Research On The Experimental Platform For Digital Substation Commucation System Based On IEC 61850

The level of automation of substation in our country is continuously enhanced with the development of information and communication technology. A important challenge of automation of substation is to realize interoperability between devices of different manufacturers, therefore the complex protocols are required to be developed so to meet the demand of communication between all devices in a substation. In order to unify interface standard, IEC and TC-57 released IEC61850 standards in 2003“communication network in substation system” which has provided all the communication mappings of the primary and secondary devices in substation automatic equipments.For the communication system of substation based on IEC61850, the protocol is only understood by practical operation on-site. There are few chances for beginners to get to know it. Currently, there is no platform in which learners are able to understand IEC61850 protocol with complicated content and various terms. Therefore, it is of particular significance to research on the experimental platform of communication network. The research content of the paper is as follows:Firstly, the paper carries out research on IEC61850 protocol and the triple layers of communication network of digital substation. What is more, it also highlights on the modeling based on key equipments of automatic system of IEC61850 substation. For the two important message in process layer device communication-SMV and GOOSE messages, the simulation modeling of the message is carried out in the demand of IEC61850 protocol and the network parameter is also set. The simulation results compare the transmission delay and jitter delay of the messages in different conditions.Secondly, Rogowski coil is used to simulate the traditional instrument transformer in the power system. The simulation signal shrunk by certain ratio will be converted to digital signal by second order Σ-Δ modulation circuit and digital filter circuit. The characteristics of high resolution, high integration and low cost of the second order Σ-Δmodulation circuit will make the digital signal meet the requirements of electronic instrument transformer.Thirdly, the hardware merging unit based on FPGA and the OPNET of virtualenvironment are directly linked by SITL model so as to complete the conversion between real data package and virtual one. The SV data stream is captured by packet capture software so as to verify the effectiveness of data stream. Based on the above research, it can be expanded to other IED devices such as the direct connection of protection device and OPNET simulation environment to get the corresponding GOOSE message. Therefore, the experimental platform of the digital substation will not only enable researchers to detect the interoperability of IED equipment, but also establish a better and more intuitive learning platform for IEC61850.Through the study of the platform, there is a more intuitive understanding of hierarchical information model of IEC61850, theoretical knowledge of MMS,GOOSE,SMV and the message content. At the same time, researchers have a more clear understanding of the architecture of the substation communication system.