一种基于滑动傅立叶分析的改进谐波电流检测方法研究

Research on improved harmonic detecting method based on sliding Fourier analysis

本文针对电网频率波动时基于滑动坐标系的窗口傅立叶分析法会产生较大误差的不足,提出了一种改进的谐波电流检测方法。该检测方法在滑动傅立叶分析方法的基础上,引入了硬件锁相环,能够实时检测电网频率的变化,提高了混合型有源滤波器谐波电流的检测精度。最终的仿真结果也证明了改进方案的有效性。

In this paper an improved harmonic current detecting method based on the sliding Fourier analysis is presented to decrease the calculating errors when the source frequency varies. The relation between the source current frequency and calculating result is discussed in detail, and hardware of PLL was induced to detecting the variation of the source frequency. At the same time, the detecting precision of the improved method doesn＇t vary with the sampling frequency. The detecting precision based on the improved method is related to the sampling frequency of the source current, and the preferable detecting precision can he attained in a less high sampling frequency. In addition, the effect of PLL＇ s precision to the detecting error is analyzed theoretically, and the rational scope is given. In conclusion, the proposed detecting method improves the detecting precision of hybrid active power filter. Lastly, simulation results based on the proposed approach also confirm the validity of the proposed method.