This paper firstly analyzes the harmonic emission characteristics of a single distributed generation (DG) device and calculates the maximum capacity of DG under harmonic emission constraint. Based on the vector summation theory

the maximum capacity of multiple DGs accessed to a common point is also calculated. Finally

a case study is carried out to analyze the harmonic characterization in the active distribution network with multiple points of common coupling. A case study is designed for three classic power accommodating modes: point accommodating

feeder accommodating and area accommodating. Three-dimensional parameters including penetration

distribution and dispersion are defined to describe the status of DGs accessed to the active distribution network. According to the study

a conclusion can be drawn that the harmonics in the active distribution network is closely related to the three-dimensional parameters. Full consideration should be given to prevent and solve the harmonic problem during the planning and operation stage of the active distribution network.