For islanded microgrids using virtual synchronous generator-based secondary voltage control, existing approaches depend heavily on continuous communication and exhibit a significant gap between the theoretical convergence upper bound and the actual convergence time. To address these issues, this paper proposes a preset-time consensus algorithm enhanced with an event-triggered mechanism. First, an event-triggered strategy is designed based on state error thresholds, enabling each inverter to communicate intermittently and only with its neighbors. This achieves voltage restoration without deviation and reactive power sharing according to inverter rating within a user-specified time. Then, the convergence of the proposed method is theoretically analyzed, and the possibility of Zeno behavior is excluded. Finally, a simulation platform of an islanded microgrid is built and the test results show that the system converges within the preset time. Compared with continuous communication schemes, the proposed method reduces communication events by more than 99% with almost no loss in recovery performance, significantly improving the efficiency and flexibility of microgrid control.