Study on Circulation and Ground Potential Characteristics of GIL Grounding System

MATLAB software is used to simulate the circulation of the gas insulated metal enclosed transmission lines (GIL) pipe corridor system and the ground potential. The 500 kV GIL grounding system and the shell circulation model are established. The analysis shows that the shell circulation decreases with the increase of the resistance of the ground lead, while the shell potential to the ground increases, and both values tend to be saturated. Under the condition of the same resistance of the ground lead, the shell circulation and potential to the ground increase linearly with the increase of line length and mutual inductance, and the ground lead impedance increases with the increase of line length. Through the simulation analysis of the shell potential to the ground of the long-distance GIL of the single phase, it is obtained that the shell potential to the ground is lowest in the center of the shell and tends to 0, and highest at both ends, showing a “V” shape distribution. When the total length of the line is constant, the more the number of segments of the shell, the lower the shell potential to the ground at both ends. It provides the basis for practical engineering design.