Abstract:
A monitoring system for at least one wind turbine includes at least one sensor disposed at the at least one wind turbine to detect wind friction at the at least one wind turbine. At least one controller is connected to the at least one wind turbine, and a monitor server is connected to the controller to change an operational status of the at least one wind turbine based on wind friction data received from the at least one sensor. A method of operation of at least one wind turbine includes continuously measuring data relative to wind friction at the at least one wind turbine via at least one sensor located thereat. The data is continuously compared to a predetermined wind friction threshold. A trend in the comparisons is evaluated, and the operational status of the wind turbine is changed via a monitor server based on a result of the comparison.

Description:
BACKGROUND OF THE INVENTION 
     The subject matter disclosed herein relates to wind farms. More particularly, this disclosure relates to monitoring of friction in wind turbines of wind farms. 
     The use of wind turbines for power generation is increasing in popularity. As such, more wind turbines, and groups of wind turbines called “wind farms” are being erected at locations subject to adverse weather conditions, for example, off-shore locations or alpine areas. In locations such as these, the wind turbines have an increased likelihood of accumulation of ice and/or snow resulting in increased mass loads and frictional loads on the wind turbines. Further, in some instances, once a wind turbine accumulates ice and/or snow to a certain degree, operation of the wind turbine must be stopped to prevent, for example, an ice or snow throw by the wind turbine. The wind turbine must be stopped until the ice or snow accumulation is reduced. Typically, monitoring of ice accumulation on such wind turbines is accomplished via inspection of individual wind turbines by, for example, a technician or field engineer. In large wind farms containing perhaps hundreds of wind turbines spread over large geographical areas, traditional monitoring of the conditions of individual turbines can be extremely time consuming and costly. 
     BRIEF DESCRIPTION OF THE INVENTION 
     According to one aspect of the invention, a monitoring system for at least one wind turbine includes at least one sensor disposed at the at least one wind turbine to detect wind friction at the at least one wind turbine. At least one controller is connected to the at least one wind turbine, and a monitor server is connected to the at least one controller to change an operational status of the at least one wind turbine based on wind friction data received from the at least one sensor. 
     According to another aspect of the invention, a method of operation of at least one wind turbine includes continuously measuring data relative to wind friction at the at least one wind turbine via at least one sensor located thereat. The data is continuously compared to a predetermined wind friction threshold. A trend in the comparisons is evaluated to determine if a change in the operational status of the at least one wind turbine is necessary, and the operation of the wind turbine is changed based on the evaluation of the comparisons. 
     According to yet another aspect of the invention, a monitoring system for a wind farm having a plurality of wind turbines includes at least one sensor located each wind turbine of the wind farm to detect wind friction at each wind turbine of the wind farm. At least one controller is connected with each wind turbine of the wind farm, and a monitor server is connected to the at least one controller to change an operational status of each wind turbine of the wind farm based on wind friction data received from the at least one sensor. 
     These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
         FIG. 1  is a schematic illustration of an embodiment of a wind turbine monitoring system; 
         FIG. 2  illustrates a wind turbine; 
         FIG. 3  is a schematic illustration of another embodiment of a wind turbine monitoring system; and 
         FIG. 4  is a view of an embodiment of a graphical user interface for a wind turbine monitoring system. 
     
    
    
     The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Shown in  FIG. 1  is a schematic illustration of an embodiment of a wind turbine or wind farm monitoring system  10 . The monitoring system  10  includes one or more sensors  12  operably connected to at least one wind turbine  14  of a plurality of wind turbines  14 . The sensors  12  are disposed and configured to quantitatively determine an amount of wind friction in the wind turbine  14  caused by, for example, accumulation of snow and/or ice on the wind turbine  14  to which the one or more sensors  12  are connected. In some embodiments, the one or more sensors  12  may be configured to determine if icing conditions exist by measuring, for example, a temperature of the wind turbine  14 . Further, referring now to  FIG. 2 , the one or more sensors  12  may include one or more ice sensors  16  disposed at, for example, one or more blades  18  of the wind turbine  14  and/or may include one or more anemometers  20  configured to determine an amount of wind friction in the wind turbine  14  as, for example, in U.S. Patent Application Pub. 2008/0141768, also owned by the present assignee, which is incorporated herein by reference. 
     Referring again to  FIG. 1 , the plurality of wind turbines  14  are connected to a plurality of controllers  22 , for example, a plurality of programmable logic controllers (PLCs). In some embodiments, each controller  22  of the plurality of controllers  22  is connected to a unique wind turbine  14  of the plurality of wind turbines  14 . Further, the controller  22  may be connected to the wind turbine  14  via the one or more sensors  12 . 
     The plurality of controllers  22  are operably connected to at least one monitoring server  24 , which in some embodiments comprises a computer. As shown in  FIG. 1 , in some embodiments, the plurality of controllers  22  are connected to a single monitoring server  24 . The plurality of controllers  22  collect data from the one or more sensors  12 , which in turn is collected from the plurality of controllers  22  by the at least one monitoring server  24 . The at least one monitoring server  24  utilizes the data collected by the one or more sensors  12  to determine an of friction in the plurality of wind turbines&#39;  14  operation caused by, for example, an amount of ice and/or snow accumulated on the plurality of wind turbines  14 . The friction at each wind turbine  14  of the plurality of wind turbines  14  is compared to a friction threshold. In some embodiments, the at least one monitoring server  24  is capable of determining the friction threshold at points during the operation of the plurality of wind turbines  14  based on, for example, weather conditions, including ambient temperature and/or wind velocity. Further, the threshold may be substantially the same for each wind turbine  14  of the plurality of wind turbines  14  in a particular wind farm or may be determined independently for each wind turbine  14 , utilizing information such as elevation of each wind turbine  14  and/or historical data from each wind turbine  14 . Based on the results of the comparison, the at least one monitoring server  24  may instruct the plurality of controllers  22  to take action regarding the operation of the plurality of wind turbines  14 . For example, if precipitation, such as ice or snow, accumulation (hereinafter referred to as “ice” and/or “snow”) at a particular wind turbine  14  results in friction which exceeds the friction threshold, the at least one monitoring server  24  may direct the controller  22  connected to the wind turbine  14  to stop the operation of the wind turbine  14  until the accumulation recedes to a level at which the friction is below the friction threshold. In some embodiments, the wind turbines  14  are substantially continually monitored. The monitoring server  24  may require that a number of friction readings, for example, three or five friction readings, exceeding the friction threshold before directing the controller  22  to stop the operation of the wind turbine  14 . At some point when the friction recedes below the friction threshold, the monitoring server  24  may direct the controller  22  to restart the wind turbine  14 . As with stopping the operation of the wind turbine  14 , in some embodiments, the monitoring server  24  may require a number or friction readings, for example, three or five friction readings, which are below the friction threshold before directing the controller  22  to restart operation of the wind turbine  14 . 
     Referring now to  FIG. 3 , in other embodiments, multiple monitoring servers  24  are utilized. Each wind turbine  14  and may be connected through its corresponding controller  22  to a separate monitoring server  24 . In such embodiments, each monitoring server  24  utilizes data collected by the one or more sensors  12  to determine the amount of friction at its associated wind turbine  14  and instructs the controller  22  of the wind turbine  14  to take action based on results of a comparison between the amount of friction and the friction threshold. Use of the at least one monitoring server  24  allows for real-time monitoring of large quantities of wind turbines  14  located over a wide geographical area and allows, via the plurality of controllers  22 , for real-time control of the operational conditions of each wind turbine  14  of the plurality of wind turbines  14  thereby preventing damage to the wind turbines  14 . 
     In some embodiments, as shown in  FIGS. 1 and 3 , the wind farm monitoring system  10  includes a graphical user interface  26  operably connected to the at least one monitoring server  24 . The graphical user interface  26  may be, for example a CRT. The graphical user interface  26  utilizes data received from the at least one monitoring server  24  and is configured to display information regarding the operational status of the plurality of wind turbines  14 . As shown in  FIG. 4 , the graphical user interface  26  includes graphic or textual representations of friction conditions due to, for example, ice and/or snow accumulation, present at each wind turbine  14  of the plurality of wind turbines  14 . Further, the graphic or textual representations may include the operational status of each wind turbine  14  of the plurality of wind turbines  14 . The graphical user interface  26  may include a graphical representation or icon which represents each wind turbine  14  of the plurality of wind turbines  14  present in, for example, a wind farm. Each displayed icon on the graphical user interface  26  may be presented in a color that represents the operational status of the icon&#39;s corresponding wind turbine  14 . 
     For example, a green icon  30  may signify a normally functioning wind turbine  14 , a gray icon  32  may signify a wind turbine  14  which has been stopped, a yellow icon  34  may indicate a wind turbine  14  which is stopped due to friction exceeding the threshold, but is ready to be restarted, and a red icon  36  may indicate a wind turbine  14  at which friction due to ice or snow accumulation presently exceeds the threshold. As stated above, a normally functioning wind turbine  14  is represented by a green icon  30 . As ice and/or snow accumulates on the wind turbine  14  causing friction in the wind turbine  14  which exceeds the friction threshold, the icon for that particular wind turbine  14  changes color from a green icon  30  to a red icon  36  indicating that friction currently exceeds the friction threshold, but the wind turbine  14  has not been stopped. If, during subsequent measurements, the friction continues to exceed the friction threshold, the controller  22  may stop operation of the wind turbine  14 , at which time the icon becomes a gray icon  32  to indicate that the wind turbine  14  is not currently operational. The ice and/or snow accumulation causing the increased friction in the wind turbine may be removed by, for example, being naturally melted or by a removal system. At this time, measurements may indicate that the friction has been reduced to lower than the friction threshold. As the number of required measurements are taken, and are below the friction threshold, the icon changes to a yellow icon  34  indicating that the wind turbine  14  is preparing to restart. When the wind turbine  14  is restarted, either manually by an operator or automatically by the controller  22 , the icon again returns to a green icon  30 . It is to be appreciated that the colors described herein are merely exemplary and other colors and/or schemes may be utilized at the graphical user interface  26 . 
     In some embodiments, the graphical user interface  26  may include textual notes  38  displayed in addition to or instead of the colored icons. For example, the textual notes  38  may include an indication of the ice and/or snow accumulation level at each wind turbine  14 , or an indication of a quantitative amount of friction present in each wind turbine  14 . Other textual notes  38  may be included, such as textual notes  38  which indicate the operational status of each wind turbine  14 , or which indicate a total operational capacity of the wind farm as a whole at any given time For example, summary boxes  40  are shown in  FIG. 4  which indicate a number of wind turbines  14  having each operational status described above. The summary boxes may be color-coded to correspond with the colors of the individual wind turbine  14  icons. The graphical user interface  26  including color-changing icons corresponding to each wind turbine  14  of the plurality of wind turbines  14  allows a user to have real time understanding of the ice accumulation and operational status of each wind turbine  14  of the plurality of wind turbines  14 , to assess, for example, down time of the wind turbines  14 , potential safety issues, and a power generation and/or revenue production status of the individual wind turbines  14  and/or the wind farm as a whole. 
     While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.