Introduction a multi-objective function in unbalanced and unsymmetrical distribution networks for optimal placement and sizing of distributed generation units using NSGA-II

Connection of distributed generation units with appropriate allocation and size in network will have different effects such as increasing of reliability in network, decreasing of losses, improving of voltage profile, decreasing of transmission and distribution energy costs and improving of power quality parameters like voltage unbalance. So far, researches about allocation of distributed generation sources would have been done in completely balanced systems. In this paper optimized allocation of these sources in unbalanced distributed system in different consumed loads and unsymmetrical in transmission lines structure has been discussed. Since the voltage unbalance is one of current problems in distribution networks, decreasing of voltage unbalance factor (VUF) in distribution network in order to increase quality of power delivery to customers is one of the aims in optimized allocation of distributed generations in this study. Introducing multi-objective function for allocation of distributed generation sources, in order to minimize voltage unbalance factor and real power loss, improving of voltage profile and increasing of economic profit, the concepts of multiobjective optimizing (PARETO) in studied networks is used. With due attention to necessity of power flow studies in studied unbalanced distribution systems, this study using Cyme-Dist software and optimizing process, with connection between the mentioned software and MATLAB software is done. In continuation, allocation of distributed generation in IEEE standard 13 bus network, in three different load levels and using NSGA-II algorithm has been studied. Results show that proper placement of distributed generation sources in unbalanced distribution systems; can decrease both losses and amount of voltage unbalance. Also in this study shown that, appropriate placing of distributed generation sources, provides considerable profit to distribution companies.