【摘要】：隨著光伏發(fā)電產(chǎn)業(yè)的蓬勃發(fā)展,光伏逆變器帶來的諧波及電磁干擾問題也越來越受到人們的關(guān)注,嚴(yán)重的電磁干擾和諧波不僅影響電力設(shè)備本身的正常運(yùn)行,并網(wǎng)運(yùn)行時還將對電網(wǎng)造成電磁污染。目前,屏蔽、濾波、接地等方法是抑制電磁干擾的主要措施。近年來,混沌PWM控制因其可以從源頭上有效降低變換器的電磁干擾而得到越來越多的關(guān)注,但目前的研究方向主要集中在仿真和實(shí)驗(yàn)驗(yàn)證方面,缺乏理論分析,尤其是頻譜量化分析方面。因此,本文根據(jù)混沌SPWM的研究現(xiàn)狀,將研究重點(diǎn)放在了混沌控制降噪量化分析上,提出了一種基于雙重傅里葉級數(shù)的多周期及混沌SPWM頻譜計(jì)算方法。 本文首先介紹了光伏逆變器的研究背景及其面臨的電磁干擾問題,然后,根據(jù)傳統(tǒng)的頻譜分析方法——雙重傅里葉級數(shù),對常規(guī)雙極性SPWM進(jìn)行了頻譜計(jì)算,并對頻譜分布特性進(jìn)行了分析,指出了頻譜在開關(guān)頻率及其整數(shù)倍處存在較大諧波峰值的特點(diǎn)。 接著,證明了常規(guī)SPWM及多周期SPWM下輸出電壓的諧波總能量不變性。并在多周期SPWM輸出波形數(shù)學(xué)建模的基礎(chǔ)上,提出了多周期SPWM波的雙重傅里葉級數(shù)頻譜計(jì)算方法,得出了多周期SPWM的頻譜量化表達(dá)式,將頻譜計(jì)算結(jié)果與MATLAB仿真結(jié)果進(jìn)行了對比驗(yàn)證。 在對多周期SPWM進(jìn)行頻譜計(jì)算分析的基礎(chǔ)上,將上述多周期SPWM的頻譜計(jì)算方法拓展應(yīng)用到了混沌SPWM頻譜計(jì)算中,分析了混沌SPWM頻譜計(jì)算的可行性。為了驗(yàn)證不同混沌映射及不同載波周期波動范圍對混沌SPWM輸出波形頻譜的影響,文中選擇了常用的Tent和Chebyshev映射分別進(jìn)行了頻譜計(jì)算與結(jié)果對比,并從短期和長期兩個方面闡述了混沌載波周期波動范圍和混沌序列初值、概率密度對擴(kuò)頻效果的影響。 最后,在理論計(jì)算和仿真驗(yàn)證的基礎(chǔ)上搭建了混沌SPWM控制光伏逆變器實(shí)驗(yàn)平臺,進(jìn)行了常規(guī)SPWM和混沌SPWM控制下的相關(guān)實(shí)驗(yàn),對比分析了不同控制策略下SPWM輸出電壓和交流電流的頻譜分布特征,與本文的頻譜計(jì)算結(jié)果進(jìn)行了比較,進(jìn)一步驗(yàn)證了本文所提頻譜計(jì)算方法的有效性。
[Abstract]:With the vigorous development of photovoltaic power generation industry, people pay more and more attention to the problem of harmonic and electromagnetic interference brought by photovoltaic inverter. Serious electromagnetic interference and harmonic not only affect the normal operation of power equipment itself. When connected to the grid, it will also cause electromagnetic pollution to the power grid. At present, shielding, filtering, grounding and other methods are the main measures to suppress electromagnetic interference. In recent years, more and more attention has been paid to the chaos PWM control because it can effectively reduce the electromagnetic interference of the converter from the source. However, the current research direction is mainly focused on simulation and experimental verification, lacking of theoretical analysis. Especially the spectrum quantization analysis. Therefore, according to the current research situation of chaotic SPWM, this paper focuses on the quantitative analysis of chaos control noise reduction, and proposes a multi-period and chaotic SPWM spectrum calculation method based on double Fourier series. In this paper, the research background of photovoltaic inverter and the electromagnetic interference are introduced. Then, the frequency spectrum of conventional bipolar SPWM is calculated according to the traditional spectrum analysis method-double Fourier series. The characteristics of spectrum distribution are analyzed, and the characteristics of large harmonic peak at switching frequency and integer times are pointed out. Then, the total harmonic energy invariance of the output voltage under conventional SPWM and multi-period SPWM is proved. On the basis of mathematical modeling of multi-period SPWM output waveform, a double Fourier series spectrum calculation method of multi-period SPWM wave is proposed, and the spectrum quantization expression of multi-period SPWM is obtained. The spectrum calculation results are compared with MATLAB simulation results. On the basis of spectrum calculation and analysis of multi-period SPWM, the spectrum calculation method of multi-period SPWM is extended to chaotic SPWM spectrum calculation, and the feasibility of chaotic SPWM spectrum calculation is analyzed. In order to verify the influence of different chaotic maps and different carrier cycle fluctuations on the spectrum of chaotic SPWM output waveforms, the common Tent and Chebyshev maps are selected to calculate the spectrum and compare the results. The effects of chaotic carrier cycle fluctuation range, initial value of chaotic sequence and probability density on spread spectrum effect are discussed in both short and long term. Finally, on the basis of theoretical calculation and simulation, the experimental platform of chaotic SPWM controlled photovoltaic inverter is built, and the related experiments under the control of conventional SPWM and chaotic SPWM are carried out. The spectrum distribution characteristics of the output voltage and AC current of SPWM under different control strategies are compared and compared with the results obtained in this paper. The validity of the proposed method is further verified.
【學(xué)位授予單位】：北京交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TM464

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