A pitch control apparatus for controlling a pitch value in a wind power generation system, the pitch control apparatus comprising: a generator comparing unit configured to calculate an error signal (e x) based on a difference between a generator measurement signal and a generator reference signal (X ref), the generator measurement signal corresponding with an operation of the power generation system; a reference pitch calculating unit configured to calculate a reference pitch value using the error signal; a compensation pitch calculating unit configured to calculate a compensation pitch value using an error value from the wind power generation system; and a pitch calculating unit configured to calculate a pitch value using the reference pitch value and the compensation pitch value, wherein the error value is a voltage error value (e v) from a direct-current capacitor included in a power converter unit of the wind power generation system, or from a grid connection point of the wind power generation system; and wherein the compensation pitch calculating unit comprises: - a compensation real power calculator configured to calculate a compensation real power value by using the voltage error value (e v); - a compensation pitch calculator configured to calculate a compensation pitch value by using the compensation real power value; - a comparer configured to calculate the voltage error value (e v); and - an error limiter configured to modify the voltage error value to a tolerable voltage error value within a predefined voltage range, if the voltage error value is outside the predefined voltage range. a generator comparing unit configured to calculate an error signal (e x) based on a difference between a generator measurement signal and a generator reference signal (X ref), the generator measurement signal corresponding with an operation of the power generation system; a reference pitch calculating unit configured to calculate a reference pitch value using the error signal; a compensation pitch calculating unit configured to calculate a compensation pitch value using an error value from the wind power generation system; and a pitch calculating unit configured to calculate a pitch value using the reference pitch value and the compensation pitch value, wherein the error value is a voltage error value (e v) from a direct-current capacitor included in a power converter unit of the wind power generation system, or from a grid connection point of the wind power generation system; and wherein the compensation pitch calculating unit comprises: - a compensation real power calculator configured to calculate a compensation real power value by using the voltage error value (e v); - a compensation pitch calculator configured to calculate a compensation pitch value by using the compensation real power value; - a comparer configured to calculate the voltage error value (e v); and - an error limiter configured to modify the voltage error value to a tolerable voltage error value within a predefined voltage range, if the voltage error value is outside the predefined voltage range. - a compensation real power calculator configured to calculate a compensation real power value by using the voltage error value (e v); - a compensation pitch calculator configured to calculate a compensation pitch value by using the compensation real power value; - a comparer configured to calculate the voltage error value (e v); and - an error limiter configured to modify the voltage error value to a tolerable voltage error value within a predefined voltage range, if the voltage error value is outside the predefined voltage range.