Thermal powerline rating and clearance analysis using thermal imaging technology

Abstract

A method and apparatus are provided to acquire direct thermal measurements, for example, from a LiDAR collecting vehicle or air vessel, of an overhead electrical conductor substantially simultaneous with collection of 3-dimensional location data of the conductor, and utilize temperature information derived from the direct thermal measurements in line modeling, line rating, thermal line analysis, clearance analysis, and/or vegetation management.

1 . A method of analyzing an overhead electrical conductor, comprising:
 by a processor, accessing 3-dimensional location data of an overhead conductor;   by the processor, accessing thermal measurement data of the conductor, wherein the thermal measurement data comprises a remotely collected thermal image wherein each element of the thermal measurement data corresponds an element of the 3-dimensional location data and has a collection time that is substantially simultaneous with a collection time of its corresponding location data element;   by the processor, generating a computer assisted design (CAD) model of the conductor using the 3-dimensional location data of the conductor and the thermal measurement data of the conductor; and   by the processor, employing the computer assisted design (CAD) model for thermal analysis of the conductor.   
     
     
         2 . The method of  claim 1  wherein the remotely collected thermal image comprises a plurality of thermal image frames, and further comprising:
 selecting, for processing, one or more frames of said thermal image frames that contain the conductor, contain a background having lower thermal values than the conductor, and exhibit image quality that allows accurate thermal reading. 
 
     
     
         3 . The method of  claim 2 , further comprising, by the processor, linking a selected frame to a geographic location. 
     
     
         4 . The method of  claim 3 , further comprising, by the processor, extracting a thermal reading from the geographically linked selected frame. 
     
     
         5 . The method of  claim 4 , further comprising, by the processor, determining emitted energy from the conductor in accordance with the following equation: 
       
         
           
             
               
                 W 
                 obj 
               
               = 
               
                 
                   
                     W 
                     tot 
                   
                   - 
                   
                     
                       ( 
                       
                         1 
                         - 
                         ɛ 
                       
                       ) 
                     
                     × 
                     τ 
                     × 
                     
                       W 
                       amb 
                     
                   
                   + 
                   
                     
                       ( 
                       
                         1 
                         - 
                         τ 
                       
                       ) 
                     
                     × 
                     
                       W 
                       atm 
                     
                   
                 
                 
                   ( 
                   
                     1 
                     - 
                     τ 
                   
                   ) 
                 
               
             
           
         
         wherein W obj  comprises a measure of energy emitted from the conductor, 
         W tot  comprises the thermal reading extracted from the geographically linked selected frame and represents total radiation, 
         W amb  comprises reflected emission from ambient sources, 
         W atm  comprises emission from an atmosphere, 
         τ comprises transmittance of the atmosphere, and 
         ε comprises emissivity of the conductor. 
       
     
     
         6 . The method of  claim 1 , further comprising acquiring the thermal measurement data of the conductor substantially simultaneously with collecting the 3-dimensional location data. 
     
     
         7 . The method of  claim 1 , further comprising:
 performing a thermal analysis of the thermal measurement data to determine temperature of the conductor at the time that the 3-dimensional location data was collected;   wherein said computer assisted design (CAD) model of the conductor is generated using a temperature of the conductor determined by the thermal reading; and   employing the computer assisted design (CAD) model of the conductor to analyze clearance between the conductor and surroundings of the conductor.   
     
     
         8 . The method of  claim 7 , wherein employing the computer assisted design (CAD) model to analyze clearance comprises conducting at least one of a sway analysis and a sag analysis to determine conductor location in different weather and/or line loading conditions. 
     
     
         9 . The method of  claim 1 , further comprising:
 performing a thermal analysis of the thermal measurement data to determine temperature of the conductor at a time that the 3-dimensional location data was collected;   wherein said computer assisted design (CAD) model of the conductor is generated using the temperature of the conductor determined by the thermal analysis; and   employing the computer assisted design (CAD) model of the conductor to determine a thermal rating of a target line that includes the conductor.   
     
     
         10 . The method of  claim 1 , wherein the 3-dimensional location data comprises LiDAR data collected from an airborne vehicle, and said thermal measurement is acquired by the airborne vehicle concurrently with the LiDAR data. 
     
     
         11 . A method for determining temperature of an overhead electrical conductor, comprising:
 by a processor, accessing 3-dimensional location data of an overhead conductor;   accessing thermal measurement data of the conductor, wherein each element of the thermal measurement data corresponds an element of the 3-dimensional location data and has a collection time that is substantially simultaneous with a collection time of its corresponding location data element; and   performing a thermal analysis of the thermal measurement to determine temperature of the conductor at a time that the 3-dimensional location data was collected.   
     
     
         12 . The method of  claim 11 , further comprising generating a computer assisted design (CAD) model of the conductor using the collected 3-dimensional location data of the conductor and the determined temperature of the conductor. 
     
     
         13 . The method of  claim 12 , further comprising employing the computer assisted design (CAD) model for at least one of: thermal line analysis of the conductor; thermal rating of a power line that includes the conductor; clearance analysis relative to the conductor; and vegetation management relative to the conductor. 
     
     
         14 . A system, comprising:
 a processor;   a computer-readable medium on which is stored location data and thermal measurement data for a plurality of overhead electrical conductors; and   a non-transitory computer-readable memory containing programming instructions that enable the processor to:
 access 3-dimensional location data of a selected one of the overhead electrical conductors; 
 access thermal measurement data for the selected conductor, wherein each element of the thermal measurement data corresponds an element of the 3-dimensional location data and has a collection time that is substantially simultaneous with a collection time of its corresponding location data element; and 
 perform a thermal analysis of the thermal measurement to determine temperature of the conductor at a time that the 3-dimensional location data was collected. 
   
     
     
         15 . The system of  claim 14 , wherein the instructions also enable the processor to generate a computer assisted design (CAD) model of the conductor using the collected 3-dimensional location data of the conductor and the determined temperature of the conductor. 
     
     
         16 . The system of  claim 15 , wherein the instructions also enable the processor to employ the computer assisted design (CAD) model for at least one of: thermal line analysis of the conductor, thermal rating of a power line that includes the conductor, clearance analysis relative to the conductor, and vegetation management relative to the conductor. 
     
     
         17 . The system of  claim 14  wherein the instructions also enable the processor to:
 access a remotely collected thermal image comprising a plurality of thermal image frames, and further comprising: 
 select, for processing, one or more frames of said thermal image frames that contain the conductor, contain a background having lower thermal values than the conductor, and exhibit image quality that allows accurate thermal reading. 
 
     
     
         18 . The system of  claim 17 , wherein the instructions also enable the processor to:
 link a selected frame to a geographic location, and   extract a thermal reading from the geographically linked selected frame.   
     
     
         19 . The system of  claim 18 , wherein the instructions also enable the processor to determine emitted energy from the conductor in accordance with the following equation: 
       
         
           
             
               
                 W 
                 obj 
               
               = 
               
                 
                   
                     W 
                     tot 
                   
                   - 
                   
                     
                       ( 
                       
                         1 
                         - 
                         ɛ 
                       
                       ) 
                     
                     × 
                     τ 
                     × 
                     
                       W 
                       amb 
                     
                   
                   + 
                   
                     
                       ( 
                       
                         1 
                         - 
                         τ 
                       
                       ) 
                     
                     × 
                     
                       W 
                       atm 
                     
                   
                 
                 
                   ( 
                   
                     1 
                     - 
                     τ 
                   
                   ) 
                 
               
             
           
         
         wherein W obj  comprises a measure of energy emitted from the conductor, 
         W tot  comprises the thermal reading extracted from the geographically linked selected frame and represents total radiation, 
         W amb  comprises reflected emission from ambient sources, 
         W atm  comprises emission from an atmosphere, 
         τ comprises transmittance of the atmosphere, and 
         ε comprises emissivity of the conductor. 
       
     
     
         20 . A method of analyzing an overhead electrical conductor, comprising:
 by a processor, accessing 3-dimensional location data of an overhead conductor;   by the processor, accessing thermal measurement data of the conductor, wherein the thermal measurement data comprises a remotely collected thermal image, wherein each element of the thermal measurement data corresponds an element of the 3-dimensional location data and has a collection time that is substantially simultaneous with a collection time of its corresponding location data element;   by the processor, generating a computer assisted design (CAD) model of the conductor using the 3-dimensional location data of the conductor and the thermal measurement data of the conductor.   
     
     
         21 . The method of  claim 20 , further comprising by the processor, the computer assisted design (CAD) model is employed for thermal analysis of the conductor.