Reactive capability limits of wind farms

Wind Energy Conversion Systems (WECS) technology can be classified into two main types: fixed speed and variable speed. Fixed speed WECS use an induction generator connected directly to the grid while variable speed WECS use a power converter to connect the generator to the grid. Fixed speed WECS require shunt capacitors for reactive power compensation, while variable speed WECS have reactive power capability. Under the Spanish grid code, wind farms have to operate in a range of power factor values. This paper determines the reactive power capability of wind farms equipped with both fixed and variable speed WECS. The reactive power capability can be represented as a reactive capability curve. In this paper, the reactive capability curve is used to calculate the additional reactive power compensation needed to meet the requirements of the Spanish grid code.