The effect of calculated wind speed on the capacity of dynamic line rating
Dynamic line rating can improve the short-term carrying capacity of transmission lines without changing existing grid structure or operating regulations such as the maximum operating current. Dynamic line rating has a broad application prospects. However, taking into account the fluctuation of wind speed and diversity of topography, wind speed is usually conservatively set as 0.5m/s, which is not in accordance with the reality and limits the enhancement of transmission capacity. In this paper, the relationship between wind velocity and carrying capacity of lines is studied statistically taking sunlight intensity, ambient temperature and other meteorological parameters into consideration. We find that the conductor temperature will decrease if the wind speed increases, but the conductor temperature tends to be stable with the continuous rising of wind speed. It can be concluded that the increase of wind speed brings improvement in the capacity of dynamic line rating in a certain range. It is also widely recognized that maximum cooling efficiency occurs when wind is perpendicular to the line. Then, we define the notion of calculated wind speed and put out an example to illustrate the approach of obtaining calculated wind speed in dynamic line rating. That is a reverse wind speed calculation method based on real-time current, conductor temperature, sunlight intensity, and environment temperature. All of this data are detected by on-line monitoring device. By choosing a proper calculated wind speed, the convey potential of transmission lines will be further explored.