基于阻尼控制的柔直系统直流侧谐波抑制方法

DC-side Harmonic Suppression Method for Flexible HVDC Transmission System Based on Damping Control

为有效抑制柔性直流输电系统中直流侧产生的低频谐波,降低直流侧谐波带来的线路损耗,减小换流阀等器件过压、过流风险,在此详细分析了直流侧低频谐波的产生机理,讨论研究直流侧低频谐波的潜在激励源和系统阻抗特性,得出直流侧谐波主要由子模块均压及直流侧系统频率阻抗低点引起的结论,并针对性提出一种柔性直流输电系统直流侧低频谐波阻尼控制方法。该方法能够有效抑制直流侧谐波,并具有实现简单、计算量小的优点,便于工程实施。最后通过仿真和实验的方法证明分析得出的谐振机理结论正确,且所提控制法能够有效抑制直流侧谐波,因此提高了柔性直流输电系统的运行安全性和可靠性。

In order to suppress the low-frequency harmonics generated by DC-side in flexible high voltage direct current transmission system effectively,reduce the line loss caused by DC-side harmonics,and reduce the risk of overvoltage and overcurrent of devices such as converter valves,the potential excitation sources and system impedance characteristics of DC-side harmonics are analyzed in detail,and the conclusion that DC-side harmonics is mainly caused by sub-module voltage equalization and low frequency-impedance operating point of the system is drawn.A low frequency harmonic damping control method for flexible high voltage direct curent system is proposed.This method can suppress DC-side harmonics effectively,and has the advantages of simple implementation and less calculation,which is convenient for engineering implementation.The simulation and experimentation results show that the conclusions of the resonance mechanism are correct,and the proposed control method can suppress the DC-side harmonics effectively.Therefore,operation safety and reliability of the system of the flexible high voltage direct curent transmission system is improved through the method.