The development of high-voltage flexible direct current transmission is gradually advancing towards higher voltages and greater capacities, with the rated current level of converters also being progressively increased from 3kA to 5kA. In order to comprehensively understand the potential electromagnetic interference (EMI) variations that may occur at high current levels, this paper conducts a detailed simulation study specifically on the 5kA modular multilevel converter (MMC) and systematically compares the results with those of the traditional 3kA submodule. To ensure the accuracy and reliability of the analysis results, a wideband equivalent circuit model suitable for flexible direct systems was first constructed. By precisely extracting the parasitic characteristics of key components in the high-frequency range, the electromagnetic transient simulation can better reflect the actual operating conditions. Subsequently, in-depth electromagnetic transient simulations were conducted using this model to compare the EMI distribution characteristics that may be triggered by 3kA and 5kA MMC under the same voltage and current reference conditions. The results indicate that when the rated current is upgraded from 3kA to 5kA, there will be a certain degree of increase in the level of conducted interference in the frequency range above 1 kHz.