A new type of power generation facility with TEG that utilizes waste pressure energy during the decompression process of liquid natural gas, and the problem of instantaneous voltage sag should be reviewed in advance for grid-connected operation mode. This study implemented an EMTP/RV simulation model and conducted a time-domain simulation for verifying transient characteristics of turbo expander driven a squirrel cage induction generator in a gas governor station. The simulation results for the case studies including parallel operation condition, reactive power compensation, and three-phase short-circuit fault condition were reviewed based on the grid code and finally contributed to propose the conceptual method for grid-connected operation of TEG.