The present invention relates to an ADRC-based sensorless control system and method of an LCL filter type grid-connected inverter. ADRC-based sensorless control system of LCL filter-type grid-connected inverter according to the present invention receives grid voltage and grid current and estimates the state of the integral-chain-based inverter model and the overall disturbance and uncertainty state affecting the inverter and a resonance extended state observer; a fundamental frequency component filter for receiving the disturbance state estimated by the resonant extended state observer and filtering out harmonics distorted from the estimated disturbance state; a grid frequency and phase angle estimator for receiving a disturbance state estimated by the resonance extended state observer through a fundamental frequency component filter, and extracting a grid voltage phase angle and angular frequency from the estimated disturbance state; and a grid voltage sensorless current controller, receiving the grid voltage phase angle and angular frequency estimated by the grid frequency and phase angle estimator, and the disturbance state estimated by the resonance extension type state observer, and the disturbance from the disturbance state estimated based thereon It includes a resonant ADRC-based current controller that removes and tracks the voltage reference value and reflects it to the control of the grid-connected inverter.
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