Universal Virtual Synchronous Generator Based on Extended Virtual Inertia to Enhance Power and Frequency Response

Abstract

Virtual synchronous generators (VSG) are considered a new generation of grid-friendly inverters with the same inertial support characteristics as synchronous generators (SG). However, the inertia support comes with the side effects of power and frequency response deterioration. The existing VSG power oscillation suppression methods have limitations such as complex controller parameter tuning, altering the frequency support characteristics, and power quality degradation. To address these issues, this paper proposes a universal VSG control strategy based on extended virtual inertia (VSG-EVI). Herein, the virtual inertia is no longer a constant or varying number; it is endowed with frequency domain characteristics to improve the VSG transient responses. Moreover, a detailed parameter design process is given in detail. Compared with the conventional VSG (CVSG), VSG-EVI significantly suppress the power and frequency oscillations. Compared with the existing VSG oscillation suppression methods, VSG-EVI addresses the issues of the reduction of frequency support capability, whereas the controller parametric design process is simplified with the proposed intuitive extended virtual inertia. Finally, the proposed VSG-EVI method is thoroughly validated by experiments under both grid-connected and stand-alone modes.