A Least-Squares-based Adaptive PI Controller for grid-tied DC-AC converters

Renewable energy generation has been a feasible solution for global energy matrix transformation. For this application, grid-tied power converters with LCL filters are commonly used as interfaces between clean energy sources and the electrical grid. However, the LCL filter can cause instability on current loops of fixed-gain controllers due to its resonance peak. Therefore, this work proposes a discrete-time PI (Proportional Integral) Controller, based on Least-Squares algorithm, to mitigate the resonance peak, through active damping, and grid-injected current control. It is highlighted that the proposed method does not need resonant controllers for grid disturbance rejection, and that it is robust to grid impedance uncertainties. Simulation results are presented to corroborate the viability of the proposed control strategy.