Voltage Stabilization Analysis of a Harmonic Excitation Generator Employing Armature Current Auxiliary Self-Excitation Scheme under Variable Load Conditions

This article proposes a new brushless hybrid harmonic excitation scheme for wind generators, in which the excitation power is provided by the armature current and the stator harmonic control winding current together. In the generation of the field current, besides the main component produced by the excitation control winding equivalent magnetomotive force (MMF), one additional field current component is also produced by on-load armature high-order harmonic and tooth harmonic MMFs, which lead to a self-excitation loop existing in the excitation process. The additional field current component can compensate the flux weakening effect of the load current, which helps to maintain the output voltage characteristic stable in the case of load fluctuation. Besides, the power level of the excitation converter can be greatly reduced. Experimental results on prototype machines validate the effectiveness of the theoretical analyses and finite element analysis (FEA) results.