基于改进mSDFT算法的谐波信号提取方法

A Harmonics Signal Extraction Method Based onImproved mSDFT Algorithm

提出了一种改进mSDFT算法,该算法通过分解传统mSDFT算法的传递函数内含的梳状滤波器的结构,保留梳状滤波器中特定的零点,用于提取电网信号中指定次谐波,其余零点组成单独因子,用于指定次谐波频谱的幅值校正和相位校正。分解梳状滤波器的结构后,梳状滤波器中包含的零点减少,从而降低了算法的瞬态响应的延迟。进一步阐述了改进mSDFT算法的原理并完成了公式推导,仿真结果表明:该算法能够在谐波信号发生突变的情况下,快速跟踪提取出变化后的谐波信号,瞬态响应的延迟由10^(-2)s量级降低为10^(-3)s量级,同时具有无累计误差和稳定的优点。

An improved mSDFT algorithm is proposed.For the improved algorithm,the structure of the comb filter contained in the transfer function generated from the traditional mSDFT algorithm is decomposed.That means retaining the specific zero points in the comb filter whose effect is to extract the specified harmonic in the power grid signal and making rest of zero points form a separate factor whose effect is amplitude correction and phase correction.The number of zeros contained in the comb filter is decreased by decomposing the structure of the comb filter,therefore,the delay time of the transient response is reduced.Besides,the principle of improved mSDFT algorithm is expounded and the formula derivation is completed.The results of simulation show that the improved algorithm can quickly track and extract the changed harmonic when the harmonic signal changes suddenly which indicates that it reduces the transient response delay of the traditional mSDFT algorithm,and has the advantages of no cumulative error and stability.