特高压直流对交流系统背景谐波的影响分析

以哈密-郑州特高压直流系统工程郑州换流站的背景谐波计算为背景,以分析特高压直流系统对交流系统背景谐波放大特性的影响为目的,利用开关函数法推导了正常运行模式下双十二脉动串联特高压直流系统在交直流混联系统中背景谐波的计算阻抗模型,可以分析直流系统接入交流系统后对原系统中背景谐波放大特性的影响。在计算过程中,由于对侧哈密换流站会对直流线路阻抗产生影响,本文使用一种平均阻抗的方法推导了其对直流线路阻抗影响的计算公式。最后利用哈密-郑州特高压直流系统设计参数以及河南电网典型系统短路阻抗在PSCAD中搭建仿真模型,验证了上述方法的正确性。

Analysis on Harmonic Influence of UHVDC on AC System

In the project of Hami to Zhengzhou UHVDC system, to analyze the harmonic enlargement effect of UHVDC system on AC system, a method based on modulation theory is proposed in this paper. In this algorithm, the impedance calculation model of background harmonic caused by double twelve-pulse series UHVDC system in AC-DC system is deduced by modulation theory under normal operation mode. By this model the influence of the access of DC system to AC system on background harmonic amplification characteristics of original system is analyzed. On the other hand, Hami converter station will influence impedance of DC line during calculation process, and its calculation formula is deduced by using of a kind of average impedance method. In the end, the simulation model is built by using design parameters of Hami-Zhengzhou UHVDC DC system and the short-circuit impedance of Henan power system, which verifies the correctness of proposed method.