Method and system for controlling wind farm when wind speed varies abruptly

The present invention relates to a method and system for controlling a wind farm when a ramp up or ramp down rate of the wind farm does not satisfy a grid-code or corresponding criteria due to an abrupt change in wind speed. The present invention relates to a method and system for controlling a wind farm while satisfying the grid-code in the case where wind power cannot be generated since the wind speed changes abruptly as much as to be out of range of wind power generation reference speed or in the case where a ramp up or ramp down rate of the wind farm does not satisfy the grid-code since the wind speed changes abruptly within the range of wind power generation reference speed, such as a case where the wind speed exceeds the limit of a reference speed or the wind is as feeble as less than a lower limit. The method and system for controlling a wind farm includes the steps of measuring speed and direction of wind performed outside the wind farm, sequentially controlling wind turbines if the wind speed abruptly changes considering a time for the wind to arrive at the wind turbines, determining the number of wind turbines to be controlled simultaneously so that the wind farm may satisfy the grid-code at this point, grouping the wind turbines, determining a control sequence and a control time of each group, and adjusting a control end time if stopping times of adjacent groups are overlapped when the wind turbines are stopped.