In order to solve the problem of three-phase unbalance of six-circuit transmission lines on the same tower

firstly decoupling calculation of the line impedance matrix is carried out and the expressions of the sequence currents are deduced. Then a method of eliminating unbalance based on compensation of asymmetrical line parameters is proposed

with the parameters of compensation capacitors calculated in theory. Finally

based on an actual project of six-circuit transmission lines on the same tower in Guangdong Province

corresponding simulation is done using the software of PSCAD. Results show that unbalance of six-circuit transmission lines on the same tower are still not able to meet the requirements with the methods of optimizing wire spacing

optimal layout of line phase sequences

etc. So the method of allocating compensation capacitors appropriately should be considered to further reduce the line unbalance. This conclusion has a certain practical significance for eliminating the unbalance of six or more circuit transmission lines on the same tower. This work is supported by National Natural Science Foundation of China (No. 51177098)

Innovation Program of Shanghai Municipal Education Commission (No. 12YZ138) and Shanghai Natural Science Foundation (No. 15ZR1418000

No. 15ZR1418200).