Researchand Application Of Web Release In Substation SCADA System

SCADA (Supervisory Control and Data Acquisition) system is a computer based process control and scheduling automation system. It is responsible for monitoring and control field equipment, collecting real-time data acquisition, processing and analyzing control field device. It can control the equipment and alarm for the abnormal situation. Its powerful function makes it have extensive application in the field of power system and so on.The development of the Internet has brought great changes to people’s life. Ways of obtaining information are becoming more and more diversified. Since the traditional SCADA system which can only be monitored in monitoring room has single sources of information, it already can’t satisfy people’s needs. It is very important to realize the remote monitoring configuration screen and reports. Web release for the SCADA system is a solution for the problem.Based on the research status of SCADA system and development status of the Internet, it has carried on the demand analysis to Web publishing. The Web publishing system can be divided into three parts:ActiveX controls, the real-time data transmission and Web site. A perfect combination of the three modules can make the Web publishing functions of SCADA system run good.ActiveX, a set of technology that using COM (Component Object Model, the Component Object Model), makes the software components contact each other in the network environment. It can use a variety of programming languages to realize. In this article it uses the C++language to realize the ActiveX controls. It has mainly realized the two main functions:displaying of the picture and refreshing real-time data. It uses the Multithreading technology to realize these functions. Displaying of the picture function uses the double buffer technology to realize. For the purpose of preventing the flicker problem in the process of the refreshing, it maps the whole picture in memory, and then shows the picture in the computer screen. At the same time real-time thread through script accesses the real-time data in the shared memory, changes the real-time data attribute of element in the picture to realize the function. When real-time data is changed and if the picture is refreshing, it will display the latest data in the picture.Real-time data transmission adopts the model of client/server mode to realize the function. The data server gets real-time data in the database of SCADA system. It uses the TCP/IP communications protocol to send the data to the client. After the client receives the real-time data, it stores the data into the shared memory. It makes it very convenient for the ActiveX control to use script to collect data in real time. The client will also be able to obtain the remote control message of ActiveX control, and transfer to the server. The server will pass the message through the message response mechanism to drive. The drive communicates with intelligent instruments, and sends the message to it to realize the control of switch quantity.Web site design mainly includes the writing of the web page and site creation. Using HTML, PHP, CSS frameworks design the web page, and embed ActiveX controls into the page. It uses DOM interface and smart Pointers in C++to create the virtual directory, and realize the site creation.After finished the Web function, it use the method of using cases to test the function in the computers with Windows XP and Windows 7 system. Through the testing, it can be found that the Web function can run well in both Windows XP and Windows 7 system and it can match the users’requirement for real-time.