Influence of SOGI Bandwidth on Stability of Single Phase Inverter in Weak Grid

With the increasing capacity of renewable energy, the interaction between power electronic equipment such as Voltage Source Inverter (VSI) and weak grid becomes an important issue, which could cause the sub-super synchronous oscillation and threaten the stability of the power system. To enhance the system stability, the influence of SOGI bandwidth in weak grid is analyzed based on the impedance method. First, the small signal model of Second Order Generalized Integrator Phase-Locked Loop (SOGI-PLL) is given. Then, the single phase inverter impedance model with different SOGI bandwidths is proposed. The proposed impedance model shows that though other parameters are the same, the SOGI bandwidth would influence the VSI impedance in the sub-super synchronous frequency band. Further, with the consideration of SOGI bandwidth, the system stability is compared by using the impedance-based Nyquist criterion. The results show that only decreasing the bandwidth of SOGI without changing other parameters could improve the system stability in weak grid. The proposed impedance model and the influence of SOGI bandwidth are validated based on Matlab/Simulink.