Optimization of energy management in hybrid SOFC-based DC microgrid considering high efficiency and operating safety when external load power goes up

Abstract

The hybrid energy direct-current (DC) microgrid shows a comparative advantage in fast load tracing to remedy the defects of slow power transients of the solid oxide fuel cell (SOFC). However, the existing methods are mainly carried out for system efficiency and operational safety from the view of only one key point; thus, there is no mature thermoelectric analysis for thermal safety, fuel exhaustion, and efficiency optimization. In this study, an optimization strategy for energy management in the hybrid SOFC-based DC microgrid is proposed, which considers fuel starvation, high efficiency, and thermal safety when the external load power goes up. First, the architectures of the hybrid SOFC-based DC microgrid system including the SOFC, lithium battery, and supercapacitor are established, and then its stable operating requirements are analyzed and discussed in detail. Moreover, this study focuses on the design of the development procedure of energy management for the hybrid SOFC-based DC microgrid system, so that the fast power transients the controller considering fuel starvation and thermal safety are comprehensively designed and discussed and can develop high-efficiency monitoring and optimization of energy management. Finally, the relative optimal regulator based on the optimal operation points and the voltage and current regulator based on the DC demanded voltage in the energy management are proposed and can obtain maximum efficiency and thermal safe operating when the SOFC system reaches the steady state. The experimental results are shown to prove that the proposed optimization of energy management has time response superiority, high output efficiency, and favorable thermal response.