Three-level NPC voltage source converter based direct power control of the doubly fed induction generator at low constant switching frequency

Abstract

This paper deals with an improvement of the direct power control ‘DPC’ for three-level voltage source inverter NPC-VSI feeds the rotor of the doubly fed induction generator ‘DFIG’ based wind power generation system. This converter allows controlling the rotor voltage in magnitude and phase angle with a high flexibility and can therefore be used for active and reactive power control of DFIG. The control is especially designed to reduce the harmonic distortion of the generated currents and active power ripples of the classical DPC control using switching table. In addition, it’s convenient for high power drive and variable speed generator applications with constant switching frequency. The detailed operation principle and simulation results of the proposed DPC-NPC strategy for 1.5 MW of DFIG are also discussed.