基于DFT的瞬时谐波检测方法

Instantaneous harmonic detection based on DFT

提出了一种用离散傅里叶变换DFT(DiscreteFourierTransform)实现特殊滤波器的瞬时谐波电流的检测方法。该滤波器在基频处的幅值无衰减,相位无延时,能将2次以上的谐波全部滤掉。根据滤波器冲激响应的特点得到了滤波算法的递推关系,大大地节约了计算量。基于此滤波器设计的数字谐波检测方法可用于任何一种电力系统的谐波补偿装置中。理论推导和仿真实验表明,该数字谐波检测系统既保留了数字滤波器的准确性,又克服了长期以来数字滤波器跟随性差的问题,算法易于实现,具有较高的实用价值。

A simple and practical instantaneous harmonic current detecting method is introduced,which realizes a special filter based on DFT(Discrete Fourier Transform).The filter has no fundamen-tal frequency decay and phase delay,and all harmonics above2nd order are filtered.The recursion of filtering algorithm is obtained according to filter’s response character and the calculation is thus greatly simplified.The digital harmonic detecting method based on this kind of filter can be used in any kind of power harmonic compensation system.The theoretical analysis and simulation have shown that it keeps the accuracy and proves the following performance of digital filters.