Improvement of DFIG-based WECS performance using SMES unit

Doubly Fed Induction Generators (DFIGs) are widely used in variable speed wind turbine owing to its superior advantages that include ability to extract more energy from turbine, capability to control active and reactive power independently and the usage of reduced converter rating that reduces its overall cost. The application of DFIG in large wind energy conversion systems (WECS) has reached 55% of the worldwide total wind capacity during the year 2012. On the other side fluctuating output power, weak fault ride through capability and high sensitivity to grid disturbances are the main issues that affect DFIG performance. In this paper, superconducting magnetic energy storage (SMES) unit is proposed to improve the overall performance of a DFIG-based WECS during voltage sag disturbance in the grid side. A new control approach for SMES unit using hysteresis current controller (HCC) along with proportional integral (PI) controller is introduced. Simulations results reveal the effectiveness of the proposed SMES controller in improving the overall performance of the WECS system under study.