Fully Distributed Energy Management Scheme for Multi-Source Hybrid Power Systems in Fuel Cell Ships Based on Extended Droop Control Strategy

Conventionally, energy management systems (EMSs) for fuel cell (FC) ships are usually implemented with centralized or hierarchical control, which causes high costs, low reliability, and poor scalability. In this paper, a fully distributed EMS (FD-EMS) applied to shipboard multi-source hybrid power systems consisting of parallel FCs, batteries (BATs), and supercapacitors (SCs) is proposed to solve the problems of mismatch load power, inconsistent performance of multi-stack FCs, and unbalanced State-of-Charges (SoCs) between parallel BATs and SCs. The proposed FD-EMS is realized based on a novel extended droop control strategy, which is achieved by using virtual inductive, resistive, and capacitive droop control for FCs, BATs, and SCs, respectively, in order to ensure automatic split-frequency response of the load power among the three types of power sources. On this basis, adaptive virtual inductance, resistance, and capacitance droop coefficients are individually designed to achieve the objectives of multi-stack FC performance consistency, dynamic equalization and adaptive regulation of SoCs for BATs and SCs, and stable bus voltage control. Moreover, the proposed strategy allows for maintaining the normal system operation in the case of power sources failures, and does not depend on a centralized communication network. Finally, simulation results based on Matlab/Simulink verify the effectiveness and superiority of the proposed strategy.