Grid-Forming Inverter-Based Resources in Electricity Systems Integration

Dear Colleagues,

The primary objective of electrical power systems is to continuously supply load demand, while complying with regulatory quality standards and minimizing costs. This is currently made possible through services provided by grid codes and/or through market mechanisms.

Over the past decades, the increasing penetration of generation systems based on non-programmable renewable energy sources, such as wind and solar, has progressively transformed electrical power systems from centralized systems to highly distributed systems. Generation systems based on non-programmable renewable energy sources are, with few exceptions, interfaced to the electrical power systems through an inverter and are, therefore, commonly referred to as inverter-based resources. The growing deployment of inverter-based resources is expected to gradually displace synchronous generators, leading to a loss of typical services intrinsically provided by synchronous generators and their associated regulation mechanisms. This transition necessitates a critical rethinking of EPS operation and control strategies.

To address this evolution, an increasing share of inverter-based resources must be capable of replicating at least some of the functionalities currently provided by synchronous generators. Currently, however, almost all IBRs deployed in electrical power systems rely on grid-following inverters, which are inherently unable to deliver the conventional services traditionally ensured by synchronous generators.

Therefore, to support this growth, it is essential to introduce inverter-based resources using alternative control strategies, specifically grid-forming control. The introduction of grid-forming inverter-based resources, particularly when combined with appropriate energy storage systems, can allow the IBR to emulate the behavior of synchronous generators in terms of inertia as well as primary and secondary frequency regulation. Thanks to inverter-based resources with grid-forming control, both renewable generation plants designed for direct injection into the grid (often utility-scale) and plants located at the demand level (typically characterized by small-scale generation units) could potentially be grouped to form microgrids. These microgrids would be capable of operating in both grid-connected and islanded modes, thus reducing the risk of large-scale blackouts in traditional electrical power systems. In this context, grid-forming inverter-based resources are considered a key enabling technology for future electrical power systems, where energy production is increasingly dominated by the combination of non-programmable renewable energy sources, energy storage systems, and grid-forming inverter-based resources.

The integration of grid-forming inverter-based resources into electrical power systems calls for rigorous validation and testing procedures to ensure their capability to operate reliably within complex scenarios. These include interactions with heterogeneous components such as grid-following inverter-based resources, energy storage systems, and diverse types of loads, all within microgrid configurations that may operate either in grid-connected or islanded mode. Assessing the dynamic behavior of such systems under varying operating conditions is inherently challenging, as it demands detailed simulations that often become computationally intensive and time-consuming when using conventional simulation tools. In this context, real-time simulations play a fundamental role. They provide a powerful tool to implement and evaluate inverter control algorithms under realistic conditions, significantly reducing both development time and costs. Real-time simulations environments support Software-in-the-Loop, Hardware-in-the-Loop, and Power-Hardware-in-the-Loop approaches, enabling the testing of software within a simulated high-fidelity physical environment or specific hardware subsystems interfaced to a simulated environment. This capability accelerates prototyping, improves design robustness, and facilitates the transition from conceptual control strategies to practical deployment.

Real-time simulations thus facilitate the assessment of inverter control performance within realistic and scalable models, ultimately accelerating the transition from theoretical design to practical implementation.

Topics:

For this Special Issue, titled “Grid-Forming Inverter-based resources in Electricity Systems Integration”, we invite the electrical community, engineers, and researchers to present their state-of-the-art findings, research, and experiences in the field covering, but not limited to, the following topics:

• Real-time simulations of grid-forming inverter-based resources using Software-in-the-Loop, Hardware-in-the-Loop, and/or Power-Hardware-in-the-Loop
• Development of realistic test scenarios to evaluate the resilience and stability of electrical power systems with grid-forming inverter-based resources under different operating conditions and in the presence of disturbances.
• Modeling and real-time simulations of energy storage systems integrated with grid-forming inverter-based resources in microgrids;
• Application of real-time simulations for the development and validation of advanced control strategies for frequency and voltage regulation using grid-forming inverter-based resources.
• Study of the interaction between grid-forming inverter-based resources and grid-following inverter-based resources, energy storage systems, and/or synchronous generators in energy transition scenarios.
• Simulation of the dynamic behavior of microgrids operating in grid-connected and islanded condition in the presence of grid-forming inverter-based resources.
• Real-time simulations for optimizing energy management and the coordination of multiple grid-forming inverter-based resources and energy storage systems in complex grids.

Dr. Nicola Sorrentino
Prof. Dr. Daniele Menniti
Dr. Giovanni Brusco
Dr. Giuseppe Barone
Guest Editors

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• inverter-based resources
• distributed electrical power systems
• energy storage systems
• grid-forming control
• renewable energy sources
• microgrids
• grid-forming inverter
• synchronous generators