多地網大型接地系統接地故障之電磁特性研究

A Study of the Electromagnetic Characteristics of Large Grounding System with Multi-grid during Ground Faults

胡開泰(Kai-Tai Hu)

指導教授 ： 周至如

中原大學/工學院/電機工程研究所/碩士(2001年)

https://doi.org/10.6840/cycu200100203

摘要

摘 要
本論文旨在探討多地網大型接地系統於接地故障時的電磁特性，包括地電位湧昇、地表面電位、步間電壓、接觸電壓、轉移電壓及電磁場分佈。本文以台北捷運系統木柵線機廠為研究的對象，該機廠有七大地網，每個地網在接地故障時所引起的地電位湧昇、地表電位、步間電壓、接觸電壓、導體電流及地表面電磁場的分佈，都將進行分析，並計算各地網之間最大的電位差（轉移電壓）。本文的分析方法是採用電磁理論分析方法，此方法較其他傳統分析法可得較精確的結果及分析項目更為廣泛。根據分析結果進一步評估人員與設備的安全及電磁干擾，這些分析及評估將分別針對地網相連與不相連兩種狀況探討之。
分析結果顯示在地網相連的狀況下，故障點所在的地網之地電位湧昇、步間電壓及接觸電壓可大幅降低，且地網間的轉移電壓亦可大幅降低，但其他地網的地電位湧昇、步間電壓、接觸電壓及電磁場強度將被提高，此現象對人員與設備的影響將在文中加以評估。經評估結果，為確保低壓設備的安全，地網以相連為宜，並應加強敏感設備及系統的電磁干擾能力，此外，為再加強人員安全及重要場所（如行控中心）的設備安全，相關防範措施亦應適度採用，本文亦整理過去文獻所提出的改善方法與措施以供參考。

關鍵字

電磁特性 ； 事故評估 ； 接地系統

並列摘要

Abstract
This thesis is to analyze the electromagnetic characteristic of large grounding system with multi-grid during ground fault. The electromagnetic characteristics include the ground potential rise (GPR), step voltages, touch voltages, transfer voltages and the distributions of ground surface potential and electromagnetic fields. The study is aimed to the grounding system in Mucha factory of Taipei-Rapid-Transit System (TRTS) which includes seven ground grids. The electromagnetic characteristics of this system will be analyzed with respect to two different cases. The case 1 consider all the grids to be connected together by copper wires with insulated sheath while the case 1 is all the grids in discrete (disconnection). The analysis method is based on the electromagnetic field theory, from which the analysis results will more precise than from other conventional methods. The analysis results have shown that the GPR, transfer voltages, step voltages and touch voltages of ground fault grid will be largely reduced in the case of all the grids being connected together, but the GPR, step voltages, touch voltages and electromagnetic field of other non-ground-fault grids will be increased. The affections of this phenomena on the personnel and equipments will be assessed. For the safety requirements of low voltage equipments, all the grid are recommended to be connected together rather discreted. The other protection measures against step voltages, touch voltage and electromagnetic interference are still required at some important locations. The improved methods and their related measures which had been proposed by the literatures will be collected and integrated here for application reference.

並列關鍵字

Electromagnetic Characteristics ； Faults ； Grounding System

參考文獻

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[3]F. Dawalibi, W. G. Finney, "Transmission Line Tower Grounding Performance In Non-Uniform Soil", IEEE Trans. on Power Apparatus and Systems, Vol. PAS-99, No.2, PP.471-479, Mar/Apr, 1980.

[5]M. A. El-Kady, M. Y. Vainberg, "Risk Assessment of Grounding Harzard due to Step and Touch Potentials Near Transmission Line Structures", IEEE Trans. on Power Apparatus and Systems, Vol PAS-102 No.10, PP.3080-3087, Sep. 1983.

[6]IEEE Working Group,"Background and Methodology for Analyzing Step and Touch Potential near Transmission Structures", IEEE Trans. on Power Apparatus and Systems, Vol. PWRD-1, N0.2, PP.150-162, Apr.1986.