發(fā)布時間：2018-07-03 01:00

  本文選題：局部放電 + 超聲波��； 參考：《沈陽工業(yè)大學(xué)》2017年碩士論文

【摘要】：伴隨著我國堅強智能電網(wǎng)的建設(shè)與發(fā)展,電力系統(tǒng)規(guī)模的日益擴大,特別是特高壓交直流輸電的建成和運營,對電氣設(shè)備的要求越來越高,因此,變壓器局部放電在線檢測技術(shù)引起了電力行業(yè)的高度重視。目前電力變壓器絕緣狀態(tài)評估的方法,主要是根據(jù)絕緣介質(zhì)在劣化過程中的一些特征參數(shù)進行評定,包括介質(zhì)損耗角的正切值、泄漏電流、局部放電量等。其中局部放電量最能反映變壓器絕緣狀態(tài),也是變壓器內(nèi)絕緣劣化的重要原因。因此,開展電力變壓器局部放電檢測方法研究具有學(xué)術(shù)意義和實用價值。本文主要研究內(nèi)容如下:(1)從氣體放電理論出發(fā),討論了局部放電過程及超聲波的產(chǎn)生機理,并以變壓器內(nèi)部氣泡放電為例,分析氣泡擊穿時的受力過程,利用電 力類比的原理,建立了基于氣泡模型的局部放電產(chǎn)生超聲波的力學(xué)等值電路模型;并以此為研究基礎(chǔ)對超聲波信號在模擬變壓器油箱內(nèi)部傳播規(guī)律進行仿真研究和實驗結(jié)果對比研究,研究主要包括超聲波在變壓器油、油浸絕緣紙和變壓器壁中的傳播速度規(guī)律,超聲波信號通過油、紙絕緣介質(zhì)時幅值的衰減。(2)針對在運行環(huán)境下變壓器局部放電信號易受電磁干擾問題,提出了一種分層抑制干擾的聯(lián)合檢測法,即以帶通濾波器和小波分析為核心。通過分析局部放電信號和擾動信號頻率分布特點,并借助MATLAB仿真軟件對變壓器內(nèi)部放電信號進行仿真研究。結(jié)果表明:采用分層式抑制干擾的方式可以有效去除干擾并保證原始信號能量損失較小,大大提高了局部放電的定位精度,滿足了變壓器局部放電在線檢測的實際要求。(3)針對傳統(tǒng)局部放電定位的最小二乘法,在迭代過程中容易陷入局部收斂且在變壓器某些特殊區(qū)域無法定位問題。采用了一種具有全局搜索特性的遺傳算法,并將其定位結(jié)果與最小二乘法進行比較。計算結(jié)果表明遺傳算法解決了最小二乘法在邊角區(qū)域定位失敗問題,其定位效果客觀。因此,具有實用價值。
[Abstract]:With the construction and development of strong smart grid in China, the scale of power system is expanding day by day, especially the construction and operation of UHV AC / DC transmission. Transformer partial discharge online detection technology has attracted great attention in power industry. At present, the methods of evaluating the insulation state of power transformers are mainly based on some characteristic parameters of dielectric deterioration, including tangent value of dielectric loss angle, leakage current, partial discharge, etc. Partial discharge (PD) can reflect the insulation state of transformer and is the important reason of insulation deterioration in transformer. Therefore, it is of academic significance and practical value to study the detection method of partial discharge of power transformer. The main contents of this paper are as follows: (1) based on the theory of gas discharge, the process of partial discharge and the generation mechanism of ultrasonic wave are discussed. Based on the principle of electric force analogy, a mechanical equivalent circuit model of ultrasonic wave generated by partial discharge based on bubble model is established. On the basis of this research, the simulation and experimental results of the ultrasonic signal propagation in the simulated transformer tank are carried out. The research mainly includes the ultrasonic wave in the transformer oil. The law of propagation velocity in oil-immersed insulator paper and transformer wall, and the attenuation of ultrasonic signal through oil and paper insulating medium. (2) in order to solve the problem that transformer partial discharge signal is vulnerable to electromagnetic interference in operating environment, In this paper, a hierarchical joint detection method for interference suppression is proposed, which is based on band-pass filter and wavelet analysis. The characteristics of frequency distribution of partial discharge signal and disturbance signal are analyzed, and the internal discharge signal of transformer is simulated by MATLAB simulation software. The results show that the interference can be removed effectively and the energy loss of the original signal can be reduced by using the method of delamination, which greatly improves the positioning accuracy of partial discharge. It meets the practical requirements of on-line detection of partial discharge of transformers. (3) for the traditional least square method of partial discharge location, it is easy to fall into local convergence in the iterative process and can not locate in some special areas of the transformer. In this paper, a genetic algorithm with global search property is used, and its localization results are compared with the least square method. The results show that the genetic algorithm solves the problem of the location failure of the least square method in the corner region, and its localization effect is objective. Therefore, it has practical value.
【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】：TM855

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