An enhanced control algorithm for stand-alone DFIG system feeding unbalanced loads with reduced current sensors

This paper presents an enhanced control algorithm for stand-alone DFIG system under unbalanced load condition with reduced current sensors at stator side. The unbalanced load regularly causes the stator current/voltage unbalance and the rotor current contains harmonic components. In order to overcome this problem, a control method is investigated based on the load side converter (LSC). In this control method, the negative sequence components of the line current of LSC are generated to compensate the unbalanced stator current. In addition, only the rotor current is used as the feedback signal to compensate the unbalanced stator current. Thus, the current sensors installed at load and stator side are totally removed, so that the number of current sensors employed in system is reduced. The simulation and experimental results are provided to verify the effectiveness of the proposed method.