During the normal operation of the power grid, voltage fluctuations are often caused by external disturbances and internal factors. This article focuses on the impact of power grid voltage fluctuations on the operation of photovoltaic inverters and uses PSCAD simulation software to establish a photovoltaic grid-connected system model. On this basis, we simulate the changes in three-phase voltage, current, effective voltage, and power of photovoltaic inverters when the power grid is subjected to severe external influences, and minor fluctuations such as electrical equipment switching and load changes. Finally, taking the case of a three-phase short circuit as an example, we conducted a physical process analysis of the inverter when voltage fluctuations occur, further exploring the impact of grid voltage fluctuations on photovoltaic inverters.