EPON's Research on Transmission of Sampling Value in Process Level of Digital Substation

摘要

Non-conventional instrument transformers and optical fiber communication are utilized in secondary system of digital substation. Sampling value signals are transmitted to Merging Unit through proprietary links and Merging Unit transmits the signals to IED equipments by means of IEC 61850-9-1 or IEC 61850-9-2. Merging Unit consists of multiple communication interfaces, connecting voltage and current signals input from non-conventional instrument transformers. In this paper, Ethernet Passive Optical Network (EPON) is proposed to connect non-conventional instrument transformers with Merging Unit. Meanwhile, the definition of OLT-Merging Unit and ONU-Instrument Transformer is put forward. Under circumstance of synchronization between Merging Unit and non-conventional instrument transformer, TDMA scheme is adopted in transmission of sampling value and performance of such data transmission scheme is analyzed. The use of EPON for sampling value's transmission is compatible with the Ethernet data transmission from Merging Unit to IED. Finally, the deployment of EPON in digital substation is suggested.