Abstract: Virtual power plant (VPP) can effectively enhance the frequency resilience of the power systems by collaboratively scheduling energy storage resources through communication networks to participate in secondary frequency regulation (SFR). However, the dynamic access/exit of energy storage resources may lead to structural uncertainties in SFR system. A SFR strategy that considers dynamic access/exit of energy storage resources in VPP has been proposed. Firstly, the SFR system is modeled as a set of subsystems depending on the participation states of energy storage resources. Secondly, to reduce communication redundancy, a dynamic event-triggered communication scheme is proposed, which only triggers information exchange when the SFR performance degrades below a preset threshold. Thirdly, considering the asynchronous switching characteristics of communication delay causing control parameters to regulate behind the participation behavior adjustment of energy storage resources, design constraints and update criteria for control parameters have been obtained based on the average dwell time (ADT) technique. Simulation results have shown that compared with existing periodic triggering control schemes, the proposed scheme can save over 50.63% of network bandwidth occupancy and SFR device operation actions.