Research on relay reliability evaluation based on information flow block diagram in smart substations

Through analysis on 220kV longitudinal differential line relay protection device in smart substation, a new method for quantitative evaluation of relay protection system reliability of smart substation is proposed, considering the influence of power circuit and synchronous clock on secondary devices, the RBD(Reliability Block Diagram) models of 220kV longitudinal differential line relay protection and 110kV line relay protection system are established and evaluated; The reliability of the integration mode of merging unit and smart terminal is also quantitatively evaluated, based on which the reliability improvement strategy is proposed.