Optimal Sizing of Hybrid PEMFC/Lithium-Ion Battery Power Systems Using Rule-Based Cycle Charging Algorithm for Telecommunication Base Stations

Fuel cell/battery systems are increasingly favored for their quiet operation, minimal moving parts, reduced environmental impact, and compact form factor, especially in telecommunication base stations (TBS). However, oversizing or undersizing these power sources can lead to cost inefficiencies or reliability issues. This study presents a sizing methodology for systems using rule-based controls, with the fuel cell operating in three modes: off, maximum efficiency, and maximum power. In the proposed system, the battery maintains the bus voltage, and controller decisions are based on the bus voltage levels. A MATLAB/Simulink model was developed to simulate system performance with different source sizes. The study focuses on a hybrid system with a proton exchange membrane fuel cell (PEMFC) and a lithium-ion battery. Results show that a small capacity battery is sufficient, and the optimal fuel cell size is one that frequently operates at rated power. Larger fuel cells, while more efficient, do not justify the cost savings. Thus, a fuel cell sized for frequent rated power operation without draining the battery is recommended for optimal performance and cost efficiency in TBS.