直流输电工程中的换流器工作时能产生大量谐波，对电力系统稳定和通信线路等造成不良影响。为了有效降低换流器谐波的危害、提高系统运行的可靠性, 分析了±800 kV特高压直流输电工程中换流器谐波的时频域特性，以换流器谐波电流与系统运行功率、输送直流电流大小之间的关系作为切入点，将谐波电流畸变率作为判断换流器谐波特性的特征量。根据直流输电工程的运行特点，随着输送功率以及直流电流的逐渐增大，各次谐波电流畸变率可以有效地表征谐波电流与系统输送功率以及直流电流大小的变化规律。所得结论为直流换流站换流器产生的谐波特性分析提供了理论基础，为后续工程谐波治理以及滤波器设计优化提供了理论指导。

The converters in DC transmission project can produce the large number of harmonics which may have harmful effect on the power system stability and the communication lines. In order to effectively reduce the converter harmonics hazards and improve the system reliability, this paper analyzed the time-frequency domain characteristics of converter harmonics in ± 800 kV UHV DC transmission project. According to the relationship between the converter harmonic current，the system operating power and the DC current value in transmission project, the harmonic current distortion rate was presented as the eigenvalues of current harmonic characteristics. Based on the operation characteristics of transmission project, the change law of harmonic current with the increase of transmission power and DC current could be effectively characterized by the harmonic current distortion rate. The study results can provide the theoretical basis for the analysis on converter harmonic characteristics in DC converter stations, as well as the theoretical guidance for the harmonic treatment in subsequent projects and the filter design optimization.