Theoretical calculation and application study on real-time capacity-increase of transmission lines

The real-time capacity-increase technology of transmission lines is adopted to increase transmission current capacity of transmission lines, by which the conductor temperature, the ambient temperature and the wind speed can be timely measured and the transmission current capacity can be adjusted dynamically without breach of available rules. The transient running formula of transmission lines is established, the mathematical relationship between the conductor allowable temperature and the variety of sag of the span is presented, and the effect of environment parameters on the transmission current capacity of lines is analyzed, such as ambient temperature, wind speed, sunshine intensity, etc. The theoretical results show that the effect of conductor limited temperature on transmission current capacity is weak (11%) when the ambient temperature is below 10°C and stronger when the ambient temperature is higher (22.7%) than 30°C. and the effect of the ambient temperature and the wind speed on transmission current capacity is greater than that of the conductor temperature. The running results show that the transmission current capacity of existing transmission lines can be improved by 50% by real-time capacity-increase technology which is more effective than the static capacity-increase technology.