Rotational speed determination

A method for operation of a wind power plant (11) with a rotor (10) and a rotating apparatus (20, 22, 24) connected with the rotor (10), wherein a rotor speed (nR) and a rotating apparatus speed (n) are interrelated via a specifiable transmission ratio, comprising steps of:

• determining the rotating apparatus speed (n), wherein for the determination of the rotating apparatus speed (n) a rotational speed measurement value (rpmi) is captured by a measurement device,
• correcting the rotational speed measurement value (rpmi) to eliminate a measurement error caused by inaccuracy of the measurement device with an intermittently variable correction value (rpmi,c), such that the determined rotating apparatus speed (rpmi,f) results, and
• feeding the determined rotating apparatus speed (rpmi,f) to a regulation apparatus (36) of the wind power plant (11) as an actual value
• wherein a difference or a quotient of the rotational speed measurement value (rpmi) to a rotational speed measurement value average ( rpmi) is made for the determination of the correction value (rpmi,c) of the rotational speed measurement value (rpmi)
• wherein a rotational speed measurement value average ( rpmi) of the rotational speed measurement value (rpmi) captured during a revolution is formed for each full revolution of the rotating apparatus (20, 22, 24)
• wherein a fitting curve (46), is formed between two consecutive rotational speed measurement value averages ( rpmi, rpmi+1), wherein a difference or a quotient of the rotational speed measurement value (rpmi) to the fitting curve (46) is also formed for the determination of the correction value (rpmi,c) of the rotational speed measurement value (rpmi), and
• wherein the formed differences or quotients are filtered for the determination of the rotating apparatus speed (n, rpmi,f) of the rotating apparatus (20, 22, 24).