Abstract: To reduce the fluctuation of bus voltage and system frequency in microgrids of highway service areas under harsh operating conditions such as islanding and heavy load switching, and operating mode switching, a control strategy based on nonlinear passivity-based control theory is designed for energy storage device inverters based on three-phase bridge converter on the AC side and half H-bridge converters on the DC side.It establishes port controlled Hamiltonian models of the system on both the AC and DC sides, and designs two passivity-based controllers to track power and control voltage respectively by setting equilibrium points, solving energy matching equations, and damping injection.The simulation results verifies the effectiveness of the control strategy.Compared with traditional control strategies, it adopts passivity-based control strategies.Not only it reduces system control parameters and complexity of control design, but also does it reduce overshoot of AC side power and DC side voltage response.It reduces dynamic adjustment time, and thus improves the stability of microgrids under harsh operating conditions.