An Improved 3-Phase Load Flow for DG Integrated Distribution Systems Based on PSO

The recent trend of integrating distributed generation (DG) units with distribution network has necessitated reformulation of conventional distribution load flow problem to incorporate the DG models. 3-phase distribution load flow with DG models included, has already been reported by a number of authors. These studies, however, suffer from two major drawbacks. Firstly, the allocation of active and reactive power outputs among the three phases of the DG units under unbalanced loading conditions of the systems could not be properly considered in these studies. Under such operating conditions, loading of the three phases of a DG unit is more likely to be unequal. But, in these studies, the active and reactive power outputs of the three phases of the DG units had been allocated equally among the three phases of those units. Secondly, the solutions provided by these studies can not ensure balance in the 3-phase internal voltages of the DG units, which is an essential requirement arising naturally due to design of 3-phase DG units and the available methods of their control. The present work applies Particle Swarm Optimization (PSO) to develop an improved methodology for 3-phase distribution load flow to alleviate the above mentioned drawbacks. The results of application of the proposed load flow on IEEE 13 node network and on IEEE 25 node network have been presented in support of the claim made by the present authors.