A Design Of Merging Unit Based On IEC61850

IEC61850 is an international standard for the future substation automation communication system. It A/Dopts Object-Oriented technology and has an open-end infrastructure to accommodate future developments. Its major objective is to achieve interoperability of Intelligent Electronic Devices (IEDs) from different manufactures. IEC61850-9-1 defines the communication service between the electrical transducers and IEDs served in the bay level. However, for the purpose of successfully applying electronic instrument transformers to substation automation system, the most typical problem to be solved is the interface between electronic instrument transformers and substation secondary equipment.Firstly, the paper introduces the background and the development of electronic instrument transformers, and then makes an analysis on the function integration scheme of substation automation based on IEC61850 standard, and does some researches on communication specification between process level and bay level, also introduces digital interface communication model of electronic instrument transformers. The paper also gives a design of Merging Unit (MU)based on FPGA/DSP and Embeded Ethernet Card , which solves the interface problem of applying electronic instrument transformers to substation automation system. The circuit of equipment interface has been fundamentally realized and the practicability has been proved by simulation. The design and research of primary device is fundamentally achieved on basis of the combination among latest electronic instrument transformers technology , IEC61850 standard and senior programming in FPGA. What are worthy paying more attentions is the synchronization in Merging Unit(MU), because the synchronization can help to have right actions and good measure precision in bay level. Also the paper gives a new method to synchronize the MU following the IEC61850 standard, and the programs programmed by VHDL are simulated. Furthermore, the sampling frequency of A/D converter controlled by FPGA is particular depiction in the paper, and the program programmed by VHDL is listed in the appendix. Finally, some explorations between electronic instrument transformers and industrial internet are carried out, and these will give some help to produce automation system equipments based on IEC61850 in the future.