【摘要】 针对电力系统中的谐波检测问题,提出了一种以变分模态分解(VMD)为核心的谐波检测算法。算法中将VMD与快速傅里叶变换相结合,使VMD能够自适应寻找模态分解数K值,以克服模态混叠现象。分别使用了希尔伯特变换(HT)和Teager能量算子(TEO)对VMD分解后的信号进行解析,仿真结果表明HT对稳态信号能准确地计算出瞬时幅值和瞬时频率,但是对于部分暂态信号会受VMD算法的影响而解析出失真的信号频率;TEO对稳态信号和暂态信号的频率都有较好的检测精度,但是对于暂态起止处的信号幅值检测精度较差。进一步分析了2种算法的计算结果,利用TEO算法的特点,消除暂态信号加入时VMD分解中产生的幅值极小但具有很大频率干扰的信号,为谐波信号快速准确检测提供了新的思路。更多还原

【Abstract】 Aiming at the problem of harmonic detection in power system,this paper proposes an harmonic detection algorithm based on variational modal decomposition (VMD).This algorithm combines VMD with fast Fourier transform (FFT) enables VMD to adaptively find the value of modal decomposition number K to overcome modal aliasing.This paper uses Hilbert transform (HT) and Teager energy operator (TEO) to analyze the decomposed signals of VMD respectively.The simulation results show that transform can accurately calculate instantaneous frequency and instantaneous amplitude,but for some transient signals,the distorted signal frequencies could be parsed out caused by the influence of VMD algorithm.TEO has a better detection accuracy for both steady-state and transient signals,but poor detection accuracy for the signal amplitude at the beginning and end of transients.The calculation results of the two algorithms are further analyzed,and the features of the TEO algorithm are used to eliminate the signals with very small amplitude but large frequency interference generated in the VMD decomposition when the transient signal is added,which provides a new idea for the rapid and accurate detection of harmonic signals.更多还原