Research on synchronization test method for distributed sampling data based on precise time-setting

Synchronous sampling data is considered as a basic condition for correct operation of all kinds of differential protections in a substation. It is necessary to test it in the substation commissioning procedure. This paper first addresses the root causes of synchronization problems and the necessity of onsite synchronization test for line differential protections and all distributed sampling differential protections in a smart substation. Then a method based on precise time-setting is proposed to test sampling synchronization of differential protections, which can solve difficulties of on-site synchronization test of distributed electrical data. Specific implementations are given and the causes of error are also analyzed in this paper. In a real 500kV smart substation project, error of data synchronization is controlled under 1.5 ° by testing line differential protections and the whole sampling circuit based on the method, which entirely meets the performance requirements of differential protections.