以長距離電纜連接至電纜連接站之大型電廠接地故障特性研究

The Ground Fault Characteristics of Large Plant with Long Cable Connection to Cable Connection Station

黃啟臺(Chi-Ti Huang)

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(2007年)

https://doi.org/10.6840/cycu200700256

摘要

本論文探討大型電廠若以長距離電纜連接至電纜連接站，在機組與開關場發生單相接地故障時，故障電流及電壓將出現在接地系統與電纜遮蔽層導體，這些現象可能造成人員與設備及電纜本身的傷害，故本文將以典型的案例來探討這些問題，首先以電磁暫態分析程式(EMTP/ATP)建構電路模型，並進行單相接地故障分析，包括暫態與穩態分析。模型的建構將考慮機組變壓器及機組地網，電纜相導體及遮蔽層導體，開關場及開關場地網及連接站地網。其中電纜遮蔽層導體交錯換位連接及經電纜被覆保護裝置(CCPU)之避雷器接地，在此研究中皆假設機組中性點皆經避雷器接地。經由ATP分析的結果可觀察出電纜遮蔽層之電流與電壓分佈狀況以及注入各地網電流大小值狀況。最後在依據所觀察的結果可進一步評估對電纜及接地系統的影響，前者將針對電纜遮蔽層之連接處及故障時產生的故障電流對設備的影響做探討，至於對接地系統影響的評估，則先應用接地系統分析軟體(CDEGS)來分析地網電磁暫態特性包括地電位昇、接觸電壓、步間電壓及地表電磁場之分析，並藉此評估對於人員與設備的影響，整體而言經分析結果顯示，人員及設備於故障點，或觸及電纜遮蔽層導體其安全將受到威脅，而電纜遮蔽層上的電流及電壓可達數kA及數kV，在連接處若處理不當很容易引發電纜損壞釀成更大的傷害。

關鍵字

避雷器 ； 電纜被覆保護裝置 ； 電纜遮蔽層導體 ； 地電位昇

並列摘要

This thesis in to steady the ground fault current and voltage appeared on grounding system and cable shielding conductor with may produce hazard on personnel and cables for the large plant with long cable interconnections to cable connection station (CCS) ﹒The single-phase-ground faults with respect to the fault locations of main transformer, switchyard and CCS are analyzed by using electromagnetic transient program/alternative transient program(EMTP/ATP) and considering transient state and steady state of ground fault﹒The circuit model constructed by EMTP/ATP will take the ground grids of generation unit, switchyard and CCS into account﹒The cross bonding and surge arresters installed in the cable cover protection unit (CCPU) for cable shielding conductors are considered in the model﹒All the analysis will aim to the main transformer neutral points with solid grounded and with arresters Based on the analysis results of fault currents injected into ground grids , a soft were package called CDEGS is used to analyze the characteristics of grounding system including ground potential rise(GPR) , touch voltage , step voltage and electromagnetic field distributed on the ground surface﹒The affections of these characteristics on personnel and equipments are evaluated﹒The study results had shown that danger touch voltage will appear on fault points and cable shielding conductor﹒Several kV and kA of cable shielding conductor voltages and currents will be arrised ﹒Thus , cable shielding conductors with defect connection may induce large hazard due to their high voltages and currents﹒

並列關鍵字

arrester ； shielding conductor ； ground ； cable-cover-protection unit

參考文獻

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