Z.-C. REN ET AL. 795

Figure 6. DC current distribution in AC transmission lines

of Jincheng city.

Figure 7. DC current distribution in AC transmission lines of

Changzhi city.

4. Conclusions

The smaller the thickness of the surface soil is, the

greater the absolute value of earth surface potential. The

farther away from the grounding electrode, the smaller

the absolute value of the surface potential, which formed

the exponential decay function and tended to zero gradu-

ally.

The DC current amount of the distal substation was

not always less than the recent substaion. The DC current

would select the pathway of which the DC resistance was

the minimum. The DC current, flowing through the sub-

station, of which the topological structure was more com-

licated, was relatively large. The soil sructure had some

influence on the DC current distribution: the smaller of

the surface soil thickness, the larger of DC grounding

current influence on the AC system.

5. Acknowledgements

The authors would like to acknowledge Shanxi Electric

Power Corporation for the facilities provided during this

research.

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