Wind turbine and support structure and method of controlling the rotational speed of such wind turbine

Abstract

A wind turbine system and a method for controlling a rotational speed of a rotor of such wind turbine system are provided. The system included a wind turbine having a rotor having airfoils having an orientation relative to wind and a rotational axis. The system further includes a structure supporting the wind turbine above ground. The support structure is coupled to the ground. The structure has first portion closer to the wind turbine and a second portion farther from the wind turbine. The first portion will move farther in response to the wind acting across the structure than said second portion causing the turbine rotational axis to tilt. The method includes tilting the rotor rotational axis about an angle, and varying the angle in response to changes of the wind force.

1 . A wind turbine system comprising: 
 a wind turbine having a rotor having airfoils and a rotational axis; and    a structure supporting the wind turbine above ground, said structure being coupled to the ground, wherein said structure has first portion closer to the wind turbine and a second portion farther from the wind turbine, wherein said first portion will move farther in response to a wind acting across said structure than said second portion causing said turbine rotational axis to tilt.    
     
     
         2 . The wind turbine system as recited in  claim 1  wherein said structure is a flexible structure comprising a flexibility allowing for said first portion to move farther than said second portion in response to said wind.  
     
     
         3 . The wind turbine system as recited in  claim 1  wherein said structure is coupled to a base with a flexible member, said base being coupled to the ground.  
     
     
         4 . The wind turbine system as recited in  claim 3  wherein said flexible member is a spring.  
     
     
         5 . The wind turbine system as recited in  claim 1  wherein said wind turbine is a vertical wind turbine and wherein the rotation axis when not tilted is generally vertical.  
     
     
         6 . The wind turbine system as recited in  claim 5  wherein said structure comprises a flexible shaft, wherein said shaft flexes in response to said wind whereby said first portion moves father than said second portion.  
     
     
         7 . The wind turbine system as recited in  claim 6  further comprising a shadowing structure coupled the turbine for blocking a portion of the wind from reaching said wind turbine rotor when said rotational axis is tilted.  
     
     
         8 . The wind turbine system as recited in  claim 7  wherein said portion of the wind being blocked increases as the flexing of said shaft increases.  
     
     
         9 . The wind turbine system as recited in  claim 7  wherein said shadowing structure defines a base of said rotor on which said airfoils are mounted.  
     
     
         10 . The wind turbine system as recited in  claim 1  further comprising a shadowing means for blocking a portion of the wind from reaching said wind turbine rotor when said rotational axis is tilted.  
     
     
         11 . The wind turbine system as recited in  claim 10  wherein said shadowing means will block larger portion of the wind as the wind speed increases.  
     
     
         12 . The wind turbine system as recited in  claim 1  wherein said structure comprises a flexible shaft formed from a glass fiber composite, wherein said shaft flexes in response to said wind whereby said first portion moves father than said second portion.  
     
     
         13 . The wind turbine system as recited in  claim 12  wherein said shaft is pultruded.  
     
     
         14 . The wind turbine as system as recited in  claim 1  wherein said structure is pivotably coupled to a member coupled to the ground.  
     
     
         15 . A method for controlling a rotational speed of a vertical wind turbine rotor mounted on a support structure and rotating about a generally vertical rotational axis by being exposed to wind having a force, said rotor comprising airfoils exposed to the wind, the method comprising: 
 tilting said rotor rotational axis about an angle; and    varying said angle in response to changes of said wind force.    
     
     
         16 . The method as recited in  claim 15  wherein varying comprises increasing said angle when said wind force increases.  
     
     
         17 . The method as recited in  claim 15  wherein said tilting comprises decreasing a rotational efficiency of said rotor for a given wind speed.  
     
     
         18 . The method as recited in  claim 15  father comprising blocking a portion of the wind from acting on said rotor as the angle increases for controlling the amount of force exerted on said rotor by said wind.  
     
     
         19 . The method as recited in  claim 17  further comprising increasing said wind portion being blocked as said wind force increases.  
     
     
         20 . The method as recited in  claim 15  wherein titling said rotational axis comprises pivoting said support structure relative to the ground for tilting said rotational axis.  
     
     
         21 . The method as recited in  claim 15  wherein said tilting comprises flexing said structure for tilting said rotational axis.