Accurate DFT Method for Power System Frequency Estimation Considering Multi-Component Interference.

Frequency estimation plays a crucial role in monitoring and protecting smart grids. The excellence of discrete Fourier transform (DFT)-based frequency estimators has been well known due to their efficiency and robustness. However, multi-component interference has become one of the biggest challenges of DFT-based estimators. To this end, we propose a novel DFT-based method for estimating multifrequency real-valued sinusoidal signals, which consist of $P$ unknown components. The proposed method first constructs a nonlinear equation to describe the relationship between the parameters of all components and their frequency spectrum. The nonlinear equation is then transformed into a linear equation with $3P$ unknowns for estimating the frequency. The proposed method takes the sidelobe interference and spectrum leakage of all components into consideration. As a result, the impacts of multi-component interference can be completely avoided. Experiments and simulations demonstrate that the proposed method not only meets the limitations of Standard IEC/IEEE 60255-118-1 but is also highly competitive with existing frequency estimators.