A variable line filter for active and reactive power control through grid-tie-inverter as a dynamic VAR compensator for WECS

This paper presents improvement technique for the power quality of the electrical part of a wind generation system which aims to optimize the utilization of wind power injected into weak grids. To realize this goal, a variable line filter connected between the grid-tied inverter and utility grid is proposed. A self-excited induction generator (SEIG) is used as an example of small scale generators. However, this method is applicable for the other wind generator types, especially the permanent magnet generators. The advantage of the proposed system is its simplicity and less control complexity. It also provides full control of active and reactive power injected into the grid using voltage source inverter (VSI) as a dynamic VAR compensator. A voltage oriented control (VOC) scheme is presented in order to control the energy to be injected into the grid. In an attempt to minimize the harmonics in the injected current and to avoid poor power quality of the wind energy conversion system (WECS), a variable L filter is inserted between VOC VSI and the grid. The proposed technique is implemented by a digital signal processor (DSP TMS320F240) to verify the validity of the proposed model.