Flicker Attenuation Using FACTS Device for DFIG-Based WECS Connected to Distribution Network

Wind being stochastic in nature results in intermittent and fluctuating wind power sources. This affects the power quality during normal operation. Major causes for such changes are mainly due to tower shadow and wind shear effects (3p oscillations), which lead to active power changes and delay penetration of wind power into the grid. At times, due to lower short circuit ratios and grid impedance angle at the point of common coupling power quality concerns, such as voltage stability and flicker occur. This literature focuses on a method to mitigate flicker by reducing the grid current deviations using flexible ac transmission system (here, static synchronous series compensator) device under different modes. Due to changes in wind speed, the mechanical torque changes and as a result, its impact is visible on the grid current at the static synchronous series compensator. A detailed case-to-case study has been made for the grid-connected system for low as well as high wind speed conditions. The static synchronous series compensator has been used for capacitive series voltage injection as well as inductive series voltage injection. The proposed method attains a better reduction in flicker using static synchronous series compensator for inductive series voltage injection as seen using MATLAB/Simulink.