特高壓變電站電磁暫態(tài)過電壓機(jī)理與控制

王磊 王浩 王玨 馬國明 王東舉

摘 要：根據(jù)研究的總體目標(biāo)及研究思路和任務(wù)，該研究總結(jié)歸納出重點(diǎn)需關(guān)注的科學(xué)問題：（1）VFTO機(jī)理及建模仿真；（2）VFTO作用下GIS破壞機(jī)理和絕緣特性。針對此科學(xué)問題的主要研究內(nèi)容包括： 基于所研制的T型電極VFTO傳感器在特高壓變電站開展了特快速暫態(tài)過電壓的實(shí)測研究，獲得了大量寶貴實(shí)測數(shù)據(jù)。為特高壓變電站隔離開關(guān)帶電操作決策及變電站設(shè)計(jì)提供了支撐。研究提出并實(shí)踐了從“SF6小間隙（間隙距離為mm級）-SF6大間隙（間隙距離為cm級）-GIS隔離開關(guān)”的系統(tǒng)技術(shù)路線，有效克服GIS隔離開關(guān)中VFTO高頻振蕩電弧難以觀測的技術(shù)難題，得到了特高壓GIS隔離開關(guān)的全過程時(shí)變弧阻模型。研究獲得了大尺度GIS部件的VFTO絕緣特性，獲得了與雷電絕緣特性的等價(jià)關(guān)系，給出了波形轉(zhuǎn)換系數(shù)1.1，為VFTO絕緣配合難題的解決提供了重要支撐。建立兩路納秒級脈沖群VFTO模擬電源及其配套的絕緣試驗(yàn)腔和測試系統(tǒng)，測試系統(tǒng)包括紫外光譜測試儀、高能電子測試裝置。模擬VFTO波形，開展納秒脈沖下SF6氣體的擊穿和閃絡(luò)特性實(shí)驗(yàn)，獲得不同氣體壓力下SF6氣體的擊穿和閃絡(luò)規(guī)律和特性；發(fā)現(xiàn)在一定壓力條件下，極不均勻場下SF6擊穿的極性效應(yīng)出現(xiàn)反轉(zhuǎn)現(xiàn)象；基于記憶效應(yīng)提出重復(fù)納秒脈沖下的放電機(jī)理。在252 kV GIS試驗(yàn)回路上，開展了鐵氧體磁環(huán)串抑制VFTO的系列試驗(yàn)，研究了不同試驗(yàn)電壓下VFTO波形的主要特征參數(shù)與磁環(huán)串長度的關(guān)系，證實(shí)了鐵氧體磁環(huán)串對VFTO的幅值和陡度均有顯著的抑制效果。

關(guān)鍵詞：特高壓 特快速瞬態(tài)過電壓 絕緣特性

The Mechanism and Control of Electromagnetic Transient Overvoltage in UHV GIS Substation

Wang Lei1 Wang Hao1 Wang Jue2 Ma Guoming3 Wang Dongju4

（1.China Electric Power Research Institute；2.Institute of Electrical Engineering，Chinese Academy of Sciences；3.North China Electric Power University；4.Zhejiang University）

Abstract：According to the goals，thoughts and tasks of 973 Program，two scientific problems are summarized in this topic：（1）Mechanisms，modeling and simulations of VFTO；（2）failure mechanisms and insulation characteristics of GIS stressed by VFTO.The main content of the topic focus on the scientific problems above is：Basic research is a driving force for the progress of human civilization，a source and backbone of S&T and economic development，VFTO measurement have been carried out in UHV substations based on the developed T-type VFTO sensor， the experiment results is valuable to support the decision about the disconnector switching operation and the design of the UHV substation.A creative technical route is studied and proposed， namely ‘small-scale SF6 gap （gap distance in mm grade）- large-scale SF6 gap （gap distance of cm-level） isolating distance of the GIS disconnector， which can effectively overcome the technical problems in observing arc with interference by high-frequency oscillation of VFTO， and a variable arc resistance model during the whole operating process of UHV GIS disconnector is obtained. In addition， research are carried out to get the insulating properties oh large-scale GIS components under VFTO， the equivalence relations between VFTO and LIWV （i.e. lightning impulse withstand voltage） is achieved and the waveform conversion factor 1.1 is put forward， which provides important support for solving insulation coordination problem. The multi-VFTO analog power， test chamber and the measuring system that included ultraviolet spectral tester and high energy electronic test device had been built. The breakdown and flashover characteristics experiment under simulation of VFTO pulse in SF6 gas was carried out. The regularity and characteristics of breakdown and flashover under different gas pressure in SF6 is given. The experinmental results shows in certain pressure conditions， the breakdown regularity of the SF6 under extremely uneven was different with DC， AC and other long pulse， the positive impulse breakdown voltage is greater than the negative pulse.The repetitive pulse discharge mechanism was obtained based on the memory effect. Series tests were carried on the 252kV GIS test circuit to research the relationship between the main parameters of the VFTO waveform and the length of the magnetic ring cluster. It is confirmed that the ferrite magnetic rings have notable suppression effects to the amplitude and steepness of the VFTO.

Key Words：Ultra High Voltage；Very Fast Transient Overvoltage；Insulation characteristic

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