Abstract: As renewable energy is connected to the distribution network in the form of distributed generator (DG) in different locations and in different grid-connected ways, the fault characteristics of active distribution networks have undergone fundamental changes. The operational performance of the current longitudinal differential protection is affected by unmeasured branches, and the limited fiber deployment rate in the distribution network hinders the effective application of the longitudinal protection. The virtual reactive power is defined in the positive sequence fault component network, and the output characteristics of the virtual reactive power after the fault of the inverter distributed power supply are investigated. In addition, the branches of the active distribution network with unmeasurable ones are further analyzed after the fault occurs. Based on the fault characteristics of the power distribution network, the 5G communication technology and multi-agent technology are employed to build a distribution network protection architecture. A virtual reactive power directional protection scheme suitable for normal and abnormal communication conditions is proposed on this architecture. Finally, the simulation and verification are carried out through PSCAD to ensure the effectiveness and reliability of protection schemes.