【摘要】：隨著我國電網(wǎng)電壓等級的不斷提升和輸電容量的不斷增加,實際運行中的變壓器不可避免地會受到更多不同程度的短路沖擊,極易引起鐵心疊片松動、繞組形變或預(yù)緊力松弛等,這將導(dǎo)致變壓器的絕緣和機(jī)械性能下降,進(jìn)而使變壓器發(fā)生故障。在線振動分析法能夠?qū)崟r監(jiān)測變壓器內(nèi)部部件的運行狀態(tài),但缺乏對采集數(shù)據(jù)進(jìn)行合理分析的理論判據(jù),診斷判據(jù)尚不完善。為此,本文以一臺型號為S11-M-500/35,聯(lián)結(jié)組別為Yyno的油浸式電力變壓器為研究對象,通過理論計算、數(shù)值仿真、試驗分析和故障模擬等手段對變壓器振動及其振動能量傳遞過程進(jìn)行了深入研究。本文的研究工作對于變壓器故障診斷過程中測點位置選擇、故障類型判斷具有重要的指導(dǎo)意義。結(jié)合目前國內(nèi)外對于變壓器振動特性研究已取得的成果,論文首先概括了變壓器振動特性以及采用振動法檢測變壓器狀態(tài)的國內(nèi)外研究現(xiàn)狀,分析了目前振動法在檢測變壓器健康狀態(tài)時存在的主要困難,明確了采用振動法檢測變壓器狀態(tài)仍需努力方向和本文開展的主要工作。變壓器是一種依據(jù)電磁感應(yīng)定律工作的靜止電器。本文利用有限元分析軟件,通過電磁固耦合計算,研究了空、負(fù)載條件下變壓器繞組和鐵心磁場分布情況,計算了負(fù)載電流條件下變壓器的振動特征。結(jié)果表明:負(fù)載電流條件下變壓器的振動特征以100Hz為主,變壓器的固體連接桿件在振動能量傳遞過程只起到衰減變壓器振動能量大小的作用,對振動信號頻率分布特性的影響較弱。通過搭建負(fù)載電流試驗平臺和振動信號采集系統(tǒng),試驗研究并確定了適宜的測點位置,分析了正常狀態(tài)下繞組振動的時頻特性,驗證了仿真模型的準(zhǔn)確性。研究結(jié)果表明:不同位置處繞組各測點的振動信號主要集中在100Hz,并含有200Hz-500Hz諧波分量,而且振動幅值很小,600Hz以上基本衰減為零,但1/6位置在300Hz處有較明顯的諧波分量。結(jié)合試驗結(jié)果并考慮實際監(jiān)測的方便性,本文認(rèn)為變壓器箱壁距地1/6位置處為適宜的測點位置。設(shè)置不同繞組故障來模擬繞組松動、變形等情況,試驗研究模擬故障狀態(tài)下變壓器箱壁不同測點的振動情況,對比分析繞組故障前后不同負(fù)載電流條件下的箱壁1/6測點處的振動加速度、頻域特性等變化情況。結(jié)果表明:繞組故障時其振動幅值(基頻)與電流之間的線性增大關(guān)系并不改變,但故障繞組基頻幅值均大于正常繞組基頻振動幅值。
[Abstract]:With the continuous improvement of power grid voltage grade and the increasing of transmission capacity in China, transformer in operation will inevitably suffer more and more short-circuit impact, which can easily lead to loosening of the core lamination. The deformation of winding or relaxation of pretightening force will lead to the deterioration of insulation and mechanical properties of transformers, which will cause the transformer to break down. On-line vibration analysis method can monitor the running state of transformer's internal components in real time, but it lacks the theoretical criterion for reasonable analysis of collected data, and the diagnostic criterion is not perfect. Therefore, a oil-immersed power transformer with S11-M-500 / 35 model and Yyno connection group is taken as the research object. Through theoretical calculation and numerical simulation, The transformer vibration and its vibration energy transfer process are studied by means of test analysis and fault simulation. The research work in this paper is of great significance for the location selection and fault type judgement of transformer fault diagnosis. Combined with the achievements of the research on transformer vibration characteristics at home and abroad, the paper first summarizes the vibration characteristics of transformers and the research status quo of transformer state detection by vibration method at home and abroad. This paper analyzes on the main difficulties existing in the vibration method in detecting the healthy state of the transformer at present, and clarifies the direction of the effort still needed to use the vibration method to detect the condition of the transformer and the main work to be carried out in this paper. Transformer is a kind of static electrical apparatus which works according to the law of electromagnetic induction. In this paper, the magnetic field distribution of transformer windings and cores under the condition of empty load and load is studied by using finite element analysis software, and the vibration characteristics of transformer under load current are calculated. The results show that 100Hz is the main characteristic of transformer vibration under load current, and the solid connecting member of transformer can only attenuate the vibration energy of transformer in the process of vibration energy transfer. The effect on the frequency distribution of vibration signal is weak. Through setting up the load current test platform and vibration signal collecting system, the suitable measuring point position is studied and determined, the time-frequency characteristic of winding vibration under normal condition is analyzed, and the accuracy of simulation model is verified. The results show that the vibration signals of the windings at different positions are mainly concentrated at 100Hz and contain 200Hz-500Hz harmonic components, and the amplitude of vibration is very small, and the attenuation above 600Hz is basically zero. But 1 / 6 position has obvious harmonic component at 300Hz. Combined with the test results and considering the convenience of practical monitoring, it is considered in this paper that the location of the transformer box wall at 1 / 6 of the ground distance is an appropriate measuring point. Different winding faults are set up to simulate the loosening and deformation of the winding, and the vibration of different measuring points of the transformer box wall under the simulated fault condition is studied experimentally. The vibration acceleration and frequency domain characteristics of the 1 / 6 measuring point of the box wall under different load current conditions before and after the winding fault are compared and analyzed. The results show that the linear relationship between the amplitude of vibration (fundamental frequency) and the current does not change, but the amplitude of the fundamental frequency of the fault winding is larger than that of the normal winding.
【學(xué)位授予單位】：沈陽工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TM411

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