PPS synchronization based on RPR for digital substation
Yuping Lu · Dianli zidonghua shebei · 2010
For the high-precision synchronization defined in IEC61850 for the data sampled on process bus,a PPS(Pulse Per Second) synchronization scheme based on RPR(Resilient Packet Ring) is proposed for digital substation.In this scheme,there are the master RPR node,which receives the PPS source,and the slave RPR node,which outputs the rebuilt PPS.The reserved control code K28.6 in Ethernet physical coding layer is used to represent the uprising edge of PPS,which is simultaneously transferred with the preemptive priority in both RPRs and a backoff algorithm is applied to balance out the propagation delay.The tolerance of PPS rebuilding is analyzed and the hardware design of FPGA(Field Programmable Gate Array) with Verilog HDL is introduced.The results of Modelsim-based simulation indicate that,the rebuilt PPS precision is up to nanosecond.The scheme makes it possible to merger the process bus and time synchronization network together in digital substation.