Design and analysis of L and LCL filters for grid-connected HNPC inverters used in renewable energy systems

Abstract

With the widespread integration of renewable energy systems (RES) into the electric grid, maintaining power quality within specified limits has become a major focus. The total harmonic distortion (THD) value of the currents transferred to the grid and directly affecting power quality in (RES) such as grid-connected photovoltaic (PV) and fuel cells (FC) should not exceed 5%. To achieve this objective, various filter topologies are used to interface between the inverters, which are components of PV and FC systems, and the grid.Although there are numerous filter topologies, L and LCL-type passive filters are the most commonly used topologies in grid-connected systems. This study analyzes the L and LCL-type filter topologies for the H-bridge neutral point clamped (HNPC) inverter. The study’s modeling was carried out in the MATLAB/Simulink®. By comparing the simulation results, L and LCL filters’ harmonic attenuation capabilities, maximum power transferred to the grid, and effects on grid current have all been investigated.