An Instantaneous Reactive Current Individual-phase Detection Method and Digital Realization Based on Fourier Transform

Abstract

Currently, the frequency-domain detection methods based on Fourier Transform theory are widely used for reactive current detection, but they usually need the voltage phase information by means of phase locked loop (PLL), which will increase the algorithm complexity and may cause the reactive current detection errors. Therefore, this paper introduces an instantaneous reactive current detection method based on Fourier transform, which abandons the PLL to improve the comprehensive performance of the reactive current detection. Moreover, a synchronous tracking method for system frequency and a compensation strategy for the time delays derived from signal sampling, analog-digital conversion and detection algorithms are embedded in the proposed method, for the purpose of further reduce the reactive current detection errors. In addition, a digital realization means for this method based on recursive Discrete Fourier Transform (DFT) is introduced. The simulation and experimental results show that, with this novel method, the reactive currents could be individual-phase detected from the three-phase distorted unbalanced load currents accurately and quickly.