Abstract: With increasingly growing scale of grid-connected wind farm, the static security constraint of the collection network within the wind farm more obviously restricts the output active capacity of the wind farm, thus it is of importance to determine the highest active power that the wind farm can transmit outward under the restriction of the interior steady-state security region for the grid-connection, planning and construction of wind farm. Firstly, Taking classic grid-connected system of wind farm as background and utilizing the static power flow analysis method for the wind farm and taking the static security of the internal voltage within wind farm as the restriction, the highest active power that the wind farm could transmit outward was calculated. Secondly, the influence of both topological structure of wind farm network and the impedance ratio of the internal collection circuit of the wind farm on the highest active power that the wind farm could transmit outward was researched. Thirdly, both influence of wind power output characteristics of and that of wind farm participating frequency regulation on internal static security of wind farm were further researched. Research results show that rational topological structure of wind farm and the t impedance ratio of collection circuit can maximize the capability of wind farm transmitting outward active power, and within the range of maximum transmitted outward active power the output characteristics of wind farm and the participation of wind farm in frequency regulation does not affect on internal static security of wind farm.