Two methods of data synchronization in optical fiber differential: Improved interpolation and clock relay

This paper designed two data synchronization methods in optical fiber differential protection connected with electronic transformers, improved interpolation and clock relay. The first can solve perfectly the data synchronization problem where the MU connected with differential protection according with IEC 60044-8 interface, the second can solve the problem where the MU connected protection device according with IEC 61850-9.The first needs the ET transfer delays at two sides as setting values, the second not. The two methods get rid of GPS recommended connotatively by the standard and improve protection´s reliability greatly; They don´t adjust the sampling time, accords with the function and frame condition ordained in standard IEC 60044-8 and can be applied flexibly to the case that one side connected with ET and one side connected with traditional transformer. In addition, the paper proposes the logic and application method that the MU transmits or self-produces the 1pps signal shared by protection and the MU. The method further improves the reliability of the protection and ensure the protect function independent of any other devices except the MU and protection.