超高壓變電所鄰近線路接地故障特性及其對所內斷路器控制系統之影響研究

Ground Fault Characteristics of Lines Nearby Extra-High Voltage Substation and their Affections on the Breaker Control System in the Substation

羅景禎(Ching-Chen Lo)

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(2007年)

https://doi.org/10.6841/NTUT.2007.00074

摘要

本研究針對典型屋外開放式超高壓變電所鄰近地區發生架空線路接地故障之特性進行分析，並探討其對變電所所內斷路器控制系統之影響，首先應用電磁暫態分析程式(EMTP/ATP)建構模型，其中考慮變電所內之主變壓器及一次側與二次側之系統包括匯流排及輸電線路與接地系統，另下游變電所之負載亦加以考慮。應用建構之模型，進一步以EMTP/ATP分析輸電線路於變電所附近發生接地故障之特性包括變電所匯流排電壓、各回路電流及主變壓器二次側輸出電流及中性電流，各種分析都將考慮故障點有不同的接地故障阻抗，以及下游變電所不同的負載狀況，主變壓器中性點注入接地系統之電流即可獲得，然後以接地系統分析軟體(CDEGS)分析故障期間之變電所接地系統特性包括地電位昇(GPR)、地表面磁場及地網導體之電流分佈。最後，根據這些分析所得數據以及現場量測數據，進一步評估接地系統對斷路器控制系統之影響。本研究結果顯示變電所接地系統之GPR及其產生的磁場對斷路器控制回路確有不利的影響，尤其當控制系統線路及端子若有絕緣不良，在接地故障發生的GPR及磁場縱向感應電壓有可能造成閃絡而引發斷路器跳脫，對於本研究所探討的案例而言，經由良好的維護或更新那些絕緣情況不良的老舊斷路器及其控制線路，對於本研究所探討的案例相當重要，而做好GPR及磁場感應干擾的防護措施亦相當重要，本研究分析結果可供規則防護措施之參考。

關鍵字

超高壓變電所 ； 線路故障 ； 斷路器控制系統 ； 地電位昇

並列摘要

In this thesis, the characteristics of line ground faults occurred nearby the typical outdoor open type of extra-high voltage substation (E/S) are analyzed, and their affections on the substation breaker control system are investigated. The circuit model considering the main transformer, primary and secondary buses and transmission lines, and the downstream substation loads are constructed by using electromagnetic transient program/alternative transient program (EMTP/ATP). Based on the circuit model, the bus voltages, transformer output currents and neutral currents, and transmission currents, are analyzed with respect to various fault ground impedance, and different load levels of downstream substations. The currents injected into grounding system will be found from neutral bus currents of main transformers. Then, the grounding system characteristics due to line ground fault can be analyzed by using a software package for grounding analysis called CDEGS. By which, the distributions of ground potential rise (GPR), ground surface magnetic field, and grid conductor current can be analyzed. Finally, based on these analysis results and the measured data from a practical case of E/S to be surveyed, the affections of grounding system on the breaker control system are evaluated. The study results had shown that the GPR and magnetic field of grounding system will produce detrimental effects on the breaker control system. Especially, for those poor insulation control lines, large GPR and longitudinal induction voltage during ground fault may lead to flash-over at control line terminals and thus inducing breaker mis-trip out. For the practical case in this thesis, to do well maintenance and to renew those old breakers and control lines with poor insulation situations are very important strategy for preventing breaker mis-tripping. Other protection measures from GPR and magnetic field induction interferences are important too. This study may provide useful information for planning the protection measures.

並列關鍵字

Extra-High Voltage Substation ； Line Fault ； Breaker Control System ； Ground Potential Rise

參考文獻

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