Grounding of Urban GIS Substation Connected to Commercial Buildings and Metallic Infrastructures

Abstract—This paper examines various aspects of the design process of an urban Gas insulate Switchgear (GIS) complex substation grounding system. The study shows how advanced simulation approaches can be used to study complex grounding systems involving gas-insulated substations and massive connected metallic infrastructure in an urban environment by following the IEEE 80-2000 recommendations and requirements. It describes why it is important to model accurately the GIS structure, ground conductors, massive reinforced steel rebar, residential neutrals, surrounding commercial buildings and residential water pipe infrastructures as well as correctly simulate fault currents and circulating currents in order to determine touch voltages accurately and avoid overestimating or underestimating them. A parametric sensitivity analysis are performed. It is shown that bonding of an urban substation grounding system to the urban city buried metallic infrastructures, in most cases, enhances the safety status inside the substation while ensuring that the transferred voltages to the city metallic infrastructures will not endanger the safety of people in the zone of influence. Furthermore, this paper suggests that the grounding grid installed beneath the GIS system does not have a major influence on the grounding grid or GIS performance. However, the method of bonding the GIS to the rebar or to the grounding system can significantly modify the building and GIS safety status. Finally, the paper demonstrates that the urban substation grounding grid performance is not very sensitive to the type of soil structures in which the system is buried due to the surrounding city buried metallic network and building rebar which are typically directly or indirectly connected to the grounding system providing thus a significant damper on the effects of soil characteristics changes.

Index Terms—substation, GIS, grounding, metallic infrastructures, touch & step voltages, ground potential rise (GPR).

Zhang Jinsong is with the Jiangsu Fangtian, Nanjing, China (email: 15905166808@163.com)
Qian Feng and Guo Bing are with the Yangzhou Power Supply Company, Yangzhou, China (email: ygsqf27144@163.com, 21340483@qq.com)
Yexu Li and Farid Dawalibi are with the SES technologies ltd. Quebec, Canada (yexu.li@sestech.com, farid.dawalibi@sestech.com)

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Cite: Zhang Jinsong, Qian Feng, Guo Bing, Yexu Li, and Farid Dawalibi, "Grounding of Urban GIS Substation Connected to Commercial Buildings and Metallic Infrastructures," International Journal of Materials, Mechanics and Manufacturing vol. 3, no. 3, pp. 191-196, 2015.