Research On Three-phase Harmonic Power Flow For Distribution System

Due to lots of nonlinear equipment and devices, there exists harmonics pollution in distribution systems, which largely influences the power quality and systems reliability. Moreover, the problem of asymmetry parameter and three-phase load imbalance is very common in distribution systems. Therefore, it is of great significance to do the three-phase harmonic power flow analysis for harmonic management and the improvement of power qualities in distribution systems.Firstly, this paper establishes the network element models for the harmonic flow in distribution system. Considering the existence of harmonic sources in distribution system, the power flow of distribution system includes fundamental power flow and harmonic flow. Accordingly, it is established three-phase fundamental model and harmonic model for distribution feeders, distribution transformers, reactive power compensation capacitors and power load in distribution system.Then this paper introduced the principle of harmonic power flow and main methods of harmonic power flow calculation in distribution system. Subsequently, this paper thoroughly analyzes the harmonic source models and compares the advantages and disadvantages of these models. At last this paper determines the harmonic source model for harmonic power flow in distribution system.Finally this paper briefly introduces open-source distribution system simulation developed by American Electric Power Research Institute. Based on OpenDSS a calculation program is designed for harmonic power flow in distribution system. It is accurate in the test on calculation of IEEE34 nodes and IEEE123 nodes distribution system. The calculation program results of mentioned distribution systems include three-phase harmonic voltages and harmonic voltage distortion rates. These data verifies the validity of network element three-phase model and harmonic source model in distribution system.