直流特高壓設備絕緣系統在復合電場作用下的擊穿機理

李盛濤 周遠翔 阮將軍 李博 吳鍇

摘 要：本研究針對油紙絕緣結構在復合電場作用下的擊穿機理進行深入的研究，目標是提出特高壓油紙絕緣結構復合電場的計算方法，對實現我國特高壓換流變壓器的國產化提供有力的支撐。在前期工作中，取得了一下階段性成果：（1） 研究了單層及雙層油紙介質在常溫及溫度梯度下的空間電荷分布以及電場畸變特性。同時，建立了空間電荷注入、遷移和聚集的數值仿真模型，可以成功地模擬油紙結構中的電荷和電場分布特性。（2） 針對換流變出線結構的電場分布進行了計算分析。研究了交直流及極性反轉下的電場分布特性，屏障結構（包括屏障的罩入深度、位置、油隙間距、油浸紙筒厚度及層數等）對電場分布的影響。對出線結構進行了優化，完成了400kV出線結構的初步設計。（3） 測量了油紙結構在交、直流復合電壓以及預加電壓作用下的擊穿特性，結果表明空間電荷特性可以對擊穿強度產生顯著的影響。同時，掌握了交直流復合電壓下油紙絕緣結構的局部放電特性。

關鍵詞：直流絕緣系統 油紙絕緣 空間電荷 擊穿

Abstract：This project plans to deeply study the breakdown mechanism of oil-paper insulation under complex electric field， propose the calculation method of the electrical field distribution in oil-paper insulation stucture of HVDC equapment， and thus provide a powerful support for the domestic manufacturing of EHVDC converter transformers. In the early stage of research， following achivements have been obtained. （1） The space charge distribution and the distortion of electric field in the single and double layers of oil-impregnated papers were studied. Moreover， a numerical simulation model was built to describe the change injection， migration and accumulation， and the distributions of charge and electric field in oil-impregnated papers were sucessfully simulated. （2）The electric field distribution in the bushing-end structure in converter transformers was analized. The effects of barrier stucture （e.g. the depth， position， oil gap， paper thickness and layer numbers etc.） on field distribution under AC/DC combined voltage and polarity reversal were investigated. A 400kV bushing-end structure was preliminarily optimized and designed. （3） The breakdown properties of oil-paper stucture under AC/DC combined voltage and the effect of pre-stressing on breakdown voltage were studied. The results showed that the breakdwon strength was greatly influenced by the space charge behavior. Moreover， the partial discharge characteristics under AC/DC combined voltage was studied.

Key word：DC insulation system， oil-paper insulation， space charge， breakdown

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