Improved ADRC With a Disturbance-Separation CESO Based on Complex Coefficient-Filter for Current Source Rectifier

Under complicated operations, the tracking performance and interference rejection ability of the LC-filtered current source rectifiers (CSRs) are inevitably compromised by various disturbances, including aperiodic and periodic disturbances. Aiming at this problem, an improved active disturbance rejection controller (ADRC) with a disturbance-separation cascaded extended state observer (DSCESO) based on a complex-coefficient filter (CCF) is proposed to improve the disturbance rejection ability. First, by integrating a CCF into the second cascade level of CESO, the proposed CCF-CESO can not only overcome the trade-off between estimation performance and noise suppression, but also accurately estimate positive and negative sequence disturbances arising from converter nonlinearity and nonideal grid conditions. Second, the CCF-DSCESO is constructed to decouple different disturbances based on disturbance separation technology, thereby further strengthening the robustness and tracking accuracy. Finally, comparative experimental results verify the superiority of the proposed method.