Smart Grid and Renewable Energy, 2014, 5, 52-62 Published Online March 2014 in SciRes. http://www.scirp.org/journal/sgre http://dx.doi.org/10.4236/sgre.2014.53006 How to cite this paper: Abul’Wafa, A.R. and Taha, A.T.M. (2014) Reliability Evaluation of Distribution Systems under μ Grid-Tied and Islanded μ Grid Modes Using Monte Carlo Simulation. Smart Grid and Renewable Energy, 5, 52-62. http://dx.doi.org/10.4236/sgre.2014.53006 Reliability Evaluation of Distribution Systems under μ Grid-Tied and Islanded μ Grid Modes Using Monte Carlo Simulation Ahmed R. Abul’Wafa, A. T. M. Taha Department of Electric Power and Machines, Faculty of Engineering, Ain-Shams University, Cairo, Egypt Email: Ahmedlaila.nelly.ola@gmail.com , adel_taha06@yahoo.com Received 13 January 2014; revised 12 February 2014; accepted 18 February 2014 Copyright © 2014 by authors and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY). http://creativecommons.org/licenses/by/4.0/ Abstract Reliability evaluation of distribution networks under grid-tied and islanded µ grid modes is pre- sented. The Monte Carlo simulation (MCS) algorithm is applied to a modified RBTS Bus 2 distribu- tion network. The network includes three types of distributed energy resources, namely, solar photovoltaic (PV), wind turbine (WT), and diesel turbine generator (DTG). These distributed ge- nerators contribute to supply part of the load during grid-connected mode, but supply 100% of the load in the islanded µ grid mode. A storage system is included to decrease the peak load since the peak of the output power of the PV’s and the peak load do not match time wise in most load profiles. The impact of implementing renewable distributed generation, storage systems, and conventional generation on the reliability of distribution network is studied. This study shows that the penetration of distributed generations can improve the reliability indices of the distribu- tion network. Keywords Reliability Evaluation; Monte Carlo Simulation; Distributed Generations 1. Introduction In recent years, interest in application of distributed generation (DG) in improving power system reliability has grown tremendously [1] [2]. This interest is motivated by the potential to use renewable resources to generate electricity in distribution networks on a small scale, which can lead to μ grid configurations. The implementa- tion of μ grids in distribution networks promises a higher level of reliability [3] [4]. One of the promising fea- tures of μ grids is the capability to perform auto-configuration of distribution networks without the interaction of