A parameter measurement theory of single and double circuit AC transmission lines

In order to obtain ground capacitances, mutual inductances and coupling capacitances of single AC line or the double circuit AC lines on a same tower, an improved model with distributed parameters and measurement method had been firstly established for a single conductor ground return line. Then, Telegrapher equations for symmetrical three phase lines were decoupled as positive and zero sequence circuits and the measurements were carried out on sequence circuits to calculate the distributed parameters. Furthermore, the coupling parameters between double circuit AC lines could be decoupled by sequence analysis of two phase systems. Based on the theoretical analysis, and by open circuit and short circuit impedance measurements of double circuit lines in three circuit modes including positive sequence circuit of a single line, positive sequence circuit of two phase systems composited by double lines and zero sequence circuit of double lines, all the parameters such as inductances and capacitances to ground of each conductor, and coupling capacitances as well as mutual inductances can all be solved by the presented method. The paper constitutes a basic theory to measure the distributed parameters of single AC line, and further the double circuit AC lines on a same tower. © 2016 Chin. Soc. for Elec. Eng.