Integration of distributed generators into distribution three-phase load flow analysis

An unbalanced three-phase load flow program taking the mathematical models of distributed generators (DGs) into account is proposed in this paper to analyze and simulate the penetrations of DGs for distribution systems. The load flow method based on the direct approach algorithm is employed in this paper. The mathematical models of DGs are then developed and integrated into the proposed load flow method. DGs can utilize the traditional energy sources such as oil and coal or renewable energy sources such as wind, solar and fuel cell, and use rotating generators or converters to transfer energy to power grids. According to the characteristics of output power, DGs can be specified as constant power factor model, constant voltage model or variable reactive power model in the load flow analysis. In this paper, these three models are all derived and integrated into the proposed load flow method. Since the proposed load flow method can fully exploit the network structures of distribution feeders and is very effective and efficient, it is very important to note that the integration of the proposed DG models will not degrade the performance of original load flow algorithm. Test results demonstrate the validity and capability of the proposed method.