Stability of inverter-based resources (IBRs) is essential right now due to the growing integration of renewable energy sources, such as solar and wind, into power grids; which displace conventional synchronous generators. Unlike synchronous generators that naturally provide inertia and help stabilize the grid during disturbances, IBRs lack this capability due to the fact that their controllers are normally in MPPT mode. As more IBRs are deployed, ensuring grid stability becomes increasingly complex, particularly during dynamic events like sudden shifts in generation or demand. Without focused research and development on advanced control systems and stability solutions, the rising dependence on IBRs could jeopardize grid reliability, potentially resulting in blackouts or other operational challenges.
Moreover, the shift towards decentralized energy systems, including the increased use of distributed energy resources (DERs) like rooftop solar panels and energy storage, adds further complexity to maintaining grid stability. Research into IBR stability is crucial for creating new strategies, regulatory frameworks, and grid codes that facilitate safe and reliable integration. This research is vital for a successful transition to a low-carbon energy future, where renewable sources can be effectively and securely incorporated into the power grid without compromising stability and reliability.
To address this pressing issue, I will offer research opportunities focused on the stability of inverter-based resources (IBRs). These projects will be designed to explore various aspects of grid stability in the context of increasing renewable energy integration. There will be approximately 6 vacancies for undergraduate students and 4 for master’s level students. These research topics will provide valuable insights and contribute to developing solutions that ensure a stable and reliable energy future. The topics are as follows:
- Inter-area power oscillations mechanism in inverter-dominated power systems
Level: Undergraduate/ master
This topic investigates how inter-area oscillations, traditionally associated with synchronous machines, manifest in systems dominated by inverter-based resources (IBRs). The study emphasizes the role of grid-forming (GFM) inverters in shaping inter-area oscillatory modes, particularly how their control parameters and virtual inertia influence damping and frequency coupling across interconnected areas. This research is important for renewable energy integration and future power systems because inter-area oscillations can limit the stability of large interconnected renewable grids if not properly understood and mitigated.
- Stability of grid forming inverters with current limiting strategies
Level: Undergraduate/ master
Grid-forming inverters must operate reliably under fault or overload conditions, where current limiting is essential to protect semiconductor devices. This topic explores the interaction between current limiting mechanisms (e.g., saturation, circular current limiters, or adaptive droop adjustments) and the overall dynamic stability of the inverter. The analysis includes small-signal and large-signal perspectives to reveal potential instabilities or performance degradation introduced by current limiting during grid disturbances. This is highly relevant for renewable energy integration and future power systems, where inverters are expected to provide both protection and stability simultaneously.
- Dynamic model of grid forming inverter in Typhoon HIL
Level: Undergraduate/ master
Hardware-in-the-loop (HIL) platforms such as Typhoon HIL provide real-time emulation of inverter behavior in realistic grid scenarios. This topic involves implementing grid-forming algorithms (e.g., droop control, virtual synchronous generator—VSG) in HIL to validate their performance under varying operating conditions. The study focuses on dynamic model accuracy, controller implementation challenges, and benchmarking against theoretical simulations. Such validation is important for renewable energy integration and future power systems because it bridges the gap between simulation studies and practical deployment of advanced inverter technologies.
- Inter-IBR oscillations
Level: Undergraduate/ master
In future 100% inverter-based systems, oscillations may no longer resemble conventional inter-area oscillations but rather emerge from complex inverter control interactions. This topic studies the oscillation mechanisms that arise exclusively between IBRs, driven by their control structures, phase-locked loops (PLLs), and virtual inertia settings. Identifying and characterizing these inter-IBR oscillations is vital for establishing new stability criteria and mitigation strategies. This work is essential for renewable energy integration and future power systems, since stability will be entirely dependent on inverter-to-inverter interactions.
- Transient stability of grid-following inverters
Level: Undergraduate/ master
Grid-following (GFL) inverters rely on PLLs to synchronize with the grid. During severe disturbances, they may lose synchronism or exhibit unstable responses due to weak grid conditions or large voltage phase jumps. This topic analyzes the mechanisms of transient instability in GFL inverters, drawing parallels to the “loss of synchronism” concept in synchronous machines, but framed within inverter control dynamics. This study is important for renewable energy integration and future power systems, where GFL inverters are widely deployed and their secure operation under disturbances is crucial.
- Transient stability of grid forming inverters
Level: Undergraduate/ master
Unlike GFL inverters, GFM inverters establish voltage and frequency references. However, during large disturbances, they too may experience instability resembling loss of synchronism, manifested as divergence in phase angle or collapse of power transfer capability. This topic examines the transient stability of GFM inverters, identifying conditions under which stability is preserved or lost. The focus includes comparing their stability mechanisms with synchronous generators and understanding the influence of droop, VSG, or grid impedance shaping. This research is particularly important for renewable energy integration and future power systems, since GFMs are expected to provide the foundation for grid stability.
- Stability analysis of grid forming inverters in frequency domain
Level: Undergraduate/ master
Frequency-domain tools such as Bode plots and Nyquist stability criteria provide valuable insights into the robustness of control systems. This topic applies these classical control analysis techniques to grid-forming inverters, allowing systematic evaluation of stability margins under different grid conditions and control parameter settings. The analysis bridges inverter control theory with well-established linear system stability methods. Such investigations are crucial for renewable energy integration and future power systems, as they provide systematic design and assessment tools for ensuring the robustness of inverter-based grids.
Students participating in these research projects are expected to:
1) Build models of inverters using differential equations (without the use of industrial-grade software). You will benefit a lot from building the model and performing appropriate analysis from stratch
2) Perform appropriate analysis to understand and assess the stability of inverter-based resources.
3) Complete a thesis write-up based on their findings and contributions. It is not compulsory, but I will encourage students to write in English.
Additionally, students are required to regularly work in the TD lab, where they will have the opportunity to collaborate with other PhD and master’s students who will be available to support and facilitate their research efforts.
Please don’t hesitate to reach out if you’re interested in any of the topics mentioned above or if you’d like to have further discussions. You can contact me via email at husni.rois.ali@ugm.ac.id. I look forward to connecting with those eager to contribute to this important area of research!
- I currently do not accept Ph.D students as the main supervisor, however I’m open as a co-supervisor
Selected research projects from my past students: see here
Please drop me an email in case you are interested in any topics listed above