An enhanced full‐feedforward strategy to mitigate output current harmonics in grid‐tied inverters

Abstract

The grid-tied inverters are the most vital components in renewable energy-based power systems. Hence, maintaining the power quality of a grid-tied inverter output within the standard range is an ongoing challenge in the power system. The appeared individual harmonics at inverter output current caused by grid voltage harmonics depend on the inverter output equivalent admittance. This consists of a combination of admittance seen from the point of common coupling and the phase-locked loop path. Therefore, the precise calculation of the aforementioned admittance is an inevitable requirement to design a harmonic mitigation strategy. By adding a virtual admittance to the system through modifications in the inverter control loop, the output equivalent admittance can be removed. For this purpose, in this paper, a novel full-feedforward harmonic suppression scheme is proposed which can effectively eliminate individual harmonics injected from the grid. Consequently, the individual output current harmonics of the inverter will be effectively suppressed. Simulation and experimental results have been carried out for a typical single-phase grid-tied inverter to verify the efficiency of the proposed scheme against emitted harmonics from the grid.