Internet 网络技术应用于变电站自动化领域将导致该领域传统运行维护模式的一场变革:将Web服务器“植入”变电站自动化系统后接入Internet,在世界上任何一个地方即可通过网络浏览器从Internet获取该Web服务器发布的系统实时信息,进而实现远程实时控制、调节与维护;并且,这种基于HTML标准化的Web用户界面降低了为不同操作平台而定制人机界面的开发费用、通信费用、人员培训费用和系统升级维护费用。显然,变电站自动化系统这种基于Web的远程监控维护方式将克服传统本地监控维护方式[1]存在的低效率、高成本的缺陷。
但是,传统的Web技术路线方案[2,3]不能直接用于构造变电站自动化系统中的Web服务器。传统Web服务器以具有高运算处理能力和海量存储容量的工作站或PC 机为硬件工作平台,以非实时操作系统为软件工作平台,其上运行的是大型复杂的服务器程序,典型的如基于Windows NT的IIS(Internet Information Server)、基于Unix 的Apache Web Server 等,服务器的这种高档配置方案对于大量使用8位、16位或32位单片机的变电站自动化系统而言是不现实的要求。
PPP链路一般工作于Server Mode以提供远程访问接入服务,当发送电子邮件告警信息时,PPP链路切换至Client Mode。电子邮件告警信息的发送采用SMTP(Send Mail Transfer Protocol)协议,发送前应设置ISP(Internet Service Provider)为到达电子邮局的出口网关,例如ISP可选用163电信局,电子邮局可选用263邮局。
参 考 文 献
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Design and Implementation of Embedded Web Server in Substation Automation System
Jin Min Zhou Xiang Wang Chuanqi Xu Tianjun
(Yantai Dongfang Electronics Information Industry Ltd. , Yantai 264000, China)
Abstracts: Aimed at the difficulty of applying traditional web technology to construct web server in substation automation system, a new ideology of adopting embedded technology to develop embedded web server in substation automation system is proposed in the paper. With an example of developing an substation automation system product, the function and architecture of embedded web server are presented. The key realization technologies are described in detail, which include using custom tags to separate page designing from server programming for the flexibility and expandability of system, putting out the double reuse based on point and page to satisfy the constraint of limited resource in embedded web server, integrating embedded JavaApplet and JavaScript to implement the broker for real-time update of lots of data points in substation automation system, adopting PPP link to provide remote access service an e-mail transmission etc. The remote monitor and control mode based on embedded web server in substation automation system will decrease system running cost and improve maintaining efficiency, which has wide application prospect and popularization value.
Keywords: embedded web server; substation automation system; custom tags; data-point reuse; embedded Java; PPP