Research On Telecontrol Communication Simulation System Based On Distributed Network Protocol

Nowadays, the telecontrol system has been widely applied to many fields, such as power transmission,hydraulic dispatch,oil transportation. Supervisory Control And Data Acquisition is a important part of the telecontrol systems. Telecontrol protocol ensure the accuracy of data acquisition and transmission of the computer monitoring systems. The telecontrol protocol also develops to a status that all kinds of protocols coexist today. Designing a efficient Simulation of communication system based on Distributed Network Protocol is necessary which is aimed at the peculiarities of peer to peer telecontrol protocol that are widely applied in various domains.The first part of the paper simply introduces the structure of SCADA system,The status and trend of development of SCADA system at home and abroad. Two major kinds of telecontrol protocols are discussed in this chapter, one kind is the traditional telecontrol protocol which includes CDT,POLLING and MODBUS, the other kind is the peer to peer telecontrol protocol which includes IEC 870-5-101 and DNPs etc. The working mode and characteristics of these protocols are also discussed in this chapter. Finally, the simulation software of remote communication and several popular remote cmmunication simulation system are presented.In the second chapter the detailed content of peer to peer remote protocol is introduced from the aspects of:Transmission frame formats, Link transmission procedures, General structure of application data, Basic application function. The explanation of the architecture and functionality provided by The distributed network protocol(DNP3) is researched deeply, such as network structure, types of application data, scan mode, message transmission collision in the data link layer and application layer. On the base of intrduction of explanation of the protocol is presented together with an general situation of layer requirements and connection management of the DNP network. An approach to implement the protocol that adopts the Single Master Connection mode and the multiple master connection is discussed.The third part of the paper includes the techniques which are used in the design and realization of the simulation software. On the base of the introduction of the C++ programme techniques is presented together with the ways of the master and RTU communication.The end of the paper discusses the test of the communication protocol, simply introduces the content and method of the test, analyzes the result of the test and achieves the conclusion of the test.Through researching into the architecture and developing trend of the SCADA system and the remote protocols, the paper designs a communication simulation system based on the distributed network protocol, which is suitable for, remote and approximate real-time data transmission. The external interface and internal structure of telecontrol protocol program is designed. The tactic of effective dividing of the program function is discussed, the effective way to divide the program function is presented in term of transparency. Master and RTU is designed and realized with VC++.The designed system is practically proved to be a reliable,flexible,widely used communication system. It can be used in the projects of distribution automation.