The development of smart substation has led to higher requirements made on the time synchronization for the merging unit. A study on how to realize highly accurate time synchronization and time keeping function is a practical need for the smart substation development. Taking into account such chief factors as the timing source error

crystal oscillator characteristics

time keeping algorithm

and logic processing

this paper discusses the design and realization methods of highly accurate time synchronization in the merging unit based on the corresponding technical demand. Then an implementation scheme of time synchronization technology in merging unit for the smart substation is proposed. By using the field programmable gate array (FPGA) as the core component

the logic design of various technical links is realized by different modules in FPGA

and accurate time synchronization and good time keeping performance is achieved by the coordination between CPU and FPGA. Experimental results on time synchronization performance and application in smart substation of merging unit indicate that this technique completely meets the requirements of the merging unit device for the time synchronization function in the smart substation.