特高壓地下環路之電纜遮蔽層及接地系統之電位及電流分佈特性研究

A study on the Potential and Current Distributions Characteristics of Cable Shielding Conductors and Grounding System of VHV Underground Distribution System with Loop Structure

朱正宏(Cheng-Hung Chu)

指導教授 ： 何金滿 ； 周至如

中原大學/工學院/電機工程研究所/碩士(2006年)

https://doi.org/10.6840/cycu200600232

摘要

特高壓地下環路供電系統的接地系統包括變電所及各用戶之地網及電纜人孔之接地棒，它們都藉由電纜遮蔽層導體及互連導體(輔助接地線)緊密互聯。在正常運轉時，電纜遮蔽層導體及互聯導體的感應電壓及感應環流都會出現在各用戶及變電所地網而有不利的影響，尤其環路上任一處發生接地故障，除感應電壓及感應環流外，大量故障電流注入接地系統，流入各用戶接地網威脅人員與設備的安全，以及對電纜遮蔽層及其被覆保護裝置(CCPU)之傷害，為防護這些傷害必須掌握整體環路接地系統的電壓電流分佈的全貌。本論文以典型特高壓(161kV及69kV)之地下環路供電系統探討其接地系統的電壓電流分佈，考慮正常運轉及各種類型的接地故障狀況下的電壓、電流分佈。文中首先以電磁暫態模型分析程式(EMTP/ATP)建構模型，並且分析前述各種狀況下之接地系統電壓及電流分佈，其中包括電纜遮蔽層在人孔處的電壓及電流以及注入用戶及變電所地網的電流，模型的建立及分析都分別考慮正常運轉及單相、兩相與三相接地故障的類型，電纜CCPU內避雷器狀況，除考慮避雷器之正常特性曲線外，更考慮CCPU滲水短路狀況。經由分析的結果進一步評估電纜遮蔽層導體及其CCPU以及接地系統的影響，其中在用戶地網造成之地電位昇、步間電壓、接觸電壓及電磁場之分佈，將在應用接地系統分析軟體CDEGS來模擬，並進一步由模擬所得的重要數據以評估對人員及設備的影響程度。

關鍵字

電纜被覆保護裝置 ； 電纜遮蔽層導體

並列摘要

The grounding system of very high voltage (VHV) underground distribution system with loop structure includes the utility substation, customers ground grids and ground rods in the cable man-holes which are connected together by cable shielding conductors and inter interconnected conductors(auxiliary ground wires). During normal operation, the induced voltages and circulating currents on the cable shielding conductors and interconnected conductors will appear on the substation and customers’ ground grids with detrimental effects. Especially, during ground faults, not only large induced voltages and circulating currents but also fault currents will appear on everywhere of grounding system to damage personnel and equipments, and to hurt cable shielding conductor and cable cover protection unit(CCPU). For preventing these damages, the understanding of the voltage and current distributions on the whole ground system is necessary. In this thesis, the voltage and current distributions on the grounding system of typical VHV(161kV and 69 kV) underground distribution system with loop structure are studied by considering the system on normal operation and various types of ground faults situations. The circuit models based on Electromagnetic Transients Program(EMTP/ATP) are constructed where the system on normal operation and single-phase, two-phase and three-phase ground faults are considered. From which, we can analyze the voltages and currents of cable shielding conductors in man-holes and the current injections of ground grids in the substation and customers, the nonlinear devices(arresters) in the CCPU of cable will approached by their characteristic curves and shorted-circuit case with respect to CCPU in normal and water seeping situations. Based on the analysis results, the affections of voltage and current distributions on the cable shielding conductors and CCPU and grounding system are evaluated. In which, a grounding system analysis software package, namely, current distribution electromagnetic, grounding and soil structure (CDEGS) is used for the simulations. Furthermore, the critical data from CDEGS simulation results is obtained for assessing their affections on the personnel and equipments.

並列關鍵字

cable shielding conductor ； CCPU

參考文獻

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[1] IEEE Std.400, "IEEE Guide for field testing and evaluation of the insulation of shielded Power cable systems", 2002.