0885-8950 (c) 2015 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information. This article has been accepted for publication in a future issue of this journal, but has not been fully edited. Content may change prior to final publication. Citation information: DOI 10.1109/TPWRS.2016.2549747, IEEE Transactions on Power Systems 1 Abstract— This paper proposes a generalized analytical ap- proach to evaluate the reliability of active distribution networks. The studies are implemented in the context of renewable-based energy hubs. The reliability of energy demands is determined as a function of reliability characteristics of energy hub input re- sources and converters as well as hub operating strategies. The framework proposed in this paper involves the main attributes of different distributed generation (DG) technologies as well as vehi- cle-to-grid (V2G)-capable vehicles in the reliability studies. Deal- ing with the uncertainty in energy services provided by the wind turbine output generation and V2G programs, efficient probabil- istic methods are presented to attain the reliability models of these energy resources for the studies. The fluctuations in energy de- mands are also represented through multi-state analytical models. Convolving the probabilistic models of energy hub resources by the load profiles’ models, different reliability indices are calculat- ed taking into consideration possible operating strategies of the energy hubs. Effectiveness of the proposed methodology is vali- dated using extensive numerical studies on an energy hub and the obtained results demonstrate its applicability in adequacy studies of active energy networks. Index Terms—Analytical approach, electric vehicles, energy hub, reliability studies, wind turbine. I. INTRODUCTION ONCERNS over environmental pollution and security of energy supply have arisen in the last few decades due to the fast increase in demand for fossil fuels and dwindling re- sources [1]. An effective strategy for mitigating these concerns is to focus on the main contributors to energy demand, i.e. electricity industry and transportation sector [2]. Some efforts have recently been devoted to the transportation sector as a major consumer of fossil energies with the target of shifting its primary source of energy from fossil fuels to electricity. Elec- tric vehicles (EVs) are currently a proper option for fulfilling this target. Therefore, in the upcoming years, large fleets of EVs will constitute a significant share of electricity demand. However, supplying this new load from conventional units, rather than This work was supported by the Iran National Sicence Foundation. M. Moeini-Aghtaie, H. Farzin, M. Fotuhi-Firuzabad are with the Center of Excel- lence in Power System Management and Control, Department of Electrical Engineering, Sharif University of Technology, Tehran, 11365-11155, Iran. (e- mails: m.moeini@ieee.org; farzin@ee.sharif.edu; fotuhi@sharif.edu). R. Amrollahi is with Department of Energy Engineering and Physics, Amirkabir University of Technology, Tehran, 15875-4413, Iran (e-mail: am- rollahi@aut.ac.ir). decreasing the emissions imposed on the environment, would merely shift its source to electricity industry. Moving towards more renewable-based distributed generation (DG) units for electricity generation can be a key solution to this dilemma. Moreover, the plug-in electric vehicles (PEVs) in discharging mode can feed the power back into the grid as vehicle-to-grid (V2G) devices. These two upcoming events, i.e. presence of PEVs and proliferation of DGs, call for a significant transition phase for power systems from passive nodes with unidirec- tional power flow to active ones with bidirectional power flow including small-scale generators [3]. These active nodes which form the future vision of distribu- tion systems call for new tools and techniques for technical studies of power systems [4]. The radial feeders with a main source of power from the higher voltage levels have been used as a widespread operating strategy in distribution systems for many years around the world. Hence, considerable engineering expertise and well-organized evaluation techniques have been resulted from the long operating experiences of such systems. Nonetheless, the next generation of distribution systems inte- grated by various technologies of DGs and electric vehicles as some dispersed storage units/systems has to face with new uncertainties and challenges, which add more complexities to technical evaluation procedures of these systems. In the future distribution systems, customers with sensitive equipment will be more dependent on the quality and continui- ty of the electrical service [5] and [6]. As a result, the reliabil- ity studies of distribution system have grabbed more attention of the researchers as a technical issue being important in view- point of both customers and utilities [7]-[9]. Random and se- quential Monte-Carlo Simulation (MCS) methods have been applied in [7] to assess the reliability level of smart distribu- tion grid considering intentional islanding. The authors in [8] tried to investigate that how the charging process of EVs can be considered as an interruption load in distribution networks. In this regard, some indices have been specialized for repre- senting the reliability level of charging services and the effects of both coordinated and uncoordinated charging schemes on reliability of distribution grid has been examined. Investigating the impacts of DG technologies especially the conventional types on the reliability of distribution systems have been extensively studied in the past works [10]-[13]. These works were unable to present an effective algorithm for adequacy studies of distribution systems including renewable- Generalized Analytical Approach to Assess Reliability of Renewable-Based Energy Hubs Moein Moeini-Aghtaie, Member, IEEE, Hossein Farzin, Mahmud Fotuhi-Firuzabad, Fellow, IEEE, and Reza Amrollahi C