Abstract: To explore the impact of photovoltaic grid connection on the operation of medium-voltage distribution networks, this paper constructs a multi-dimensional analysis framework based on actual grid data. By establishing and verifying a digital simulation model for feeder lines, and using multi-condition simulation methods, the dynamic effects of photovoltaic integration on key parameters such as voltage under different load conditions and network topologies are quantitatively analyzed. The results show that with a 1.8MW photovoltaic capacity, the system's power quality indicators meet the standards; under normal load conditions, photovoltaic significantly improves the voltage distribution of feeder lines, but extreme light load conditions can cause overvoltage risks as high as 113.3%; there is a clear upper limit to the network's photovoltaic acceptance capacity, and exceeding this limit will lead to voltage over-limit. When a branch fault prolongs the power supply distance, the line reactance voltage drop component dominates the voltage drop, and photovoltaic, unable to provide reactive power support, only slightly improves the active power voltage drop component, with a voltage increase amplitude as low as 1.2%. In open-loop point adjustment, the terminal voltage can be precisely regulated by ±1.4%, while closedloop operation will amplify the overvoltage at light load conditions to 116.5%. In actual engineering, the penetration rate needs to be controlled through capacity assessment, the open-loop point and transfer strategy need to be optimized, dynamic reactive power compensation or inverter reactive power support capabilities need to be configured, and the risk of closed-loop operation needs to be carefully assessed.