Modified virtual inertia control method of VSG strategy with improved transient response and power-supporting capability

Virtual synchronous generator (VSG) controlled grid-tied converters could increase power overshoot and oscillation if real power reference disturbance (PRD) occurs. Existing VSG methods can mitigate the power oscillations, but they may reduce the supporting capability of grid contingency. To cope with the issue, a modified virtual inertia control method of VSG strategy is proposed. The proposed modified VSG method introduces two frequencies of point of common coupling into the virtual inertia control. The estimated frequency is used to mitigate the power oscillations and the measured frequency aims to provide extra power supporting. The formulated parameters design principles are given according to the transient characteristics. Stability analysis of power and frequency response is carried out to evaluate the proposed method. Besides, the transient power and frequency response of the PRD case and grid-frequency disturbance (GFD) case are studied. The power overshoot of the proposed modified VSG method decreases by 52.5% under the PRD case and the power support peak increases by 34.3% under the GFD case. Experimental results show that the transient performance of the proposed modified VSG controlled grid-tied converters is improved.