Reliability Evaluation and Improvement in Voltage Profile of Distribution System Rashmi Kannur Shivaleela Kori Dept. of EEE Dept of EEE SDM College of Engineering and Technology Acharya Institute Of Technology Dharwad-580002 Bangalore-576107 Dr. S. G. Ankaliki Arathi Sunkara Professor, Dept. of EEE Dept of EEE SDM College of Engineering and Technology SDM College of Engineering and Technology Dharwad-586002 Dharwad-586002 Abstract-In this paper an effective approach of real time evaluation of radial distribution system is done. A power flow solution with an objective of determining the reliability indices, improving the voltage profile and reduction of power loss by placement of shunt capacitor is carried out. In this approach an analytical method is used to calculate the load and system indices for existing distribution system. To demonstrate the effectives of the proposed method, a 110/11KV substation is selected for analyzing the performance. From the result it is observed that by placement of shunt capacitor in the distribution system there is improvement in voltage profile and reduction in total loss. Keywords: Radial distribution system, Reliability indices, Voltage profile, Total loss. I. INTRODUCTION Power system efficiency depends on distribution system. Distribution system provides link between transmission system and actual customers. A distribution system normally consists of main feeder or primary feeder and laterals. The primary feeder starts from substation and passes through the major loads. Laterals connect between individual load and main feeder with distribution transformers. Radial distribution systems are popular because of their simple design and low cost. The main function of power system is to feed loads with electric energy as economically as possible with a reasonable level of reliability and power quality. Distribution system is one of the main part of power system. It is responsible for transferring electrical energy to its end users. A distribution system is relatively cheap and outages in this part of the system have a very localised effect compared with generation and transmission system. However, analysis of the customer failure statistics of most utilities indicates that the distribution system makes the greatest individual contribution to the unavailability of supply to a customer. Distribution system performance evaluation usually relies on reliability index to evaluate system operation. Hence, important aspects form system operations such as voltage profile, line/transformer, over loadings are normally assessed for scenarios. Recently, some researchers have focused on improving distribution system performance assessment. For that in [1] the probability distributions from the distribution system reliability indices are evaluated using a Sequential Monte Carlo simulation (SMCS) approach from the service adequacy perspective. In [2], DG peaking and standby modes are represented in an analytical approach for distribution system reliability assessment. In [3], an analytical technique for distribution system reliability is developed, where the probability of successful islanding is taken into account. In [4], the stochastic nature of the system operation with parallel connected customer controlled DG units is evaluated from the adequacy point of view. Capacitor placement has been discussed in technical literature since 1980‟s as the distribution system planning and operation started. Shunt capacitors are commonly used in distribution systems to reduce the power losses, to improve the voltage profile and to increase the power flow. The [6] method of placement of capacitor done by considering some constraints like load constraints and operational constraints are presented and simulated annealing is used to solve this optimization. A [7] new and fast energy loss calculation technique is presented in this literature. The optimal placement of capacitors using loss minimization as the object is presented in lot of literatures. The energy loss calculation method is changed to make it faster. Genetic algorithm is used to solve the optimal placement problem Here [1].There are two types of switches in primary distribution systems: normally closed switches which connect line sections, and normally open switches on the tie-lines which connect two primary feeders, or two substations or loop-type laterals. II. RELIABILITY INDICES The distribution system operation can be assessed using analytical and Monte Carlo Simulation techniques. The reliability indices that have been evaluated using classical concepts are the three primary ones of average failure rate, 1827 Vol. 3 Issue 4, April - 2014 International Journal of Engineering Research & Technology (IJERT) ISSN: 2278-0181 www.ijert.org IJERTV3IS041823 International Journal of Engineering Research & Technology (IJERT)