Virtual Oscillator-Controlled Inverters with Adaptive Virtual Inertia and Damping to Support Frequency Stability

Virtual oscillator control (VOC) is a grid-forming controller designed for microgrids, where inverters are regulated to mimic the dynamics of weakly nonlinear oscillators. VOC operates in the time domain and offers a faster transient response compared to the virtual synchronous generator. However, conventional VOC implementations often result in reduced power system inertia, which poses a risk to frequency stability due to the lack of inertia. The inertial response is introduced into VOC by integrating the swing equation of a synchronous generator to represent virtual inertia and damping. Unlike real synchronous generators, the parameters of the swing equation can be adjusted in real time to support frequency stability. By employing varying levels of virtual inertia and damping during frequency deviation and recovery, improvements of 10.4% in frequency nadir and 4.9% in the rate of change of frequency are achieved compared to fixed inertia setups. Simulation results confirm the effectiveness of the proposed approach.