大環境變遷與因應高科技產業快速發展,為提高供電品質,高壓輸電線路之規劃設計已逐漸由架空方式轉變為地下化,同時採用氣封開關設備(GIS)之室內變電所設計方式日益普及。由於電力系統開關操作時,GIS 外殼易發生感應暫態過電壓,與其他設備具電位差時(如電纜遮蔽層),極易造成過電壓火花放電,除威脅人員安全外,對電力品質亦成為一潛在影響因素。GIS 外殼分成數段,各段GIS 內的相導體對外殼有分佈電容存在。為避免造成環流,支持鐵架與避雷器接地線分別單獨接至共同接地匯流排。因此兩端電壓差即可能造成環流及暫態電壓之火花放電。本計畫以南科超高壓變電所345kV GIS 為研究對象,除模擬雜散電流外,同時針對斷路器啟、閉時之暫態特性,探討其對GIS 外殼感應電壓影響;本報告利用ATP 電磁暫態軟體,進行模擬驗證。另外地網高頻模型亦為一影響開關突波重要參數,本計畫亦一併列入分析。Owing to the variances of living environment and promoting the power quality, TPC’s transmission lines are gradually designed as the underground type. In the meanwhile, the gas-insulated switchgear (GIS) is employed for the indoor-type substations. When the switching operations are performed, the transient high voltage will occur on the enclosure of GIS. This transient voltage may lead to flashover between the junction with different voltage(like sheath layer of power cable). The phenomenon of flashover will result to the danger of crews and influence the power quality. GIS is composed of several segments of metal compartment, the capacitance exists between the phase conductor and enclosure. To prevent the loop current happen, the grounding of supporting shelf and sheath layer of power cable are connected to ground network independently. In this report, based on the Nan-Ke E/S 345 kV GIS, the stray current and switching transient voltage of the enclosures of GIS are studied. The ATP software package is used for simulations. The effects of high frequency ground network model on the switching transient are taken into consideration in this report.