:e & Technology 101 (2014) 012-019 Distribution System Reconfiguration Considering Distributed Generation for Loss Reduction Using Gravitational Search Algorithm Nguyen Thanh Thuan', Truong VietAnh^* 'Dong An Polytechnic ^University of Technical Education Ho Chi Minh City, No.}, Vo Van Ngan Thu Due District, Ho Chi Minh City Received- March 04, 2014; accepted: April 22, 2014 Abstract This paper presents a method for determining radial configuration of distribution network which is used in reconfiguration problem and an effective method based on Gravitational Search Algorithm(GSA) to identify the tie switchs in distribution network with Distributed Generation (DG) The mam objective is to reduce the real power losses in the system while satisfying all the distribution constraints To demonstrate the validity of the proposed algorithm, computer simulations are earned out on buses, 16 buses, 33 buses, 69 buses systems and the results are presented and compare with the TOPO/PSS-Adept software and PSO Algonthm.The simulation results have showed that the method of determining the radial configuration enables the optimization algorithms not lose results and GSA algorithms are powerful optimization algorithm with a fast convergence and can be applied in reconfiguration distribution netvt/ork problems having large searching space Keywords: Reconfiguration Gravitational Search Algorithm, Loss Reduction Introduction The distribution network transfers the electric energy directly from the intermediate transformer substations to consumers The transmistion networks are often operated with loop or radial structures, the distribution networks are always operated radially By operating radial configuration, it significantly reduces the short-circuit current The restoration of the network from fauls is implemented through the closing/cutting manipulations of electrical switch pairs located on the loops, consequently, hence, there are many switches on the distribution network Network reconfiguration is the process of altering the topological structures of distribution feeders by changing the open/close status of the sectionalizers and tie switches, while respecting system constraints to satisfy the operator's objectives This is a non-linear optimization problem, (he objective fiinction is always interrupted so it is difficult to solve the problem by the traditional mathematical techniques In recent years several optimizafion methods have been proposed for solving the reconfiguration problem such as GA, PSO, ACS, ABC [1-4], which is contributed to improve the convergence and calculation speed and the newest technique which is developed based on Newton's laws is the Gravitational Search Algonthm (GSA), This algorithm has showed many advantages in solving optimization problems [5-7] * Conesponding Author' Tel (+84) 953117659 Email tvanhspkt@gmail.com This paper uses GSA to reconfigure the elecfric distribution network with DG connection to reduce power loss The major contribution of this research is to present a method of determming the optimal operating structure for the network and a simple method of determining the radial structure to achieve the minium power loss Mathematical model The distribution network often uses loop structure but operates radially through open switches in the electrical systems.The power loss on the system IS equal to the total loss on the branches [ 1,3,4] 1.1' Pf + 0? (1) • active power loss on the i* branch : total number of branches P-,Q : active power and reactive power on the i"' branch : connection bus voltage of the branch and current on the i"" branch active power loss of system slate of switches, if k, = 0, the i"" switch opens and vice versa Journal of Science & Technology 101 (2014) 012-019 To reduce power loss of the electric distribution network, the objective function is: F(x) = mm (Pi„„) (2) And the network constramts must be satisfied are voltage and current that maintained within theu: permissible ranges to maintain power quality Vi.min^\K\^V,„^ l'il