In order to solve the problem of voltage distribution, network loss and short-circuit current change caused by photovoltaic system access, the access location and capacity of a photovoltaic system need to be reasonably planned. First, a simulation model is established based on the 9-node ring network model of a WSCC3 machine, and some parameters in the simulation process are simplified. Secondly, the influence of photovoltaic grid-connection on grid voltage is studied through simulation analysis of access location and capacity of single and multiple photovoltaic power generation systems. Then, the influence of photovoltaic access position and access capacity on system network loss is simulated and analyzed. Finally, the influence of photovoltaic access on short-circuit current is studied. The above simulation analysis and research can guide photovoltaic system access location and capacity. This work is supported by Beijing Natural Science Foundation (No. 3202032).