大型電廠屋外式氣封絕緣開關場之突波與接地故障特性分析及其影響評估

Surge and Ground Fault Characteristics Analysis and Affection Assessments for the outdoor type GIS of Large Power Plant

林于軒(Yu-hsuan Lin)

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(2014年)

https://doi.org/10.6841/NTUT.2014.00152

摘要

大型電廠均併聯至超高壓系統，其超高壓開關場若採用屋外式氣封絕緣開關場(Gas Insulated Switchyard, GIS)，在事故發生時可能比傳統開放式開關場嚴重。常見的電氣事故中以雷擊、開關突波及接地故障最常發生，對系統的衝擊及人員與設備的威脅相當大，故為本文探討的重點。本文將以台電系統典型發電廠之345kV GIS為探討對象，首先以電磁暫態分析軟體（EMTP/ATP）建構整體GIS模型，然後分別模擬開關突波、雷擊突波與接地故障之特性，包括在系統重要設備之電壓及電流變化特性，涵蓋穩態特性及暫態特性，而系統除涵蓋開關場本體外，更擴及發電機、變壓器及聯外輸電線路部分。其中開關場之接地系統與人員及設備安全關係密切，必須進一步分析其電磁特性，因此，本文將進一步用ATP模擬注入開關場接地系統之電流，即獲得GIS各接地點之電流數據，接著應用接地系統電磁特性分析軟體(CDEGS)，進行GIS地網之電磁特性分析，包括地電位昇(GPR)、地表電位、接觸電壓、步間電壓、導體電流及地表電磁場之分布狀況。最後，整合ATP及CDEGS的分析結果，比較GIS相關設備及人員可承受之電壓，以評估開關突波、雷擊突波與接地故障等特性對GIS之影響。

關鍵字

氣封絕緣開關場 ； 開關突波 ； 雷擊突波 ； 接地故障

並列摘要

Large power plants usually connect to extra high voltage systems (EHV). If the EHV switchyard use outdoor type GIS (Gas Insulated Switchyard, GIS), it may be more serious than conventional open type switchyard when the accident occurs. Switching surge, lightning surge and ground fault are the common and frequent electrical accidents. These accidents have significant impact on the system and have threats to personnel and equipment. Therefore, exploring these accidents is the key point of this thesis. In this thesis, we explore typical power plant 345kV GIS of Taipower system. Firstly, the model of whole switchyard is constructed by the alternative transient program (EMTP/ATP). Then, the characteristics of switching surge, lightning surge and ground fault are simulated, respectively. The characteristics include vital equipment voltage and current change on the system. The current and voltage change cover transient and steady-state. The system includes switchyard itself, generators, transformers and transmission lines. Switchyard grounding system is closely related to the personnel and equipment safety. Therefore we must further analyze its electromagnetic characteristics. In this thesis, ATP is used to simulate the current of every grounding point that injects into GIS grounding grid. Then this data is analyzed by a software package named Current Distribution Electromagnetic Ground and Soil Structure Analysis (CDEGS). The analysis focus on the following characteristics: the distribution of ground potential rise (GPR), potential on the ground surface, touch voltage, step voltage, conductor current and electromagnetic field (EMF) on the ground surface. Finally, in order to assess the impact of the switching surge, lightning surge and ground fault characteristics on GIS. Analysis results of ATP and CDEGS are integrated, and are compared with the voltage that GIS equipment and personnel can withstand.

並列關鍵字

Gas Insulated Switchyard ； Switching Surge ； Lightning Surge ； Ground Fault

參考文獻

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