Certain investigations on a grid connected induction generator with voltage control

With the large number of wind energy conversion systems established in India, the utility grid is facing a severe problem of poor power factor at low wind speeds. This is because of the reactive power taken by the induction generator from the grid. The use of an AC voltage controller, as in the case of an induction motor, is suggested as one of the methods to improve the power factor. In this paper, detailed investigations are carried out on a grid connected induction generator with voltage control. The generator performance was determined theoretically under different operating conditions. Experimental investigations carried out using an autotransformer as a voltage controller confirm the theoretical results. Further, the feasibility of using a three phase thyristorised AC voltage controller, used in a wind energy conversion system for the soft start of an induction machine as a motor, for the power factor improvement of the system, is studied. Here, the problem is that the voltage applied to the induction generator can not be reduced below a particular value. The reason for this problem is analysed in this paper and a solution suggested