Virtual Oscillator Control Without Third Order Harmonics Using Average Filtering Method

Virtual oscillator control (VOC) is a grid-forming controller utilised in microgrids, where inverters are regulated to mimic the behaviour of weakly nonlinear oscillators. Compared with droop control, VOC operates in the time domain and offers a faster transient response. However, the output voltage of the Van der Pol oscillator contains harmonics, particularly the third-harmonic, deteriorating power quality. Existing methods for harmonic voltage suppression in virtual oscillator control mainly involve modifying the internal structure of the oscillator or employing external filtering techniques. This paper proposes employing the average filtering method as an external filtering measure, effectively reducing the output voltage's third-order harmonic. Simulation results validate the effectiveness of the proposed implementation.