Research Of The Merging Unit Based On IEC61850-9-2

With the development of the smart substation toward a miniaturization, intelligent, highreliability direction, the performance of the merging unit (MU) which the substationautomation system demands has to be better. The MU based on IEC60044-7/8communicatesinefficiently. The MU adopted of unidirectional multidrop point to point link based on IEC61850-9-1has a high communication efficiency but the data between different MUs can’t beshared. The advantage of the electronic transformers were not be really used. IEC61850-9-2which could configure the sampled rate and the number of the sampled channels according tothe situation is flexible and adaptable. The sampled values are transmitted in multicast VLANway. The MU based on process bus can realize the share of the data in process layer, whichbroke through the limitations of the bays.First of all, the essay described the information modeling and communication servicemapping of MU on the basis of IEC61850. Then according to IEC61850-9-2, a design of MUbased on ARM9&FPGA has come out in this paper. Then the paper has a detailed analysis ofthe boot process of ARM, the implementations of the exchange of the data with FPGA, thecompensation method of phase-delay and the driven development of the Ethernet controlledchip. Then we summarized several common synchronization methods and their feature.Besides that, the design of FPGA was also discussed by Verilog, included of the realization ofreceiving high speed serial data, sorting and access of the data in different channels, theoperation of the dual-port RAM and so on.Furthermore, we test the performance of the MU, and analyze the packets which meetthe standard of9-2. A series of test were made with different sampled rate and differentnumber of the sampled channels. It was verified that the performance in real time, speed,interoperability and reliability meet the demand. The device we made has practical value to acertain extent.