特高壓輸電系統含有架空線路及地下電纜時之雷擊及接地故障特性研究

A Study of Lightning and Ground Fault Characteristics for VHV Transmission System with Overhead Lines and Underground Cables

曹峰愷(Feng-Kai Tsao)

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)

摘要

特高壓輸電系統含有架空線路及地下電纜的情況愈來愈多，此種系統的線路必須設置電纜連接站供架空線路及地下電纜連接，其系統架構及線路參數於電纜連接站呈現不連續，容易引發電氣事故，其中以雷擊及接地故障相關的事故最為普遍，常造成電纜連接站及地下電纜相關設備的損壞，嚴重影響輸電系統，亟待深入探討解決；為此，本文針對典型的特高壓161kV輸電系統在有架空線路及地下電纜的情況下，分析其雷擊及接地故障特性，並評估其可能造成的損壞及提出改善對策。
本文首先應用電磁暫態分析程式(EMTP)之改良程式(ATP)建構系統模型及進行各項分析，模型涵蓋輸電線路及其連接的上、下游變電所；上游變電所為超高壓變電所(E/S)，其345kV/161kV主變壓器及345kV等效電源將建置在模型中；而下游變電所將以其等效負載及其他161kV線路等效電源代表之；至於輸電線路將考慮典型161kV雙回路之線路，涵蓋架空線路、地下電纜及電纜連接站三部分，每部分均須配合分析的項目建構其詳細的ATP模型，即針對不同位置發生雷擊及接地故障時建置ATP模型；然後用這些模型進行模擬分析重要位置的電壓及電流之變化，從中可獲得絕緣礙子跨壓、鐵塔各段電位、塔腳地電位昇及電纜連接站避雷器之電壓及電流，以及地下電纜之遮蔽層及輔助接地線之電壓與電流分佈、電纜被覆保護裝置(CCPU)內之突波電壓抑制器電壓及電流。此外，將分別針對架空線路有無裝線路避雷器及地下電纜不同連接架構下進行這些模擬。最後，基於模擬結果將評估雷擊及接地故障可能造成的損害，其中將特別檢討對架空線路礙子、電纜連接站避雷器、電纜接續匣及CCPU的損害，並提出改善對策。

關鍵字

雷擊 ； 接地故障 ； 電纜被覆保護裝置 ； 線路避雷器 ； 地下電纜 ； 架空線路

並列摘要

It is more and more popular that very high voltage (VHV) transmission system is composed of overhead lines and underground cables. Such system needs cable connection station (CCS) for overhead lines and underground cables connections. The system frameworks and line parameters are discontinue at CCS, which let the electrical faults to happen easily; where the faults associated with lightning and ground fault are the most of all. The faults usually caused to the damages on the equipments of CCS and underground cables, and thus cause to serious affection on power transmissions. These faults are in urgent need of study and solutions. This thesis will aim to study these faults for typical 161kV transmission system with overhead lines and underground cables, in which, the lightning and ground fault characteristics are analyzed, and the damages due to the faults are evaluated. Also, the mitigated strategies are proposed. First of all, system modeling and analysis are based on the alternative program (ATP) of electromagnetic transient program (EMTP). The system model will cover the transmission lines and their upstream and down stream substations. The upstream substation is extra-high voltage substation (E/S) where the 345kV/161kV main transformer and the equivalent 345kV system source are considered in the model. Meanwhile, the down stream substation is modeled as an equivalent load connected with a 161kV other line system source. As to transmission line, the typical 161kV double-circuit transmission lines are considered, in which the detail ATP models of overhead lines, underground cables and CCS should be constructed with respect to analysis items, i.e., the detail ATP models are constructed for different lightning and ground fault locations. Then, the voltage and current variation of various important points are analyzed based on ATP simulation by these models. The insulator voltages, tower section potentials and foot ground potential rises, CCS arrester voltages and currents, the voltage and current distribution on cable shields and auxiliary grounding wires, and voltages and currents on the surge suppressors in the cable cover protection units (CCPUs) can be obtained from the ATP simulation results. In addition, the simulations will consider the situations of overhead lines with and without line arresters, and the underground cables with different frameworks. Finally, based on simulation results, the damages due to lightning and ground fault are evaluated. The damages on overhead line insulators, CCS arresters, cable joints and CCPUs will be further surveyed, and the mitigated strategies are proposed.

並列關鍵字

Lightning ； Ground Fault ； Cable Cover Protection Unit ； Line Arrester ； Underground Cable ； Overhead Line

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