ADRC-Based Current Control for Grid-Tied Inverters: Design, Analysis, and Verification

The conversion and utilization of renewable energy generations often require grid-tied inverters. When an LCL filter is applied to attenuate the high switching frequency harmonics, it is complex to design a controller with proper parameters due to the characteristics of the LCL filter and system uncertainties. In this article, with LCCL filter, the order of the inverter system is degraded from third order to first order, and an active disturbance rejection control-based current control strategy for LCCL-type grid-tied inverters is proposed. The proposed strategy is able to treat the unknown dynamics and the external disturbance of the inverter system as overall disturbance through a single structure, and the closed-loop system is regulated by an improved control law with reference differential feedforward. Moreover, with parameter uncertainties considered, the robustness of the proposed strategy is studied through an internal model control structure. A 2-kW experimental prototype has been tested to verify the effectiveness of the proposed scheme.