With the rapid development of new energy power generation and the widespread application of DC microgrids, this paper tackles power coordination and smooth grid-connected/off-grid switching issues in multi-distributed power source parallel operation. A wind-photovoltaic-storage integrated DC microgrid simulation model is constructed, adopting droop control as the core coordination strategy and a dual closed-loop control (voltage outer loop + current inner loop) for the battery energy storage module. The model includes a permanent magnet direct-drive (PMDD) wind power system, a photovoltaic system with incremental conductance MPPT, and an energy storage system for power balance. Simulations on MATLAB/Simulink (initial irradiance 1000W/m², wind speed 4.8m/s; 1s disturbance: 800W/m², 5.2m/s) show: DC bus voltage stabilizes near 900V with ±2% fluctuation (within ±5% allowable range); wind/photovoltaic units achieve stable output in 0.1s; energy storage fluctuates ±1%, enhancing anti-disturbance. This research resolves parallel power conflicts, supports grid switching, and lays a foundation for practical engineering.