基于加四项Nuttall窗递推DFT插值算法的高精度测频方法研究

Study on High-precision Frequency Measurement Method Based on the 4-term Nuttall Windowed Recursive DFT Interpolation Algorithm

为了提高电力系统频率计算的精度,提出了一种基于加四项Nuttall窗递推DFT插值算法的高精度测频方法.由于四项余弦窗的能量更集中在主瓣,旁瓣非常小,因此加四项余弦窗FFT插值算法能极大地减小频谱泄漏的影响,谱间干扰很小,能较好地减小频谱泄漏和谐波等给频率测量带来的干扰,且该方法采用的频率偏移量计算公式简单.为了减小加四项余弦窗FFT的计算量,采用加四项余弦窗递推DFT的方法对传统方法进行了改进,有效减小了算法的计算量,提高了频率的计算精度.仿真计算结果验证了所提算法的计算精度.

In order to improve the accuracy of calculation of the power system frequency, a high-precision fre-quency measurement method based on the 4-term Nuttall windowed recursive DFT interpolation algorithm has been put forward. Energy of four cosine window is more concentrated in the main lobe, very small in the side lobe, so the 4-term Nuttall windowed recursive FFT interpolation algorithm can greatly reduce the effects of spectral leakage, and spectral interference is very small, which can reduce the frequency measurement inter- ference caused by spectrum leakage and harmonic, and the frequency offset formula of the method is simple. In order to reduce the amount of plus four cosine windowed FFT calculation, this paper introduces the plus four cosine window recursive DFT method which improves the traditional method, these improvements effec-tively reduce the 4-term Nuttall windowed recursive DFT interpolation algorithm and improves the calculation accuracy of the frequency. Simulation results verify the calculation accuracy of the proposed algorithm.