Equivalent Representation of Modern Power Systems with Power Electronics for Stability Analysis

Project Information

EQUATOR

Grant agreement ID: 101153248

DOI

10.3030/101153248

Project closed

EC signature date 7 May 2024

Start date 1 July 2024

End date 30 June 2026

Funded under

• Marie Skłodowska-Curie Actions (MSCA)

Total cost

No data

EU contribution

€ 191 100,00

Coordinated by

KATHOLIEKE UNIVERSITEIT LEUVEN
Belgium

Periodic Reporting for period 1 - EQUATOR (Equivalent Representation of Modern Power Systems with Power Electronics for Stability Analysis)

Reporting period: 2024-07-01 to 2026-06-30

Summary of the context and overall objectives of the project

The transition towards a carbon-neutral energy system is rapidly increasing the penetration of power-electronic converters in modern power systems. While this transformation is essential to achieve the European Green Deal objectives, it also introduces new challenges for system stability, protection, and operation. In particular, conventional equivalent representations and grid-strength concepts, such as Thévenin equivalents and short-circuit ratio (SCR), are increasingly unable to accurately capture the dynamic behavior of modern converter-based power systems. The EQUATOR project was established to address this challenge by developing new equivalent-modelling methodologies for converter-dominated power systems. The project aimed to create simplified yet accurate representations suitable for both small-signal stability analysis and transient stability assessment under large disturbances, while explicitly accounting for converter controls, grid-forming operation, frequency dynamics, and converter current limitations. The expected impact of EQUATOR is to provide researchers, transmission system operators and manufacturers with more effective tools for analyzing future converter-dominated power systems. By improving the understanding and assessment of stability, protection, and security challenges in low-inertia networks, the project contributes to the reliable integration of renewable energy and supports the development of resilient and sustainable electricity systems in Europe.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The EQUATOR project developed novel equivalent-modelling methodologies for the stability analysis of modern power systems with high penetration of power-electronic converters. The work advanced both small-signal and transient stability assessment by developing new equivalent representations of grid-forming converters, frequency dynamics, and converter-dominated networks. Key scientific achievements include: (i) the development of an equivalent model explaining the loss-of-synchronism mechanism of grid-forming converters under current-limited operation, (ii) a reduced-order high-frequency dynamic model for passivity assessment and harmonic-stability analysis of grid-forming converters, (iii) a renewed framework for assessing grid strength beyond conventional short-circuit-ratio-based concepts, (iv) an equivalent frequency-dynamics framework capable of analyzing voltage-induced frequency disturbances in low-inertia power systems, and (v) a novel methodology for cascading-failure analysis explicitly considering converter controls, current limitations, and protection systems. The developed methods were validated through analytical studies, electromagnetic-transient simulations, controller-hardware-in-the-loop experiments, and practical applications including renewable-energy integration, protection-performance assessment, and the impact of hyperscale AI data centers on grid frequency stability. Together, these achievements established new foundations for the efficient analysis of future converter-dominated power systems while significantly reducing computational effort compared with detailed simulation models.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The EQUATOR project delivered several advances beyond the current state of the art in the modelling and stability analysis of converter-dominated power systems. The project developed novel equivalent representations for grid-forming converters, revealing new stability mechanisms associated with converter current limitations and loss of synchronism, while also providing reduced-order models for passivity assessment and harmonic stability analysis. In addition, new methodologies were established for analyzing voltage-induced frequency disturbances and cascading failures in systems with high penetration of inverter-based resources, explicitly considering converter controls, current limits, and protection systems. The project further renewed the concept of grid strength by demonstrating the limitations of traditional short-circuit-ratio-based approaches and proposing a broader framework suitable for modern power systems dominated by power electronics. The developed methodologies were successfully validated in applications ranging from renewable-energy integration and protection studies to the analysis of hyperscale AI data centers. These results provide valuable tools for system operators, manufacturers, software developers, and research organizations involved in future power-system planning and operation. Further impact can be achieved through continued collaboration with industry, integration of the developed methods into commercial analysis tools, large-scale demonstration studies, and ongoing engagement with international technical organizations such as IEEE and CIGRE.