小電流接地系統(tǒng)單相接地選線裝置的設(shè)計(jì)
摘要

在配電網(wǎng)中，單相接地故障率最高，但由于故障后接地電流小，故障特征不明顯，因此小電流接地系統(tǒng)單相接地故障選線問(wèn)題雖已經(jīng)研究多年卻一直未能很好解決。
本文針對(duì)小電流接地系統(tǒng)發(fā)生單相接地時(shí)，系統(tǒng)的故障特征進(jìn)行了分析。針對(duì)小電流接地故障時(shí)的特點(diǎn)，結(jié)合目前用的較多群體比幅比相原理，提出了一種新的選線原理即過(guò)半選線原理，來(lái)實(shí)現(xiàn)小電流接地系統(tǒng)選線保護(hù)。在此原理基礎(chǔ)上設(shè)計(jì)了以AT89C51單片機(jī)為核心的小電流接地系統(tǒng)單相接地故障選線裝置，詳細(xì)論述了該裝置的實(shí)現(xiàn)原理、系統(tǒng)結(jié)構(gòu)及其軟件與硬件實(shí)現(xiàn)方法。
該裝置靈敏性和可靠性高、運(yùn)行穩(wěn)定、抗干擾能力強(qiáng)，系統(tǒng)能夠正確區(qū)分母線和線路故障，準(zhǔn)確地選出故障線路，具有一定理論意義和實(shí)際應(yīng)用價(jià)值。
關(guān)鍵詞：小電流；單相接地；過(guò)半選線；單片機(jī)；硬件

Abstract

In the distribution network, the single-phase earth failure rate is highest, because breakdown, the earth current is small, the breakdown characteristic is not obvious, although the undercurrent earth system single-phase earth fault route selection question already studied many years actually not to be able very good to solve.
This article has the single-phase earth in view of the undercurrent earth system, system's breakdown characteristic has carried on the analysis. In view of the undercurrent earth fault's time characteristic, many communities which the union uses at present compared to compared to the principle, proposed one kind of new route selection principle namely more than half route selection principle, realizes the undercurrent earth system route selection protection. Has designed in this principle foundation take AT89C51 monolithic integrated circuit as the core undercurrent earth system single-phase earth fault route selection installment, elaborated this equipment to realize the principle, the system structure and the software and the hardware in detail realizes the method.
The fault line selection installment movement correct, the sensitivity and the reliability high, the movement are stable, antijamming ability, the system can differentiate the bus bar and the line fault correctly, selects the faulty line accurately, has certain theory significance and the practical application value.
Key word：Undercurrent；Single-phase earth；More than half route selection；Monolithic integrated circuit；Hardware

目錄

0前言 ……………………………………………………………………………1
1小電流接地系統(tǒng)單相接地故障分析……………………………………………2
1.1中性點(diǎn)不接地電網(wǎng)發(fā)生單相接地故障的特點(diǎn)………………………………2
1.2中性點(diǎn)經(jīng)消弧線圈接地當(dāng)網(wǎng)單相接地故障的特點(diǎn)…………………………5
2 小電流接地選線的算法………………………………………………………8
2.1 現(xiàn)有選線算法綜述 …………………………………………………………8
2.1.1零序電流比幅算法…………………………………………………………8
2.1.2群體比幅比相法……………………………………………………………8
2.1.3無(wú)功功率算法………………………………………………………………9
2.1.4五次諧波分量算法…………………………………………………………9
2.1.5有功分量法…………………………………………………………………9
2.1.6小波算法……………………………………………………………………10
2.1.7注入信號(hào)法…………………………………………………………………10
2.1.8首半波法……………………………………………………………………10
2.2 選線影響因素分析 …………………………………………………………11
2.3 過(guò)半選線原理的提出 ………………………………………………………12
2.3.1故障信息分析………………………………………………………………12
2.3.2過(guò)半選線原理………………………………………………………………12
3硬件電路設(shè)計(jì) …………………………………………………………………14
3.1 總體思路 ……………………………………………………………………14
3.2  CPU處理模塊………………………………………………………………15
3.2.1 AT89C51的結(jié)構(gòu)與性能特點(diǎn)………………………………………………15
3.2.2 AT89C51的引腳使用分配…………………………………………………17
3.3 數(shù)據(jù)采集模塊 ………………………………………………………………19
3.3.1傳感器的選取………………………………………………………………19
3.3.2采樣信號(hào)的調(diào)理……………………………………………………………20
3.3.3濾波電路……………………………………………………………………21
3.3.4多路轉(zhuǎn)換器…………………………………………………………………21
3.4 鎖相功能模塊 ………………………………………………………………22
3.5 A/D轉(zhuǎn)換模塊…………………………………………………………………23
3.5.1 AD1674內(nèi)部結(jié)構(gòu)及其功能………………………………………………23
3.5.2 AD1674引腳及其功能……………………………………………………25
3.5.3 A/D轉(zhuǎn)換與單片機(jī)接口電路………………………………………………26
3.6 復(fù)位電路……………………………………………………………………27
3.7 存儲(chǔ)空間擴(kuò)展………………………………………………………………28
3.7.1程序存儲(chǔ)器擴(kuò)展……………………………………………………………29
3.7.2數(shù)據(jù)存儲(chǔ)器擴(kuò)展……………………………………………………………30
3.7.3外部存儲(chǔ)器與單片機(jī)接線…………………………………………………31
3.8通信系統(tǒng)……………………………………………………………………32
3.9人機(jī)對(duì)話模塊………………………………………………………………35
3.9.1鍵盤(pán)部分……………………………………………………………………35
3.9.2液晶顯示部分………………………………………………………………35
3.10 裝置硬件設(shè)計(jì)的抗干擾措施………………………………………………38
4系統(tǒng)軟件流程圖設(shè)計(jì) …………………………………………………………39
4.1軟件總體框架…………………………………………………………………39
4.2軟件流程圖…………………………………………………………………40
4.2.1主程序流程…………………………………………………………………40
4.2.2采樣子程序…………………………………………………………………41
4.2.3故障檢測(cè)流程……………………………………………………………42
4.2.4選線流程設(shè)計(jì)……………………………………………………………42
4.2.5單片機(jī)通信程序……………………………………………………………44
4.3軟件抗干擾措施……………………………………………………………45
5技術(shù)經(jīng)濟(jì)分析…………………………………………………………………46
6結(jié)論……………………………………………………………………………47
致謝……………………………………………………………………………48
參考文獻(xiàn)…………………………………………………………………………49
附錄A 譯文………………………………………………………………………50
附錄B 外文文獻(xiàn)…………………………………………………………………61