半波长交流输电点对网双落点系统的穿越功率特性

Research on Cross Power Characteristics of the Half-wavelength AC Transmission in the System of Single Point Connected to Two Terminals

随着大电网发展,半波长交流输电技术受到关注。采用双回半波长线路构成点对网双落点系统,两落点之间产生穿越功率,对线路潮流分布产生重要影响。为深入研究该问题,该文基于分布参数传输线方程,从理论上推导半波长线路输送功率和首末端电压的关系,提出了点对网双落点系统中穿越功率的概念和定义,并研究其机制、特性,分析了穿越功率与落点母线电压的关系,通过仿真验证了理论分析结果。结果表明,因半波长线路极小的等值电抗,功率与电压关系具有与常规交流线路不同的"反向特性",对点对网双落点系统,穿越功率由落点母线电压和电源功率决定;当无电源送出时,穿越有功仅与落点母线电压幅值的平方差线性相关,穿越无功与母线相角差强相关。最后,得到了半波长系统运行与控制的相关结论。

With the development of large power grids, half-wavelength alternating current transmission technology becomes concerned. Two half-wavelength transmission lines can be used to establish the system of single point-two terminals, in which cross power is produced between the two terminals, affecting the power flow distribution. In order to investigate this phenomenon, this paper derivated the relationship between the power and terminal bus voltages in theory based on the transmission line formulas. The concept and definition of the cross power was proposed, whose principles and characteristics were investigated. The relationship between the cross power and the terminal bus voltages was analyzed, and the results of theory analysis were validated through simulations. Results show that, due to the extremely small equivalent reactance, the cross power has ＂reverse characteristics＂ that differs from ordinary transmission lines. When the source power output equals zero, the active cross power in the system of single point-two terminals is only linearly dependent on the difference of amplitude square of the two terminal bus voltages, while the reactive cross power is strongly related to the angle difference of the terminal bus voltages. Finally, relevant conclusions about the operation and control for the half-wavelength transmission lines are drawn.