Influence of voltage sags on the power system with high penetration of photovoltaic power generation

The influence of voltage sags on systems with high penetration of photovoltaic power generation (PV) should be clarified not only for low-voltage networks but also for medium-and high-voltage networks. Because the Fault Ride Through (FRT) requirement is a promising solution for mitigating such influence, its improvement effect on voltage response was examined using a realistic model of the system in Japan including medium- and high-voltage networks. It was revealed that the slow voltage recovery phenomenon will occur following voltage sags due to the dynamic behavior of the PVs regardless of the FRT requirement. The results showed that the FRT requirement significantly improved the dynamic voltage response following voltage sags in case of no self-disconnection of loads. However, with self-disconnection of loads, the requirement could cause high post-disturbance steady-state voltages, leading to rejection of the PVs due to overvoltage relay operation.