International Electrical Engineering Journal (IEEJ) Vol. 4 (2013) No. 1, pp. 987-991 ISSN 2078-2365 987 ENHANCING RELIABILITY BY RECONFIGURATION OF POWER DISTRIBUTION SYSTEMS CONSIDERING LOSS ENHANCING RELIABILITY BY RECONFIGURATION OF POWER DISTRIBUTION SYSTEMS CONSIDERING LOSS Jency Sara John 1 ,S.T.Suganthi 2 . 1 Department of Electrical and Electronics Engg, SNS College of Tech, Coimbatore 2 Department of Electrical and Electronics Engg, SNS College of Tech, Coimbatore 1 jencysara@gmail.com, 2 suganthi_thangaraj@yahoo.co.in Abstract- The paper describes an effective method to reconfigure a power distribution system using optimization techniques. Here genetic algorithm is used for the reconfiguration to enhance reliability and to reduce losses. The reliability at the load points is evaluated using probabilistic reliability approach. For finding minimal cut sets and losses different algorithms are used. To maximise the reliability and to reduce the losses, the status of the switch is controlled using genetic algorithm. The effectiveness of the system is tested in 33 bus distribution system. Keywords- Reliability, power losses, reconfiguration, genetic algorithm. I. INTRODUCTION As the demand for electrical energy is increasing day by day, the transmission and distribution lines are heavily loaded. From the recent black outs, we can see that most of failures occurs at the distribution level will result in cascading effect[1]. So reliability evaluation of distribution system gains significance in planning and operating stage of power system. Here the reliability at loads points and reducing the total losses of the system is considered as objectives. The optimal status of the switches considering reliability and power losses was done by particle swarm optimisation[2]. To find the reliability at the load points ,minimal cut set for the network has to be found out. [3] suggests an algorithm to find minimal cut sets. The subject of minimizing distribution losses become important due to the rising prices of electrical energy. By reducing the losses, system acquires longer life span and high reliability.[4] presents a systematic feeder reconfiguration technique that develops an optimal switching scheme to achieve a maximum reduction of losses in a distribution network by restructures the distribution feeders by changing the open/closed status of the sectionalizing and tie switch. [5] presents an algorithm for loss minimization by using an automatic switching operation in large scale distribution systems by simulated annealing. In this paper, probabilistic models of the distribution system components are considered while evaluating the reliability at the load points. Minimal cut sets between the source and the load points are first determined, and then the expected availability of power is computed by using the joint failure probability distribution of the components involved in the cut set. The genetic algorithm technique is used to determine the optimal reconfiguration of switches in the network in order to maximize the reliability at the load points, and minimize the real power loss in the system. II. RELIABILITY ASSESSMENT AT THE LOAD POINTS For the reconfiguration of power distribution system, one of the objective is the reliability taken between source and load point. For that , minimal cut sets and minimal paths has first to be for the given network In order to.evaluate the reliability at various load points, probabilistic reliability models of various components are considered. A.MINIMAL CUT SETS The minimal cut set effectively describes the combinations of component failure the top event to occur.