Patent ID: 6891280

Claim:
A method for operating an offshore wind power plant, the offshore wind power plant having a rotor operable at different speeds, the steps of the method comprising: a) providing a rotor speed regulation device and a sensor for the measurement of a frequency change over a period of time; b) determining in regular intervals a range of critical natural frequencies of the offshore wind power plant, the range of critical natural frequencies defining a highest threshold rotor speed by which the offshore wind power plant can operate; c) determining a forbidden rotor speed range defined as speeds above the highest threshold rotor speed; d) shifting the forbidden speed range corresponding to the critical natural frequencies regularly determined; e) determining a safe rotor speed range wherein there is an excitation of the offshore wind power plant in the range of critical natural frequencies; and f) operating the offshore wind power plant within the safe rotor speed range by constantly determining a current critical natural frequency of the offshore wind power plant and ensuring that the offshore wind power plant is not operated within the forbidden rotor speed range.