Amir Reza Zamani Babgohari Electrical engineering

Amir Reza Zamani Babgohari is a PhD student in the research group Power grids and Components at the unit Electric power engineering.

Discussion leader is Rasool Heydari, R&D team manager, Hitachi energy research

Examiner is professor Massimo Bongiorno, Chalmers

Abstract:
This project deals with the modeling and small-signal stability of converter-dominated
power systems. The first part develops scalable models and aggregation tools for
multi-converter systems using both dq-admittances and the Power Response Matrix
(PRM). The second part investigates stability assessment methods. While centralized
eigenvalue and Nyquist analyses give exact stability margins, they provide little information
about connected subsystems. In this regard, classical decentralized approaches
such as the passivity tools are more practical and provide subsystem level analysis.
However, they are often more conservative as they require full-spectrum passivity to
ensure stability. To address this, the project introduces reactive-characteristic analysis
and a new reactivity index that complements the passivity index. Together they
locate resonances and quantify available damping, forming a practical subsystem-level
framework for multi-converter stability assessment.