输电线路三相不平衡电流及高抗过补偿仿真分析

  目的  超高压输电线路的安全稳定运行对电网安全至关重要，在电网规划建设中、新建变电站对原有长线路解口构网时，可能出现以下问题:如线路的三相不平衡电流不满足整定要求、线路高抗过补偿而产生过电压等，这些问题严重威胁电网的安全稳定运行，必须予以解决。  方法  为了解决上述问题，利用电磁暂态软件ATP-EMTP，依托同塔双回500 kV输电线路工程实例，对线路中出现的不平衡电流与过电压等进行仿真研究，以探究这些参数的影响因素与变化机理，进而提出应对方案。  结果  仿真结果表明，影响同塔双回线路不平衡电流的主导因素包含换位与相序布置，增加换位次数、采用逆相序布置可有效降低其不平衡电流水平；影响工频谐振过电压的主要原因是补偿度是否接近全补偿，过补偿时提高补偿度可降低恢复电压、但潜供电流会相对升高。  结论  上述结论对电网规划建设与安全运行具有指导与借鉴意义，可有效解决实际工程中相关问题。

Simulation Analysis of Three Phase Unbalanced Current and Over Compensation of High Voltage Reactor in Transmission Line

  Introduction  The safe and stable operation of UHV transmission lines is essential to the safety of power grids. When the new substation deconstructs the original long line in the power grid planning and construction， the following problems， such as the three-phase unbalanced current line does not meet the setting requirements， line high impedance over-compensation generates overvoltage， may occur. These problems may seriously threaten the safe and stable operation of the power grid and should be solved.  Method  In order to solve the above problems， the electromagnetic transient software ATP-EMTP was used to simulate the unbalanced current and overvoltage in 500 kV transmission lines on the same tower， so as to explore the influencing factors and change mechanism of these parameters， and then put forward countermeasures.  Results  The simulation results show that the main factors affecting the double circuit line's unbalanced current on the same tower include transposition and phase sequence arrangement. Increasing the number of transpositions can effectively reduce the unbalanced current level. By adopting a reverse phase sequence arrangement is also efficient. The main reason that affects the power frequency resonance over-voltage is whether the compensation degree is close to full compensation. During over-compensation， increasing the compensation degree can reduce the recovery voltage， but the potential supply current will increase relatively.  Conclusion  The above conclusions have guiding and reference significance for power grid planning， construction， and safe operation. Furthermore， it can effectively solve related problems in actual projects.