To address the impact of access voltage level selection on system security in photovoltaic (PV)bundled hydropower transmission systems,this paper investigates the differences in the effects of high-voltage side versus low-voltage side PV access on the internal equipment safety of hydropower stations and power grid stability.Taking a large-scale PV project in a hydropower station reservoir area as a case study,a system simulation model was constructed using PSD-BPA software.Two PV access schemes —high-voltage side (500 kV)and low-voltage side (15 .75 kV)—were established for comparative analysis through static short-circuit calculations and dynamic transient simulations.The results indicate that high-voltage side access significantly reduces the short-circuit current at the 15.75 kV and 35 kV generator buses,thereby increasing the safety margin of equipment.In the event of faults at the 500 kV and 35 kV buses,this scheme demonstrates smaller power angle swings,faster damping attenuation,and smoother voltage recovery.Consequently,the high-voltage side access mode effectively mitigates the risk of excessive short-circuit current associated with low-voltage side access through electrical isolation,enhances system transient stability,and represents the superior engineering implementation solution.