本文選題：變壓器 + 縱差保護(hù)�。� 參考：《湘潭大學(xué)》2014年碩士論文

【摘要】：近些年來(lái)，中國(guó)國(guó)民經(jīng)濟(jì)飛速發(fā)展，用電量突增，電網(wǎng)規(guī)模不斷發(fā)展和擴(kuò)大，電壓等級(jí)不斷升高，變壓器作為電力系統(tǒng)中的極其重要的傳能變壓設(shè)備，其安全性穩(wěn)定運(yùn)行關(guān)系著整個(gè)電網(wǎng)的供電可靠性，于是對(duì)變壓器差動(dòng)保護(hù)提出了新的更高的要求。由于變壓器產(chǎn)生的勵(lì)磁涌流會(huì)流入變壓器縱差保護(hù)的差動(dòng)回路中，有可能導(dǎo)致縱差保護(hù)誤動(dòng)作。因此，如何正確有效的識(shí)別勵(lì)磁涌流和內(nèi)部故障電流是一個(gè)重要而困難的問(wèn)題。論文從以下幾方面進(jìn)行了研究。 首先，本文密切結(jié)合現(xiàn)場(chǎng)工程實(shí)踐，開(kāi)展了變壓器勵(lì)磁涌流對(duì)電力系統(tǒng)安全穩(wěn)定性影響的研究。簡(jiǎn)要綜述了國(guó)內(nèi)外勵(lì)磁涌流的研究現(xiàn)狀，分析了勵(lì)磁涌流對(duì)變壓器繼電保護(hù)帶來(lái)的不良影響；根據(jù)進(jìn)一步提高變壓器勵(lì)磁涌流識(shí)別準(zhǔn)確率的要求，闡述了繼續(xù)研究勵(lì)磁涌流識(shí)別方法具有的理論和實(shí)際工程意義。 然后，深入研究了變壓器差動(dòng)保護(hù)的保護(hù)原理以及勵(lì)磁涌流的產(chǎn)生機(jī)理，對(duì)常用的勵(lì)磁涌流識(shí)別方法進(jìn)行了詳盡分析，得出了各自的優(yōu)缺點(diǎn)。對(duì)比分析了變壓器勵(lì)磁涌流與內(nèi)部故障電流的波形特征，進(jìn)而利用小波理論中的多分辨率分析檢測(cè)勵(lì)磁涌流和內(nèi)部故障電流的時(shí)頻域特征信息。 再次，在以上分析研究的基礎(chǔ)上，結(jié)合小波分析和信息熵理論，提出了基于Tsallis小波熵（能量熵和時(shí)間熵）的勵(lì)磁涌流識(shí)別方法，該方法是先將電流進(jìn)行小波分解重構(gòu)，然后利用熵的概念來(lái)定量分析其能量的分布情況。并且采用的Tsallis小波能在很大程度上改善頻域混疊和能量泄露的問(wèn)題，因此，該方法能夠準(zhǔn)確識(shí)別勵(lì)磁涌流。同時(shí)還根據(jù)變壓器瞬時(shí)無(wú)功功率特性得到另一種基于瞬時(shí)差有功無(wú)功比率的涌流識(shí)別方法，其主要原理是當(dāng)變壓器出現(xiàn)勵(lì)磁涌流時(shí)，變壓器兩側(cè)的有功功率差變化比較小，，而無(wú)功功率差變大相對(duì)較大，此方法也能有效識(shí)別勵(lì)磁涌流。 最后，通過(guò)Matlab/Simulink搭建勵(lì)磁涌流仿真模型，利用上述兩種識(shí)別方法對(duì)單相三繞組變壓器和三相三繞組變壓器在各種故障條件下進(jìn)行了仿真驗(yàn)證，比如空載合閘、單相接地短路以及故障切除恢復(fù)供電等等，相應(yīng)的實(shí)例仿真結(jié)果表明，在系統(tǒng)各種運(yùn)行工況下，所提方法都具有良好的識(shí)別效果，從而驗(yàn)證所提兩種識(shí)別方法的可行性和靈敏性，克服了以往保護(hù)的不足，提高了變壓器縱差保護(hù)的保護(hù)性能。
[Abstract]:In recent years, with the rapid development of China's national economy, the rapid increase in electricity consumption, the continuous development and expansion of the scale of the power grid, and the constant increase in voltage levels, transformers are regarded as the most important power transmission and transformer equipment in the power system. Its safe and stable operation is related to the power supply reliability of the whole power network, so a new and higher requirement for transformer differential protection is put forward. The inrush current generated by the transformer will flow into the differential circuit of the differential protection of the transformer, which may lead to the misoperation of the differential protection. Therefore, how to correctly and effectively identify inrush current and internal fault current is an important and difficult problem. The thesis has carried on the research from the following several aspects. Firstly, the paper studies the influence of transformer inrush current on power system safety and stability. This paper briefly summarizes the research status of inrush current at home and abroad, analyzes the adverse effect of inrush current on relay protection of transformer, and further improves the accuracy of inrush current identification of transformer. This paper expounds the theoretical and practical engineering significance of continuing to study the method of inrush current identification. Then, the principle of transformer differential protection and the generation mechanism of excitation inrush current are deeply studied, and the common methods of inrush current identification are analyzed in detail, and their advantages and disadvantages are obtained. The waveform characteristics of inrush current and internal fault current of transformer are compared and analyzed, and the time-frequency characteristic information of excitation inrush current and internal fault current is detected by multi-resolution analysis in wavelet theory. Thirdly, on the basis of the above analysis, combined with wavelet analysis and information entropy theory, a Tsallis wavelet entropy (energy entropy and time entropy) based inrush current identification method is proposed. Then the concept of entropy is used to quantitatively analyze its energy distribution. And the Tsallis wavelet can improve the frequency domain aliasing and energy leakage to a great extent, so this method can accurately identify the inrush current. At the same time, according to the instantaneous reactive power characteristics of the transformer, another inrush current identification method based on the instantaneous difference between active and reactive power ratio is obtained. The main principle is that the difference of active power on both sides of the transformer is relatively small when the inrush current occurs in the transformer. However, the reactive power difference is relatively large, and this method can also effectively identify the inrush current. Finally, the simulation model of inrush current is built by Matlab / Simulink, and the simulation of single-phase three-winding transformer and three-phase three-winding transformer under various fault conditions, such as no-load closing, is carried out using the above two identification methods. The simulation results of single-phase grounding short circuit and fault resetting and restoring power supply show that the proposed method has a good recognition effect under various operating conditions of the system. Thus, the feasibility and sensitivity of the two identification methods are verified, the shortcomings of the previous protection are overcome, and the protection performance of the transformer differential protection is improved.
【學(xué)位授予單位】：湘潭大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TM774

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