<p>With the large-scale integration of renewable energy, local power grids are increasingly dominated by power electronic converters, leading to high system nonlinearity and complex dynamic behaviors. Recent studies have shown that the wide-frequency oscillations observed in renewable energy stations often arise from the coupled effects of small-signal and large-signal disturbances, rather than from either type alone. As a result, conventional PI control strategies based on small-signal models are unable to handle the nonlinear and time-varying characteristics of grid impedance. Passivity-based control (PBC), which is rooted in energy-based system theory, offers a promising alternative by enabling robust performance across nonlinear conditions and supporting scalable interconnections from single-inverter to multi-inverter systems. However, the digital control delays introduced by sampling and PWM processes can degrade system passivity, limiting the scalability and stability of delayed multi-inverter networks. To address this issue, a novel PBC strategy based on time-delay Hamiltonian theory is proposed in this paper for grid-connected inverters. Casimir-like functions are introduced to compensate for the passivity degradation caused by control delays, and a Lyapunov-based framework is developed to guarantee the stability of the overall system. The proposed control strategy is validated through extensive simulations and hardware experiments under various operating conditions, demonstrating its effectiveness and robustness in maintaining stable multi-inverter operation under delay-afflicted scenarios.</p>