Distribution System Harmonic Compensation Methods: An Overview of DG-Interfacing Inverters

Today, many renewable energy-based distributed generation (DG) units are connected to the grid with interfacing converters. Therefore, the harmonic compensation functions can be realized through flexible control of these converters. This article reviews the distribution system harmonic compensation methods using the DG units with a focus on the DG local controllers. How to realize the harmonics compensation functions in the traditional current controlled and voltage-controlled DG systems is presented. A hybrid-control method (HCM) is also discussed, which features better compensation performance and more flexible compensation strategies. Other issues, including harmonics current sharing among the DG units, are also discussed in this article. With the harmonics compensation functions, future DG systems could actively participate in the distribution system power quality control activities.