Review of Harmonic Mitigation Methods in Microgrid: From a Hierarchical Control Perspective

The microgrid concept has been emerged into the power system to provide reliable, renewable, and cheaper electricity for the rising global demand. When the microgrids are introduced, there will be several concerns, such as active and reactive powers' sharing, load management, connecting to the main grid, and voltage and current deviations. Recently, with the fast deployment of distributed generation, methods to mitigate microgrid harmonics caused by nonlinear loads and power electronic devices have become one of the main focus areas. Consequently, many research works are devoted to this area, introducing different harmonic mitigation methods suitable for the microgrids. Hence, the main goal of this article is to clearly present a comprehensive review of harmonic mitigation methods from a hierarchical control viewpoint. The control strategies proposed to mitigate harmonics are classified into three groups: primary, secondary, and tertiary. Furthermore, this overview draws a sketch on the global trends in harmonic mitigation methods of an ac microgrid directly applicable to today's smart grid applications.