Optimal Feeder Reconfiguration with Distributed Generation in Three-Phase Distribution System by Fuzzy Multiobjective and Tabu Search

Abstract

Distribution systems are normally configured radially for effective coordination of their protective devices (Kashem et al., 2006). Two types of switches are generally found in the system for both protection and configuration management. These are sectionalizing switches (normally closed switches) and tie switches (normally opened switches) (Su & Lee, 2003). By changing the status of the sectionalizing and tie switches, the configuration of distribution system is varied and loads are transferred among the feeders while the radial configuration format of electrical supply is still maintained and all load points are not interrupted. This implementation is defined as feeder reconfiguration. The advantages obtained from feeder reconfiguration are, for example, real power loss reduction, balancing system load, bus voltage profile improvement,(Baran & Wu, 1989) increasing system security and reliability, and power quality improvement (Kashem, et al., 2000). Over the last decade, distribution systems have seen a significant increase in small-scaled generators, which is known as distributed generation (DG). Distributed generators are gridconnected or stand-alone electric generation units located within the distribution system at or near the end user. Recent development in DG technologies such as wind, solar, fuel cells, hydrogen, and biomass has drawn an attention for utilities to accommodate DG units in their systems (Gil & Joos, 2008, Jones & Chowdhury, 2008, Quezada, et al., 2006, Carpaneto, et al., 2006). The introduction of DG units brings a number of technical issues to the system since the distribution network with DG units is no longer passive. The practical aspects of distribution system should also be considered for the implementation of feeder reconfiguration. The actual distribution feeders are primarily unbalanced in nature due to various reasons, for example, unbalanced consumer loads, presence of single, double, and three-phase line sections, and existence of asymmetrical line sections. The inclusion of system unbalances increases the dimension of the feeder configuration problem because all three phases have to be considered instead of a single phase balanced representation. Consequently, the analysis of distribution systems necessarily required a power flow algorithm with complete three-phase model. This paper emphasizes on the implementation of feeder reconfiguration to the distribution system with distributed generators. Three objectives to be minimized are real