Analysis of Grounding Grids Connection Between Photovoltaic Farm and Its Substation

• Main Authors: Ge, Aixin, Xie, Dongsheng, Shi, Zhuopeng, Yu, Guomei, Zhang, Xiaohong
• Format: Conference Proceeding
• Language: English
• Subjects: Conductivity; Electric potential; Grounding; grounding system; numerical simulation; photovoltaic farm; Power transmission lines; Resistance; Soil; substation; Substations
• ISSN: 2474-3852
• DOI: 10.1109/ICHVE49031.2020.9280034

Photovoltaic (PV) farms often surround their supporting substations, which are sometimes built in mountainous regions with high soil resistivity. When the farm and the substation are independently grounded, if there is a fault in the substation, the grounding system of the PV farm will collect most of the fault currents from the substation, which can generate a very high potential difference between the two grounding systems, and give rise to very high step voltages and touch voltages which are hazards to personnel safety and reliable equipment operation. This paper discusses this issue in depth based on numerical simulation of the grounding systems of a PV farm and its 220 kV substation. The grounding resistance, step voltage, touch voltage, and the ground potential difference in the grounding grid are considered, especially in the PV farm. The dangerous place and the mechanism are discussed. The measures to protect the device in the PV farm are investigated. The research finds that if the two grounding system are interconnected, all of the parameters decrease greatly. Therefore, interconnection two grounding system is necessary even they belong to different companies.