Sensorless Active Damping of LCL_Filter based on MRAS Estimator for Single-Phase Grid-Connected Inverter

摘要

To meet standards regarding grid-tied systems, LCL filters are used instead of L filters because they allow lower inductances while reducing cost and size. However, LCL filters present resonance that cause instability issues. In view of this, two damping methods were proposed in the literature: Passive and Active Damping. Active damping techniques are preferred to avoid additional losses with passive techniques and thereby increasing the inverter efficiency but need the use of an additional sensor to measure the capacitor filter current.This paper addresses a MRAS (Model Reference Adaptive System) based capacitor filter estimator with an active damping current control of a single phase grid connected inverter.In order to guarantee the robustness of the designed MRAS estimator, the inverter control operation is tested under a wide range of grid impedance variation.