本文關(guān)鍵詞： 三電平逆變器 空間矢量調(diào)制 故障特征 小波變換 神經(jīng)網(wǎng)絡(luò)　出處：《寧夏大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：隨著世界各國(guó)對(duì)新能源的關(guān)注和開(kāi)發(fā),利用太陽(yáng)能這種資源豐富并且無(wú)污染的新能源發(fā)電已經(jīng)被廣泛的運(yùn)用。在太陽(yáng)能發(fā)電結(jié)構(gòu)中,并網(wǎng)逆變器有著相當(dāng)重要的作用,若是逆變器有了故障沒(méi)有得到該有的診斷,就會(huì)產(chǎn)生經(jīng)濟(jì)上的損失,對(duì)人的生命安全也會(huì)帶來(lái)威脅。所以對(duì)逆變器的故障診斷就有很大的意義,本文通過(guò)運(yùn)用小波變換結(jié)合神經(jīng)網(wǎng)絡(luò)的方式對(duì)逆變器的不同故障類型進(jìn)行診斷研究。首先介紹了光伏發(fā)電技術(shù),對(duì)光伏并網(wǎng)逆變器的拓?fù)浣Y(jié)構(gòu)進(jìn)行了說(shuō)明,選定應(yīng)用較為廣泛的二極管NPC型三相三電平逆變器為研究對(duì)象,對(duì)它的工作原理和故障類型進(jìn)行了說(shuō)明,主要研究逆變器電路A相上典型的11種故障類型。接著在matlab/simulink仿真環(huán)境中構(gòu)建了三電平逆變器的故障仿真模型,對(duì)這11種不同故障類型展開(kāi)了仿真模擬,從仿真模擬的結(jié)果中得到了后續(xù)故障診斷所需要的故障信息,即為A相電路上的橋臂電壓、上橋臂電壓和下橋臂電壓。最后完成逆變器不同故障模式的診斷。整個(gè)過(guò)程分為三個(gè)階段:故障信息的采集,故障特征的獲取和最后的故障類型辨別。故障信息的采集就是分別采集不同故障類型對(duì)應(yīng)的橋臂電壓波形;故障特征的提取采用小波變換的方法,將采集到的電壓波形經(jīng)過(guò)小波變換展開(kāi)三層小波包分解,不同故障類型的電壓信號(hào)被分成了八個(gè)頻帶的能量值,把這些能量值做歸一化處理,處理后的數(shù)據(jù)構(gòu)成特征向量,作為設(shè)計(jì)好的BP網(wǎng)絡(luò)的輸入樣本數(shù)據(jù),然后對(duì)期望的輸出目標(biāo)進(jìn)行編碼。最后設(shè)置直流側(cè)電壓分別為720V、700V和680V,選取調(diào)制比為0.2～0.9,每一種故障類型獲取到了 24組樣本數(shù)據(jù),總共得到264組故障特征。2/3的數(shù)據(jù)作為訓(xùn)練使用,1/3的數(shù)據(jù)作為測(cè)試使用。將這些數(shù)據(jù)放入到神經(jīng)網(wǎng)絡(luò)中展開(kāi)了訓(xùn)練和測(cè)試,仿真測(cè)試結(jié)果表明,該方法診斷正確率較高,易于實(shí)現(xiàn),具有一定的工程應(yīng)用價(jià)值。
[Abstract]:With the attention and development of new energy sources in the world, the use of solar energy, which is rich and pollution-free, has been widely used. In the solar power generation structure, grid-connected inverter plays a very important role. If the inverter fails to get the correct diagnosis, it will cause economic losses and threaten the safety of human life. Therefore, it is of great significance to the fault diagnosis of the inverter. In this paper, the different fault types of inverter are diagnosed by wavelet transform and neural network. Firstly, the photovoltaic generation technology is introduced, and the topology of grid-connected photovoltaic inverter is explained. The working principle and fault type of diode NPC three-phase three-level inverter, which is widely used, is selected as the research object. In this paper, 11 typical fault types in A phase of inverter circuit are studied. Then, the fault simulation model of three-level inverter is constructed in matlab/simulink simulation environment, and the simulation of 11 different fault types is carried out. The fault information needed for the subsequent fault diagnosis is obtained from the simulation results, that is, the voltage of the bridge arm on the A phase circuit. The upper arm voltage and the lower leg voltage. Finally, the different fault modes of the inverter are diagnosed. The whole process is divided into three stages: the fault information collection, Fault information acquisition is to collect voltage waveforms corresponding to different fault types, and wavelet transform is used to extract fault features. The collected voltage waveforms are decomposed into three layers by wavelet transform. The voltage signals of different fault types are divided into eight frequency band energy values. These energy values are normalized, and the processed data form the eigenvector. As the input sample data of BP neural network, the expected output target is encoded. Finally, the DC side voltage is set to 720V, 700V and 680V, respectively, and the modulation ratio is 0.20.9.The 24 sets of sample data are obtained for each fault type. A total of 264 sets of fault feature. 2 / 3 data were obtained as training data and 1 / 3 data were used as test data. These data were put into neural network for training and testing. The simulation results show that this method has a high diagnostic accuracy. It is easy to realize and has certain engineering application value.
【學(xué)位授予單位】：寧夏大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TP183;TM464

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