Ethernet Interface Development Of Analog-input Merging Unit

As the level of digitization and intelligence is being improved in substation,the intelligentized and networked process based on IEC61850 protocol is accelerating.On the power primary equipment,in order to realize the compatibility of electronic transformers and traditional transformers,the merging unit needs to be designed to receive digital sampling signal and analog signal.On the power secondary side,in place of traditional point-to-point connection of hard wire,the Ethernet technology has realized the network connection between devices in the process layer.In order to meet the requirements of the IEC61850 protocol,the proposal of built-up network in the process layer is presented.But because domestic intelligent substation has a short time of engineering application,and operational experience and relevant technology is insufficient,the built-up network scheme is not yet unified.Accordingly the design method of devices' communication interface will be different.In the case of SV and GOOSE built-up network,this thesis analyzes the characteristics and problems of analog-input merging unit when processing the process layer packets.In this case,due to different packet types,increased flow rate,and network storm caused by equipment failure,the network interface of MU should have to bear more communication burden.In view of these problems,the thesis analyzes the functional requirements of MU's network interface,and proposed to redevelop MAC core by FPGA instead of traditional MAC chip.The development of MAC core based on FPGA implemented each module in MAC,and improved the filtering function.In addition,the thesis puts forward a scheme to realize the packet decoding module and MAC core in the same FPGA,which can avoid the transmission delay and error caused by external connection to improve the real-time and reliability.Through the test of SV transmission and GOOSE receiption on the experimental platform,the transceiver function and the filtering function of MAC core were verified.In the network pressure test,when 90 Mbps flow was exerted to the network interface,the received GOOSE can still work properly.So the developed network interface has the ability to resist the network storm.The developed MU's network interface improves the real-time and reliability of receiving and processing the process layer packets,which provides a new idea for design of process layer devices,and betterly satisfies the requirements of the IEC61850 protocol.