With a large number of distributed photovoltaic power generation systems connected to the power grid, the penetration rate of new energy power generation is continuously increasing, which brings many challenges to the stability of the power system. This paper builds a high-permeability photovoltaic power generation cluster model based on RT-LAB real-time simulation platform that can reflect the frequency fluctuation of power system. On FPGA high-speed power electronic real-time simulation system, a detailed model of photovoltaic grid-connected inverter is constructed. At the same time, the use of three controlled voltage sources instead of a three-phase bridge inverter is applied to construct an inverter equivalent simplified model. A synchronous generator set model is used to simulate the frequency modulations of the power system. And the ZIP load model is used to simulate the actual load characteristics. Finally, based on RT-LAB real-time simulation platform for verification, the results show that under the requirements for large-scale and high-accuracy simulation, this paper provides a feasible real-time simulation and modeling method.