Method for operation of a wind energy installation

A method for operation of a wind energy installation (10), with the wind energy installation (10) having a rotor (18) that is driven by wind and that has at least one rotor blade (22), a generator for conversion of the mechanical energy of the rotor (18) to electrical energy, and a tower (14) on which the rotor (18) is arranged, comprising the step of

• measuring at least one measurement variable by means of a suitable measurement device during operation of the wind energy installation (10),
• wherein the at least one measurement variable is a measure of the bending of the at least one rotor blade (22) in the tower direction as a result of a given wind load, and is thus a measure of the risk of the at least one rotor blade (22) colliding with the tower (14) of the wind energy installation (10) as the at least one rotor blade passes the tower,
• with at least one operating parameter of the wind energy installation (10) being adjusted as a function of the at least one measurement variable for determination of the at least one rotor blade bending,
• wherein the at least one measurement variable is the physical distance between the at least one rotor blade (22) and the tower (14), the physical distance being measured at a predetermined point in an area in which the at least one rotor blade passes the tower by means of a distance measurement device during operation of the wind energy installation (10) during a plurality of times at which the at least one rotor blade (22) passes the tower,
• wherein the at least one operating parameter of the wind energy installation (10) is adjusted as a function of the measured distance.