高压并联输电线路无功环流问题的影响机理分析

针对部分相同参数的并联高压交流输电线路实际运行过程中无功潮流差异大，甚至出现双回线无功潮流反向形成环流的典型问题，分析了影响环流问题的机理。首先由传统对称分量法入手，对传统变换矩阵进行扩展变换，形成了针对多回高压交流线路的扩展序阻抗矩阵，对其分析表明扩展序阻抗矩阵为非对称矩阵，说明同塔并架双回线路中，存在一线对二线的互感与二线对一线的互感不对等的情况，严重时甚至出现线路正序电阻反向耦合的问题，解释了双回线路间无功潮流反向问题产生的原因。在双回线参数解耦等值的基础上，进一步推导了双回线无功环流问题的理论形成条件，解释了三邵双回线无功潮流异常问题的影响因素及作用机理。最后，通过实际系统的算例分析证明了所提方法的有效性。

Study on Reactive Power Circulation Mechanism for High Voltage Common-Tower AC Transmission Lines

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.