本文選題：流注放電 + 變壓器油�。� 參考：《東北電力大學》2017年碩士論文

【摘要】：在變壓器的日常運行中,其最重要的內(nèi)絕緣介質(zhì)是變壓器油,由此可見變壓器油在保障電力系統(tǒng)的穩(wěn)定運行中扮演著至關(guān)重要的作用。因此,其絕緣性能的好壞直接影響到電網(wǎng)能否穩(wěn)定運行。人們研究變壓器油中放電理論基本上都是從研究帶電粒子在電場中的運動規(guī)律及推廣應(yīng)用方面入手。無論是實驗研究或是理論探討油中放電的原理過程,分析不同的條件或是電極系統(tǒng)下的液體放電規(guī)律,進而保障各類電力設(shè)備能夠穩(wěn)定安全地運行都有十分重要的研究價值和應(yīng)用意義。目前,在研究變壓器油中放電現(xiàn)象的過程中,經(jīng)過大量的研究工作與試驗,現(xiàn)已取得了豐碩的成果。本文在參考和比較國內(nèi)外一系列變壓器油中放電理論和試驗成果的同時,由基礎(chǔ)物理過程定律入手,構(gòu)建了變壓器油流注放電發(fā)展過程的物理模型,包括電極結(jié)構(gòu)以及仿真計算區(qū)域。在變壓器油流注放電的發(fā)展過程中,影響其發(fā)展的物理過程的因素主要有兩方面,一方面是帶電粒子在電場中的運動過程,另一方面是空間電荷對電場的影響。經(jīng)過實踐對比和大量參考文獻的查閱,確定了切實可行的帶電粒子連續(xù)性方程,以及反應(yīng)帶電粒子對電場影響的空間泊松方程。同時,在查閱許多相關(guān)文獻之后,找出了由國內(nèi)外學者從變壓器油流注放電試驗中獲取到的經(jīng)驗公式計算出來的變壓器油流注放電仿真的輸運和反應(yīng)系數(shù)。之后,分別考量物理模型、帶電粒子連續(xù)性方程以及空間泊松方程的不同條件,確定了相應(yīng)的邊界條件和參數(shù)選擇�？紤]到在帶電粒子的連續(xù)性方程的求解過程中,其對流項是遠遠大于擴散項的,因此適當引入了人工擴散項用來抑制求解過程的數(shù)值振蕩問題。通過對空間電荷在變壓器油中的產(chǎn)生與消失機理的研究,確定了其在帶電粒子連續(xù)性方程中的表達式,進而明確了場致電離為影響流注放電發(fā)展過程的主要電離機制。采用COMSOL Multiphysics仿真軟件進行變壓器油中流注放電數(shù)值模擬,建立相應(yīng)的二維軸對稱流體模型,模擬脈沖電壓下油中球板電極的放電過程,分析不同電壓幅值與間隙距離對油中流注放電發(fā)展過程的影響。通過對油中流注放電這一過程進行仿真,比對不同條件下的流注發(fā)展情況和特性,并依據(jù)得到的流注放電過程的仿真結(jié)果,分析流注放電這一過程中影響其發(fā)展特性的一些影響因素進行對比分析。由于變壓器油所處的工作環(huán)境極其復雜,因此在變壓器的實際運行過程中,變壓器油的絕緣性能受多種外部因素的影響。為了了解不同因素對變壓器油絕緣特性的影響,設(shè)計試驗,研究了不同溫度以及間隙距離條件下,變壓器油的擊穿電壓變化情況,并基于流注放電的理論和仿真對試驗結(jié)果進行探討。
[Abstract]:In the daily operation of transformers, the most important internal insulating medium is transformer oil, which shows that transformer oil plays an important role in ensuring the stable operation of power system. Therefore, its insulation performance directly affects whether the power grid can run stably. The theory of discharge in transformer oil is studied by studying the moving law of charged particles in electric field and its popularization and application. Whether it is an experimental study or a theoretical study of the principle of discharge in oil, and the analysis of different conditions or the law of liquid discharge under the electrode system, Therefore, it is very important to ensure the stable and safe operation of all kinds of electric power equipment. At present, in the process of studying the phenomenon of discharge in transformer oil, a great deal of research and experiments have been done and fruitful results have been obtained. In this paper, a series of theoretical and experimental results of transformer oil discharge are compared and a physical model of transformer oil flow-discharge development process is established based on the basic law of physical process. It includes electrode structure and simulation calculation area. In the development of transformer oil streamer discharge, there are two main factors that affect the physical process of transformer oil development, one is the moving process of charged particles in the electric field, the other is the influence of space charge on the electric field. By comparing the practice and consulting a lot of references, the feasible continuity equation of charged particle and the space Poisson equation of the effect of reactive charged particle on electric field are determined. At the same time, after consulting many related literatures, the transport and reaction coefficients of transformer oil flow-discharge simulation are found out, which are calculated by empirical formulas obtained from transformer oil flow discharge test. Then, considering the different conditions of physical model, charged particle continuity equation and space Poisson equation, the corresponding boundary conditions and parameter selection are determined. Considering that the convection term is much larger than the diffusion term in the solution of the continuity equation of charged particles, the artificial diffusion term is appropriately introduced to suppress the numerical oscillations in the solution process. Through the study of the generation and disappearance mechanism of space charge in transformer oil, the expression of space charge in the equation of continuity of charged particles is determined, and the ionization mechanism of field ionization is defined as the main ionization mechanism affecting the development of streamer discharge. The flow discharge in transformer oil was simulated with COMSOL Multiphysics software, and the corresponding two-dimensional axisymmetric fluid model was established to simulate the discharge process of spherical electrode in oil under pulse voltage. The effects of different voltage amplitude and gap distance on the development of flow discharge in oil are analyzed. By simulating the flow-discharge process in oil, the development and characteristics of the streamer under different conditions are compared, and the simulation results of the flow-discharge process are obtained. The influence factors on the development characteristics of streamer discharge are analyzed. Because the working environment of transformer oil is extremely complex, the insulation performance of transformer oil is affected by many external factors during the actual operation of transformer. In order to understand the influence of different factors on the insulation characteristics of transformer oil, the breakdown voltage of transformer oil was studied under different temperature and gap distance. The experimental results are discussed based on the theory and simulation of streamer discharge.
【學位授予單位】：東北電力大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TM41

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