Wind power will replace marginal production at each instant – but instant (regulated)
hydro production can be postponed and will replace condensing power at a later instant
• Wind power will replacing coal condense, when that exists in the system (800-900
gCO2/kWh)
• Example of simulations in Nordic countries gives the combined average effect of 700
gCO2/kWh
Effects of wind energy on the system
• Varying production. For the system, relevant is production of larger areas
smoothing out the variations, especially the faster ones.
• First: as negative load. Production less than 1 % of the yearly demand. Variations of
wind power production absorbed by the load variations.
• Wind power penetration from 1 % to 5…10 % of the yearly demand: varying
production with predictions. Changes in scheduling/how the system is run. Prediction
errors of wind power still small compared with load variations. Wind power has a
capacity credit, of the order of average production as long as the varying production in
the system is small. Wind farms can provide some fast power regulation too (Horns
Rev concept).
• Wind power penetration > 5…10 % of the yearly demand. More regulation needed for
the system. Costs of wind power integration increase with increasing wind power
penetration. Capacity credit decreases.
• The impacts of wind power to the system are different for thermal and hydro
dominated systems, and combined ones. The cost of integration depends on how much
the electricity system has flexibility and how much extra flexibility costs.