基于虚拟仪器和DFT滤波器的瞬时谐波检测

Instantaneous Harmonic Detection based on Instrument and DFT Filter

提出了一种基于DFT(DiscreteFourierTransform)系数实现FIR滤波器的瞬时谐波电流的检测方法。该滤波器在基频处无衰减,相位无延时,能将2次以上的谐波全部滤掉。得出了该滤波器的递推关系,大大节约了计算量。基于该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。理论推导和基于虚拟仪器的实验表明,该数字谐波检测系统既保留了数字滤波器的准确性,又克服了其跟随性能差的缺陷。

A simple and practical instantaneous harmonic current detection method is introduced, which realizes a special filter based on DFT (Discrete Fourier Transform). The filter has no fundamental decay and phase delay, and all harmonics above 2nd order are eliminated.The recursion of filtering algorithm is obtained and the calculation is thus greatly simplified.The digital harmonic detection based on this kind of filter can be used in any kind of harmonic compensation system.The theoretical analysis and test based on virtual instrument have shown that it keeps the accuracy and improves the following performance of digital filters.