An AC/DC/AC Interface Control Strategy to Improve Wind Energy Economics

A control strategy for an AC/DC/AC interface to smooth or limit wind farm output is investigated. The need to follow rapid power variation from uncontrolled wind farms with expensive gas turbines limits the amount of penetration of wind energy systems in existing utilities. An AC/DC/AC interface makes it possible to limit the power variations from the wind farm. An optimal level to which the wind output should be limited is found in terms of the distribution of wind power output and the relative cost of the fast acting and base loaded units. Using the optimal cutting point for the wind output each wind farm can be included in the economic dispatch calculation. The economic advantage of limiting wind power output is demonstrated on an example system. Using a hypothetical system it is shown that wind penetrations as high as 16.75% may be economical using the optimal strategy made possible by the AC/DC/AC interface.