科學園區高壓用戶變電站與電力公司之接地最佳整合研究

Optimal Integration for the Grounding of HV Customer Substation and Utility Power Supply System in the Science Park

丁年平(Nien-Ping Ting)

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(2013年)

https://doi.org/10.6841/NTUT.2013.00198

摘要

典型的科學園區高壓供電系統供電方式為三相四線式地下電纜供電，各饋線電纜中性導體是多重接地，但引接至用戶高壓變電站之電纜通常無中性導體層，僅有薄金屬帶遮蔽層，此遮蔽層僅允許單端(點)接地，即若在用戶變電站接地，在台電變電室則不接地。此架構於接地故障時，大量故障電流將注入用戶地網，造成極高之地電位昇(GPR)威脅人員與設備之安全。本研究針對此問題，首先使用電磁暫態分析程式(ATP)針對系統不同用戶故障、變電所與用戶變電站開關操作及各地網遭受雷擊時進行模擬分析，取得注入各地網之電流數據，再應用接地系統電磁特性分析軟體(CDEGS)，進行用戶地網電磁特性分析，根據上述分析結果確認用戶高壓變電站之風險程度後，以模擬退火法為基礎針對接地故障建立用戶地網電壓數學模型，採行之控制變數含：改變用戶及變電所地網電阻、增設輔助接地線、改變人孔及受電室接地電極之阻值、增設用戶變電站地網及台電受電室接地電極間互連裝置等。進行接地系統之最佳整合，使接地系統之建置成本最小化並改善故障期間故障電流回流路徑不佳之問題。之後再以ATP及CDEGS驗證最佳化整合後之接線架構能有效降低流入用戶地網之故障電流而降低GPR，使人員及設備安全獲得確保。

關鍵字

最佳整合 ； 模擬退火法 ； 故障分析

並列摘要

The typical high voltage (HV) (22.8kV and 11.4kV) utility power supply system (UPSS) in each science park is fed by three-phase four-wire underground cables. The main grounding problem is that the neutral conductors of underground feeder cables are not drawn into customer substations, which lead to detrimental effects on ground fault protection and ground potential rise (GPR) of customer substation. In addition, transfer voltage to customer substation due to ground fault at utility substation is severe, especially supplied by extra high voltage substation (E/S). Moreover, those customers near utility substation are subject to very high lightning and switching surges from utility substations. Obviously, to mitigate these problems, the grounding of both customer substation and UPSS should be improved together. In thesis, we use alternative transient program (ATP) to construct the HV UPSS model and then simulate the characteristics of ground fault, lighting surge and switching surge to get the data of fault current that injected into customer grounding system. Furthermore, we use these data to analyze the electromagnetic chacacteristic of grid of customers by a software package namely the current distribution electromagnetic ground and soil structure analysis (CDEGS) program. The analysis result ensure that the original ground system is highly risky. Obviously, to mitigate these problems, the grounding of both customer substation and UPSS should be improved together. The grounding improved measures include not only reducing ground resistance but also the use of related supporting measures and their integration which produce more effective results. This thesis aim to find all the feasible supporting measures of grounding base on simulated annealing method, the variables include the measures used in customer substation and that of used on UPSS. The costs of the measures will be assessed and optimal integration based of them are implemented to satisfy all the grounding requirements and constraints by lowest total cost. Thereby, all the touch voltage, step voltage and metal-to-metal touch voltage at customer substation will be confined within safe range to assure the personnel safety when ground fault, lightning and switching surges; and the transfer voltage, GPR and magnetic field are all under the limits for protecting equipments from over voltage and magnetic interference. Moreover, the total cost for grounding integration will be minimized, thus this research will upgrade the electric supply safety in science park and conform with economy.

並列關鍵字

Science Parks ； Customer Substations ； Grounding ； Optimal Integration ； Ground Fault ； Lightning Surge ； Switching Surge

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