Applications & Pathways

Hydrogen fuel cells (HFCs) are an efficient clean energy solution that performs well in backup or remote application but requires an uninterrupted supply of hydrogen. Current manual refueling procedures are laborintensive pose safety risks due to hydrogen’s explosive nature and can lead to power interruption if neglected. An automated system that manages the refueling procedure safely using computer simulations has been designed and demonstrated. The system employs a pressure sensor to monitor hydrogen levels and the microcontroller scans the safety of the environment by sensing leaks and ensuring there is no risk of over-pressure activates an electric solenoid valve when the pressure falls to or below a specified low threshold of 20 bar (P_low). The valve automatically closes when the tank reaches a high-pressure value of 280 bar(P_high) or immediately upon detection of anomalies such as a sensed leak excessive pressure exceeding 320 bar(Pmax_safe) or a prolonged refilling duration beyond 400 seconds. The whole system has been simulated using MATLAB/Simulink executing five distinct test scenarios including normal operation leaks over-pressure and time-out conditions. Simulation results indicate the design is robust with all safety features performing as intended. Furthermore a roadmap for the physical prototyping and testing of the system beginning with inert gases is presented. The automated system has the potential to enhance the ease and safety of operating stationary HFCs.

This study considers the use of an enhanced super-twisting sliding mode control (STSMC) scheme via the incorporation of a hybrid extended state observer (ESO) and a higher order sliding mode observer (HOSMO) state estimation and disturbance observer (DO) based on exponential decay embedded via a tracking element in order to hasten the estimation of disturbance thus improving performance significantly. This scheme is employed to generate single and multiple control signals per agent based on the microgrid’s presented components such as energy storage devices and renewable energy sources (RESs) alongside the harness of a puma optimizer (PO) metaheuristics scheme to optimize each area regulator’s performance. The sliding surface incorporated is chosen based on desired control objectives. Adjusting the constricted area frequency and reducing tie-line power transfer fluctuations are considered the primary goals for frequency regulation in a multi-area power system. Also based on the presented simulations adequate performance in terms of minimum chattering low complexity fast convergence and adequate robustness has been achieved. Using various microgrid peripheral components such as a multi-terminal soft open point (SOP) with a dedicated terminal for hydrogen energy storage alongside the proposed enhanced STSMC the frequency change and power transfer rate of change are maintained within the range of ×10−6 values substantially preserving proper performance compared to other simulated scenarios. In regard to the final simulated case involving SOP the following has been achieved: steady state errors of 2.538×10−6 Hz for ΔF1 3.125×10−6 Hz for ΔF2 and 1.920×10−6 p.u for ΔPtie alongside peak disturbance overshoot reduction in comparison to stochastic case of 99.580% 99.605% and 99.771% for same mentioned elements respectively. Also a reduction in peak disturbance undershoot of 95.589% 99.547% and 99.573% respectively has been achieved. Thus the enhanced STSMC can effectively mitigate frequency fluctuations and tie-line power transfer abnormalities.