A Voltage Modulated Direct Power Controlled Wind Energy System Connected to a Weak AC Grid with Maximum Power Point Tracking

Abstract

A Voltage Source Inverter (VSI) when connected to a weak AC grid exhibits instability problems due to the unfavourable interactions between the Phase Locked Loop (PLL) and inner current controller of the VSI. In this paper a voltage modulated direct power control technique is used to integrate a Permanent Magnet Synchronous Generatr (PMSG) based wind energy system to a weak AC grid. This control technique does not need a PLL for its operation. The perturb and observe algorithm based maximum power point tracking is used to extract maximum power from wind. The performance of the system is evaluated using simulation studies done in MATLAB/Simulink. The effects of change in wind speed and sag in grid voltage are also analyzed. The results show that the controller is able to follow the active and reactive power commands with permissible THD in the current injected to grid.