With large-scale photovoltaic power stations and energy storage stations being connected into AC and DC power grid

it is difficult to analyze the interaction between AC and DC power grids after faults by analytic methods

so it is necessary to construct the full electromagnetic transient simulation model

and analyze the interaction between AC and DC power grids according to the simulation results. Based on the HYPERSIM electromagnetic transient simulation platform

this paper constructed the electromagnetic transient simulation model of an actual AC and DC power grid under different operation modes with large-scale photovoltaic power stations and energy storage stations

and conducted a series of simulation tests on the AC and DC faults at different voltage levels of different regions. Then

the stable operation characteristics of the power grid under DC forward transmission and reverse transmission modes were studied. Finally

the improvement effect of DC emergency power modulation function and the addition of grid-forming converters or synchronous condensers on the stability of the weak system were verified through the simulation tests. The research in this paper can provide reference for future research on the interaction between AC and DC power grids with multi grid-following and multi grid-forming energy storage stations being connected.