International Journal of Engineering Research-Online A Peer Reviewed International Journal Articles available online http://www.ijoer.in Vol.3., Issue.6., 2015 (Nov.-Dec.,) 207 ARADHANA, VIKRAMJEET SINGH I. INTRODUCTION The main task of a power system is to fulfill the demands of the customers by remaining in the economic limits for reliability as well quality [1] and for satisfying this condition, the system should remain operational [2].The most important consideration that need to be taken care of while designing a power system is to determine whether the generation is adequate to meet the requirements of customers or not. Another important consideration is to ensure a suitable transmission network for transmitting the generated electrical energy to load points [3]. The network used for transmission is further divided into two parts: the bulk transmission facilities and the distribution facilities. These two areas do not differ only in the level of voltages but also differ on the basis of their function in the system. The transmission facility or system is required to move the generated energy from the generating systems to such points through which the distribution facilities are required to provide a direct and radial path for this energy to reach the customers. The process of designing the distribution system does not depend on the transmission facilities. However, the transmission network must be carefully matched with the generation facilities in order to ensure a continuous supply to the customers. Apart from the function of moving the energy that has been generated at the generating stations to the terminal stations, the transmission system must ensure adequate voltage level within the system and maintain the system within the limits of stability. The system which takes into account both the generation and transmission facilities is called as the composite system .The evaluation of the composite system takes into account both the static and dynamic conditions of the system. The evaluation of the static conditions of the system is mainly concerned with the ability of the system to meet the load requirements is termed as the adequacy evaluation. On the other hand, the evaluation of the RESEARCH ARTICLE ISSN: 2321-7758 EVALUATION OF COMPOSITE POWER SYSTEM RELIABILITY INDICES ARADHANA 1 , VIKRAMJEET SINGH 2 1 Student Electrical Department, 2 Assistant Professor Department of Electrical Engineering SSCET Badhani, Punjab Technical University, India ABSTRACT The reliability evaluation of the power system is gaining importance as there is a need to provide a continuous supply of electrical energy to the consumers with acceptable value of voltages. In the past, emphasis was laid on the reliability evaluation of the generating systems only. This was because of the huge investment in such systems; however, nowadays the trend is to evaluate both the generating and transmitting systems. Such a system which takes into account both the generation and transmission system is known as the composite system. In this paper, an algorithm is proposed for evaluating the indices of reliability for a composite system. Then the results are obtained by using the algorithm developed with the help of PSO. Keywords— Power system reliability, Reliability evaluation, Reliability indices, Loss of Load Probability, Expected Load Loss. ©KY Publications