Power system oscillations pose a significant threat to power grids, potentially resulting instability and blackouts. Traditional solutions for damping these oscillations include power system stabilizers (PSS) associated with synchronous generators and Flexible AC Transmission Systems (FACTS) devices [1,2]. However, as renewable energy sources replace conventional power plants, the PSS based on synchronous generators is no longer feasible. Consequently, damping power system oscillations in large systems with large share of renewable energy sources becoming a challenging task, e.g. the low-frequency oscillation before the blackout in Spain on 28.April 2025 shown in Fig. 1 [3].

Fig. 1. Virtual synchronous generator control

This paper investigates the influence of grid forming controls, specifically the virtual synchronous generator (VSG), as shown in Fig. 2, on oscillation stability in power systems with high penetration of renewable energy. The study employs modal analysis and time-domain simulations to evaluate the interactions between VSG controllers and synchronous generator controllers. Results reveal that VSGs are participating the inter-area oscillations and could improve overall system stability, even in scenarios where conventional stabilizers are deactivated. The findings underscore the importance of VSGs in ensuring the reliability of modern power systems under the global energy transition.

Fig. 2. Virtual synchronous generator control

The paper applies grid forming controllers to the VSG of the four machine two area power system as shown in Fig. 3 [1,2]. The PSSs are disabled to emphasize the impact of VSG. A 100MW VSG is connected to Bus 6, operating in parallel with synchronous generator G2, resulting in a reduction of G2's active power output to 600MW. This setup allows analyzing the influence of the VSG on power system oscillations. The system structure and power flow results are depicted in Fig. 3. Dynamic simulation results demonstrate their effectiveness in damping power system oscillations in the presence of high renewable energy penetration.

Fig. 3. four-machine two area power system

In conclusion, this paper highlights the potential benefits of using grid forming control for damping oscillations in large power systems and its possibility for improving the system stability.

References

[1] P. Kundur, Power System Stability and Control, McGraw-Hill Education Ltd, ISBN-10:‎ 007035958X.

[2] G. Rogers, Power System Oscillations, Springer, 978-1-4615-4561-3.

[3] https://www.linkedin.com/posts/philippe-jacquod-76227a5_time-will-tell-what-circumstance-or-chain-activity-7322729833828945920-HS44/