Grid Forming: Academic Approaches and Modelling Aspects [Academic GF Tutorial]

LUNCH

Lecture 1 (45 min.)
Grid-forming and wide-area damping control
Rossano Musca (University of Palermo, Italy)

Grid-forming converters represent a unique opportunity in contributing to power system operation and control. A relevant area which recently started to receive attention is the application of grid-forming converters within the wide-area damping control of power systems. Thanks to the flexibility in the formulation of the power-angle control law, grid-forming technology can play a fundamental role in the actuation of wide-area damping control schemes.

The tutorial will first recall the main concepts and characteristics of wide-area damping control. Then, the tutorial will delve into the integration of grid-forming converters within specific architectures for the wide-area damping control of power systems. It will be shown the potential benefit in terms of damping of inter-area oscillations and improvement of power system dynamics, highlighting the theoretical aspects and referring to the interconnected power system of Continental Europe as demonstrative example.

Discussion (15 min)

Lecture 2 (45 min.)
Data-driven methods for assessment and control of power systems with GFMs
Francisco Fernandes (INESC TEC, Portugal)

This tutorial demonstrates how the integration of high‑fidelity power system modelling environments with interpretable, data‑driven learning methods can support dynamic security assessment and the design of controllers in power systems dominated by grid‑forming (GFM) converters.

It first discusses a range of learning approaches capable of generating interpretable, equation‑based representations of system dynamics, followed by an analysis of the modelling requirements necessary to support such methodologies. The tutorial then presents several representative test cases, including the co‑design of GFM converter controllers, dynamic security assessment of islanded power systems, and the development of load‑shedding schemes.

Throughout, particular emphasis is placed on identifying where these approaches provide insights into system physics and on understanding how appropriate modelling choices enable the extraction of actionable physical knowledge from data‑driven methods.

Discussion  (15 min)

Coffee Break

Lecture 3 (45 min.)
Current limitation techniques for grid-forming converters in three-phase and single-phase systems
Frédéric Colas (University of Lille, France)

Grid-forming converters, unlike synchronous machines, are highly sensitive to overcurrents and therefore require dedicated protection mechanisms. This tutorial first introduces two classical strategies for current limitation. The first is the increase of virtual impedance, which effectively reduces the current but can introduce long transients. The second is the saturation of current references, which directly enforces a current limit but may compromise the ability of the system to resynchronize after a fault. Simulation results will demonstrate that while both methods are capable of protecting the converter, they can have adverse consequences for stability after large disturbances. Differences between three-phase and single phase systems will be also highlighted.

The second part of the tutorial focuses on large disturbance stability. From static models originally developed for synchronous machines, the presentation shows how grid-forming converters react under severe events such as bolted faults, and sudden phase shifts. Traditional stability assessment tools such as the Equal Area Criterion are shown to be of limited use for converters due to their inherent damping. Fault scenarios highlight the difficulty of maintaining synchronism once current limitation is activated. Classical enhancement methods such as phase angle freezing and voltage-dependent adaptations—based on adaptive inertia or power reference reduction—are discussed. These methods can improve stability during voltage dips but fail to address pure phase-shift disturbances, leaving a gap in robustness.

The third part introduces a novel approach based on the concept of virtual power. By redefining the power variable used in control, this method decouples current limitation from large disturbance stability and increases the stability margin of the system. It allows converters to resynchronize reliably after severe faults, whether caused by voltage dips or angle shifts. Experimental results obtained on a 7.5 kVA three-phase test bench and on a single-phase industrial converter confirm the validity of the method and its potential for practical deployment.

Discussion (15 min)

Lecture 4 (45 min.)
Frequency Characteristics and Requirements for Grid-forming Converter Control
Massimo Bongiorno (Chalmers University of Technology, Sweden)

Grid-forming (GFM) capabilities are increasingly regarded as an essential requirement for grid-connected converters, particularly in high-power and high-voltage applications. Over the last decade, the rapid integration of renewable energy sources and the growing need for controllability in electric power systems have driven a transition in converter control philosophy, moving from purely fast-acting control schemes toward strategies that inherently contribute to grid stability and resilience during disturbances. At the same time, a universally accepted definition of GFM control remains elusive.

Starting from the needs of the power system, this talk discusses the key requirements of GFM converters and investigates the frequency-domain characteristics that such systems should provide to support the grid effectively. With the objective of ensuring continuous grid support, modifications to the classical GFM control structure are presented that naturally enable the provision of essential services, including inertial response, damping of sub-synchronous oscillations, and handling of unbalance and harmonic disturbances.

Discussion & Closing (15 min)