Moonshot update: Integrate power systems: Simulation platform for [EM1.1][EM1.2][M1.3] new grid stability phenomena

Context

This project is one of five Moonshots in Elia Group’s new Moonshot programme, which brings together ambitious innovation projects designed to address key challenges for the future energy system and deliver significant impact.

As converter-based resources such as wind and solar parks, battery storage, HVDC links and, more recently, data centres and other power-electronics-based assets keep connecting to the Belgian grid, the power system is starting to behave differently. Their fast control systems can cause oscillations and control interactions that conventional root-mean-square (RMS) simulation tools may not fully capture. The 2023 system split in Brazil showed why these new stability risks matter: the models in use did not predict the oscillations that followed a grid event.Electromagnetic transient (EMT) simulations can represent these fast phenomena in much greater detail, but they require significant computing power and are difficult to scale across an entire national grid. Elia Group therefore needs a practical way to determine which modelling approach and level of detail are appropriate for each study. By finding the right balance between speed and accuracy, Elia Group can assess new stability risks efficiently, support the secure connection of low-carbon assets and avoid making every grid study unnecessarily complex.

This is the ambition of the System Operations Moonshot: to make the connection process for new assets 50% faster by accelerating the modelling and assessment of emerging grid-stability phenomena, without compromising grid security.

Approach

The project follows a step-by-step approach. In a first phase, together with Fraunhofer, Elia identified and classified the stability phenomena relevant for the grid, evaluated the available modelling and simulation options, and analysed how well the models of grid assets can represent them. This exploration showed that no single method fits every case: full EMT, hybrid RMS–EMT co-simulation and reduced models (aggregation and dynamic equivalents) each have their strengths and limits.

Based on these insights, Elia decided to move from theory to practice and test these approaches on real Elia use cases. For each use case, the same situation is simulated three ways – a full EMT model as reference, an RMS–EMT co-simulation, and a reduced model – and compared on accuracy, computation time and data needs. Both grid-following and grid-forming converters are included. Two use cases have been [SJ3.1]selected:

• Long-distance stability effects: this use case covers a large part of the Belgian grid and studies how distant areas and assets interact with the zone under study, and whether these external areas can be represented by simplified dynamic equivalents without losing critical dynamics. It’s particularly important to represent accurately the neighboring transmission systems whose behavior can still affect the Belgian grid.
• Impact of units connected at lower voltages: this use case looks at the many smaller units connected to the distribution level and assesses when they can be grouped into aggregated models and which effects may be lost when doing so. The goal is also to evaluate the impact of the Distribution System Operators (DSOs) on the grid.

Results

The first phase delivered a clear classification of the new stability phenomena and an in-depth evaluation of modelling options, including a first proof of concept of co-simulation between the two simulation tools used at Elia (PowerFactory and PSCAD). It confirmed the need for a dedicated simulation capability, and that the right choice of method depends on the study objective, the available data and the computing constraints.

The pilot phase is now well under way: the drafting of both use cases is being finalised and the modelling of the grid areas is taking place.

Next steps

In the coming months, the simulation campaigns will be run on both use cases and the three approaches will be compared side by side. The outcome will be a practical decision matrix and guidelines telling Elia’s experts which modelling approach to use, where to draw the boundary between detailed and simplified areas, and what trade-offs to expect. These results will lay the foundation for a future phase focused on automation and large-scale implementation[SJ4.1]. By accelerating the modelling and assessment of dynamic phenomena, the project will contribute to Elia Group’s ambition to reduce the approval time for new grid elements by 50% by 2028. [EM5.1][EM5.2][EM5.3][M(5.4]An alternative track is to link the project directly to the ongoing Conformity Platform initiative, allowing vendors to test whether their proposed connection meets the relevant grid-security requirements.

Partners

Fraunhofer IEE (Institute for Energy Economics and Energy System Technology) and Fraunhofer ISE (Institute for Solar Energy Systems)