基于AVR單片機的電力諧波分析系統設計

電子論文編號:JD1096  論文字數:18346,頁數:47，有仿真
目   錄
中文摘要 I
ABSTRACT II
1. 緒論 1
1.1 課題背景 1
1.2 衡量電能質量的主要指標 1
1.3 電能質量問題的產生 1
1.4 電能質量的國家標準 2
1.5 本設計需要完成的主要任務 2
2. 諧波分析基礎 4
2.1 傅立葉分析概要 4
2.2 傅立葉級數 4
2.2.1 周期函數傅立葉級數的三角函數形式 4
2.2.2 傅立葉級數的指數函數形式 5
2.3 采樣信號的傅立葉變換 6
2.3.1 采樣定理 6
2.3.2 采樣信號的傅立葉變換 6
2.4 離散傅立葉變換(DFT)與快速傅立葉變換(FFT) 7
2.4.1 DFT 7
2.4.2 FFT 8
2.5 時抽選奇偶分解FFT計算的一般規則 12
2.5.1 基2時抽選奇偶分解FFT對輸入序列的要求 12
2.5.2 輸入序列的碼位倒置 12
2.5.3 即位運算 12
2.6 時抽選奇偶分解FFT的C語言程序實現 13
2.6.1 變量的設置與定義 13
2.6.2 逆序部分 13
2.6.3 FFT計算 13
3. 諧波分析系統的硬件電路設計 15
3.1 硬件電路的系統設計任務 15
3.2 單片機選型 15
3.3 電源電路 17
3.4 最小系統設計 17
3.4.1 復位電路 18
3.4.2 時鐘信號電路 18
3.4.3 A/D轉換濾波電路 19
3.4.4 ISP接口 19
3.4.5 熔絲位設置 19
3.5 信號預處理電路 21
3.6 TTL與RS－232電平轉換電路與接口 22
4. 諧波分析軟件設計 24
4.1 程序總體框架 24
4.2 常量與變量定義 25
4.3 寄存器初始化 25
4.4 A/D采集與存儲 26
4.5 諧波分析處理 26
4.5.1 電壓有效值 26
4.5.2 各次諧波含量 27
4.6 上位機通信 28
4.7 軟件上的抗干擾設計 30
5. 提高分析精度方法的研究 31
5.1 計算結果的處理 31
5.2 提高信號檢測的質量 32
5.3 采用更先進的數字信號處理技術 33
結    論 34
致    謝 36
參考文獻 37
附    錄A：英文翻譯原文 38
附    錄B：英文翻譯譯文 48
附    錄C：諧波分析軟件源程序 55
附    錄D：諧波分析系統硬件電路圖 60

摘要
 隨著國民經濟的發展，電網中各種非線性負荷及用戶不斷增長；各種復雜的、精密的，對電能質量敏感的用電設備越來越多。上述兩方面的矛盾越來越突出，在這樣的環境下，探討電能質量的分析方法，可以為分析我國電能質量管理和控制的發展趨勢提供必要的依據，具有很強的現實意義。
 本設計采用ATMEL公司的ATmega32L單片機完成一個電能質量檢測系統。電壓信號經過變壓器隔離降壓，幅值較低的交流信號再通過運算放大器構成的加法器變成可供A/D轉換電路轉換的直流信號。單片機使用內部的定時器每1/3200秒對電壓信號采樣一次，用片內自帶的10位精度A/D轉換器對每周波的電壓信號采樣64個點后，進行FFT運算，FFT的運算過程采取查表法進一步提高運算速度，分析出小于21次的各次諧波的含量，并計算出電壓信號的有效值(RMS)，將諧波分析結果通過RS-232串行接口上傳到上位機并顯示存儲。通過對硬件軟件的調整，使輸出的結果達到相應的要求，然后對實際諧波信號分析，對結果進行進一步數據處理，以提高結果的準確性。最后本文簡單介紹了一下提高諧波檢測精度的硬件和軟件措施。
關鍵詞：　電能質量，諧波，單片機，FFT

A Harmonic analysis system design based AVR MCU
ABSTRACT
 Along with the development of national economy, and the highly automatization of the production process, so in the electrical network, all kinds of non-linear loads and users continuously growing; there are more and more kinds of electro-equipments which are complicated, precise, and sensitive to the electrical energy quality. Contradictions of these two aspects become more and more prominent, under such environment, exploring the analyzing methods which discussed electrical energy quality, may provides the necessary basis for analyzing the tendency of China’s electrical energy quality management and control. It obviously has significance to the realism.
This design uses the ATmega32L Microcontroller of ATMEL Corporation to complete an electrical energy quality examination system. The voltage signal steps down after the transformer isolation, the lower breadth Alternating signal re-passes the summing circuit, which constituted by operational amplifier, become the direct current signal, which may supply the A/D switching circuit transforms. MCU uses interior timer sample voltage signal every 1/3,200 second, uses the internal 10 bit precisions A/D switcher sample voltage signal of each cycle for 64 spots, carries on the FFT operation, the FFT operation process adopts look-up table method to enhance the operating speed, analyzes the Harmonic content which is smaller than 21 times, and calculates the RMS(Root-mean-square value) voltage of signal, upload the Harmonic analysis result through the RS-232 serial interface on Epigyny Computer and demonstrate the storage.Through the adjustment of the hardware and software to enable the outputresult achieve the corresponding request, then analyze the actual harmonicsignal and carry on the result for a further data processing in order toenhance the accuracy of result. Finally, this article briefly introducesthe hardware and software measures for harmonic examination.
KEY WORDS：power quality, harmonics,Microcontroller,FFT