Received October 9, 2021, accepted October 29, 2021, date of publication November 15, 2021, date of current version November 24, 2021. Digital Object Identifier 10.1109/ACCESS.2021.3128370 Real-Time Hardware-in-the-Loop Testing of IEC 61850 GOOSE-Based Logically Selective Adaptive Protection of AC Microgrid AUSHIQ ALI MEMON , (Member, IEEE), AND KIMMO KAUHANIEMI , (Member, IEEE) School of Technology and Innovations, University of Vaasa, 65200 Vaasa, Finland Corresponding author: Aushiq Ali Memon (amemon@uwasa.fi) This work was supported in part by Business Finland through the SolarX Research Project under Grant 6844/31/2018, and in part by the European Regional Development Fund (ERDF) through the VINPOWER Research Project under Grant A73094. ABSTRACT The real-time (RT) hardware-in-the-loop (HIL) simulation-based testing is getting popular for power systems and power electronics applications. The HIL testing provides the interactive environment between the actual power system components like control and protection devices and simulated power system networks including different communication protocols. Therefore, the results of the RT simulation and HIL testing before the actual implementation in the field are generally more acceptable than offline simulations. This paper reviews the HIL testing methods and applications in the recent literature and presents a step-by-step documentation of a new HIL testing setup for a specific case study. The case study evaluates real-time implementation of previously proposed communication-dependent logically selective adaptive protection algorithm of AC microgrids using HIL testing of IEC 61850 generic object-oriented substa- tion event (GOOSE) protocol. The RT model of AC microgrid including the converter-based distributed energy resources and battery storage along with IEC 61850 GOOSE protocol implementation is created in MATLAB/Simulink and RT-LAB software using OPAL-RT simulator platform. Local area network (LAN) at the laboratory acts as IEC 61850 station bus for exchanging GOOSE Boolean signals between the RT target and the actual digital relay. The evaluation of the round-trip delay using the RT simulation has been performed. It is found that the whole process of fault detection, isolation and adaptive setting using Ethernet communication is possible within the standard low voltage ride through curve maintaining the seamless transition to the islanded mode. The signal monitoring inside the relay is suggested to avoid false tripping of the relay. INDEX TERMS Adaptive protection, AC microgrid, logic selectivity, IEC 61850 GOOSE, real-time simulation, HIL testing, converter-based DERs, battery storage. I. INTRODUCTION Microgrids are the local distribution systems connected with many local distributed energy resources (DERs) and controllable/non-controllable loads with the capability of operating in both the grid-connected and intentional or unin- tentional islanding modes. The DERs or generators in micro- grids include the small-scale variable or non-dispatchable renewable energy sources (VRES) like the wind tur- bine generators (WTGs) and solar photovoltaic (PV) sys- tems and non-variable or dispatchable RES (NVRES) like The associate editor coordinating the review of this manuscript and approving it for publication was Siqi Bu . mini-hydropower, biomass, geothermal and other combined heat and power (CHP) generators. The VRES usually require some form of energy storage systems (ESS) like bat- tery energy storage systems (BESS), superconducting mag- netic energy storage (SMES), supercapacitors (SC), flywheel energy storage systems (FESS) and pumped hydroelectric energy storage (PHES) to smooth out the short, medium and long term operational and weather-related power fluctu- ations. The ESS including BESS, FESS, and electric vehicles (EVs) may behave like controllable loads when working in the charging mode and as controllable generators when working in the discharging mode. So, depending on the avail- ability of power generation resources measured in terms of 154612 This work is licensed under a Creative Commons Attribution 4.0 License. For more information, see https://creativecommons.org/licenses/by/4.0/ VOLUME 9, 2021