Improved Three-Dimension Mathematical Model for Voltage Inversion of AC Overhead Transmission Lines

Abstract

The voltages on the AC overhead transmission lines (OTLs) can be calculated inversely based on the measured electric field around the lines, which will much contribute to the non-contact condition monitoring of OTLs. To more realistically simulate the actual operating state of OTLs in the wild, a refined catenary equation of OTL with consideration of the vertical suspension and horizontal deflection is established, and the according improved three-dimensional electric field mathematical model are proposed. Furthermore, the OTLs' voltages are calculated based on an improved optimization algorithm that combines particle swarm algorithm and genetic algorithm. Some simulation and experiment cases by setting different measurement errors and wind speeds are employed to verify the improving effect of the proposed model. The analysis results shown that the three-phase maximum amplitude error is 6.48% and maximum phase error is 6.26° when the electric field measuring error is as high as 20% (beyond the normal level); on the other hand, the maximum amplitude error and phase error are 2.54% and 0.96° respectively when the wind speed is set to the strong wind of 15m/s. The results demonstrate the accuracy and robustness of the proposed model.

Keywords

• Overhead transmission lines (OTLs)
• three-dimension electric field mathematical model
• accuracy of inversion
• non-contact condition monitoring