A method for controlling a wind farm electrical power system is presented. The wind farm electrical power system includes a controller and a plurality of wind turbines electrically connected to an electrical grid through a point of interconnection. Each wind turbine includes a voltage regulator. The method includes receiving, via the controller, one or more electrical signals associated with the point of interconnection for a frequency domain. Further, the method includes estimating, via an estimator of the controller, a voltage sensitivity of the electrical grid using the one or more electrical signals. Moreover, the method includes dynamically controlling a voltage of the wind farm electrical power system at the point of interconnection based on the voltage sensitivity.