Research on AC-DC-AC Converter for Wind Power Doubly-Fed Induction Generator

AC-DC-AC converter is the essential technology for grid-connected variable speed constant frequency (VSCF) doubly-fed induction generator (DFIG) wind power generation systems. In this paper, a practical AC-DC-AC converter with IGBT modules is presented based on the DFIG model and field oriented control theory. The power flow of the converter is bi-directional. It can operate at a relative wide speed range in different modes: sub-synchronous and super-synchronous. The active and reactive power can be controlled flexibly and no harmonics are injected to the grid. And the power flowing through the converter is just the slip recovery power of the DFIG. The converter offers high power quality, good performance and low cost. A prototype system is set up and the experimental results indicate that the converter can fulfil the requirements of the VSCF DFIG wind turbines