一种基于三端直流输电系统的架空线路谐波电流计算方法

针对三端直流输电系统可能出现的架空输电线路谐波电流放大问题，对不同运行方式下的双极线路谐波电流开展研究。基于波阻抗理论，将对称运行的直流线路简化为对称分量回路，并求取单位长度参数；分析了均一线路谐波电流的计算方法；在此基础上结合波的折反射原理，提出了一种计算混合线路谐波电流的方法。通过在PSCAD/EMTDC平台上搭建相应的直流线路模型进行仿真，并与理论计算结果对比，表明该计算方法在求取三端直流输电系统不同运行方式下的线路谐波电流方面具有较高的准确性。

A Calculation Method for Line Harmonic Current Based on Three-Terminal HVDC Transmission System

In view of the potential problem of harmonic current amplification of overhead transmission lines in three-terminal DC transmission system, a study is conducted on the harmonic current of bipolar overhead lines under different operating modes. Based on the theory of wave impedance, the symmetrical DC lines are simplified into the symmetrical component loops, and the unit length parameters are obtained. The calculation method for harmonic current of uniform line is analyzed. Based on the theory of wave refraction and reflection, a method for calculating harmonic current of hybrid transmission lines is proposed. By building the corresponding DC line model on the PSCAD/EMTDC platform for simulation, and comparing with the theoretical calculation results, it is shown that the proposed calculation method has a high accuracy in obtaining the line harmonic current under different operation modes of the three-terminal DC transmission system.