Patent Publication Number: US-2011068577-A1

Title: Apparatus for providing overload protection for wind power generator and method thereof

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention relates to apparatuses for protecting wind power generators, and more particularly, to an apparatus allows a fan set and a nacelle of a wind power generator to automatically change direction when the fan set encounters a wind force exceeding a preset safety threshold for protecting the wind power generator. 
     2. Description of Related Art 
     It is known that a wind power generator serves to convert a mechanical energy generated by a wind-driven fan set into electrical power and save such electrical power in a battery. While the wind power generator is designed to operate under a wind force below a recognized safety threshold, the optimum wind power conversion rate can be achieved when the fan set has its rotational plane set perpendicular to the direction the wind comes in, hereafter referred to as the wind direction. 
     Conventionally, when the wind power generator faces a wind speed higher than the safety threshold, a brake system built in the nacelle of the wind power generator will automatically start to stop the operation of the wind power generator so as to protect the fan set and other mechanical parts from being broken or being destroyed due to overload. 
     In the traditional technology, the brake systems can be classified into the electromagnetic type and the mechanical type. The former costs highly and fails to work without power supply. The latter relies on complicated mechanical structure and requires frequent maintenance. In either case, an excessive wind force can burden the brake system and once the brake system fails, the wind power generator is exposed to the risks of broken fan set, destroyed mechanisms, and even leaned or collapsed tower of the wind power generator. 
     SUMMARY OF THE INVENTION 
     In view of that the traditional brake systems fail to provide adequate protection to wind power generators under excessive wind force, the present invention proposes an approach to reduce the load on a brake system of a wind power generator, so as to provide protection to the wind power generator under excessive wind force. 
     The objective of the present invention is to provide an apparatus for providing overload protection for a wind power generator, wherein the apparatus starts when the wind power generator is expose to a wind force greater than a preset safety threshold so as to rotate a fan set of the wind power generator and such pose the fan set that a rotational plane of the fan set is parallel to the wind direction, thus reducing a windward area of the fan set, reducing a rotation rate of the fan set, decreasing the load on a brake system, and in turn preventing the wind power generator from being damaged by the excessive wind force. 
     In the present invention, an apparatus for providing overload protection for a wind power generator comprises: an aerovane assembled to the wind power generator for generating signals related to wind direction and wind velocity; a processor assembled to the wind power generator and coupled with the aerovane for receiving the signals related to wind direction and wind velocity, determining an off angle for a nacelle of the wind power generator to deflect accordingly, and converting the off angle into an off-angle signal; and a steering controller assembled to the wind power generator for controlling the nacelle to deflect, wherein the steering controller is coupled with the processor for receiving the off-angle signal and deflect the nacelle accordingly by the off angle. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention as well as a preferred mode of use, further objectives and advantages thereof will be best understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawing, wherein: 
         FIG. 1  is a perspective view of a wind power generator having an apparatus for providing overload protection of the present invention taken from a first viewpoint; 
         FIG. 2  is another perspective view of the wind power generator having the apparatus for providing overload protection of the present invention taken from a second viewpoint; 
         FIG. 3  is a partially enlarged view an area circled in  FIG. 1 ; 
         FIG. 4  shows the wind power generator having the apparatus for providing overload protection of the present invention with a rotational plane of its fan set perpendicular to the wind direction, assuming that a wind force is under a safety threshold; and 
         FIG. 5  shows the wind power generator having the apparatus for providing overload protection of the present invention with the rotational plane of its fan set parallel to the wind direction, assuming that the wind force thereon excesses a safety threshold. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     While a preferred embodiment provided hereinafter for illustrating the concept of the present invention as described above, it is to be understood that the components of the embodiment shown in the accompanying drawings are depicted for the sake of easy explanation and need not to be made in scale. 
     Referring to  FIGS. 1 through 3 , an apparatus for providing overload protection for a wind power generator is illustrated. The wind power generator includes a tower  10  with a top thereof mounted with a nacelle  11 , which has a fan set  12  provided at a front end thereof. The generation device and brake system inside the nacelle  11  as well as the connection between the both and the fan set  12  are known to one skilled in the art and need not to be described in any length herein. 
     The apparatus of the present invention includes an aerovane  20 , a processor  30 , and a steering controller  40 . The aerovane  20  is positioned at a front windward end  111  of the nacelle  11  while the processor  30  is fixed to the tower  10  and coupled with the aerovane  20 . The steering controller  40  is herein realized by a direct-drive motor  42  mounted on a top of the tower  10  and has a driving shaft  41  connected to the nacelle  11  for controlling the nacelle  11  to rotate by a predetermined angle. 
     The aerovane  20  is a known device. It substantially has a streamlined body  21  that has a front end equipped with a four-blade propeller  22  as a wind velocity sensor and has a rear end provided with an empennage  24  as a wind direction sensor. The aerovane  20  serves to detect wind velocity and wind direction, and to generate and transmit signals related to wind direction and wind velocity to the processor  30 . The processor  30  then uses its built-in program to calculate an off angle for the nacelle  11  to deflect according to the signals, and transmits an off-angle signal related to the off angle to a controller of the direct-drive motor  42 , so that the direct-drive motor  42  is actuated by the controller to rotate its driving shaft  41  and in turn rotate the nacelle  11  by the off angle. 
     When a rotational plane  121  of the fan set  12  is perpendicular to the wind direction (as indicated by Arrow A), the fan set is posed at its optimum windward position, as shown in  FIG. 4 . When the rotational plane  121  of the fan set  12  is parallel to the wind direction, the fan set is disabled to acquire the wind force. Basing on this principle, according to  FIG. 5 , when the wind force detected by the aerovane  20  is greater than a preset safety threshold, the steering controller  40  controls the nacelle  11  to rotate by the determined off angle so as to pose the rotational plane  121  of the fan set  12  parallel to the wind direction (as indicated by Arrow A), causing the fan set not to acquire the wind force and reducing its rotation rate, thereby preventing the fan set  12  from rotating out of control or breaking due to overload, in turn unburdening the brake system and the tower  10  so as to prevent the tower  10  from leaning or collapsing under excessively strong wind. 
     The present invention has been described with reference to the preferred embodiment and it is understood that the embodiment is not intended to limit the scope of the present invention. Moreover, as the contents disclosed herein should be readily understood and can be implemented by a person skilled in the art, all equivalent changes or modifications which do not depart from the concept of the present invention should be encompassed by the appended claims.