Multiple-Consecutive-Samples Based Approach of Frequency Estimation in Three-Phase Grid Under DC-offsets

This paper proposes a method of frequency estimation based on multiple-consecutive-samples (MCS-FE) for a three-phase grid, which can estimate the grid frequency quickly and accurately. In particular, the proposed method shows strong robustness against dc-offsets. On the basis of the relationship of distorted grid voltage and four consecutive sampling signals, the model of MCS-FE is established. According to this, estimated frequency, positive-sequence and negative-sequence components can be obtained at the same time. Compared with traditional second-order generalized integrator (SOGI) based frequency locked loops (SOGI-PLLs), MCS-FE shows fast response, high accuracy and good capability of rejecting dc-offsets, and simulation results confirm that.