Study Of Hollow Grounding Device And Its Application

As a new type grounding device, hollow grounding device has played an important role in high resistivity soil and less-area grounding engineering. But it is still blank in the theoretic aspect of grounding resistance calculation, design method for substation which is important to the design and application for that device. Based on the ground current field theory, this paper built an operation model of hollow grounding device according to the configuration. According to the characteristic and the precision demand, it improved the electric calculation method of surface charge. With the model and electric calculation method, it programmed for the calculation of hollow grounding device resistance. Comparison results of the standard hemisphere grounding device grounding resistance values by theoretical calculation to those by program validate the model and the electric calculation method. The results also indicate that the program could get enough precision for engineering demand. This paper also analyzed the effect to grounding resistance of the device's shape, device's section diameter, height and depth which was the base of engineering application through lots of simulate calculations. It also analyzed the effect of grounding hole to the resistance, the influence of backfill soil resistivity, the hole's section diameter and the hole's depth to the resistance. By lab simulate experiments, it verified the model, the calculation model and the program. It also proved the effect of grounding hole and affused water to the device's grounding resistance. This paper analyzed the effect of shielding between hollow grounding devices and between hollow grounding device and ground grid. It also put forward the way to apply the hollow grounding device. Based on the research of this paper, two substations' grounding system have been designed and rebuilt successfully.