A helical charge simulation based 3-D calculation model for corona loss of AC stranded conductors in the corona cage

Corona loss generated from conductors is an indispensable factor in the design of alternating current(AC) transmission lines. Based on a helical charge simulation method, a 3-D calculation model for corona loss considering the outer strands of the conductor in the corona cage was established. Compared to the 2-D corona-loss calculation method, the calculation model proposed in this study incorporates the heterogeneity of the electric fields strength along the axial direction of the stranded conductor. Furthermore, it was also able to calculate the corona loss when the conductor had sagged. The calculation results of the LGJ-300/40 and LGJ-400/35 in the small corona cage show close agreement with the measurement results indicating that the corona-loss calculation model was accurate. In addition, the corona loss of the bundle conductors 4 × LGJ720 with sag in the UHV corona cage was also analyzed.