A short-circuit calculating model of an actual power network integrated with wind farm group is built with the PowerFactory simulation software. The electromagnetic-transient behavior and the relay action of different wind farms with or without the low voltage ride through（LVRT） capability in the wind farm group are analyzed to compare with the traditional electric power， such as the hydroelectricity or the heat electricity. Based on the studies， a control strategy of the tie-lines equipped with overload safety device adapted for the wind power characteristics is proposed. The control strategy is designed for the discrimination of the faulty line and the choice of the right cutoff time， which significantly improves the transmitting capability and the reliability of the tie-lines of wind farms.