Comparison of Current Grid Controllers in a DG Inverter with Grid Harmonic Distortion

摘要

This paper aims to present the analyzes of different grid current controllers applied in a full-bridge inverter used in distributed generation (DG). The presence of harmonic interaction in the grid, can be explained by the impedance-grid resonance problem between the equivalent grid impedance and the inverter impedance. The analyzes of different control strategies involve aspects such as power losses, quality of the current injected into the grid and dynamic performance during grid disturbances. In order to study the converter performance connected to the grid, it is made a comparison in this work by means of three controllers: proportional and integral (PI), proportional resonant (PR) and repetitive (RT). The simulation results show the higher efficiency of the PR and RT controllers in grid distorted conditions. The modulation techniques and discretization methods also affect the grid power quality, focusing in particular on the Bipolar technique. Therefore, this work proposes with these mechanisms to improve the performance of the operation DG grids, and consequently to increase the system power quality.