Information Model And Mapping Implementation Of Merging Unit Based On IEC61850-9-2

As the development of information technology, microelectronic technology and network communication technology, intelligent automatic devices which are with a microprocessor core has been widely applied in the power control area, and also promoted the rapid development of substation automation system technology which is a major support on power grid operation. The emergence of IEC61850 protocol lays the foundation of the pattern of "unified standard, unified model, the opening Internet" for power system automation products. The protocol formulates service model to satisfy the requirements of real-time information transmission according to the characteristics of power system production process; adopt Abstract Communication Service Interface (ACSI) and Specific Communication Service Mapping (SCSM) to adapt to network development; use object-oriented modeling techniques, modeling and self-description for the equipment to accommodate function extensions to meet the requirements of open and interoperable application.The development of substation automation technology provide a better stage to promote electronic transformer, digital substation based on intelligent primary equipment and electronic transformer has become the direction of power system technology development. Electronic Transformer not only overcomes various problems existed in the traditional electromagnetic transformer, but also has low power, high precision, compact, easy to implement communication with the computer directly and other characteristics. High voltage and current directly can be converted to low-level signals or digital signals, and high-speed Ethernet is used to complete the collection and transmission of data. Electronic transformer technology for substation automation system is mainly reflected the digital application of data collection. Merging unit as the digital interface of electronic transformer is becoming the key of realizing the digital electronic transformer.IEC61850-9-2 protocol formulates the Specific Communication Service Mapping between bay layer and process layer, specifies the network transmission of sample value in merging unit of electronic transformer. The protocol defines the transmission of process bus, simplifies the complex connection of the substation system with the characteristics of flexibility, opening and extension, in accordance with the present development of digital systems. Thus, with the maturity of electronic transformer technology, the research of merging unit based on IEC61850-9-2 will lead substation automation technology into a new development stage.This paper firstly introduces the frame of content and major characteristics, also the effect and communication characteristics of the electronic transformer digital interface—merging unit. Based on the deep research of information model and object-oriented modeling, the information model of sampled value transmission in merging unit has been build. For Special Communication Service Mapping (SCSM) process bus of IEC61850-9-2 process bus protocol, sampled value model service is mapped to the Ethernet link layer using the multicast communication sampled value services. And the hardware of communication system about sampled value transmission is designed based on Ethernet. As a result, it is tested to achieve with IEC61850-9-2 protocol and completed full-duplex 100Base-FX optical Ethernet transmission.