Analysis of Electromagnetic and Grounding Characteristics of Conductive Concrete

• Main Authors: Siang-Ren Wang, 王湘仁
• Other Authors: Chun-Yao Lee
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/8jcu4b

碩士 === 中原大學 === 電機工程研究所 === 98 === The purpose of this thesis is to improve the electromagnetic characteristics of grounding grid with the conductive concrete for an extra high voltage (EHV, 345kV) and very high voltage (VHV, 161kV) system, located in a high-tech industry or science-based industrial park. The Study focuses the switching surge is injected to grounding grid caused by operations of breakers or switches. Instead of traditional soil around grounding grid, the conductive concrete can reduce equipment damage and the body damage, caused by switching surges. First, the properties of the conductive concrete, including resistivity and permeability, are studied. The resistivity is measured by both using four-electrode method and stress-electrode method. Test their stability and considering the influence of temperature and humidity. Then, we discuss and compare what the differences between four-electrode method and stress-electrode method. The permeability is simulated and measured based on simple magnetic circuit model. Finite Element Method Analysis (ANSYS) is employed to simulate the magnetic intensity and the magnetic flux density for estimating relative permeability. Subsequently, the conductive concrete is measured partically. Second, the circuit model is used to analyze surge currents constructed by the electromagnetic transient program (EMTP/ATP), and the injection currents to grounding system since the switching action on the primary and secondary transmission lines and buses are analyzed. Furthermore, based on the analysis results of switching surge current which is injected into the ground grid of substation, various electromagnetic characteristics of grounding system are analyzed by a software package (CDEGS). Finally, the variations of different soil materials around the grounding grid are analyzed. The influences of electromagnetic characteristics of grounding system on the personal, equipments and systems are evaluated. Comparing to several soil material styles, the study results have shown that the conductive concrete can effectively reduce the negative damage, caused by electromagnetic transient, and obviously improve the protection of grounding system under the condition that the grounding gird is located 1.0(m) underground, and the conductive concrete is applied from the ground surface to 1.25(m) underground.