An Improved FCS-MPC Strategy for Low-Frequency Oscillation Stabilization of PV-Based Microgrids

With the rapid promotion of photovoltaic (PV) power generation, the local consumption of distributed PV power generation at medium and low voltage levels widely forms PV-based microgrids. The continuous increase in the penetration rate of uncertain PV power generation requires it to actively participate in the frequency and voltage regulation of weak microgrid systems. Finite control set-model predictive control (FCS-MPC) for voltage source converter (VSC) shows remarkable advantages in fast dynamic response and robustness compared with traditional cascaded linear control methods. However, the traditional FCS-MPC method for VSC without considering the DC-link voltage dynamics of the PV generators will face oscillations of power and frequency in PV-based microgrids. In this paper, to suppress the low-frequency oscillation issue caused by PV generations, an improved FCS-MPC (I-FCS-MPC) strategy considering the DC-link dynamics of PV generation is proposed, in which the AC side and DC side of the VSC are comprehensively considered to enhance the dynamic performance of the PV-based microgrids. Moreover, a DC-link voltage regulation mechanism is introduced, enabling the PV generators to operate in the maximum power point tracking (MPPT) mode. Finally, experiments are conducted to verify the effectiveness of the proposed control strategy comprehensively.