双向牛顿插值的电力系统谐波分析方法

Bidirectional newton interpolation analysis method for harmonics in power system

在电力系统谐波分析的过程中,由于非同步采样使信号在进行FFT变换的过程中产生频谱泄露和频谱混叠,分析精度大大降低。现有的加窗FFT谐波分析方法虽然能在一定程度上抑制频谱泄露,但存在插值修正公式复杂、不同频率成分检测互相干扰的缺点。提出了一种基于双向牛顿插值同步化采样序列的电力系统谐波检测方法。在非同步采样情况下,利用正向牛顿插值计算得到信号基波的周期,然后根据计算所得周期设置新的插值点,再利用反向牛顿插值得到该处的信号幅值,使得调整后的采样序列近似于同步采样情况下获得的采样序列,从而减小傅里叶分析时的频谱泄漏。仿真结果表明,该方法能够很好的解决频谱泄露的问题,相较于经典窗函数插值谐波分析方法,具有较高的谐波检测精度。

In the harmonic analysis of power system, the accuracy is badly influenced by spectral leakage and fence effect during FFT transform. The current analysis method of windowed FFT interpolation can suppress the spectral leakage to a certain degree have mutual interference , but it has a complex interpolation formula, meanwhile, different frequency components damaging the effect of harmonic analysis. This paper presents a bidirectional Newton interpolation method which can synchronize the sampling sequence.. In the case of asynchronous sampling, positive Newton interpolation is used to calculate the primitive period of periodic signal, and then setting new interpolation points according to the calculation of the period, the signal amplitude can be calculated by using the reverse Newton interpolation. The adjusted sequence is approximately like the acquired sample sequence under synchronous sampling condition, so that can effectively reduce the spectral leakage during fast Fourier transform. The simulation results show that, the method can solve the leakage of spectrum, and its harmonic detection has a higher precision compared with harmonic analysis method of classic window function interpolation.