Abstract
As application of electric energy have expanded, the uninterruptible power supply (UPS) concept has attracted considerable attention, and new UPS technologies have been developed. Despite the extensive research on the batteries for UPS, conventional batteries are still being used in large-scale UPS systems. However, lead-acid batteries, which are currently widely adopted in UPS, require frequent maintenance and are relatively expensive as compared with some other kinds of batteries, like metal-air batteries. In previous work, we designed a novel metal-air battery, with low cost and easy maintenance for large-scale UPS applications. An extensive analysis was performed to apply our metal-air battery to the hybrid UPS model. In this study, we focus on including an optimal control system for high battery performance. We developed an algorithm based on receding horizon control (RHC) for each fan of the cooling system. The algorithm reflects the operation properties of the metal-air battery so that it can supply power for a long time. We solved RHC by applying dynamic programming (DP) for a corresponding time. Different variables, such as current density, oxygen concentration, and temperature, were considered for the application of DP. Additionally, a 1.5-dimensional DP, which is used for solving the RHC, was developed using the state variables with high sensitivity and considering the battery characteristics. Because there is no other control variable during operation, only one control variable, the fan flow, was used, and the state variables were divided by section rather than a point. Thus, we not only developed a sub-optimal control strategy for the UPS but also found that fan control can improve the performance of metal-air batteries. The sub-optimal control strategy showed stable and 6–10% of improvement in UPS operating time based on the simulation.
Highlights
To date, many electrical storage systems (ESS), such as novel types of batteries and ultracapacitors, have been studied and applied to various systems
Where Tk,t is the temperature of the kth cell at time t, Qcell,k is the heat of the chemical reaction, Qcase,k is the heat of the natural cooling from the aluminum case, Qair,k is the negative heat forced by air-cooling, and Qconduct near,k is the negative heat caused by conduction to the neighboring cell
The target of this research is the optimal control strategy of an uninterruptible power supplies (UPS) system based on metal-air battery
Summary
Many electrical storage systems (ESS), such as novel types of batteries and ultracapacitors, have been studied and applied to various systems. The secondary batteries must be always activated when connected to the main power source In this aspect, though reliable, lead-acid batteries require frequent maintenance, and they are not affordable [6]. Metal-air batteries are suitable for high-power UPSs, which require high capacity and no recharge In these systems, the initial standby time after triggering can be supplemented by hybridization with a small-sized lithium-ion battery. Zhan developed a rule-based control strategy for cooling PEM fuel cells in UPS systems [18]. This study devised a control strategy of air-cooling system for fuel supply using battery cell experimental data. We applied the existing discrete dynamic programming (DP) algorithm, optimization theory, considering the characteristics of the metal-air battery This is the second contribution of this paper and main contents.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
