地下超高壓變電所接地故障電流於樓層地網之分佈及其影響研究

A Study on the Distribution of Ground Fault Current on the Grounding Grid of Floors and Their Affections in the Underground EHV Substation

楊致嘉(Chih-Chia Yang)

指導教授 ： 周至如

國立臺北科技大學/電資學院/電機工程系研究所/碩士(2009年)

https://doi.org/10.6841/NTUT.2009.00515

摘要

由於都會區電力需求量快速增加且為有效提昇供電可靠度及品質。在電力負載中心建置超高壓變電所漸成發展趨勢，但因都會區變電所用地取得不易，與居民的抗爭，變電所朝室內地下化或立體化發展是必然的趨勢。地下超高壓變電所是將各種電力設備設置在地下不同樓層形成立體式架構，因土地面積有限難以建構大型接地網，各樓層必須廣設接地匯流排及接地引線形成樓層地網，接地功能是否良好由各樓層地網與基礎地網的特性共同決定，且超高壓變電所其短路容量很大，一旦發生接地故障時，有大量故障電流注入各樓層地網，對所內人員及各種設備的安全影響極大，亟須加以探討。本論文主要探討地下超高壓變電所接地故障時各樓層地網及基礎地網，接地系統的各項電磁特性，包括地電位昇(GPR)、步間電壓、接觸電壓及電磁場的分佈情形，並藉此評估對於人員、設備及其它系統之影響。文中應用電磁暫態分析程式之改良程式(ATP)建構模型以分析不同故障位置之接地故障，經由分析結果可獲得故障電流及注入各樓層地網的電流，包括故障點、主變壓器中性點及地下電纜遮蔽導體等處之電流，然後進一步應用接地系統電磁分析軟體(CDEGS)分析不同故障條件下各樓層地網之電磁特性，包括穩態及暫態特性。最後根據這些分析結果以評估其影響，包括對人員及其他系統的影響，本研究相關分析所得之數據可作為進一步探討地下超高壓變電所之參考防護措施。

關鍵字

地下超高壓變電所 ； 接地系統 ； 接地故障 ； 電磁特性

並列摘要

For the fast increasing demand of power in the city and in order to promote reliability and quality of power system, it is a trend to build EHV substations in the area of load center. However, due to the difficulty of obtaining right-of-way and the local residents protest, it is unavoidable to build indoor substations as underground type or layered type. There are various electrical equipments install on different floors in the underground Extra High Voltage (EHV) substation and to form a cubic structure, however, the area is too limited to construct large grounding grid, the method for that is to widely install grounding buses and grounding conductors to form the grounding grid for each floor, and its grounding performance will depend on the grounding buses, grounding conductors and the characteristics of ground gird. Due to the large short circuit capacity of EHV substation, the large amount of fault current will inject into substation ground grid during ground fault, and that will damage the personnel and equipments in the substation.
This thesis aims are to study the various electromagnetic characteristics of ground system of main grounding grid and grounding grid of each floor during ground fault, which including ground potential rise (GPR), step voltage, touch voltage, and the distribution of electromagnetic field. Based on the analysis results, the influences of ground fault on the personnel, equipment and other system are assessed. The circuit model for analyzing the ground faults with respect to different fault locations are first constructed by the alternative transient program (ATP), from which we can obtain the fault currents and the injection current to ground grid of each floors at fault points, natural point of main transformers, grounding points of cable shielding conductors. Furthermore, the electromagnetic characteristics of grounding system at transient states and steady states are analyzed by the software namely CDEGS (Current Distribution Electromagnetic Grounding and Soil Structure Analysis). Finally, based on the results, the affections of electromagnetic characteristics of grounding system on personnel, equipments and other systems are assessed. The study results can be used for further studied the protection measures in the underground EHV substation.

並列關鍵字

Underground EHV Substation ； Grounding System ； Ground Fault ； Electromagnetic Characteristics

參考文獻

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