When complex fault simulations are conducted during cross-bay testing and cross-station joint commissioning

several challenges arise

including insufficient on-site synchronization accuracy

difficulty in simulation modeling

complex deployment

and low testing efficiency. This article proposes a distributed testing technology for relay protection based on 5G synchronization. The technology adopts a modular configuration model to construct the power grid topology

realizes real-time simulation calculation of the fault process based on the admittance matrix and composite sequence network algorithm

and achieves multi-terminal data coordination and distributed testing control through 5G high-precision time synchronization. The results of the on-site pilot application show that the system can effectively simulate the entire process of line faults

significantly improve the accuracy and efficiency of coordinated testing of protection devices

and provide a feasible technical solution for distributed testing in complex outdoor power grid environments with broad prospects for engineering application.