Study On Multi-protocol Communication Technology For Intelligent Circuit Breaker

Because of the company’s communication protocols being various, and protocol standardsbeing not unified and opaque, these cause networking communication difficulties of theintelligent circuit breaker from different companies. Aimming on the difficult problems ofmulti-protocol network communication, the thesis carries out the research of multi-protocolcommunication technology, the multi-protocol conversion architecture and communicationmodel are established, then the multi-protocol converter is developed, at the same time, themulti-protocol conversion hardware and software application and test platform are built. Finally,the communication problem between the protocols is better solved. The paper discussesmulti-protocol communication technology and carries out the following research:1. This paper analyzes the development status and trend of the intelligent circuit breaker andits networking. The key technical problems of the intelligent circuit breaker networking arepointed out. The thesis studies and analyzes the structure of the commonly used protocols, suchas Profibus-DP, Modbus, multi-function electric energy meter protocol, CAN bus, and theEthernet. The relationship between the each of the protocols and the OSI reference model isanalyzed. The communication data frame formats of the protocols are studied. Thecharacteristics of the protocols are summarized. Based on analysis and research of the protocols,the paper designs the communication network structures for the each of the protocols, anddevelops the communication interface hardware circuits and softwares for the each of theprotocols.2. This thesis analyzes and studies the feasibility of multi-protocol conversion from twoaspects of hardware and software. The paper analyzes and studies the multi-protocol conversiontypes, such as OPC conversion, bridge conversion, router conversion and gateway (protocolconverter) conversion, et al. Considering the difference between the physical layer, data linklayer, network layer, application layer of the protocols, and the networks of the protocols beingheterogeneous network, these requires using the gateway to achieving multi-protocol conversion,and the overall scheme of multi-protocol conversion is presented.3. Multi-protocol conversion can be realized through the ways of nontransparentcommunicaiton and transparent communication. In the way of nontransparent communicationmulti-protocol conversion, the multi-protocol conversion is responsible for processing theprotocol data frames, and the user data is extracted, and the user data is processed by thedestination host protocol, finally, the user data is converted to the data frame of the destination host protocol. The user data is a link among the protocols. Based on technical analysis ofmulti-protocol conversion, the nontransparent communication multi-protocol user dataprocessing model is proposed. In order to solve the identification problem of the differentprotocols equipment connected to the same protocol converter, this paper presents a deviceidentification method that using Profibus-DP address plus the protocol type code. In order tosolve the problem of nontransparent communication multi-protocol conversion, thenontransparent communication multi-protocol conversion model based on dynamic memorybuffer is established.4. In the case of no parsing user protocol frames, the user protocol data frames are directlyencapsulated and decapsulated by the protocol. The user protocol data frames transparently passthe protocol network, and this is the transparent communication. Power line carriercommunication can use the transparent communication. Through studying the power line carriercommunication technology, the power line carrier communication network architecture of theintelligent circuit breaker is built, the communication data frame structure is analysed anddesigned, and the hardware and software of power line carrier communication interface aredesigned. In order to solve the transparent communication problem between the protocols, thetransparent communication form and communication principle between the protocols areanalyzed, the transparent communication model between the protocols is presented, the datarange structures of Profibus-DP sending and receiving messages are designed, and thetransparent communication multi-protocol conversion model is established.5. This paper built multi-protocol conversion hardware and software application and testplatform for multi-protocol communication of intelligent circuit breaker. The multi-protocolconverter hardware circuit is designed and made, the software of nontransparent communicationand transparent communication are developed. The relevant GSD files are edited. The PCsoftware for the multi-protocol platform are analysed and studied, such as Profibus-DP masterconfiguration software, CAN bus protocol analysis software, TCP&UDP test tool, GSD fileediting software,et al. Using the hardware and software platform, nontransparent communicationand transparent communication multi-protocol conversion experiments and simulation arecarried out, between Profibus-DP master and Modbus protocol intelligent circuit breaker,multi-function meter electric energy meter protocol intelligent circuit breaker, CAN bus protocolanalysis software, Ethernet TCP&UDP test tool. Through the analysis of the obtained results,the correctness of the multi-protocol conversion model is proved.