Impact of Phase Displacement among Coupled Inverters on Harmonic Distortion in MicroGrids

This paper presents the results of a study on the impact of coupled integrated inverter-based resources (IBRs) on the total level of harmonic distortion in a microgrid such as those powered by battery storage systems and electric vehicle charging stations. Through insensitive simulation studies with generic models of inverters and software, we analyze the relationship between the carrier frequency phase displacements in pulse-width modulation (PWM) among coupled IBRs and the harmonic level in a microgrid. We found that the harmonic level varies in different scenarios of the phase displacements. It is also discovered that there might exist an optimal phase displacement condition under which IBRs will produce a minimum amount of harmonics. This study suggests that by appropriately coordinating the phases among coupled inverters in their PWM operation can minimize the level of harmonic distortion of total IBRs' output, while with few or no impact on the active powers of the loads in a microgrid. This could lead to low cost technical solutions to reduce the impact of harmonics on transient stability of microgrid, particularly during the fault or disturbance ride-through periods.