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  本文關鍵詞： 變壓器 差動保護 勵磁涌流 故障電流 小波變換 仿真　出處：《南京師范大學》2014年碩士論文　論文類型：學位論文

【摘要】：電力變壓器作為現(xiàn)代電網中最重要的設備之一,承擔著電壓變換的重要任務。它的可靠運行是電網安全運行的必要條件。現(xiàn)代電力變壓器電壓等級高且價格昂貴,旦由于故障受到破壞,檢修難度大,且耗時傷財。因此,現(xiàn)場對變壓器保護的選擇性、速動性、靈敏性和可靠性有了更高的要求。為了深入分析變壓器在故障時的暫態(tài)情況,改進現(xiàn)有變壓器保護中的不足,有必要研究變壓器保護的算法和仿真模型。 目前變壓器差動保護的算法仍以比率制動特性原理為重點。采用差動保護作為變壓器的主保護后,要解決內部故障電流和勵磁涌流的識別問題。為了深入分析故障電流和勵磁涌流的差異,本文首先分析了變壓器的數(shù)學模型,并構建了變壓器故障和勵磁涌流仿真模型,仿真結果發(fā)現(xiàn)勵磁涌流的波形有大量二次諧波和有明顯間斷角等特征。在勵磁涌流識別的算法上,二次諧波制動原理在變壓器保護設備中有著豐富的現(xiàn)場運行經驗,然而在某些情況下存在變壓器保護動作時間較長的問題。文中通過引入了小波變換的方法,能夠解決二次諧波制動原理缺乏空間局部性的問題,并提高變壓器保護的整體性能。 嵌入式函數(shù)模塊能夠方便地編寫程序代碼,并且可以直接植入Simulink仿真建模中。論文基于MATLAB嵌入式函數(shù)模塊建立了變壓器差動保護的仿真模型,該模塊能夠區(qū)分區(qū)內和區(qū)外故障以及區(qū)分區(qū)內故障和勵磁涌流。文中給出了仿真過程的參數(shù)整定計算方法及設計流程和邏輯動作方案。 最后,針對變壓器后備保護過電流保護,通過分析和研究某變電所變壓器后備保護整定方案的缺陷,設計了將通信技術引入變壓器后備保護方案,并且給出了后備保護方案原理圖。該方案能夠有效解決變壓器后備保護的選擇性和速動性的矛盾,同時該方案能夠判斷出故障位置。
[Abstract]:Power transformer is one of the most important equipments in modern power network. It is a necessary condition for the safe operation of power grid. Modern power transformers have high voltage grade and expensive price, so it is difficult to overhaul because of the failure. Therefore, the field has higher requirements for the selectivity, rapidity, sensitivity and reliability of transformer protection. It is necessary to study the algorithm and simulation model of transformer protection. At present, the algorithm of transformer differential protection is still focused on the principle of ratio braking characteristics. The differential protection is adopted as the main protection of transformer. In order to solve the problem of identifying internal fault current and inrush current, in order to analyze the difference between fault current and inrush current, this paper first analyzes the mathematical model of transformer. The simulation model of transformer fault and inrush current is constructed. The simulation results show that the waveform of inrush current has many characteristics such as second harmonic wave and obvious discontinuous angle. The second harmonic braking principle has rich field operation experience in transformer protection equipment. However, in some cases, the transformer protection operation time is longer. The method of wavelet transform is introduced in this paper. It can solve the problem that the second harmonic braking principle lacks space locality and improve the overall performance of transformer protection. Embedded function module can easily write program code. And can be directly implanted in the Simulink simulation modeling. Based on the MATLAB embedded function module, the paper establishes the transformer differential protection simulation model. The module can distinguish the fault in and out of the region and the inrush current in the region. The parameter setting calculation method, design flow and logic action scheme of the simulation process are given in this paper. Finally, aiming at the over-current protection of transformer backup protection, by analyzing and studying the shortcomings of the setting scheme of transformer backup protection in a substation, the paper designs a transformer backup protection scheme which introduces the communication technology to the transformer backup protection. The schematic diagram of the backup protection scheme is given, which can effectively solve the contradiction between the selectivity and the rapidity of the transformer backup protection, and at the same time, the scheme can judge the fault location.
【學位授予單位】：南京師范大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TM41

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