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Wind Farm Energy Loss Factors

When WFDTs have been used to predict the output of a wind farm, it is necessary to estimate or calculate a range of potential sources of energy loss.  There is considered to be six main sources of energy loss for wind farms, each of which may be subdivided into more detailed loss factors:

  • the wake effect;
  • availability;
  • electrical efficiency;
  • turbine performance;
  • environmental losses; and
  • curtailments.

A rather comprehensive list of potential losses is presented in Table I.2.5 below. Several of the loss factors will not be relevant to most projects, but they are listed here for the sake of  completeness   Following the table below, a description of each of the losses is provided.  Wind farm availability and the influence of tree growth on energy production may be time-dependent factors.  As the values in the table below are site specific, example values have not been presented, although in aggregate the total losses for a wind farm site would typically be in the 10-20 per cent range.

Table I.2.5: Comprehensive List of Loss Factors



 
Wind Farm Rated Power ##.# MW
  Gross Energy Output ##.# GWh/annum
1 Wake effect    
1a Wake effect internal ##.#  
1b Wake effect external ##.#  
1c Future wake effect ##.#  
2 Availability    
2a Turbine availability ##.#  
2b Balance of plant availability ##.#  
2c Grid availability ##.#  
3 Electrical efficiency    
3a Operational electrical efficiency ##.#  
3b Wind farm consumption ##.#  
4 Turbine Performance    
4a Generic power curve adjustment ##.#  
4b High wind speed hysteresis ##.#  
4c Site-specific power curve adjustment ##.#  
5 Environmental    
5a Performance degradation – non-icing ##.#  
5b Performance degradation – icing ##.#  
5c Icing shutdown ##.#  
5d Temperature shutdown ##.#  
5e Site access ##.#  
5f Tree growth (may be time dependant) ##.#  
6 Curtailments    
6a Wind sector management ##.#  
6b Grid curtailment ##.#  
6c Noise, visual and environmental curtailment ##.#  
  Net Energy Output ##.# GWh/annum
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