Power systems worldwide are transitioning to higher penetration of non-synchronous renewable energy sources (RESs) (e.g., wind and solar) and less traditional thermal generation. This change in the generation mix brings significant operational challenges to transmission system operators (TSOs). These challenges include frequency, voltage and transient stability, as well as congestion and power quality issues, among others. For example, it is well-known that RESs provide fluctuating production, less inertia and voltage support. While such challenges are being recognized by TSOs how to deal with them is still an open question. In this context, the aim of this special session is threefold:

• Highlight the main drivers of the energy transition and the above challenges.
• Present potential solutions and/or mitigations proposed in the literature.
• Share real-world experience of different TSOs operating power systems with high levels of non-synchronous RESs. Specifically, the list of TSOs includes Energinet Denmark, EirGrid Ireland and APG Austria.

Furthermore, the special session includes distinguished researchers from both academia and industry that will shed light on the recent solutions proposed in the literature.