Reasons behind this project

Due to the massive development of power-electronics based components, the limits between the different power system modelling domains are becoming more and more questionable. Indeed, these components lead to fast dynamics in the system that both interact with the classical components slow dynamics but also between themselves [1].

For the former, in other words, the electromechanical components dynamics through the whole system can be strongly impacted by the electromagnetical components dynamics. It means that  sticking to electromechanical studies for transient stability would surely not be sufficient in the future. For the latter, there are new phenomena appearing in systems with a large share of power-electronics based involving the controls of the different power-electronics based components that can jeopardize the system stability. In particular, a new type of stability, known as converter-driven stability, has been added to the traditional stability problem classification. Indeed, examples have shown that the dynamics of the PLL or the value of some gains of the control can lead to a system instability even for small variations. In addition, a few preliminary results tend to indicate that these problems can appear before other traditional stability issues in case of weak networks (small SCR).

In order to be able to capture these phenomena in a correct way, it is necessary to go beyond the traditional phasor modelling approach by not neglecting the existing faster dynamics. However, doing large scale long term EMT simulations is impossible at the moment due to the computational burden and lack of data that it represents. It is thus necessary to find new simulation approaches enabling to get similar results than the EMT ones without the disadvantages of it. These new methods should be scalable, robust, transparent and flexible if possible

Project objectives

BiGER (“Bridging the Gap between EMT and RMS”) – Explore shall make possible the appropriate dynamic simulation tools for network operators and stakeholders by:

• Build and share a set of use cases and their associated open-source benchmarks that illustrate the need for more detailed simulations

• Build and share a state of the art of the existing methods developed to handle this issue

After this first exploration, BiGER may be extended to tackle the following objectives:

• assess the quality of alternative and new methods (other than classical EMT and RMS) for ensuring the system stability in situations with a large penetration (up to 100%) of power-electronics based components
• identify potential improvements in those and benchmark them.

Project members:

BiGER is a common project, explored in 2023 by TU Delft, RWTH Aachen and RTE.

[1] This limit was manageable in the past as transient phenomena fade away with the distance on the system and very few sensitive components would then actually interact together. The future, higher geographical density of such sensitive components, namely PE-equipment, is a game changer.