| 毕业设计 电力线远程自动抄表系统的研制 随着我国国民经济和电力事业的迅速发展，绝大部分地区的用电已没有限制，一户一表制已基本普及。企业级的电力负荷监测、控制系统已在一些地区投入使用，取得了较好的效果。但低压电力用户由于数量多，地域分布广，电力公司的抄表工作量相当大。因此采用新的技术手段，利用本地和远程自动抄表技术，完成自动抄表并达到实时监控电能表计的目的;同时减少人工上门抄表、数据输入等繁杂又容易出错的劳动，提高工作效率，真正做到用电管理自动化，自动抄表系统就成为电力公司解决抄表问题的一种选择。 目前，远程自动抄表技术(AutomaticMeterReadingSystemAMRS)主要有专线通信技术和电力线载波通信技术。专线通信技术作为常规方法，其特点是通信稳定性好;但是需铺设专用通信线路，存在施工量大、综合成本高、维护费用高、旧城区施工难度大等问题，难以大规模应用。电力线载波通信技术采用电力线作为通信介质，具有充分利用现有资源、易施工、综合成本低、不受环境条件限制等优点。但是，电力线通信信道存在间歇性噪声大、阻抗随负载变化大、信号衰减大等缺点，严重制约了它的有效利用。 针对上述问题，本文提出了一种解决方案。本方案采用扩展频谱通信技术，利用扩频通信抗干扰能力强的特点，大大提高了数据传输的可靠性，实现了在中、低压电力线上的进行远程抄表的功能。扩频技术种类较多，主要包括直接序列扩频、跳频、跳时和线性调频。由于电力线通信环境的特殊性，主要是频率的限制，以及成本、设计复杂程度等因素，在低压电力线上只能利用扩频通信中的线性调频技术。线性调频技术能够很好的实现低成本的将信号扩展到可用频段，同时它不使用伪随机码，从而不存在伪随机码同步问题。其组网采用以太网的冲突检测方式，实现总线复用。基于此，本文设计了一种在低压电力线上进行数据传输的电路模块，以实现数据的准确传输。此电路模块的核心部件就是一种基于线性调频的扩频载波adSpeetrumCarrierSSC)技术的电力线网络接口控制器。本文试图从通信的角度探讨电力线远程抄表系统的设计和实现。首先就设计中采用的线性调频技术的基本原理作了分析，随后详细论述了系统的硬件设计合软件开发。其中硬件设计包括用户数据采集器、数据集中器和数传机。软件开发包括各模块单片机汇编程序的编写。最后，对该系统进行了调试和性能分析。实验室调试及现场测试结果说明，本抄表系统性能优越、性价比高，稍加改动即可进入真正的实用阶段。 关键词:抄表系统 扩频通信 电力线 线性调频 目录 摘要 ABSTRACT 1概述 1.1课题的目的、意义和必要性······························……1 1.2国内外技术研究现状及发展趋势·····························……2 1.3课题研究的主要内容和技术关键························4 2扩展频谱通信原理概述 2.1扩展频谱通信基本原理······························· 2.1.2分类··································································……5 2.1.3理论基础··························································…..…6 2.1 . 4处理增益与抗干扰容限··········································……7 2.1.5主要特点····························································……8 2.2线性调频原理··································································……8 2.2.1基本概念····························································……8 2.2.2线性调频信号的频谱··········································……10 2.2.3线性调频信号的产生和接收·································……12 3远程抄表系统的硬件设计 3.1电力线通信信道传输特性分析··········································……17 3.1.1载波信号在低压电力线路上的衰减···························……17 3.1.2低压电力线上的干扰·············································……17 3.2远程抄表系统的整体框架················································……19 3.3抄表系统硬件设计一原理···················································……20 3.4抄表系统软件设计·························································……26 3.4.1抄表系统软件设计的层次结构·································……26 3.4.2微机一单片机通信协议··········································……27 序设计源程序··········································……29 4调试与性能分析·······························································……54 结论····················································································……56 致谢·············································································.······……57 声明····················································································……58 |
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