Grid Side Converter Based Shunt Active Power Filter of Variable Speed Doubly Fed Induction Generator Driven by Wind Turbine

This paper presents power quality improvement by using Grid Side Converter (GSC) of variable speed Wind Energy Conversion System (WECS) based Shunt Active Power Filter (SAPF). Maximum Power Point Tracking (MPPT) is carried out by its Rotor Side Converter (RSC) using Genetic Algorithm (GA). The optimal Tip Speed Ratio (TSR) is determined to extract the maximum available wind power at any wind speed until rated wind speed. Doubly Fed Induction Generator (DFIG) has stator terminals are connected directly to the grid. However, the rotor terminals of DFIG are connected to the mains via a partially rated variable frequency ac/dc/ac converter. The ac/dc/ac converter system is consisting of RSC and GSC are connected back-to-back by a DC-link capacitor. Stator Voltage Orientation (SVO) is the principle control for both RSC and GSC controlled by hysteresis current controller. The GSC has two functions the first function is to keep the DC link voltage constant at its level and get unity power factor for GSC of DFIG. The second function is acting as SAPF to obtain unity power factor at power grid side due to presence of inductive load and cancel current harmonic due to presence of nonlinear load at Point of Common Coupling (PCC) connected in parallel with inductive load. The system under study is simulated using MATLAB/Simulink package. The digital simulation results show that the output power and rotor speed response for step change in wind speed prove the effectiveness and powerful of the proposed GA controller for MPPT and also achievement of the power quality improvement.