Screening method for optimal phase sequence of quadruple circuit power transmission line on the same tower based on a self-built PSCAD/EMTDC phase sequence commutation module

To meet the large transmission capacity requirement, the technology of multi-parallel transmission lines on same tower has been widely applied. However, the wrong arranged phase sequence easily triggers the unbalance of the electrical circuit. Therefore, through analyzing factors that influencing the electrical unbalance in four-parallel transmission line on the same tower and setting an objective function based on zero sequence and negative sequence through unbalanced degree, current circulation sequence unbalanced degree, and electrostatic sequence unbalanced degree, the study has aimed at screen the optimal phase sequence. The optimal phase sequence screening module for four-parallel transmission lines on the same tower was programmed by C and FORTRAN language in the PSCAD software. By traversing all the phase sequence automatically and analyzing the simulation result by MATLAB, The module can obtain phase sequence alignments and screen the optimal phase sequence. The simulating experiment result has illustrated that arranging four-parallel transmission lines on the same tower by the optimal phase sequence commutation model can effectively resolve the three-phase unbalance problem. In addition, it is also very economical and workable.