中文摘要：

对电力系统电压或电流信号进行离散傅里叶变换得到的间谐波频谱，不仅由真实的间谐波成分产生，也可由其他的系统扰动引起，因此，从频谱上判断真实问谐波的存在性是进行间谐波具体参数计算的前提。首先从理论上分析并指出，分析窗口内各周波之间的波形差异是间谐波频谱产生的原因，并在此基础上提出一种基于间谐波时频等值线图和成分出现率的真实间谐波存在性判别方法。该方法首先对某考察时段内的所测信号做连续离散傅里叶变换，得到该信号的幅值时频矩阵，结合该矩阵对应的成分出现率和判别阀值，判别出信号中的真实间谐波成分。所提方法实现过程简单，原理清晰，能够判别出所测信号中的真实间谐波成分。对多个现场测量数据的分析验证了所提方法的有效性和实用性。

英文摘要：

The interharmonic spectrum of an electrical voltage or current from discrete Fourier transform can not only be caused by genuine interharmonic components, but can also be caused by other system disturbances. Therefore, the existence determination of genuine interharmonics from the spectrum becomes the premise for further calculation of interharmonic parameters. From the theoretical perspective, this paper firstly analyzed and pointed out that the waveform difference among each cycle in the analysis window was the cause of the existence of interharmonic spectrum, and then presented a method to determine the existence of genuine interharmonic components, which was based on interharmonic time-frequency contour chart and the component appearance rate. The presented method firstly performed continuous discrete Fourier transform on the captured signal with certain duration and obtains the corresponding absolute time-frequency matrix, and then the genuine interharnmics could be distinguished based on the component appearance rate of the matrix and the criterion threshold. The method is easy to be implemented with clear principle, and it can distinguish the genuine interharmonics from the measured signal. The analysis on several data groups from real measurements verifies the effectiveness and the practicability of the method.