Experience with Advanced Static VAR Compensators Operating on Wind Farms and in Laboratory in Denmark.

Wind turbines with induction generators consume reactive power. Apart from the no-load consumption that is almost constant, the consumption of reactive power varies almost in proportion with the power production, which can vary immensely. Apart from the fact that the grid must supply the reactive current with ensuing losses, the strong variationS also will cause varying inductive voltage losses in the supply with flicker as a consequence. With power electronic equipment it is possible to produce the reactive power on location and thus reduce the losses and voltage fluctuations in the grid. This paper describes a 100 kvar power electronic reactive power compensator. The compensator was tested in a wind farm in Western Denmark. The electrical circuit and the working principle of the compensator are described and some survey data are shown. The paper also describes a 2x4 Mvar reactive power compensator placed in another wind farm of a total of 24 WM in Western Denmark with the aim to compensate the whole farm. Measurements of operation and losses are given. Finally the paper describes a new control strategy tested on a 10 kvar multilevel reactive power compensator.