The transmission systems are heading towards hybrid using high-voltage AC and DC connections. Power electronic converters contribute to significant changes in the operation and control of the system, its stability, and robustness. For the design of a hybrid electrical grid and preparation for its physical deployment, real-time simulations and hardware-in-the-loop testing are a must. This tutorial covers the design aspects of the power electronic converters used for DC applications (MMCs) and control of the power systems with the high penetration of renewable energy sources using the real-time hardware, RTDS©. The tutorial will use RSCAD/RTDS open-source libraries during the “hands-on” sessions in RSCAD/RTDS. The participants will be divided into 10 groups, supported by a computer with installed RSCAD and secured access to RTDS cores. Furthermore, one RTDS NovaCor (10 cores) will be present, and the participants will be able to see its operation and connection. Participants: Dr. Aleksandra Lekić, Assistant Professor, Delft University of Technology, Delft, Netherlands, A.Lekic@tudelft.nl Prof. Dr. Pablo Eguia Lopez, Professor, University of the Basque County UPV/EHU, Spain, pablo.eguia@ehu.eus Dr. Vaibhav Nougain, Postdoc, Delft University of Technology, Delft, Netherlands, V.Nougain@tudelft.nl Milovan Majstorović, Ph.D. researcher, University of Belgrade, Serbia, majstorovic@etf.bg.ac.rs Remko Koornneef, Technician, Delft University of Technology, Delft, Netherlands, R.N.Koornneef@tudelft.nl

There are major discussions worldwide on how the production of clean fuels, such as hydrogen, could facilitate the whole-energy system decarbonization. From a power system perspective, green hydrogen production results in massive grid integration of electrolyzers, that needs to be considered in power system analysis. This tutorial presents the modelling foundations of utility-scale hydrogen electrolyzers with alkaline and proton exchange membrane (PEM) technology, including electrolysis stack models, power electronics interface (PEI) and control, thermodynamics, hydrogen production formulations, and operational constraints in downstream hydrogen process/buffer, required for system-level steady-state and dynamic studies in both transmission and distribution grids. Possible PEIs for grid integration of electrolyzers will be discussed, along with the associated control schemes in particular grid-forming load control. It will be discussed how and to what extent electrolysis plants could impact system stability and operation, from both steady-state and dynamic perspectives