Calculation of zero-sequence mutual inductance for multi-circuit parallel transmission line

A method for calculating the zero-sequence mutual inductance of multi-circuit parallel transmission line on the same tower is proposed. It is pointed out that, the zero-sequence mutual inductance matrix is a set of independent parameters, based on which, the zero-sequence parameters of transmission line in different operation modes can be deduced by matrix transformation. Without the repeating experimental measurement, the proposed method simplifies significantly the acquisition of zero-sequence mutual inductance, which improves the work efficiency. Results of field test for a four-circuit parallel transmission line show its correctness and accuracy.