An Approach for Suppressing the Grid-Connection Fluctuation of a DFIG Based on Wu Elimination Method

For decreasing the influence of high frequency switch harmonics on the stability of a DFIG, the relationship between the switch angles and modulation ratio of the excitation converter was studied with the help of mechanized mathematics-WEM (Wu Elimination Method). The expression of the switch angles and the modulation ratio was obtained off line and used to control the rotor excitation converter on line. It indicates that the no-ideal modulation ratio that would induce nonlinear dynamics response of the converter bridge can be avoided. The practicability of this approach has been verified by the simulation results achieved by proposed simulation model of the DFIG. It may provide some reference for smoothen the fluctuation of output power of a wind generator system.