【正文】 es the actual measurement value is easy to be inundated by error. Therefore, accurate measurement of the dielectric loss factor of power capacitor is the key problem. Based on the traditional fast Fourier transform (FFT), the harmonic analysis method with less hardware link, strong antiinterference ability, has bee the main method to pute the electric power capacitor dielectric loss Angle. But in the use of the harmonic analysis method to calculate the dielectric loss Angle, as a result of continuous power frequency periodic signal of truncation and nonsynchronous sampling, will produce frequency spectrum leakage and fence effect, thus affecting measurement precision. Therefore, power grid voltage and current signals needs to be synchronous sampled. For deficiencies of harmonic analysis, this paper puts forward an improved harmonic analysis, which can calculate the tan delta of dielectric loss. For actual acquisition of discrete sampling voltage and current signals, using the Hilbert transform of signals to eliminate the negative frequency ponents。 In addition, fullwave Fourier algorithm with window interpolation is used to correct phase Angle measuring error caused by the frequency fluctuation. Finally, the device model is set up in Matlab/Simulink environment to verify the developed system can effectively and reliably online monitor the tan delta of dielectric loss. When the waveform data simulated in this model calculated with the proposed research method in this paper and pared with the theoretical value of dielectric loss, and the actual model of measurement data to calculate the dielectric loss tan delta for online monitoring, the experimental results show that the system in the measurement of tan delta has high stability and accuracy. Key words: Capacitive equipment online insulation monitoring dielectric loss factor modified harmonic analysis algorithm X 目錄 開題報告 ...................................................................... I 背景 .......................................................................... I 國內(nèi)外現(xiàn)狀 .................................................................... I 研究路線 .................................................................... III 工作進度安排 .................................................................. V 參考文獻 ..................................................................... VI 摘要 ....................................................................... VIII ABSTRACT ..................................................................... IX 目錄 .......................................................................... X 1. 緒論 ...................................................................... 1 . 選題背景及研究意義 .................................................... 1 . 電容型設(shè)備絕緣在線監(jiān)測技術(shù)的研究現(xiàn)狀 ................................... 1 . 過零比較法 ........................................................ 2 . 傅里葉分析法 ...................................................... 2 . 高階正弦擬合法 .................................................... 3 . 相關(guān)函數(shù)法 ........................................................ 3 . 本文的主要工作 ........................................................ 3 . 介損 tanδ 在線監(jiān)測方法的研究 ...................................... 3 . 信號的預(yù)處理的研究 ................................................ 4 . 檢測系統(tǒng)的總體硬件設(shè)計 ............................................ 4 . 檢測系統(tǒng)的總體軟件設(shè)計 ............................................ 4 . 結(jié)果驗證 .......................................................... 4 2. 介損 TANΔ 在線監(jiān)測方法的研究 .............................................. 5 . 電力電容器中的介質(zhì)損耗 TANΔ ............................................ 5 . 諧波分析法測量 TANΔ 的基本原理 .......................................... 7 . 實際電網(wǎng)中的干擾因素 .................................................. 9 . 諧波的影響 ........................................................ 9 . 頻譜泄漏和柵欄效應(yīng) ................................................ 9 . 其他干擾因素 ..................................................... 10 . 信號預(yù)處理 ........................................................... 10 . Hilbert 變換 ..................................................... 10 . 加 Hanning窗的 FIR 低通濾波器 ..................................... 12 . FIR 低通濾波器的 MATLAB 驗證 ....................................... 15 . 改進型諧波分析法算法 ................................................. 17 3. 介損 TANΔ在線檢測系統(tǒng)的硬件研究 .......................................... 19 . 介質(zhì)損耗在線監(jiān)測系統(tǒng)的總體結(jié)構(gòu) ........................................ 19 . 采集信號的傳感器設(shè)計 ................................................. 19 . 電流傳感器的選擇 ................................................. 19 XI . 電壓傳感器的選擇 ................................................. 21 . 前置處理電路 ......................................................... 22 . AD7656 采樣電路 ...................................................... 23 . AD 芯片的精度需求分析 ............................................ 23 . AD7656 介紹及工作原理 ............................................ 23 4. 介損 TANΔ 在線檢測系統(tǒng)的軟件研究 .......................................... 25 . 介損 TANΔ 在線檢測軟件界面的總體介紹 ................................... 25 . 電力電容器測量系統(tǒng)仿真模型的搭建 ...................................... 26 . 介損 TANΔ 在線檢測軟件重要模塊的編寫 ................................... 27 . 希爾伯特變換的程序設(shè)計 ........................................... 27 . FIR 數(shù)字低通濾波器的程序設(shè)計 ...................................... 27 . 介損 tanδ的計算程序的程序設(shè)計 .................................... 28 . 系統(tǒng)數(shù)據(jù)分析及畫圖分析模塊 ............................................ 28 5. 實驗結(jié)果及分析 ........................................................... 29 . 實驗方案 ............................................................. 29 . 當頻率波動、諧波含量均為零時計算介損值的誤差研究 ....................... 30 . 當頻率波動、含有諧波時計算介損值的誤差研究 ............................ 31 . 當電路元件信息變化時計算介損值的誤差研究 .............................. 32 . 導入實際波形數(shù)據(jù)時的軟件運行情況 ...................................... 33 6. 總結(jié) ....................