The present invention concerns a method of controlling a wind power installation having a control apparatus for operational management of the wind power installation, in which the acceleration of the pylon is detected.  The invention further concerns a wind power installation comprising a pylon, a control apparatus for operational management of the wind power installation and a device for detecting the acceleration of the pylon. 
Disposed at the top of the pylon of a wind power installation of the horizontal-axis type are the generator, the entire drive train and the rotor, that is to say all movable parts of the wind power installation, which take energy from the wind and convert it into electrical energy. 
Conversion is effected by the rotor being caused to rotate by the wind and by that rotary movement being transmitted to the generator or generators.  Therefore the speed of rotation is dependent on the one hand on the wind and on the other hand on the aerodynamic properties of the wind power installation. 
It will be seen from the foregoing that the pylon must therefore not only carry the rotor, the drive train and the generator (and the pod) but in addition it must also securely withstand the loadings which act thereon in operation.  In addition the pylon must withstand high wind speeds, even if the wind power installation is already out of operation. 
DE 33 08 566 and corresponding U.S. application U.S. Pat.  No.  4,435,647 disclose a wind turbine installation in which arranged on the pylon is a motion measuring device which generates a motion signal, depending on how the top of the pylon is moving in operation. 
DE 100 11 393 discloses a regulating system for a wind power installation, having means for the detection of measurement parameters which permit direct or indirect quantification of the current turbine loading and/or stressing which are dependent on location and weather, and a downstream-connected electronic signal processing arrangement which makes it possible for the reduction in power required in optimised wind power installations to be limited to the economic optimum which corresponds to the current operating conditions, in the range of the nominal wind speed and at high wind speeds. 
DE 100 16 912 discloses operational management of offshore wind power installations, which is dependent on the natural frequency of the pylon, wherein firstly the respective critical natural frequencies of the installation and/or parts of the installation are determined, and thereafter the rotary speed range of the rotor in which excitation of the overall installation and/or individual parts of the installation occurs in the range of the critical natural frequencies thereof is determined, so that the wind power installation is operated only below or above the critical rotary speed range, passing quickly through the critical rotary speed range. 
Therefore, given load situations in respect of which the pylon must be designed are derived from those loadings.  Such loads are referred to as dimensioning loads and thus determine the dimensioning of the pylon.  In turn, that dimensioning procedure also affords the oscillation characteristics of the pylon, its natural frequencies (the fundamental frequency and harmonics thereof) and so forth. 
Now, for wind power installations there is a series of regulations which they have to observe.  That also includes a ‘Directive for Wind Power Installations’, issued by the ‘Deutsche Institut für Bautechnik (DIBt)’ [‘German Institute for Construction Technology’] in Berlin.  That Directive sets forth inter alia a regulation regarding operational oscillation monitoring of the pylon.  Accordingly, in an operating range in which the excitation frequency of the rotor is in a band width of the natural frequency of the pylon +/−5%, permanent operation without operational oscillation monitoring is inadmissible.