特高壓地下環路接地系統開關突波特性研究

A Study on the Switching Surge Characteristics of grounding System of Closed-Loop VHV Underground Distribution Systems

溫茂廷(Mao-Ting Wen)

指導教授 ： 周至如 ； 何金滿

中原大學/工學院/電機工程研究所/碩士(2006年)

https://doi.org/10.6840/cycu200600225

摘要

本文探討特高壓地下環路接地系統的開關突波特性，即探討變電所與用戶在開關操作時在接地系統所造成的開關突波強度及其對電纜被覆保護裝置（CCPU）的避雷器及接地系統的影響，其中對接地系統的影響是指開關突波電流流入接地系統後在地網產生的各種開關突波電磁特性，如地電位昇（GPR）、地表面電位、步間電壓、接觸電壓、磁場及導體電流等。文中首先以電磁暫態程式（EMTP/ATP）建立（161kV與69kV）地下環路供電系統之電磁暫態分析模型，並針對變電所及用戶開關在不同的操作模式下進行開關突波模擬分析以獲得出現在變電所、用戶及人孔處之突波電壓及電流，其中考慮開關操作共分為兩個狀態（投入操作與切離操作）四種情形（三相同時投入、三相同時切離、三相不同時投入與三相不同時切離）等狀況。根據分析所得的開關突波電流注入變電所及用戶地網之值，再進一步應用接地系統分析軟體（CDEGS）分析各項電磁特性，最後根據分析的結果進行評估各項影響包括CCPU內避雷器所承受的開關突波電壓之最大值，以及對接地系統之電磁特性對人員與設備影響的程度。整體而言由模擬的結果比對CCPU避雷器之特性，可發現各環路正常狀況下之開關投入時的突波皆不致危害CCPU避雷器及電纜絕緣被覆，但切離時可能承受危險的突波電壓，至於對接地系統的影響應注意接地系統突波GPR對敏感設備之影響，及電纜遮蔽層導體突波電壓轉移成人員接觸電壓之危害，尤其在電纜接地點應避免人員靠近以免發生電纜遮蔽層導體突波電壓轉移之接觸電壓之傷害。

關鍵字

特高壓地下環路 ； 開關突波 ； 地電位昇 ； 接觸電壓 ； 步間電壓

並列摘要

This thesis is to study the switching surge characteristics of grounding system of very high voltage (VHV) underground distribution system with loop structure (VHV underground loop). The switching surge intensity and its affections on cable-cover protection-unit (CCPU) and grounding system due to switch operations at substation and/or customers are evaluated. The circuit model of typical VHV underground loops with their grounding systems are first constructed and analyzed by electromagnetic transient program (EMTP/ATP). The switching surge voltages and currents of grounding system at substation ,customers and cable man-holes are obtained from the simulation with respect to switch-close and switch-open operations. Four switch operation modes, namely three-phase synchronized close, three-phase synchronized open three-phase asynchronism close and three-phase asynchronism open are considered. Based on the simulation results , the maximum switching surge voltages forced on CCPU and the largest switching surge current injected in to grounding grids at substation and customer are found out and their affections are evaluated by comparing the characteristic values of arresters and further analyzing the electromagnetic characteristics of ground grids, respectively. Finally, a software package for grounding system analysis, namely, Current Distribution Electromagnetic Grounding and Soil Structure Analysis (CDEGS) are used, from which we can find voltages and electromagnetic fields (EMF) on the ground surface of ground grids in the substation and customers. The personnel and equipments affected by these distributions are assessed. In the whole, the study results have shown that the CCPU can with stand the switch surge when switch-close operation but may access danger surge voltage when swich-open operation. As to grounding system, the switching surge voltage of shielding conductors may transfer to personnel to form as touch voltage damage and to sensitive equipments to burn out their devices, especially, the grounding points of cable shielding conductors should be considered as danger points for personnel safety.

並列關鍵字

Switching Surge ； Very High Voltage Underground loop ； Step Voltages ； Touch Voltages

參考文獻

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