以長距離電纜併聯的大型電廠接地系統之接地故障特性及其影響研究

Ground Fault Characteristics of Grounding System in the Large Plants with Long Cable Interconnections

周至如(Chih-Ju Chou) ； 翁瑋澤(Wei-Tse Weng) ； 蕭智鴻(Chih-Hung Hsiao)

《先進工程學刊》 1卷1期 (2006/07) Pp. 7-14

https://doi.org/10.29948/JAE.200607.0002

摘要

探討典型多機組的大型電廠以長距離電纜併聯時，其接地系統的穩態接地故障特性，包括機組地網及開關場地網之地電位昇、接觸電壓、步間電壓及地表面磁場之分佈，以及電纜遮蔽層導體之電流及電壓分佈，其中將考慮機組地網、開關場地網及電纜遮蔽層導體與互連導體，而電纜遮蔽層導體之交錯換位連接及電纜充電電容亦被考慮以建構其等效電路模型。研究結果顯示，主變壓器的中性點接地與否及電纜遮蔽導體與互連導體對整體的接地系統故障特性有關鍵性的影響。主變壓器中性點接地將增加故障電流亦增加開關場及機組地網的危險性，本文將評估這些危險性包括對人員、設備及電纜之影響。

關鍵字

多機組大型電廠 ； 地電位昇 ； 接觸電壓 ； 步間電壓 ； 磁場分佈

並列摘要

regards the characteristics of grounding system during steady state grounding fault in the multi-unit large plant with long cable interconnections. The ground potential rises (GPR), touch voltages, step voltages and magnetic fields distributions on the ground grids of generators and switchyard caused by grounding fault are analyzed. The current and voltage distributions on the shielding conductors of cables are studied. Also, the transposited cross bonding between cable shielding conductors and the cable capacitances are considered in modeling of equivalent circuit. The study results reveal shown that the ground fault current will increase with the number of main transformer with neutral to be solidly grounded. The hazards will be increased in the switchyard and generator ground grids. Moreover, the hazards on personnel, equipments and cables are assessed.

並列關鍵字

multi-unit large plant ； ground potential rise ； touch voltage ； step voltage ； magnetic fields distributions