Voltage Regulation of Weak Grid-Tied DFIG based WECS using ε-VPNMN Control

Voltage regulation is very much common in weak grid scenario. In this work, small scale doubly fed induction generator (DFIG) based wind energy conversion system (WECS) is tied to weak distribution grid. When power exchange occurs in a weak grid, the voltage at common connection point (CCP) fluctuates. To avoid the adverse impact of CCP voltage on indirect current control technique of converters, the CCP voltages are filtered using dual-second order generalized integrator (Dual-SOGI) based voltage filtering units (VFUs). Moreover, to achieve proper voltage regulation, a ε-variable parameter normalized mixed-norm (ε-VPNMN) filter controlled grid side converter (GSC) is used. By using this control, the voltage at CCP is maintained irrespective of change in generation as well as loads. Along with it, load balancing is also achieved. Moreover, stator field oriented vector control is implemented for rotor side converter. However, optimum tip speed ratio control is implemented to track peak power from the wind turbine. Simulation of this system is done using MATLAB-SIMULINK platform and the results obtained are satisfactory, which validate the robust behavior of ε-VPNMN algorithm. Moreover power quality of CCP is improved.