This paper discusses power quality improvement in a DFIG based WECS connected to a distribution system. A WECS is usually affected by issues such as high frequency oscillations, harmonics, transients, voltage sags, swells, voltage unbalance etc., These result in malfunction or damage to the electrical equipment in the system and lead to financial losses. So in order to mitigate the power quality events a UPQC device is employed which integrates series and shunt active filters that provide satisfactory compensation for power quality problems. The performance of UPQC is compared by using Fractional-Order PID controller and Adaptive Neuro Fuzzy Logic Controller. Modeling of DFIG and WECS systems is discussed with relevant equations. Design of UPQC and controllers is also discussed in detail. The proposed DFIG based WECS employing UPQC is simulated on MATLAB/ Simulink platform. The compensation capabilities of UPQC are assessed for both controllers for the proposed system and simulation results are presented.

Integration of a wind farm with electric grid is an issue that has gained interest due to poor power quality and unmatched power and frequency of grid. Maintenance of power quality has become an important factor in modern power systems. The usage of non-linear loads results in various power quality events which over a period would reduce life and deteriorate the performance of end user equipment. FACTS devices are available that use power electronic components provide efficient solutions for improving power quality in Distribution systems. This paper discusses performance of three FACTS devices SSSC, DSTATCOM and UPQC for mitigating voltage sags, swells and harmonics injected into a DFIG based WECS. The model is developed on MATLAB/ SIMULINK platform and results are presented.