Contactless Phase Comparison Method for Overhead Transmission Lines

We propose a new contactless phase comparison method for high-voltage overhead lines. Combined with single-axis electric field (EF) sensing technologies, the new phase comparison method can perform a remote field measurement before the measured two overhead lines are interconnected. In the new phase comparison method, two single-axis EF sensor arrays are placed below the two measured overhead lines individually. A synchronous driver system wirelessly triggers the two EF sensor arrays synchronously to measure space electric fields. Then, two sets of measured electric fields are received by the synchronous driver system, and these data are used to carry out 1) positive/negative sequence evaluation and 2) phase evaluation. Finally, the proposed method can determine whether the three-phase voltage phases of the two overhead lines are identical. In addition, in order to ensure that the EF sensor arrays can synchronously measure electric fields, each EF sensor is designed with a built-in GPS device. Firstly, we simulated the electric field distribution of overhead lines using a finite element analysis (FEA) software, and then designed the placement of EF sensors on the ground. Finally, we validated the proposed method by experimental tests on a reduced scale model of overhead lines.