地下超高壓變電所接地系統之接地故障特性及其影響研究

A Study on the Ground Fault Characteristics and Affections of Ground System of Underground Extra-High Voltage Substation

李宛真(Wan-Chen Li)

指導教授 ： 周至如

國立臺北科技大學/電資學院/電機工程系 優質電力產業研發專班/碩士(2008年)

摘要

為因應都會區電力需求量快速增加且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加上居民抗爭，變電所朝室內地下化或立體化發展是必然的趨勢。而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其接地系統，對變電所的人員及各種系統與設備帶來危險。本研究以一個典型的超高壓變電所為對象，分別探討所內發生接地故障時，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。文中首先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接地網的電流，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，然後應用接地系統電磁分析軟體(CDEGS)分析不同故障條件下之各項電磁特性，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，包括對人員及設備的影響，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

接地故障 ； 地電位昇 ； 接觸電壓 ； 步間電壓

並列摘要

For the fast increasing demand of power in the city, it is a trend to build EHV substations in the area of load center so as to promote reliability and quality of power system. However, due to the difficulty of obtaining right-of-way (ROW) and the protests from local residents, it is unavoidable to build indoor substations of underground type or layered type.
On the other hand, the short circuit capacity of EHV substation is very large, so once a ground fault occurs with large amount of fault current injected into substations ground grid, it will bring hazards to the personnel and equipment in the substation. This thesis focuses on a typical EHV substation, to study various electromagnetic characteristics of ground system, during ground fault 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 at fault points, natural point of main transformers, grounding points of cable shielding conductors.
Furthermore, the electromagnetic characteristics of grounding system at transient states steady states are analyzer by the software namely CDEGS (Current Distribution Electromagnetic Grounding and Soil Structure Analysis). Finally, based on their analysis results, the affections of electromagnetic characteristics of grounding system on personnel and equipments are assessed. The study results can be used for further studied the protection measures in the underground EHV substation.

並列關鍵字

Under EHV Substation ； Ground Fault ； Ground Potential Rise ； Touch Voltage ； Step Voltage

參考文獻

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