Effect of DC-Side Dynamics on Interactions in Grid-Forming Inverter Systems

• Published in: IEEE transactions on energy conversion 2024-10, p.1-13
• Main Authors: Thilekha, T., Filizadeh, S., Annakkage, U. D., Karawita, C., Muthumuni, D.
• Format: Article
• Language: English
• Subjects: dc-side dynamics; eigenvalue analysis; Eigenvalues and eigenfunctions; Grid following; Grid forming; Grid-forming inverters; HVDC transmission; interactions; Inverters; Microgrids; Power system dynamics; Power system stability; Synchronous machines; Transformers
• ISSN: 0885-8969; 1558-0059
• DOI: 10.1109/TEC.2024.3474481

The power modulations carried out by a grid-forming inverter are profoundly affected by the capability of the inverter's dc-side circuit to support such modulations. Although preliminary work on dc microgrids includes the dc-side dynamics, analysis of potential ac-side interactions in the presence of grid-forming inverters is lacking. This paper presents an in-depth study of the interactions in grid-forming inverter systems considering the critical dynamics contributed by the inverter's dc-side circuitry. The study in this paper is based upon dynamic phasor modeling and eigenvalue analysis techniques. The results presented for an exemplar system of a grid-forming inverter paralleled with a synchronous machine prove the significance of including dc-side dynamics to accurately capture the full range of interactions that may occur in such systems. Detailed electromagnetic transient simulation results from PSCAD/EMTDC are included to verify the validity of the predictions of the dynamic-phasor-based model.