Fault Ride-Through Capability Improvement of Grid Connected PV System Using Dynamic Voltage Restorer

When a fault occurs at a grid-connected photovoltaic (PV) system, the grid voltage drops significantly, and this causes a spike in the DC link voltage. The high DC voltage, in turn, causes faults in the Power-Electronics inverters and choppers. In addition, PV plants form a significant portion of modern power systems and disconnecting them during faults (as conventional) is no longer an option. This work proposes the dynamic voltage restorer (DVR) to improve the fault ride-through (FRT) capability of PV systems under a three-phase-to-ground fault. In order to evaluate the effectiveness of the proposed DVR method, its performance is compared with that of the series dynamic braking resistor (SDBR). The comparison is made in terms of performance and control complexity. Simulation results show that the DVR can improve the FRT capability seamlessly. Also, despite its higher cost and controller complexity, the proposed DVR outperforms the SDBR in all aspects.