Deadbeat current control for wind-energy inverter application with LCL filter

This paper proposes a deadbeat control system for the output LCL filter in a grid-connected inverter with a settling time of three sampling periods. Unlike the conventional analysis, the proposed control algorithm is derived in the descritised time-domain instead of the s-domain. In order to bring the robustness about the grid voltage distortion or the inaccurate inverter with non-linearity between the output voltage and its command, the adaptive predictor which acts as an integral controller is required. Furthermore, a comparison of the measured THD of the grid current is included for two different types of feedback, inverter current feedback and the grid current feedback. From the measured total harmonic distortion (THD) of the grid current, the grid current feedback significantly reduces the THD by 2.0% as compared to the converter current feedback. This is directly due to the detected control variable is precisely controlled in order to follow up its reference current using the adaptive predictor.