基于环型电网的输电线路相序排列方法研究

同塔多回输电线路之间存在着复杂的电磁耦合关系，当其合环后，各段线路本身的不平衡相互叠加，加剧了环型电网的三相不平衡性。为了减小环型电网的三相不平衡性，结合线路相序排列方式进行研究。通过分析环型电网中的线路电流与线路阻抗之间的关系，提出了环型电网中各段线路采用同一相序排列方式，能够大幅度降低环型电网中的线路不平衡度。通过对双回线路组成的环型电网进行PSCAD/EMTDC建模分析，并对不同相序排列下的不平衡度进行对比。结果证明了两回线路均采用同相序或逆相序排列时，线路不平衡度较小，为环型电网的最优相序排列提供了理论依据。

Research of phase sequence arrangement of transmisson lines in the loop network

The complex electromagnetic coupling between transmission lines exists in multi-circuit transmission line on the same tower. When the radial network forms loop network, the imbalance of each part of transmission lines will be superimposed, which will aggravate the problem of three-phase imbalance of loop network. In order to decrease the three-phase imbalance of transmission lines, this paper analyzes the relation between current and impedance of transmission lines in loop network under different phase sequence arrangements, and it also proposes that if each part of it applies the same phase sequence arrangement, the unbalanced degree of transmission lines in loop network can be greatly reduced. Through analyzing the model of loop network consists of double-circuit transmission lines by PSCAD/EMTDC, and comparing the unbalanced degree under different phase sequence arrangements, the results verify that if both of the transmission lines use the same phase sequence arrangement or inverse phase sequence arrangement, the imbalance degree of transmission lines is smaller, which provides theoretical basis to the optimal phase sequence arrangement of loop network.