Frequency estimation of sine wave distorted by noise plays an important role in modern power systems. The widely used windowed interpolation fast Fourier transform (WIFFT) can only reduce, but not completely remove, the estimation errors at the cost of an increment in the computation burden of frequency estimation. This paper proposes a frequency estimator by using the prior rough frequency estimation and trigonometric decomposition under white Gaussian noises. Firstly, a prior rough frequency is estimated by the three spectral lines WIFFT based on the Hanning window. Then, a parallel iteration of trigonometric decomposition is applied for the accurate frequency estimation. The gradient-descent method is used in the parallel iteration procedure, which can effectively restrain the interferences from harmonics and noise. Simulation and experiments results show that the proposed method can achieve accurate frequency estimation within one cycle.
Parallel Iteration Method for Frequency Estimation Using Trigonometric Decomposition
