750 kV同塔双回不换位线路电流不平衡度研究

在线路走廊特别紧张的地区，部分线路可能没有条件采用完全换位的方式架设，而同塔多回线路采用不换位架设将导致电气三相参数不对称。针对这个问题，对同塔双回不换位线路不平衡度计算进行了推导，并应用PSCAD/EMTDC软件从杆塔类型、相序排列方式、回间距离、线路长度几个方面对750 kV同塔双回不换位线路进行了仿真分析。仿真结果表明，输电线路较短时采用同塔同窗逆相序方式架设并适当调整回间距离，电流不平衡度能控制在一定的范围之内。输电线路较长时则需进行换位，避免对系统造成不良影响。

Analysis on current imbalance of un-transposed 750 kV double-circuit lines on the same tower

Transmission lines in some areas may have no condition to be transposed completely, because of shortage of the line corridor. And multi-circuit transmission lines, if un-transposed, will cause electrical three-phase parameters asymmetry. To solve this problem, the formulas of calculating the current imbalance on double-circuit lines without transposition are presented. Using PSCAD/EMTDC, the zero-sequence current unbalance and negative sequence current unbalance of a 750 kV double circuit lines without transposition are calculated in different types of tower, different phase sequence arrangement, different distance between the two loops and different line length. According to the simulation results, when the transmission line is short, the current imbalance can be controlled within a certain range by adopting the reverse phase sequence in the same tower window and adjusting loops distance properly. To avoid bad effect on the power system, transmission line must be transposed when the line is long.