Optimum capacity allocation of DG units based on unbalanced three-phase optimal power flow

In this paper, a methodology for determining optimum generation capacity of multiple distributed generation (DG) units is presented. The proposed method is based on unbalanced three-phase optimal power flow (TOPF) using particle swarm intelligence. To solve the optimum generation capacity problem, a co-simulation platform has been used under the MATLAB and OpenDSS environment. An adaptive weight particle swarm optimization algorithm has been developed in MATLAB and the unbalanced three-phase distribution load flow (DLF) has been performed using Electric Power Research Institute´s (EPRI) open source tool OpenDSS. The analysis is carried out on IEEE 123 node distribution test feeder for three different DG technologies. The results obtained from the proposed method have been compared with the results obtained from a `brute-force search´ method. This analysis shows that the proposed method finds out the optimum solution successfully while computational complexity and time is reduced extensively. Using multiple DG units with optimum generation capacity, power loss of the network is reduced significantly while voltage profile remains within stability margin.