摘要:
The accurate measurement of harmonic parameters is the basis for harmonic control in microgrid.Since the bigger frequency offset,the lower signal-to-noise ratio in the microgrid,harmonic measurement error by using conventional discrete Fourier transform (DFT) is large.According to the characteristics of electrical signal in microgrid,a harmonic parameter estimation algorithm based on Nuttall-windowed Fourier transform was proposed in this paer.Firstly,the sampling data was windowed by Nuttall whose side lobe is low and attenuation is fast,so the spectrum interference between different frequency components was reduced.Secondly,the DFT algorithm was used to estimate harmonic frequency,amplitude and phase,which can reduce the error caused by spectral leakage.Finally,under the bigger frequency offset,the lower signal-to-noise ratio in the micro grid,the proposed method was simulated.The simulation results show that the proposed algorithm can effectively restrain the effect of synchronous sampling error of harmonic measurement,and significantly improve the accuracy of the micro grid harmonic measurement.%谐波参数的准确估计是微电网谐波治理的基础和依据,微电网频率偏移大,信噪比低,采用常规傅里叶算法测量谐波误差大.提出基于Nuttall窗离散傅里叶变换(DFT)校正的谐波检测算法.首先,对采样数据加Nuttall窗,利用Nuttall窗旁瓣低且衰减快的特点抑制各频率成分间的频谱干扰;其次,采用DFT校正算法估计谐波频率、幅值、相位等参数,减小频谱泄露引起的谐波测量误差;最后,对微电网较大频率偏差和较低信噪比的情况下,对所提方法进行仿真分析.仿真结果表明,所提算法能有效抑制同步采样误差对谐波测量的影响,可显著提高微电网谐波测量的精确性.