A Tuning Framework for VSG-Based Controllers Considering Frequency Stability and Control in Microgrids

Microgrids have emerged as an effective solution for integrating distributed energy resources, providing operational flexibility by their ability to operate in grid-connected and islanded modes. However, the high penetration of inverter-based sources in these systems introduces significant stability challenges. Grid-forming converters, especially those based on the Virtual Synchronous Generator (VSG) concept, offer a promising means of frequency control by emulating inertial and damping characteristics. Nevertheless, tuning the VSG’s parameters remains challenging, as these coefficients strongly influence multiple and often conflicting performance metrics. This work proposes a comprehensive framework for the optimal tuning and validation of VSG strategies, targeting both inertial and primary frequency control. The framework integrates small-signal stability analyses for both grid-connected and islanded operation modes and transient frequency response for unintentional islanding events. In addition, it applies to conventional and enhanced VSG structures with adaptive or supplementary loops. A detailed case study demonstrates the framework’s effectiveness in improving frequency performance and maintaining stability across varying operating conditions. The proposed framework provides a systematic and adaptable tool for frequency control enhancement, for identifying the most suitable VSG strategy for a given system, and for defining protection thresholds through statistical assessment of dynamic responses.