A method for controlling a wind farm comprising a plurality of wind turbines, the method comprising: measuring a wind condition of a wind entering the wind farm; calculating a demanded power generation quantity for each of the wind turbines to satisfy a total power generation quantity demanded of the wind farm based on the measured wind condition; and calculating a time at which the measured wind condition will arrive at a location of each of the wind turbines; and controlling each of the wind turbines at the calculated arrival time to generate power according to the demanded power generation quantity calculated for each of the wind turbines; wherein calculating the time at which the measured wind condition will arrive at the location of each of the wind turbines comprises using a distance between a point where the measuring is performed and a location of a target wind turbine, a wind speed of the measured wind condition, a wind speed at the location of the target wind turbine and a measuring time of the wind; and wherein calculating the demanded power generation quantity for each of the wind turbines further comprises: calculating a predicted power generation quantity and a predicted load of each of the wind turbines based on the measured wind condition; and calculating the demanded power generation quantity for each of the wind turbines to satisfy the total power generation quantity demanded of the wind farm based on the predicted generation power quantity and the predicted load of each of the wind turbines; and wherein calculating the predicted power generation quantity and the predicted load comprises: regarding a specific wind turbine from among the plurality of wind turbines, calculating a predicted wind condition of a wind entering the specific wind turbine by calculating wake streams caused by other wind turbines and applying the wake streams to the measured wind condition; and calculating the predicted power generation quantity and the predicted load of the specific wind turbine at a time at which the predicted wind condition will arrive at the specific wind turbine; and wherein calculating the predicted wind condition, the predicted power generation quantity and the predicted load are performed in parallel for each of the plurality of wind turbines; and wherein calculating the predicted wind condition further comprises: calculating a reduction coefficient by considering a wind reduced by at least one wind turbine located ahead of the specific wind turbine; and calculating the predicted wind condition of the wind entering the specific wind turbine by applying the reduction coefficient to a strength of the measured wind condition. measuring a wind condition of a wind entering the wind farm; calculating a demanded power generation quantity for each of the wind turbines to satisfy a total power generation quantity demanded of the wind farm based on the measured wind condition; and calculating a time at which the measured wind condition will arrive at a location of each of the wind turbines; and controlling each of the wind turbines at the calculated arrival time to generate power according to the demanded power generation quantity calculated for each of the wind turbines; wherein calculating the time at which the measured wind condition will arrive at the location of each of the wind turbines comprises using a distance between a point where the measuring is performed and a location of a target wind turbine, a wind speed of the measured wind condition, a wind speed at the location of the target wind turbine and a measuring time of the wind; and wherein calculating the demanded power generation quantity for each of the wind turbines further comprises: calculating a predicted power generation quantity and a predicted load of each of the wind turbines based on the measured wind condition; and calculating the demanded power generation quantity for each of the wind turbines to satisfy the total power generation quantity demanded of the wind farm based on the predicted generation power quantity and the predicted load of each of the wind turbines; and wherein calculating the predicted power generation quantity and the predicted load comprises: regarding a specific wind turbine from among the plurality of wind turbines, calculating a predicted wind condition of a wind entering the specific wind turbine by calculating wake streams caused by other wind turbines and applying the wake streams to the measured wind condition; and calculating the predicted power generation quantity and the predicted load of the specific wind turbine at a time at which the predicted wind condition will arrive at the specific wind turbine; and wherein calculating the predicted wind condition, the predicted power generation quantity and the predicted load are performed in parallel for each of the plurality of wind turbines; and wherein calculating the predicted wind condition further comprises: calculating a reduction coefficient by considering a wind reduced by at least one wind turbine located ahead of the specific wind turbine; and calculating the predicted wind condition of the wind entering the specific wind turbine by applying the reduction coefficient to a strength of the measured wind condition.