With the development of High Voltage Direct Current (HVDC) and ultra HVDC, a growing number of high voltage film filter capacitors have been installed for harmonic suppression. But the capacitors generate severe audible noise in the converters, which has become more and more serious. Then it is important to imitate the practical working situation of capacitors for the research of noise characteristics to improve the capacitive performance in lab. In this paper, a FFT-based harmonic current control method is proposed for audible noise analysis of AC filter capacitor. Firstly, mathematical model of the Harmonic Current Injection System (HCIS) is built based on MATLAB. Then a Fast Fourier Transform (FFT) harmonics detection method is analyzed and used to detect the amplitude and phase of each harmonic considering a number of harmonic currents flowing through AC filter capacitors. Since the amplitude and phase spectrum of capacitor current are obtained, the Proportional Integral (PI) regulator is applied to adjust the specified harmonic amplitude to achieve zero-error control. Then accurate harmonic current can be injected to the tested capacitor and it will help to acquire the noise characteristics of the tested plant. At last, the simulation and experimental results validate the proposed strategy.

随着高压直流（HVDC）和超高压直流（HVDC）的发展，已经安装了越来越多的高压薄膜滤波电容器来抑制谐波。但是电容器在转换器中产生严重的可听噪声，这种噪声变得越来越严重。因此，模仿电容器的实际工作情况对研究噪声特性，提高实验室的电容性能具有重要意义。本文提出了一种基于FFT的谐波电流控制方法，用于交流滤波电容器的可听噪声分析。首先，基于MATLAB建立了谐波电流注入系统（HCIS）的数学模型。然后，对快速傅立叶变换（FFT）谐波检测方法进行了分析，并考虑到流过交流滤波电容器的大量谐波电流来检测每个谐波的幅度和相位。由于获得了电容器电流的幅度和相位频谱，因此应用了比例积分（PI）调节器来调节指定的谐波幅度，以实现零误差控制。然后，可以将准确的谐波电流注入经过测试的电容器，这将有助于获取经过测试的设备的噪声特性。最后，仿真和实验结果验证了所提策略的有效性。比例积分（PI）调节器用于调节指定的谐波幅度，以实现零误差控制。然后，可以将准确的谐波电流注入经过测试的电容器，这将有助于获取经过测试的设备的噪声特性。最后，仿真和实验结果验证了所提策略的有效性。比例积分（PI）调节器用于调节指定的谐波幅度，以实现零误差控制。然后，可以将准确的谐波电流注入经过测试的电容器，这将有助于获取经过测试的设备的噪声特性。最后，仿真和实验结果验证了所提策略的有效性。