Study on Unbalance Factor of Sequence Impedance for Parallel Multi-circuit Cable Lines

Parallel multi-circuit cable lines are wildly used to improve the transmission capacity of urban power grid, but the study on sequence impedance parameters’ asymmetry of multi-circuit cable lines is not available. To analyze the asymmetry of multi-circuit cable lines’ parameters, a method to measure the unbalance factor is introduced in this paper. Furthermore, take engineering practice as an example, the electromagnetic unbalance factor of two-circuit cable lines under different arrangements are calculated by this method. Finally, a comparison among these unbalance factor is made. The comparative results show that the triangle arrangement has better symmetry than straight-vertical and straight-horizontal arrangement, in which the triangle-vertical arrangement’s symmetry is the best.