An Impedance Parameters Online Measuring Method of Multi-circuit Transmission Lines on the Same Tower

In view of the present common transmission line parameters online measurement methods having shortcomings of being unable to measure the asymmetric transmission line parameters of multi-circuit transmission lines on the same tower, this paper presents a new impedance parameters online measuring method for asymmetric transmission lines. This method considers multi-circuit transmission lines as a multi-conductor coupling transmission line system. According to multi-conductor coupling transmission line model, using the voltage and current signals of both ends of the transmission line by multiple synchronous measurements, the method establishes over determined equations to solve multi-conductor coupling transmission line impedance parameters and derives the calculation formulas of asymmetric multi-circuit transmission line impedance parameters based on the least square method. This method can not only calculate the self impedance and mutual impedance of multi-circuit transmission lines on same tower, but also the sequence impedance can be given. In addition, it solves the problem that line parameters cannot be measured under the strong interference signal with the traditional measurement method, and improves the accuracy of the measured line parameters. The simulation result proves the correctness of this method, which provides a theoretical basis for the online measurement method of multi-circuit transmission lines on the same tower.