Fault ride-through control strategy based on active power increment control of energy-stored inverter

The grid-connected reliability of DG(Distributed Generation) is posed challenges under grid-side short-term faults. By the conventional fault ride-through control method of suppressing overcurrent and compensating reactive power to support voltage of grid-connected access point, it is difficult to effectively eliminate the imbalance of DG source-load power. A fault ride-through control strategy based on active power increment control of the energy-stored QZSI(Quasi-Z-Source Inverter) is proposed. The supercapacitor energy storage and its control are introduced in the QZSI DC link, and the fast discharge characteristics of supercapacitor and the strong resistance to load impact of QZSI are utilized to rapidly adjust the output power increment of grid-connected DG. Thus, the grid-side fault power flow can be compensated, the source-load power balance of DG during fault transient can be effectively improved, and the abilities of DG to adapt to short-term fault power flow and to support grid-side voltage are enhanced. The simulative and experimental results verify the effectiveness of the proposed fault ride-through control strategy. © 2021, Electric Power Automation Equipment Press. All right reserved.