Update Moonshot System Operations: INtegration of POWer ELectronics (INPOWEL)

Introduction

In 2021, Elia Group launched its ambitious multiyear Moonshot programme, aimed at tackling some of the biggest challenges in the energy transition and demonstrating the use of concrete solutions to reach this goal.

One of the key initiatives within this program is the System Operations Moonshot. As our power system is undergoing a major transformation, ensuring it remains stable and reliable throughout this journey is paramount. The INPOWEL (Integration of POWer Electronics) project is at the heart of our efforts to navigate these changes successfully.

Context: Why are we doing this, what do we want to achieve?

As our society moves toward a net-zero future, more renewable sources like solar and wind are being connected to the grid. While this is essential for the planet, it challenges grid stability, which traditionally relied on large spinning generators to provide inertia and buffer disturbances.

Renewables connect through power electronic converters that lack these stabilizing properties, leading to faster frequency changes and a weaker grid more prone to voltage issues. Elia, like other TSOs, is addressing these challenges through projects like INPOWEL, which aim to integrate converter-based technologies that not only follow the grid but actively help form and stabilize it. Grid-forming converters, unlike grid-following ones, can set their own voltage and frequency, making them vital for a stable, renewable-powered grid.

Approach: What have we done and where are we today?

The INPOWEL project focuses on modelling and understanding the behaviour and interactions of power electronic technologies within the grid. A central component of the project involves conducting detailed simulations. To accurately capture the fast and complex dynamics of power electronic converters, the project employs advanced simulation techniques known as ElectroMagnetic Transient (EMT) simulations. Unlike traditional Root Mean Square (RMS) simulations, which average values over a cycle and may miss rapid transients, EMT simulations operate with much smaller time steps, typically in the microsecond range, enabling the observation of fast switching events and transient phenomena that are critical for assessing stability in converter-dominated grids.

As part of the project, detailed generic EMT models have been developed for technologies such as Battery Energy Storage Systems (BESS) and Enhanced Static Synchronous Compensators (E-STATCOM), in both Grid-Following (GFL) and Grid-Forming (GFM) modes. Collaboration with manufacturers is ongoing to obtain proprietary "black-box" models that incorporate actual control code. These models enhance simulation accuracy and support the validation of the generic models.

The models are being tested under a variety of grid conditions, including different levels of grid strength (measured by Short Circuit Ratio) and disturbances such as voltage or frequency deviations and faults. These tests aim to evaluate the performance of GFM devices, particularly their capabilities in providing inertia, fast frequency response, fault ride-through, and black start support. The behaviour of these devices under operational constraints, such as current limitations during faults, is also being assessed.

A major area of investigation is the identification and mitigation of new stability challenges introduced by the increasing presence of power electronics. These include interactions between power electronic converters (PE-to-PE), resonance phenomena between converters and grid components (PE-to-grid), and interactions with remaining synchronous generators (PE-to-SG). The project is developing methods and indices to detect and quantify these emerging risks.

Significant progress has been made in defining a structured process for stability assessment related to power electronic systems. Tools such as EMT simulations and frequency scans are being used to evaluate associated risks. Current efforts are concentrated on understanding phenomena like converter instability and interactions, and on developing initial strategies for their detection and mitigation.

Next steps

The next phase of the INPOWEL project involves expanding the existing models to include additional renewable technologies such as wind power, high-voltage direct current (HVDC) links, and potentially solar photovoltaic (PV) systems. Efforts are also underway to enhance model accuracy, particularly in representing current limitations and recovery behavior following disturbances.

Drawing on insights from extensive simulations and testing, the project will formulate proposals for specific technical requirements to support the integration of Grid-Forming (GFM) converters into the Belgian grid. This includes defining expected performance during disturbances—such as required current or power output and response times. These proposals will be benchmarked against international best practices from organizations and regions including ENTSO-E, the United Kingdom, and Australia.

In addition to technical specifications, the project will assess the potential impact of these new requirements on overall grid stability. Practical operational guidelines will be developed to support real-time risk management associated with GFM assets.

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