Synchronized sampling of merging unit with FPGA

A synchronized sampling scheme of MU(Merging Unit) with FPGA(Field Programmable Gate Array) is proposed to improve the synchronization precision of analog sampling for digital substation.Analysis shows that the synchronization error is mainly caused by the crystal oscillator of MU.According to the requirement of MU synchronized sampling,the reception and processing of PPS(Pulse Per Second) is realized separately in two function modules:the PPS reception and the equal-interval sampling,which precisely detects the rising edge of PPS and divides the sampling interval to improve the synchronization precision.These two modules are compensated and treated separately with FPGA to control the error within a certain range.Experiments prove the synchronization accuracy reaches 1μs.