关键词: 无功环流, 扩展对称分量法, 反向耦合, 解耦等值

Abstract: In view of the typical problem of large reactive power flow difference and even reactive power circulation in some high voltage common-tower AC transmission lines, the mechanism of reactive power circulation is analyzed in this paper. An extended symmetrical component method and extended sequence impedance matrix are proposed based on the symmetrical component method. The analysis shows that the extended sequence impedance matrix is asymmetric, which implies that the mutual inductance will be not equal and even in the opposite direction for those phase un-conversed common-tower AC transmission lines. The result illustrates the causes for the reactive power circulation problem of the common-tower AC transmission lines. In order to solve the problem, a parameter decoupled equivalent method for the common-tower AC transmission lines is proposed, and the prerequisites for reactive power circulation phenomenon is derived, which explains the influencing factors and mechanism for the reactive power circulation problem of 220 kV Sanshao common-tower AC transmission lines. The validity of the proposed method has been proved by a case study of an actual power system.

Key words: reactive power circulation, extended symmetrical component method, reverse-coupling, decoupled equivalence method