Current Carrying Capacity Analysis

Background

The current carrying capacity and temperature of the power line are important parameters for operation and design. At present, there are two main methods for increasing the current carrying capacity of high-voltage overhead transmission lines: static capacity increase and temperature calculation. Based on the thermal balance equation, the design code of China gives the formula for calculating the allowable current carrying capacity of overhead transmission line conductors. It is the most commonly used formula for calculating the current carrying capacity in China. In practical applications, the calculation direction opposite to the above is more applicable in the design steps of the power transmission project, that is, given the maximum allowable carrying capacity, the amount to be calculated is the temperature or temperature rise of the power line. Reference of the algorithm: (Lin et al., 2012)

Summary

The carrying capacity analysis function is mainly used to calculate the temperature rise of the power line under a certain ambient temperature and carrying capacity. The function interface is shown in the figure below.

Usage

Click Early Warning Analysis > Current Carrying Capacity

Settings

• Parameter Settings:
  • Power Line Type("LGJ-240/30" by default): Select the power line type. After selecting any power line type, the electrical parameters below will change accordingly. Currently, only cored power line types are supported, such as "steel core aluminum stranded conductor" LGJ-300 / 40, where "300" represents the diameter of the power line and "40" represents the diameter of the steel core.
  • Electrical Parameter: Parameters related to the power line. Among them, "DC resistance at 20℃", "inner diameter of the power line", "outer diameter of the power line", and "calculated cross-sectional area" will be automatically read from the file according to the selected power line type, without adjustment.
  • Current Frequency (Hz) (default value is "50.0"): Current frequency of AC resistance.
  • Environment Parameter: Environment-related parameters. Need to adjust according to the actual situation. The "radiation heat dissipation coefficient" and "strand surface heat absorption coefficient" are both 0.9, and no adjustment is required.
  • Sun Irradiance (W/m^2) (default value is "1000"): Heat from the sun absorbed per square meter of the power line.
  • Wind Speed (m/s) (default value is "0.5"): Wind speed of the environment where the power line is located.
  • Resistance at 20℃ (per degree Celsius) (default value is "0.004040"): DC resistance of the power line at 20℃.
• Initial Parameter:
  • Ambient Temperature (Celsius) (default is "40"): The actual temperature of the environment where the wire is power line.
  • Input Carrying Capacity(Ampere): The current passing through the power line.
  • Power Line Temperature Simulated(Celsius): Output the actual power line temperature simulated under the above environmental conditions.

    @inproceedings{
        author={Lin},
        title={The Calculation of Current Carrying Capacity and Temperature of High Voltage Overhead Lines},
        booktitle={SOUTHERN POWER SYSTEM TECHNOLOGY, 6(4):23-27},
        year={2012},
    }