Wind turbine and method for ice removal in wind turbines

Abstract

A wind turbine is disclosed which comprises a control system configured to execute at least one ice removal routine which comprises a heating stage of at least one of the blades ( 3 ), and a mechanical removal ice stage. A wind turbine removing ice method is also disclosed which comprises a stage wherein the presence of ice is detected on at least one of the blades and, once said presence of ice is detected, comprises a stage wherein at least one ice removal routine is activated which comprises, in turn, a heating stage of at least one of the blades and a mechanical removing ice stage on at least said blade.

1 . A wind turbine of the type comprising:
 a rotor having at least two blades ( 3 );   a control system;   means for detecting the presence of ice on at least one of the blades ( 3 );   a heating system with a heating element ( 31 ) connected to the control system and configured to carry out a heating stage of at least one of the blades ( 3 );   characterised in that the control system is configured to execute at least one ice removal routine that comprises the following stages:   a heating stage of at least one of the blades ( 3 ); and   a mechanical ice removal stage.   
     
     
         2 . The wind turbine, according to  claim 1 , wherein the control system is configured to execute the ice removal routine in such a manner that the mechanical ice removal stage is carried out when the heating stage is at least partially carried out. 
     
     
         3 . The wind turbine, according to  claim 1 , wherein the mechanical ice removal stage in at least one of the blades ( 3 ) comprises adjusting rotor rotation speed. 
     
     
         4 . The wind turbine, according to  claim 1 , wherein the mechanical ice removal stage in at least one of the blades ( 3 ) comprises adjusting blade pitch angle. 
     
     
         5 . The wind turbine, according to  claim 4 , wherein the mechanical ice removal stage in at least one of the blades ( 3 ) comprises consecutive braking and acceleration orders in blade pitch angle adjustment. 
     
     
         6 . The wind turbine, according to  claim 1  wherein the means for detecting the presence of ice in at least one of the blades are selected from among:
 a comparing algorithm for comparing between a signal indicative of the power generated and a signal indicative of the power expected at the wind speed measured (or incoherence between the wind speed and power signals measured); 
 equipments for estimating the natural frequency to each blade based on accelerometer measurements and comparison with respect to inherent frequency without ice; 
 ultrasound or capacitive ice detection sensors located in the interior of the blade; 
 an algorithm for estimating the presence of ice and thickness thereof based on the temperature measurements in the interior of the blade. 
 
     
     
         7 . The wind turbine, according to  claim 1 , comprising temperature sensors disposed in the interior of at least one blade ( 3 ). 
     
     
         8 . The wind turbine, according to  claim 7 , wherein the sensors are disposed in a blade control station disposed at a point situated at a distance from the blade root between 60% and 90% of the length of the blade. 
     
     
         9 . The wind turbine, according to  claim 8 , wherein the sensors are disposed at a point situated between 75% and 90% of the length of the blade. 
     
     
         10 . The wind turbine, according to 9, wherein the temperature sensors comprise:
 a sensor disposed in the interior of the blade in contact with the wall of the leading edge, configured to measure a surface temperature (T 1 ) at that point;   a sensor disposed in the interior of the blade, configured to measure the air temperature (T ia );   a sensor disposed in the interior of the blade in contact with the wall opposite the leading edge configured to measure a surface temperature (T 2 ) at that point;   
       and the wind turbine comprises means for estimating the temperature on the outer blade surface from the signal of said temperature sensors disposed in the interior of the blade. 
     
     
         11 . A wind turbine removing ice method comprising:
 a rotor having at least two blades;   a wind turbine control system;   means for detecting the presence of ice on the blades;   a heating system having at least one heating element connected to the control system and configured to carry out a heating stage of at least one of the blades;   
       said method comprising the following stage:
 detection of the presence of ice on at least one of the blades; 
 
       characterised in that, upon detecting the presence of ice, it comprises activating at least one ice removal routine comprising the following stages;
 a heating stage wherein of at least one of the blades; 
 a mechanical ice removal stage on at least said blade. 
 
     
     
         12 . The wind turbine removing ice method, according to  claim 11 , wherein the mechanical ice removal stage is carried out when the heating stage has been carried out at least partially. 
     
     
         13 . The wind turbine removing ice method, according to  claim 12 , wherein the time established in the heating stage of at least one of the blades depends on the amount of ice detected in the stage wherein the presence of ice is detected. 
     
     
         14 . The wind turbine removing ice method, according to  claim 12 , wherein the time established in the heating stage of at least one of the blades is a predetermined time. 
     
     
         15 . The wind turbine removing ice method, according to  claim 11 , wherein the heating stage of at least one of the blades and the mechanical ice removal stage are carried out at least partially simultaneously. 
     
     
         16 . The wind turbine removing ice method, according to  claim 11 , wherein the mechanical ice removal stage on at least one blade is carried out upon completing the heating stage of at least one of the blades. 
     
     
         17 . The wind turbine removing ice method, according to  claim 11 , wherein, after carrying out the mechanical ice removal stage on at least one of the blades, the method is executed again until determining the non-presence of ice or a substantial reduction thereof. 
     
     
         18 . The wind turbine removing ice method, according to  claim 11 , wherein the mechanical ice removal stage comprises at least one of the following substages:
 executing a blade movement by adjusting blade pitch angle,   executing a blade movement by adjusting rotor rotation speed.   
     
     
         19 . The wind turbine removing ice method, according to  claim 18 , wherein blade pitch angle adjustment is performed between pitch angle positions of at least one of the blades ( 3 ) of 90° and 30°. 
     
     
         20 . The wind turbine removing ice method, according to  claim 18 , wherein the adjustment of the blade pitch angle is performed by means of controlled acceleration and deceleration. 
     
     
         21 . The wind turbine removing ice method, according to  claim 18 , wherein the adjustment of rotor rotation speed comprises consecutively accelerating and braking the rotor. 
     
     
         22 . The wind turbine removing ice method, according to  claim 18 , wherein the mechanical ice removal stage is carried out with the wind turbine stopped and wherein the adjustment of rotor rotation speed comprises performing a wind turbine rotor starting sequence, such that the rotor starts rotating. 
     
     
         23 . The wind turbine removing ice method, according to  claim 11 , wherein the mechanical ice removal stage is carried out with the wind turbine stopped and wherein it comprises a stage wherein at least one of said blades ( 3 ) is disposed at a predetermined azimuth angle prior to carrying out the mechanical ice removal stage. 
     
     
         24 . The wind turbine removing ice method, according to  claim 11 , wherein the mechanical ice removal stage is carried out with the wind turbine stopped and wherein it comprises a stage wherein at least one of said blades ( 3 ) is positioned at an angle of 180° prior to carrying out the mechanical ice removal stage. 
     
     
         25 . The wind turbine removing ice method, according to  claim 11 , wherein the mechanical ice removal stage is carried out with the wind turbine stopped and wherein it comprises a stage wherein at least one of said blades ( 3 ) is positioned at an angle of 270° prior to carrying out the mechanical ice removal stage. 
     
     
         26 . A wind turbine control method, comprising:
 a rotor having at least two blades;   a wind turbine control system;   a heating system having at least one heating element connected to the control system and configured to carry out a heating stage of at least one of the blades;   
       characterised in that it comprises a heating system effectiveness estimation stage. 
     
     
         27 . The wind turbine control method, according to  claim 26 , wherein the heating system effectiveness estimation stage according to the method includes carrying out the following substages:
 a stage wherein the wind speed and temperature conditions envisaged for the heating stage are determined;   a stage wherein the wind speed and temperature conditions envisaged for the heating cycle are compared with the wind speed and temperature conditions whereunder the heating system is effective.   
     
     
         28 . The wind turbine control method, according to  claim 26 , which comprises a heating system activation stage if the heating system effectiveness estimation stage results that the heating system is effective. 
     
     
         29 . The wind turbine control method, according to  claim 26 , wherein the heating system effectiveness estimation stage includes carrying out the following substages:
 a stage wherein wind speed and temperature conditions whereunder the heating system is effective are determined;   a stage wherein wind speed and temperature conditions envisaged for the heating cycle are determined;   a comparing stage for comparing the wind speed and temperature conditions envisaged for the heating cycle with respect to wind speed and temperature conditions whereunder the heating system is effective.   
     
     
         30 . The wind turbine control method, according to  claim 27 , which additionally comprises a heating system activation stage if the comparison between the speed and temperature conditions envisaged for the heating cycle with respect to the wind speed and temperature conditions whereunder the heating system is effective results that the heating system is effective. 
     
     
         31 . The wind turbine control method, according to  claim 26 , which comprises a stage for detecting the presence of ice or of conditions favorable to the presence of ice prior to the heating system effectiveness estimation stage. 
     
     
         32 . The wind turbine control method, according to  claim 27 , wherein the stage wherein the wind speed and temperature conditions whereunder the heating system would be effective comprises the determination of wind speed and temperature conditions whereunder the formation of ice can be prevented. 
     
     
         33 . The wind turbine control method, according to  claim 27 , wherein the stage wherein the wind speed and temperature conditions whereunder the heating system would be effective comprises the determination of wind speed and temperature conditions whereunder the ice can be removed. 
     
     
         34 . The wind turbine control method, according to  claim 33 , which comprises a stage wherein the thickness of the ice layer is quantified and the stage wherein the speed and temperature conditions whereunder the ice can be removed are determined consider the thickness of the ice layer.