In order to reduce the master station state estimation error caused by asynchronous substation measuring data .Methods for improving time synchronism of substation measuring data are researched. According to the bus power imbalance phenomenon of some 500kV UHV substation, the main factors which affected time synchronization of substation basic measuring data are analyzed. Several methods to improve the synchronization of the basic measuring data in substation are proposed. The methods are based on fast measuring algorithm, send the measuring data with time stamp, and set suitable changing threshold to improve the refresh rate of measuring data. The retransmission unit aligned measuring data according to the time stamp and send it to master station in one packet. A simulation test system is built by using RTDS and several kinds of comparative test are done. The test result proves that the methods are effective.
