High-Order LADRC-Based Current-Decoupling Control With Embedded Grid Impedance for LCL-Type Energy Storage Converters

Current decoupling control for LCL-type threephase energy storage converters under weak grid conditions faces challenges including multiple control variables, complex decoupling processes, and poor stability. To achieve costeffective and highly stable current decoupling, this study proposes a grid-impedance-embedded higher-order Linear Active Disturbance Rejection Control (EGI-LADRC) method. The approach treats three internal coupling terms in the current control loop as disturbances and implements sensorminimized current decoupling by constructing a third-order controller to eliminate these disturbances. In the design of the Linear Extended State Observer (LESO), a compensation factor b0 incorporating grid impedance information is introduced, enabling the observer to rapidly estimate and mitigate adverse grid impedance effects on output current under varying grid conditions, thereby enhancing system stability. Through impedance modeling and stability analysis, parameter design guidelines for the proposed EGI-LADRC are established, along with comparative stability evaluations against other algorithms under diverse operating scenarios. Experimental validation on a 4kW prototype confirms that the converter achieves low-distortion current output under large grid impedances using only two sensor sets, significantly outperforming PI-based and conventional LADRC-based methods.