Method for operating mechanical emergency brake for wind turbines

Abstract

A method for operating a mechanical emergency brake for a wind turbine is disclosed. The method includes providing a mechanical emergency brake for a wind turbine comprising a spring energy storage; measuring a variable indicative of a holding torque of a pitch drive motor; comparing said measured value of said variable with a desired value of said variable; and shutting down said wind turbine if the comparison of said actual with said desired value reveals that the wind turbine is in a fault condition.

1 . A method for operating a mechanical emergency brake for a wind turbine, comprising the steps of:
 providing a mechanical emergency brake for a wind turbine comprising a spring energy storage;   measuring a variable indicative of a holding torque of a pitch drive motor;   comparing said measured value of said variable with a desired value of said variable; and   shutting down said wind turbine if the comparison of said actual with said desired value reveals that the wind turbine is in a fault condition.   
     
     
         2 . The method according to  claim 1 , wherein said pitch drive motor is a dc series-characteristic motor and said variable indicative of said holding torque is the motor torque. 
     
     
         3 . The method according to  claim 1 , wherein said pitch drive motor is a three-phase asynchronous motor and said variable indicative of said holding torque is the active current component. 
     
     
         4 . The method according to  claim 1 , wherein the moving average of said variable indicative of said holding torque is calculated. 
     
     
         5 . The method according to  claim 4 , wherein the moving average is calculated over at least two complete rotations of the rotor. 
     
     
         6 . The method according to  claim 1 , wherein said desired value is determined during the set-up operation of the wind turbine and/or wherein said desired value is obtained from another spring energy storage located at another rotor blade of the wind turbine. 
     
     
         7 . A method for operating a mechanical emergency brake for a wind turbine, comprising the steps of:
 providing a mechanical emergency brake for a wind turbine comprising a spring energy storage;   detecting the number of rotations of a pitch drive motor after releasing a motor break;   blocking servo converters at a pitch angle between feather and work position;   comparing the detected number of motor rotations with a desired number of motor rotations;   shutting-down the wind turbine if the detected number of motor rotations is smaller than said desired number of motor rotations.   
     
     
         8 . The method according to  claim 7 , wherein said method is accomplished during the start-up of the wind turbine before the wind turbine is connected to the grid.