Multi-Objective Fusion Controller for Plug-and-Play Distributed Energy Storage Systems in Shipboard DC Microgrids Based on Dynamic Diffusion Algorithm

In this paper, a novel multi-objective fusion (MOF) controller is proposed to achieve rapid State-of-Charge (SoC) equalization, proportional load current distribution, and stable bus voltage regulation for distributed energy storage systems (DESSs) in shipboard DC microgrids. Compared with conventional distributed cooperative controllers, the designed MOF controller integrates the functions of SoC equalization, current distribution, and voltage regulation, and allows just one intermediate variable to be exchanged between each DESS to achieve the above three control objectives. On this basis, a combined state variable consisting of virtual voltage drop and output voltage is designed, its average value is estimated in the local controller by dynamic diffusion algorithm (DDA). The DDA assists the MOF controller to respond continuous data flows on a single time-scale, and ensures more thorough diffusion of the dataset over the distributed communication network. The designed MOF controller also provides excellent plug-and-play performance, which allows the DESSs to be plugged in/out the shipboard DC microgrid seamlessly under any sailing conditions without causing surge currents and impulse voltages. Moreover, the closed-loop characteristic equations of the parallel DESSs are derived, and the stability of the designed MOF controller is analyzed using the characteristic root trajectory method. Finally, the StarSim experimental platform for shipboard DC microgrid is built, and the test results under various scenarios verify the effectiveness and superiority of the designed MOF controller.