Effect of blade passing on a wind turbine output

Renewable energy such as wind and solar is a clean source of energy that can be integrated with conventional ways of producing energy. Power utility companies are looking at ways to integrate renewable energy with conventional methods. The Central and South West (CSW) renewable project (USA) was designed to investigate the role of solar and wind energy in a utility system. When connecting a wind farm to a utility grid, several issues must be taken into consideration such as stability, load matching, cost, location and the wind profile in relation to the peak loads on the system. One other parameter that is seldom considered is the effect of power oscillations due to turbine blades passing through their full arc of motion and periodically encountering different wind speeds at different vertical positions. In the following, this effect is called 'blade passing'. This paper evaluates the effect of blade passing on the output voltage and current for a grid connected wind farm. The effect of blade passing as a function of the number of wind turbines connected to the grid is also investigated. The exact causes of the blade passing effect are also discussed.