Completely Decentralized Energy Management System with High Reliability for the Fuel Cell-Ultracapacitor Auxiliary Power Unit

摘要

For the fuel cell-ultracapacitor auxiliary power unit (FC-UC APU), the basic energy management objectives could be summarized as achieving dynamic load power sharing (i.e. the FC supplies the average load power while the UC buffers all the fluctuating load power), extending the service life, improving energy efficiency, and ensuring the system stability. Conventionally, the dynamic load power sharing objective is achieved by using centralized energy management system (EMS) which suffers from poor flexibility, scalability and reliability. What’s more, the system stability can hardly be guaranteed because serious interactions between source converters and power-electronic interfaced loads, which behave as constant power loads (CPLs), always exist. In this paper, a completely decentralized EMS based on modified droop control and passivity-based control (PBC) is proposed to achieve the required objectives simultaneously in a decentralized way. First, the architecture and model of the FC-UC APU are described in detail. Then, analysis on the operational principle of the proposed EMS is deeply studied. Finally, simulation results verified the correctness of the theoretical analysis and effectiveness of the proposed decentralized EMS.