Experiment on grid-connection process of wind turbines in fractional frequency wind power system

The basic idea of the fractional frequency transmission system (FFTS) is to use lower frequency to reduce the effective electrical length of the ac transmission line, thus increasing its transmission capacity. Because the rotational speeds of the generators in hydro and wind power generation systems are very low, the FFTS is particularly suitable for transmitting electricity produced by renewable energy sources. The fractional frequency wind power system (FFWPS) provides an effective approach for integrating the large-scale and long-distance wind power into the grid. A novel method of the integration of the wind turbines in direct-driven FFWPS is introduced in this paper. A full-power ac-dc-ac converter is used as the grid-connection device in the experiment, and the experiment results verify the feasibility and effectiveness of the proposed method.