Real-time (RT) simulation and Hardware-in-the-Loop (HIL) techniques are crucial for modelling, analyzing, and testing electric power equipment and control systems in modern industry and research. This special issue focuses on RT-based systems and HIL experiments in power electronics and energy systems, exploring both theoretical and practical applications.

RT-based HIL simulation is a powerful tool for accurate, safe, and repeatable system analysis, covering areas like electromagnetic transient simulation, transient stability, shifted frequency analysis, and phasor-EMT simulation. HIL enables a real-time interaction between hardware and models using a simulator and HIL interface. There are two main HIL methods: Controller HIL (CHIL), which connects the hardware and model at the signal level without preserving natural coupling, and Power HIL (PHIL), which intends to maintain natural coupling at power interfaces to conserve power and ensure a realistic interaction between hardware apparatus and software model.

Global efforts, including IEEE Task Forces and Working Groups, are uniting manufacturers, academia, and industry to establish standards. The IEEE WG P2004 “Recommended Practice for Hardware-in-the-Loop (HIL) Simulation-Based Testing of Electric Power Apparatus and Controls” is set to release the first comprehensive HIL simulation standard in 2025.

Based on that, this special issue covers subsequent topics of high interest to the power system community and others:

  • Progress in HIL systems for power electronics, DC charging, and modern power grids,

  • Real-time controller testing using delay locked loop-based HIL setups,

  • Developing and validating real-time models through simulation and experiments,

  • HIL applications in standardised testing for power electronics and energy systems, and

  • Practical insights from industrial use of real-time HIL simulation in these areas.

These points are addressed in five selected articles in this issue. Mathews Boby et al. present a comparative study on emulating brushless DC machines using an advanced PHIL test bench, demonstrating improved accuracy and efficiency. Felix Göke et al. focus on the critical role of PHIL in testing low-inertia grids, addressing stability challenges in future energy systems. Paul Herbert Julius Kleutgens et al. detail the development of a high-power DC charging station test bench, enabling emulation of complex test scenarios and mission profiles. Tomasz Lerch et al. showcase rapid voltage fluctuation compensation using grid-tied converters, validated through PHIL experimentation. Finally, Aleksandra Lekic et al. introduce a converter controller DLL tailored for real-time HIL simulations, paving the way for enhanced simulation precision and control development. Together, these works underline the transformative potential of PHIL in advancing power system innovation.

We kindly invite the reader to take advantage of the presented innovations in science and engineering in these published original works. We truly hope you enjoy reading all these publications, anticipating, and understanding their ideas and concepts implemented—Bon Courage!

We would like to thank all authors for their excellent contributions and all reviewers for securing the quality of contributions being published in this journal. Finally, we would like to thank the e+i editorial team for their continuous support regarding the making and editing of this special issue.

Sincerely,

The Guest Editors:

Georg Lauss, Catalin Gavriluta, Thomas I. Strasser, and Friederich Kupzog