A study on the harmonic contributions of DGs connected to unbalanced power systems

The impacts of distributed generation (DG) units on the unbalanced three-phase power systems are analyzed. Line loss mathematic model caused by harmonic with unbalanced three-phase loads is proposed through theoretical derivation. The corresponding simulation model based on typical 10kV medium voltage microgrid is established with Matlab/Simulink. The simulation results show that an optimal grid connection point can be decided. The FACTS devices typically such as Unified Power Flow Controller (UPFC) can be utilized to balance three-phase power flow and reduce total harmonic distortion.