The access to distributed generation has enabled the application of current differential protection in the distribution network. One of the key technologies to be solved first is fault data synchronization. As a self-synchronization algorithm based on fault instant detection can achieve fault data synchronization without extra investment

it has found definite application in the distribution network. But its synchronization precision has not been studied or verified intensively. In this paper

based on theoretical analysis of the phase current increment

the delay times of protection starting with different attenuation speeds of the DC component are calculated. Then

the law of variation of the maximum delay time with the initial phase and attenuation speed and maximum self-synchronization error are obtained. Analysis results show that the error of fault data synchronization based on phase current increment detection is affected by fault inception

feeder parameters

pick-up threshold

etc. In some cases

the self-synchronization error will be greater than the allowed margin of differential protection. Finally

analysis results are checked by relay test instrument. This work is supported by National Technology Research and Development Program of China (863 Program) (No. 2012AA050213).