Modern Applied Science; Vol. 8, No. 5; 2014 ISSN 1913-1844 E-ISSN 1913-1852 Published by Canadian Center of Science and Education 45 Reliability Worth Assessment in Composite Power System Planning and Operation Ali Khraiwish Dalabeeh 1 & Eng.Hani Hasan Saleh Al-Hajbi 2 1 Department of Electrical Engineering, Faculty of Engineering Technology, Al-Balqa' Applied University, Jordan 2 National Electric Power Company, Amman, Jordan Correspondence: Ali Khraiwish Dalabeeh, Department of Electrical Engineering, Faculty of Engineering Technology, Al-Balqa' Applied University, P.O.BOX 15008, Amman 11134, Jordan. E-mail: alidalabeeh@yahoo.com Received: May 20, 2014 Accepted: June 3, 2014 Online Published: August 6, 2014 doi:10.5539/mas.v8n5p45 URL: http://dx.doi.org/10.5539/mas.v8n5p45 Abstract This study presents a comprehensive procedure for evaluating the reliability indices incorporating reduction in interruption cost, and to relate reliability investments with customer’s benefits. An analytical algorithm is used to obtain the final optimal operational solution by determining unit commitment for each generating unit to reach the maximum profit (minimizing cost) subjected to operational constraints. The paper describes a method based on the complementing short-term planning with long-term planning take into account the cost benefit approach. The proposed method has been demonstrated on the RBTS to show the feasibility and the economic effect of the proposed method, and was applied to the Jordanian Electric Power System (JEPS) to show its application capability. Keywords: reliability indices, power system planning, power system operation, interruption cost 1. Introduction The primary function of a modern power system is to supply its customers with electrical energy as economically as possible with an acceptable degree of reliability. Load curtailment takes place in the system as a result of the inadequacy of the generation unit’s capacity to meet the demand or the deficiencies in transmission lines. This is a result of poor planning and failure to take the appropriate steps to use available resources to meet deal with the increase in future loads economically with acceptable reliability and quality. Evaluation of restructured power systems provide both economic and reliability information for generation companies and transmission companies to enhance generation capacity and to expand transmission lines, so a decision should be made to choose among the various transmission system expansion or the new generating units addition alternatives the most reliable and beneficial one not only from a power utility’ standpoint but also from customers’ viewpoint. There is a need to know customer and user outage costs and to be included and considered in system planning and operational decisions. Power suppliers aimed to enhance system reliability within the available amount of investment while the customer needs fewer service interruptions, and less destruction caused by these interruptions. The main objective of power system restructuring and deregulation is to introduce competition in the power industry and to allow customers to select their suppliers based on price and reliability (Wang & Billinton, 2003). In recent years and at the same time as the restructuring in the power industry, various studies have been carried out into the Transmission Expansion Planning (TEP) in electricity markets and its adjustment to market conditions (Shayeghi, et al., 2008; Buygi, et al., 2003; Wu, et al., 2006). In Sirjani, et al., (2008) and Fu, et al. (2008), there are some criteria and models for creating competition in the electricity market. In (De la Torre, et al., 2008), by considering that users’ benefit increase is one of the TEP goals a model is presented that can be utilized by all participants. Also, in Shrestha and Fonseka (2004), optimization the users’ benefit and investment cost is evaluated as a single-objective model. In Wangdee (2005), Eliassi, et al., (2009), a probabilistic criterion, known as Expected Customer Interruption Cost (ECOST) due to transmission constraint is presented to evaluate the value of reliability. In (Bresesti, et al, 2009), a method is presented for evaluating the users’ benefit and reliability in TEP, which is based on Monte Carlo simulation. TEP should serve its users, so the benefit of both participants in the market and investment cost are considered as economic criteria for the