Nonlinear Load Harmonic Mitigation Strategies in Microgrids: State of the Art

A generational shift has led to the evolution of distributed generation (DG) and microgrids. The loads connected in a microgrid can be both linear and nonlinear. Nonlinear loads deteriorate the power quality by drawing harmonic currents. Drawing of nonlinear currents will make the voltage waveform nonsinusoidal, which may prove harmful for other loads connected to the system. Previously, passive and active filters were used to mitigate harmonics, but they are expensive and bulky. The state of the art is to exploit multifunctional capabilities of inverter-interfaced DGs to deal with the power quality issues. This article presents the typical sources of generation of the harmonics, their deleterious effects, available standards, and detection techniques. Harmonic mitigation strategies for both grid-connected and islanded microgrids have been discussed in detail. The aim is to review and categorize the various strategies adopted by authors in recent times to mitigate harmonics and bring out the research gaps so that further avenues can be explored in this area.