Renewable and Sustainable Energy Reviews 133 (2020) 110140 Available online 2 August 2020 1364-0321/© 2020 Elsevier Ltd. All rights reserved. Shunt fault analysis methodology for power distribution networks with inverter-based distributed energy resources of the Korea Electric Power Corporation Namhun Cho a , Sangwon Yun b , Jaesung Jung b, * a Korea Electric Power Corporation Research Institute, Daejeon, South Korea b Department of Energy Systems Research, Ajou University, Suwon, South Korea A R T I C L E INFO Keywords: Shunt fault analysis Inverter-based distributed energy resources Sequence network Superposition principle Distribution management systems ABSTRACT Recently, the interconnection of distributed energy resources (DERs) has been observed to hinder the reliability of power supply. To solve this problem, the Korea Electric Power Corporation (KEPCO) has attempted to develop a practical fault analysis methodology for DERs that can be applied to distribution management system (DMS). This novel methodology to analyze the impacts of various DERs during shunt faults is presented in this paper. First, the basic concepts behind the proposed methodology are introduced. Then, the fault analysis methodology is introduced to determine the contributions of balanced and unbalanced DERs during shunt faults. Finally, the accuracy and feasibility of the proposed method are confirmed using SIMULINK and the IEEE 30-bus system, respectively. Based on the analyses, the proposed methodology is expected to be integrated with the rapidly developing distribution automation and management system of the KEPCO. 1. Introduction In recent times, the strong desire for green and less-polluting power generation to meet environmental policy targets and technological re- quirements of alternative energy sources have motivated the rapid growth of distributed energy resources (DERs) for power systems in many countries, including South Korea [1–6]. Emphasis on the smart grid technology has enabled electrical power distribution systems to be more important parts of electrical power systems [7]. Thus, power utilities are interested in exploring distribution management systems to enhance their own distribution systems such that they are more intel- ligent, efficient, reliable, and cost-effective. The interconnection of distributed generation (DG) to electrical distribution systems, which is primarily designed to serve radial loads, must not affect the reliability and quality of supply to consumers or the safety of the public and equipment [8–11]. Thus, Korea Electric Power Corporation (KEPCO), which is the sole electrical utility in South Korea, needed to develop a calculation methodology for fault current contri- bution of inverter-based renewable energy sources in accordance with the IEEE Standard 1547. Generally, utility providers who have distri- bution management systems (DMS) prefer steady-state fault analysis methodologies for their simplicity and associated computational time. Two types of technologies for grid connections are commonly used in DER applications: inverter-based technology and rotating machine technology [12]. Distributed generators based on synchronous genera- tors (SGs) connected to the grid can be modeled as voltage sources using the Thevenin equivalent circuit. However, generators interfaced via inverter-based DERs can be modeled as current sources because the converters are often current-controlled voltage sources whose contri- butions are balanced by control designs in most cases and by the re- quirements of current grid codes (resulting in positive-sequence contributions only) [13–17]. Because inverter-based DERs have different structures and control strategies compared to conventional SGs, their impacts on the power grid require different analysis ap- proaches. Thus, the IEEE Standard 1547 assumes that the fault current from a self-commutated inverter usually ranges between 1.2 and 1.5 times the rated load current of the inverter [18]. Previous studies note that the current magnitude limit of the DER is maximally 1–2 times that of the rated current during a fault [19,20]. Another study suggested that the source impedance of the inverter-based DER seen from the grid was “very high” and that the source should be able to limit the output current up to approximately 1.1 per unit [21]. Moreover, in Refs. [22], the fault-current contributions of inverter-based DERs were not severe when compared to those of the SGs. This is because inverter-based DERs could limit the output current by control logic or hardware capabilities during * Corresponding author.Power System Laboratory, Energy Center 210, Ajou University, Worldcup-ro 206, Yeongtong-gu, Suwon, South Korea. E-mail address: jjung@ajou.ac.kr (J. Jung). Contents lists available at ScienceDirect Renewable and Sustainable Energy Reviews journal homepage: http://www.elsevier.com/locate/rser https://doi.org/10.1016/j.rser.2020.110140 Received 9 September 2019; Received in revised form 20 July 2020; Accepted 21 July 2020