1 Abstract—Simulation tools for analysis and design of distribution systems with distributed resources (DR) must include modeling capabilities for representing the various DR technologies. Since distribution systems were not designed for the inclusion of DR, most distribution software packages were not designed for the analysis of systems with embedded generation either. Present distribution tools can efficiently cope, for instance, with unbalanced load-flow, but they cannot deal with transient stability. This paper is aimed at reviewing the present status and the future trends of simulation tools for planning, design and operation of distribution systems with penetration of DR. Index Terms—Distribution Systems, Distributed Energy Resources, Simulation, Modeling. I. INTRODUCTION ISTRIBUTED Energy Resources (DR) are a combination of power-generating technologies, energy storage devices and demand-side measures [1] - [3]. Although DR devices can be used to improve the performance of distribution systems and defer transmission and distribution system upgrade, distribution utilities are concerned with a wide range of issues associated with the interconnection of DR, such as protection coordination problems, islanding conditions, or power quality impact, [4], [5]. Some aspects to be considered are the great variety of generating and energy storage devices [6], the fact that some DR devices are connected to the utility network via a static converter [7], and the intermittent nature of some renewable sources. Depending on size, DR devices are either connected to the MV level or at the LV level. Simulation tools must combine traditional and new analysis capabilities with a vast number of modeling capabilities for representing the various DR and energy storage technologies, in addition to the conventional distribution system components. The development of a fit-all solution for simulation of distribution systems with DR penetration is a Juan A. Martinez is with the Departament d’Enginyeria Elèctrica, Universitat Politècnica de Catalunya, 08028 Barcelona, Spain. Email: martinez@ee.upc.edu. Francisco de Leon is with the Department of Electrical and Computer Engineering of Polytechnic Institute of NYU, Six Metrotech Center, Brooklyn, NY 11201. Email: fdeleon@poly.edu. Venkata Dinavahi is with the Department of Electrical & Computer Engineering, University of Alberta, Edmonton, Alberta, Canada T6G 2V4. Email: dinavahi@ece.ualberta.ca. major challenge for software manufacturers. Distribution software packages were primarily designed for analyzing distribution systems that are radial and were not conceived with DR in mind. There have been, on the other hand, general purpose simulation tools, such as EMTP-type tools [8], that can cope with many of the new modeling challenges, but they are not adequate for some types of studies (e.g., reliability performance, optimization studies), although most EMTP-type tools can perform both steady-state and transient calculations, and even allow users to create custom- made packages by adding capabilities from general purpose and specialized simulation tools [8]. Software manufacturers are updating and expanding tool capabilities taking into account the new simulation challenges. New and specialized tools have been developed to cope with some important distribution system problems related to the installation of DR devices, and a new generation of simulation tools is under development; see for instance [9]. This paper includes sections dedicated to summarize the present status of simulation tools (i) for feasibility studies of distributed generation plants, (ii) for planning, design and operation of distribution systems, as well as (iii) new trends in software development for distribution system studies with DR penetration, including real-time simulation platforms. Section II summarizes the type of studies and models that are required to carry out these tasks. II. STUDIES AND MODELS The studies related to the interconnection of DR devices and the development of distribution software packages are performed under the assumption that the basic distribution infrastructure and characteristics will remain as they are today. Therefore, current models can be useful for studies with a high penetration of DR. Performance criteria currently applied at the distribution system level can be also used for assessing interconnected DR operation; however, the possible interconnections to DR are many, and it is not realistic to anticipate all the practical concerns of future designs; for instance, the future assessment of island scenarios could be less restrictive than today. Distribution packages must include models for conventional power components (lines, cables, transformers, voltage regulators, capacitor banks), protective devices, loads, DR devices and associated controls. Models for energy resources (e.g., wind, solar, biomass, fuel or hydro resources) Simulation Tools for Analysis of Distribution Systems with Distributed Resources. Present and Future Trends Juan A. Martinez, Francisco de León, and Venkata Dinavahi D 978-1-4244-6551-4/10/$26.00 ©2010 IEEE Authorized licensed use limited to: UNIVERSITY OF ALBERTA. Downloaded on April 30,2022 at 22:25:45 UTC from IEEE Xplore. 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