Precise Virtual Admittance Synthesis for Enhanced Grid-Forming Performance

Paper i proceeding, 2026

Virtual admittance control has emerged as an effective approach to enhance the performance and exploit the capabilities of grid-forming converters (GFMs) in terms of system robustness, stability, and flexibility. Shaping GFM admittance/impedance (immittance) at low frequencies enables outer-loop power regulation and stable operation under varying grid strengths. To further support synchronous-machine-like behavior, shaping GFM immittance at higher frequencies is also important, as e.g., it can help prevent destabilizing interactions in the harmonic range. In this regard, wide-band frequency-domain analysis not only provides a practical means to verify compliance with grid codes, but also enables the demonstration of sophisticated GFM functionalities, particularly those related to stability. To this end, this article addresses frequency-domain accuracy characterization and presents a virtual admittance controller design approach that, unlike the conventional approach, ensures that the GFM's output immittance accurately matches the target across a wide frequency range. Consequently, the GFM's admittance passivity properties are enhanced with the proposed approach, which can be considered a solid base for enabling advanced grid-forming performance, especially from the stability perspective.