A FPGA-based digital synchronous methodology for IEC 61850-9-2 process bus

In this paper, a network synchronization proposal for digital substation process bus in the process layer was designed. It appears differences of timing grouping queuing delay in the forward and backward on the channel due to the switch/routing device, thus introducing queue-induced asymmetry, which is a major contributor to time offset and time delay between master and subordinate clocks. The sampled value of the transmission time error caused by the electronic transformer (ECT) signal processing channel and Ethernet communication channel is analyzed. An FPGA-based (field-programmable gate array, FPGA) digital synchronization approach for merging unit (MU) was proposed, which included oversampling, linear phase-shifting, dynamic interpolation resampling technique. It solved the sampled value message precise synchronization problems on the IEC61850-9-2 process bus. Time offset and delay were reduced more than 70 μs between the master and subordinate clocks based on IEEE 1588v2, and he test results were well in 0.2 S level of IEC 60044 standard. Numerical examples are presented to demonstrate the effectiveness of the theoretical results.