The present invention concerns a method of feeding electric power into an electric network wherein the feed is effected by means of at least one wind power installation with a first feed-in arrangement at a feed-in point into the electric network, and the feed is effected in dependence on electric parameters in the network and measurement values of the electric parameters or measurement values for determining the electric parameters are detected at measurement times at predetermined time intervals and wherein the measurement times are synchronized to an external time signal available outside the first feed-in arrangement.