Accurate Estimation of Positive- and Negative-Sequence Components for Three-Phase Grid Voltage Under Disturbances

In order to achieve the stable operation of three-phase grid systems, it is important to find an effective grid synchronization method for detecting the grid voltage parameters. A challenge for this problem is how to extract the positive- and negative-sequence components of the grid voltage rapidly and accurately under distorted conditions. Different from traditional phase-locked-loop (PLL)-based methods, in this article, an adaptive observer-based method is proposed to estimate the positive- and negative-sequence components of the grid voltage. By establishing a dynamic model containing the three-phase grid voltage signal and its derivatives, an adaptive observer is obtained to estimate the grid frequency and then obtain the estimation of the positive- and negative-sequence components of the grid voltage. The experimental results show that the proposed method has good dynamic response and steady-state accuracy under distortion conditions.