【正文】 陜西理工學(xué)院畢業(yè)論文第 I 頁 共 49 頁畢業(yè)論文變壓器差動保護的研究[摘要]電力變壓器作為聯(lián)系不同電壓等級網(wǎng)絡(luò)的設(shè)備，是電力系統(tǒng)中非常重要的元件。 長期以來電力變壓器一直只采用差動保護作為內(nèi)部故障的主保護。因此，差動保護的可靠性和安全性對變壓器保護來說最為關(guān)鍵。其中勵磁涌流的識別一直是研究的熱點，國內(nèi)外許多研究人員做了大量工作，也取得了許多成果。由于變壓器勵磁涌流受變壓器鐵心剩磁、 飽和磁密、系 統(tǒng) 阻抗、接線方式、鐵心結(jié)構(gòu)、合 閘初相角等因素影響，所以這些方法都不能保證百分之百的可靠性，鑒別勵磁涌流的 問題成為制約變壓器差動保護能否正確和靈敏動作的瓶頸。本文研究了 變壓器產(chǎn)生勵磁涌流的機理，分析了幾種鑒別 勵磁涌流方法的優(yōu)缺點。 針對二次 諧波制動原理存在著不著之處，提出了基于等效瞬時電感鑒別勵磁涌流的方法并用 MATLAB/SIMULINK 建立了仿真模型，對 變壓器在不同合閘角、不?/0Y同剩磁的情況下進行了大量仿真。仿真 結(jié)果表明基于等效瞬時電感 鑒別勵磁涌流的方法能夠有效鑒別變壓器的內(nèi)部故障和勵磁涌流，具有一定的實用價 值。[關(guān)鍵詞]變壓器 差動保護 MATLAB/SIMULINK 勵磁涌流 等效瞬時電感 仿真Expioitation transformer differential protection陜西理工學(xué)院畢業(yè)論文第 II 頁 共 49 頁Li Xin(Grade06 Class3,Major Electric engineering，Electric engineering and automation Dept.，Shaanxi University of Technology，Hanzhong 723003，Shaanxi)Tutor：Yang LinxiaAbstract： Power transformers as very important elements in power system require very reliable protection has been adopted as main protection against inner fault of transformer for a long time , since it has high reliability and high sensitivity, which are most important for transformer protection. Identification of inrush current has been a key problem to be researcheres have done a lot of work on this the inrush current of transformer is influenced by many factors such as residual flux of iron core,saturation flux density,system impedance,mode of connection,iron core structure,closing angle and so on,but all of the proposed methods can’t make sure 100%reliability, Identification of inrush current is the most critical factor that limits differential protection operation. In this thesis , the mechanism of inrush current occurring in transformer is well researched , the advantages and disadvantages of several methods for checking inrush current are discussed. Based on equivalent instantaneous inductance to discriminate between internal fault current and inrush current is put forward in this thesis . A numeric simulation model is built with the simulation software SIMULIINK based on MATLAB , numerous simulations are carried out on an connected transformer with different switchingon angle ?/0Yand remanent flux. The simulation results show that the proposed method based on equivalent instantaneous inductance possesses certain practicability and can distinguish internal fault current from inrush current effectively.Key words：power transformer differential protection MATLAB/SIMULINK inrush current equivalent instantaneous inductance simulation 目 錄 .....................................................1 選題意義 .....................................................................................................1陜西理工學(xué)院畢業(yè)論文第 III 頁 共 49 頁 變壓器差動保護的發(fā)展狀況 .....................................................................1 差動保護的研究現(xiàn)狀 ..........................................................................1 變壓器差動保護的發(fā)展趨勢 ..............................................................1 變壓器差動保護研究的主要內(nèi)容 ..........................................................12. 變壓器的差動保護 ........................................2 變壓器差動保護的基本原理 .....................................................................2 差動保護中不平衡電流產(chǎn)生的原因 .........................................................5 變壓器的勵磁涌流 .....................................................................................6 勵磁涌流產(chǎn)生的原因 ..........................................................................6. 變壓器勵磁涌流的特點 ...................................................................8 .............................................................................9 本章總結(jié) ....................................................................................................9 ...........................9 諧波識別法 .................................................................................................9 二次諧波電流鑒別勵磁涌流 ..............................................................9 諧波電壓鑒別勵磁涌流 ....................................................................10 波形特征識別法 ......................................................................................10 基于間斷角原理鑒別勵磁涌流 ........................................................10 基于波形對稱原理鑒別勵磁涌流 ....................................................11 基于波形凹凸性識別勵磁涌流 ........................................................11 磁通特性識別法 ......................................................................................12陜西理工學(xué)院畢業(yè)論文第 IV 頁 共 49 頁 等值電路識別法 ......................................................................................12 有功功率識別法 ......................................................................................12 文章小結(jié) ..................................................................................................13 ..............................13 故障電流的波形特征 ..............................................................................13 正弦函數(shù)波形特征 ...........................................................................13 故障電流中衰減直流分量的影響 ...................................................14 變壓器勵磁涌流的波形特征 ..................................................................16 單相變壓器單向涌流的上下對稱系數(shù) ...........................................16 三相變壓器單向涌流上下對稱系數(shù) ...............................................18 對稱涌流的上下對稱系數(shù) ...............................................................19 波形上下對稱系數(shù)的計算 ...............................................................20 本章小結(jié) ..................................................................................................205 電力系統(tǒng)仿真及新方法驗證 ................................20 仿真模型的建立 ......................................................................................20 Matlab 的電力工具箱 ......................................................................20 電力系統(tǒng)模型 ...................................................................................20 勵磁涌流仿真 ..........................................................................................21 無剩磁情況下空載合閘 ................................