電網(wǎng)系統(tǒng)對接地電阻的智能測量

電子機電論文編號:JD598 論文字?jǐn)?shù):28017,頁數(shù):62

電力網(wǎng)系統(tǒng)對接地電阻的智能測量

目錄
摘  要 I
Abstract II
前言 III
第1章  緒論 1
1.1 引言 1
1.2 接地電阻的測量的關(guān)鍵技術(shù) 1
1.3 國內(nèi)外對電網(wǎng)接地電阻測試的現(xiàn)狀與前景展望 3
1.4 課題的研究內(nèi)容 3
第2章  智能測量系統(tǒng)的總體構(gòu)思 4
2.1 總體構(gòu)思 4
2.2 框圖與各模塊功能 4
第3章  測試原理與技術(shù) 7
3.1 系統(tǒng)的測量方法 7
3.2 信號激勵源設(shè)計與控制 7
3.3 采用DDFS方法產(chǎn)生激勵源控制信號 10
3.4 硬件軟化技術(shù)：軟件鎖相環(huán)技術(shù) 12
3.4.1基本原理 12
第4章 硬件系統(tǒng)的設(shè)計與組建 21
4.1 MCS-51系統(tǒng)模塊的硬件設(shè)置 21
4.2激勵信號源的硬件設(shè)計 30
4.3外圍接口模塊的硬件設(shè)計 32
第5章  測試系統(tǒng)軟件的設(shè)計思想與方法 33
5.1系統(tǒng)軟件的設(shè)計思想 33
5.2 系統(tǒng)軟件實現(xiàn)的功能 33
5.3系統(tǒng)軟件設(shè)計方法及流程 33
結(jié)束語 44
參 考 文 獻(xiàn) 45
致  謝 46
附錄1 系統(tǒng)電路原理圖 47
附錄2 程序清單 48

摘  要：本文闡述了電力系統(tǒng)接地電阻測量的意義與必要性，指出傳統(tǒng)測量方法所存在的問題，闡述了接地電阻測試原理和方法，討論了一種克服了傳統(tǒng)方法缺點的電力網(wǎng)接地電阻的智能測試的新方法--智能激勵與頻譜分析的方法，組建了一實際的基于MCS.51單片機控制處理的接地電阻的自動、實時、在線的測試系統(tǒng)。并闡明了硬件系統(tǒng)和軟件系統(tǒng)的設(shè)計思想和實現(xiàn)方法。
采用信號激勵、將信號從時域變換到頻域用FFT算法分離被測信號基波，提高了接地電阻測試精度和靈活性，從而實現(xiàn)一種既不影響供電系統(tǒng)正常工作又可以提高測量精度的設(shè)計思想和智能系統(tǒng)構(gòu)成的方法。它在電力系統(tǒng)中具有較大的應(yīng)用價值。
整個系統(tǒng)在硬件上采用數(shù)字信號處理技術(shù)，鎖相同步數(shù)據(jù)采集技術(shù)完成對電流、電壓信號的測量，采用信號激勵技術(shù)即對于電流近乎于零的情況添加輔助完成測量任務(wù)的電流激勵源，采用RSC-232接口將數(shù)據(jù)傳送到上位機。
整個系統(tǒng)在軟件設(shè)計上采用系統(tǒng)自檢驗算法保證測量通道可用，采用硬件軟化技術(shù)--軟件鎖相環(huán)技術(shù)，達(dá)到對外部信號頻率的跟蹤，給出頻率為電網(wǎng)工頻128倍的采樣控制信號：直接數(shù)字頻率合成技術(shù)(DDFS)將基波參數(shù)表轉(zhuǎn)換成需要的電流信號，采用FFT變換及基波幅度的計算方法得到被測電流、電壓基波幅度和電阻大小。
根據(jù)模擬電力網(wǎng)中性線上電流、電壓的實驗測試結(jié)果，表明該測量系統(tǒng)的性能基本達(dá)到了系統(tǒng)設(shè)計的要求，具有比傳統(tǒng)測試方法高的準(zhǔn)確性和靈活性，為實用的系統(tǒng)設(shè)計提供了必要的依據(jù)和基礎(chǔ)條件。
關(guān)鍵詞：接地電阻、信號激勵、FFT算法、DDFS、單片機

Measurement of grounding resistor of
electric power system

Abstract：The paper describes the significance and necessity of measurement of grounding resistor of electric power system. It points out the shortcomings of traditional method. In  order to overcome the disadvantage of it, we try to use a new method to measure grounding resistor intelligently , which add current power to measure and frequency analyse to get the result. We set up an automatic ,real-time ;online practical system based-on MCS-51 single chip control and disposal, it can get the radical waveform by FFT, which change signals from real field to frequency field .The system improve the precision and agility of grounding resistor testing. It makes a way come true that does not affect normal working of power system and improve measurement precision .It will bring great application value in electric power system.
     The system hardware makes use of digital signal processing technique, synchronic data sampling technique to get the samples of current and voltage. Add current power to assist the measurement when current of neutral almost zero. Transmit data to PC by RSC-232 interface .
     Its software uses system self-detecting algorithm to assure measurement channel .It uses softening hardware technique software synchronic data sampling to trace the frequency of exterior signal, in other words , it gives sampling control signals 128 times of power net's frequency .It uses Direct Digital Frequency Synthetics (DDFS) algorithm to transform radical sine waveform parameter table into needed current. It uses FFT algorithm to get radical waveform altitude of current ,voltage and resistor .
     The system simulator and experimental results show the system reaches design request . The result also demonstrate the correctness and feasibility of the methods in the paper. It provides a practical application system with requisite gist and foundational condition.
Keywords: Grounding resistor、signal power、Fast fourier transforms (FFT)、Direct Digital Frequency Synthetics(DDFS)、singlechip