Time synchronzing implementation for digital protection devices

The main feature of time synchronizing in the IEC61850 digital substation is analysed systematically,the error of clock source proved to be produced from crystal oscillator.Based on the analysis conclusion,a general software scheme of time synchronizing is presented to correct the error caused by external time source and protection device crystal oscillator using the methods of backfill crystal oscillator time's counter by capturing the two different trigger edge's time and using one-place quadratic equation of regression.Based on the mentional software scheme,a general hardware design is proposed to meet the demands of each time synchronizing nets.Engineering application and test results for various time-synchronizing error proved the mentional hardware and software are valid to the time synchronizing of digital protection devices in IEC 61850 communication and other applications of high precision time synchronizing.