A grid-operated NPC inverter control using voltage and current control loops

The goal of this work is to model a dual loop controlled 3-level (3-L) neutral point clamped (NPC) inverter that is operating in grid-tied mode. The adopted control strategy includes voltage and current regulation in addition to a phase-locked-loop for synchronizing the grid's phase and frequency with that of the NPC inverter. The power source is configured to generate 1.3 MW AC power at 600 V from a 1.54 MW proton exchange membrane (PEM) fuel cell (FC) stack that runs at 1400 V. The NPC inverter is fitted with an LCL filter that was positioned between the grid and the inverter to ensure that the amount of system harmonics is decreased. The arrangement also ensures that the inverter meets the required standards, such as the IEEE 519 & IEC 61000-3-6. Matlab (Simelectrical) is utilized for the modeling and simulation. In overall, the designed system performed excellently based on the observed simulation results.