Accurate IpDFT-based Frequency Estimation Algorithm for the Unbalanced Three-phase Voltage Signal

It is difficult to precisely estimate frequency of the unbalanced signal since its unknown parameters make the spectrum different from the real-valued sinusoidal signal. Moreover, spectral leakage the unbalanced signal also brings large estimation errors when the acquired signal cycles become very small. In this paper, we proposed a two-point IpDFT algorithm for frequency estimation of the unbalanced/balanced three-phase voltage signal. The signal was decomposed into a real-valued sinusoidal signal, and then the system frequency was estimated through the spectrum equation. Both long- and short- range leakage was compensated to obtain precise frequency. Simulation results proved the effectiveness of our method, compared with other DFT methods.