In this paper

the adoption of phase selection closing measures are described in order to prevent the failure of power supply due to excitation inrush current of transformer during the completion of the power supply of offshore VSC-HVDC system. For assuring the smooth implementation of phase selection operation

the maximum allowable deviation of operation time permitted by the circuit breaker is determined by the simulation calculation of excitation inrush current of transformer. Through the test verification

the factors and ranges affecting the operation time dispersion of circuit breaker are confirmed. According to the above calculation and verification results and the idle time dispersion test of the circuit breaker

the intermediate value of multiple making time is selected as the final parameter

the influence of mechanical and electrical dispersion of circuit breaker is reduced

the excitation inrush current of transformer is effectively suppressed in the actual operation assessment. It can provide reference for the coordination and control strategy of the offshore VSC-HVDC phase selection closing device

operation characteristics of circuit breaker and excitation inrush current of transformer of subsequent offshore VSC-HVDC system.