Grid interconnection for variable-speed wind farm with multi-level inverter

This paper presents design, modeling, and control of grid interconnection for a wind farm with round-rotor synchronous generators. The grid interconnection proposed in this paper supports the variable-speed wind turbine concept with the three-phase diode bridge as a front-end rectifier. The wind energy resources and the utility grid are isolated by intermediate fly-back converters. The grid interface multi-level inverter with H-bridge converters improves the power quality of the utility grid. The fast transient response of the real and reactive power control is achieved by the feedback control in synchronous rotating reference frame. Stability of the integrated subsystems is also analyzed with the Nyquist criteria and classical control theory. Simulation results with PSCAD in normal operations and short circuit fault operations are illustrated.