A Design Of Electronic Transformer Digital Interface Based On IEC61850

Comparing with traditional electromagnetic transformer, people pay more and more attention to electronic transformer, because of its various advantages such as: small shape, light weight, easy insulation, wide frequency response range, wide transient response range, high measure precision, dependable security, low cost and etc.For high degree power system automation, IEC and some leading power equipment manufacturers finalized the protocol IEC61850. The part IEC61850-9-1/2 defines the electronic transformer digital interface, the merging unit (MU). For expedite communication between the transducer in process level and bay level, MU samples the voltage and current signal, packets them into digital frames and sends them to Ethernet for relay protection, quality analysis, PMU equipments.The paper researches the electronic transformer digital interface model based on IEC61850, and designs a DSP+FPGA MU shame. DSP takes charge of data acquiring, framing and packing; FPGA is responsible for sequential control. Functionally, MU can be divided into two parts: synchronous high speed data acquisition module and process level communication module. For synchronous high speed data acquisition module, paper introduces the method how to use FPGA cooperating with DSP to control AD7656 to sample all 12 voltage and current signals, and how to realize GPS based clock synchronization. For process level communication module, paper introduces the method how to use DSP to control embedded Ethernet controller LAN91C111 to packing the voltage and current information into frames in the standard defined in IEC61850-9, and how to send the frames to Ethernet.At the end, the paper looks forward to the following work. In next vision of MU, it not only needs to improve the electro magnetic compatibility, but also to improve the MU structure, so as to expediently interface to all kinds of electronic transformers.