Power quality improvement using hybrid active power filter for a DFIG based wind energy conversion system

In recent years, there has been a considerable interest in installation of dispersed generation systems such as wind farms. The DFIG based variable speed wind turbine is the most popular in the growing wind market. This machine can be operate either in grid connected or stand alone mode. The interaction between the wind farm and the grid should be in compliance with the power quality standards. The system uses two back-to-back PWM voltage source converters in the rotor circuit designed as grid side converter (GSC) and rotor side converter (RSC). The vector control strategy is used for both converters. These high frequency switching converters of DFIG will inject additional harmonics in the system, which are increasing with wind speed variations. The presence of non linear load will further inject harmonic current and as a consequence, there is a violation of IEEE-519 power quality standard, and chances of damage of power system equipment may increase. As a solution, Hybrid Active Power Filter; a combination of shunt active filter and shunt passive filter is used in conjunction with non linear load. Indirect current control scheme based on hysteresis controller has been used for controlling of active filter. The SAPF eliminates higher order harmonics while most dominant lower order harmonics are filtered out using passive filter. In this paper the performance of wind driven DFIG feeding non linear load with HAPF is analyzed for steady state and dynamic conditions, using MATLAB/Simulink.