Nowadays, with the vigorous development of offshore wind power and desert photovoltaic projects, especially with grid-connected inverters as the key interface for renewable energy grid integration, the traditional control methods based on linear architectures such as proportional-integral (PI) control are no longer suitable for the novel scenarios. This is due to the nonlinear scenarios resulting from changes in grid structure or parameters caused by inverters plug-and-play and random switching conditions. In these situations, there is a risk of wide-band oscillation in the grid-connected current. Therefore, this paper proposes a passivity-based feedback controller designed using the port-controlled Hamiltonian model (PCH) for grid-connected inverters operating in traditional grid-following (GFL) modes. Considering nonlinear control delays, a parameter design scheme optimized for multiple performance indexes is obtained using the D-partition method. This scheme ensures that the grid-connected inverter can resist external disturbances and operate reliably under nonlinear conditions, with strong robustness.