Experimental Analysis for enhancement of unbalanced standalone Wind Energy Conversion System

In this paper, the control of an autonomous doubly fed induction generator (DFIG) based Wind Energy Conversion System (WECS) with unbalanced loads is studied. The most used index for calculating the imbalance rate is the Voltage Unbalance Factor VUF. To maintain the Voltage Unbalance Factor $VUF$ on the stator side to reasonable values of the order of 1–2 %, an auxiliary three-phase voltage system is integrated on the rotor side of the generator. Its RMS value and phase are fixed in order to compensate the stator voltage unbalance. Experimental results are carried out using a DFIG and a dSpace DS1104 card. These results demonstrate that the proposed strategy can maintain $VUF$ under 0.02 for strict limits of unbalance and, consequently to obtain a balanced system at the output of the machine even when the loads are unbalanced.