Operation Control Strategy of DC Grid Connected DFIG

In DC microgrids, the grid-connected structure of doubly-fed generators connected to the DC grid through uncontrolled rectifier bridges is characterized by low converter cost and simple controller structure compared to the traditional DC grid-connected structure of pulse-width modulated converters. In this paper, a control method for grid-connecting the stator side through an uncontrolled rectifier bridge is proposed for this structure. This article develops a control method for grid connection of the stator side through an uncontrolled rectifier bridge for this structure. Firstly, according to the characteristics of the system without grid frequency support, a stator frequency control method based on stator flux angle is designed. Secondly, a stator current direct resonance closed-loop control structure was designed to reduce the harmonic components present in the system. The simulation results indicate that this method is effective and feasible.