Analysis on Performance of UHVDC Cirque Grounding-electrode

The performance parameters of UHVDC cirque grounding electrode are computed by 3D finite element method when self-resistance of grounding-electrodes was involved in. The work is carried that compare grounding performance of single-cirque, two-cirques and three-cirques grounding electrode on condition of same electrode length by calculation. The results show that there have the minimum value, intermediate value, maximum value of maximum potential, grounding resistance and maximum temperaturerise when grounding electrode is arranged in single-cirque, two-cirques and three-cirques respectively. These indicate shielding effects intensify that influence current to diffuse when augment number of cirque. So it can be considered that select single-cirque as grounding electrode if suitable grounding field can be imposed on condition of maintain electrode length and don't increase engineering investment. At the same time, because most of uneven soil can be modeled approximatively by double-layer soil, so a series of influencing factor of grounding performance such as electrode's depth of burial, top-layer soil resistivity and bottom-layer soil resistivity are analyzed when considered double-layer soil model. The results show the more depth of burial is, the lower maximum potential and earthing resistance are. However, the temperature is difficult to spread, which will result in the maximum temperaturerise grow as depth of burial increase. Furthermore, it can be affirmed that soil resistivity play a important role on performance of grounding electrode. With soil resistivity increase, the maximum potential and earthing resistance, etc were heightened in a certain extent. But the influence of top-layer soil resistivity to grounding electrode performance is more than bottom-layer soil resistivity.