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Dynamic line rating system with real-time tracking of conductor creep to establish the maximum allowable conductor loading as limited by clearance

  • US 7,504,819 B2
  • Filed: 01/17/2007
  • Issued: 03/17/2009
  • Est. Priority Date: 07/21/2004
  • Status: Active Grant
First Claim
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1. An apparatus for determining the maximum conductor current loading of an overhead transmission line or conductor that comprises a spanning transmission line catenary spanning two transmission line towers, comprising:

  • a sensing device adapted to be clamped to said overhead transmission line or conductor near one of the two said transmission line towers to acquire real-time information and including a transmitter for transmitting said acquired real-time information to a remote information processing center, said acquired real-time information including at least parameters of an angle of inclination from a horizontal line of said transmission line or conductor and a surface temperature of said transmission line or conductor; and

    means for performing a two step iterative process using said angle of inclination to determine the present sag of said transmission line or conductor;

    wherein said performing means performs a first step that operates in accordance with the algorithm wherein a value for said conductor'"'"'s unit weight w and a value for horizontal tension in the conductor Fh is assumed and a horizontal distance X1 from the lowest point of said spanning transmission line catenary to said transmission line tower closest to said sensor is first assumed to be equal to a horizontal distance X2 from said lowest point to the other said transmission line tower, wherein X1+X2=X0, the horizontal distance between said two transmission line towers, and Y1 and Y2 are sags relative to said respective transmission line towers determined in accordance with the following Equation (1);

    Sag = Y = F h w

    [ Cosh

    ( w F h

    X
    )
    - 1
    ]
    ( 1 )
    and X1 is reduced by an incremental amount and X2 is increased by said incremental amount if Y2

    Y1<

    H, where H is the difference in height between said transmission line towers and said Equation (1) is repeated successively until Y2

    Y1

    H, at which time X1 is increased by said incremental amount and X2 is reduced by said incremental amount, said incremental amount is decreased by dividing it by a fixed factor, said decreased incremental amount is subtracted from X1 and added to X2 and said sags Y1 and Y2 are computed in accordance with Equation (1), said difference Y2

    Y1 is compared to said H, and said iterative process is repeated successively until Y2

    Y1 is substantially equal to said H, thereby determining the position of said lowest point of said catenary consistent with said assumed horizontal tension Fh.

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