Research And Design On Merging Unit Of Electronic Current Transformers

The technique of electronic transformers, based on computer and photoelectric sensor technology, is the hot topic of the research both at home and abroad. The connectors between electronic transformers and protective devices have become important. The IEC standards agreements have furthered the progress of Electronic transformers’ development. Based on the introduction of ECT/EVT and their framework, this thesis presents an important component part of electronic transformer’s digital output interface-merging unit. The merging unit’s characteristics of the function are analyzed in this thesis.At first, this thesis summarizes the principal and development of electronic transformers and completes the integral design scheme which is based on Rogowski coil. Then two ISO standards are introduced:IEC60044-8and IEC61850.Both the analysis of the realization of the digital output of electronic transformers and the research on the structural design, communication design and function divide of the merging unit are based on these standards. Besides, a new method to implement the merging unit with FPGA/DSP is proposed, which transmits the Manchester-coded data including framed multisampling data to merging unit using FPGA. The circuit of decoding module based on Manchester code, CRC code module and FIFO module are designed for receiving, unpacking and checking of the multi-channels data. These data are finally transmitted to the protective devices via Ethernet controller after being merged in a high speed using DSP and packed according to ISO standard IEC61850-9.