volume | PIER Journals

Abstract

When a high voltage direct current (HVDC) system works at single line operation mode, a big current will flow into the earth through the grounding system directly. Then the large current can cause damage to surrounding equipment and the environment. Therefore, it is significant to study the current dispersion characteristics of HVDC grounding system. Firstly, a ±800 kV HVDC model operated at single line mode is built. The grounding current can be seen as the equivalent current source injecting to the grounding system. Secondly, the current dispersion characteristics of horizontal, cross and ring electrodes are investigated. It proves that the ring grounding electrode shows better current dispersion characteristic. And the double-ring grounding electrode whose ratio of inner and outer rings is controlled at 0.7 to 0.75 can get a better current dispersion characteristic. In addition, a dynamic seasonal frozen soil resistivity changing model is built to study the effects of season on the grounding electrodes. The frozen soil would not only increase the ESP, the resistance to ground, and step voltage, but also reduce the current density and electrical field. When the frozen soil is melting, the current dispersion characteristics are the best. The results provide meaningful reference for the design of the grounding system in extremely cold regions.

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Dr. Lekai Zou

Prof. Fan Yang

Dr. Bing Gao

Dr. Hanwu Luo

Dr. Ligang Ye

Dr. Wenzhen Li