Design And Implement Of Online Monitoring System Based On GPRS Used In Transformer Substation

Instead of testing power equipments off line, Online monitoring system is gradually becoming the main means to overhaul power equipments in recent years. Most of monitoring systems in service nowadays adopt communication cable to transmit data. Because of complicated and multiplicate circumstance in some substation, such as remote or scattered distributing, it's expensive or inconvenient to using communication cable. So we think of wireless communication as a substitute.In this paper, we design and implement the online monitoring system after analysing requirement and characteristic of power system deeply. The system is designed to be the structure of C/S, various monitoring units are managed by one server and all data is displayed in one terminal. Wireless communication between monitoring units and server is achieved by equipping monitoring units with one GPRS DTU that can connect to internet. After thinking over character of GPRS and actual application, we adopt UDP protocol in the transport layer to make the system to response faster and run with less cost. In the application layer, we own define one custom-built application protocol to fit the potential alterations of monitoring units and improve reliability of communication. The monitoring server is designed based on the overlap server theory and is implemented with Asynchronous Socket technology to resolve the parallel request caused by multi-monitoring units. We partition the server program to two processes that respectively answer for monitoring units and end users. In virtue of this program structure the monitoring server have higher efficiency and better expansibility. Interproces communication between these two processes is implemented with Subclassing technology based on Windows message mechanism. As to server's performance, we validate the efficiency and response speed of the server to prove the rationality . Finally,we design and describe the main program flows in the server in detail.We pay sufficient attention to expansibility of system, reliability and consistency of data transmission in the design phase. In the implementation phase of the program, we analyze and compare various software technology extensively in order to choose more advisable software technology. Now, the system is used in many transformer substations and create quite a bit economy benefit.