Fuel Cell Hybrid Power System Research Articles

Energy Management Strategy for PEM Fuel Cell Hybrid Power System Considering DC Bus Voltage Regulation

Developing an energy management strategy (EMS) is an important requirement to satisfy the load power demand for a proton-exchange membrane fuel cell (PEMFC) hybrid system under different working conditions. For this objective, this paper proposes an EMS to control the power distribution between the PEMFC, battery (BAT), and supercapacitor (SC) and regulate the DC bus voltage for matching the load power demand. In this strategy, fuzzy logic rules (FLRs) and low-pass filters (LPFs) are utilized to determine the reference currents for energy sources based on their dynamic response. In addition, current and voltage control loops are designed to provide the appropriate gains for compensators that can maintain a stable voltage on the DC bus. Finally, simulations are conducted in the MATLAB/Simulink environment to validate and compare the effectiveness of the proposed strategy with others. The simulation results present that the proposed EMS achieves the highest distributed power accuracy with an error of (−2.1→2.6) W, while reducing the DC bus voltage ripple by 1% under various load working conditions in comparison to the other approaches.

A review of energy management optimization based on the equivalent consumption minimization strategy for fuel cell hybrid power systems

AbstractThe high global demand for fossil fuels and resulting climate‐change effects due to air pollution have led to the rapid development of renewable energy sources. Battery and proton exchange membrane fuel cells have high power densities and high energy, and supercapacitors can provide peak power. These devices have the advantages of high thermal efficiencies and no carbon emissions during use, which have far‐reaching applications in the fields of hybrid vehicles and ships. To compensate for the slow dynamic response of fuel cells, batteries or supercapacitors are often used as auxiliary power sources to form hybrid powertrains in practice. Therefore, to take full advantage of the hybrid system, energy coordination between multiple energy sources using an energy management strategy is important. The equivalent consumption minimization strategy has been widely investigated due to its simplicity, small operation, good control, and real‐time optimization. In this paper, the topologies of fuel cell hybrid power systems are first systematically classified and characterized. Then, the calculation of equivalent hydrogen consumption for a battery, fuel cell, and supercapacitor is reviewed. To reduce overall hydrogen consumption and extend the life of fuel cells and batteries, an equivalent hydrogen consumption minimization strategy is applied to the energy management of hydrogen fuel power systems.

Fuel Cell Hybrid Locomotive with Modified Fuzzy Logic Based Energy Management System

As one of the most environmentally friendly energy sources today, fuel cells have become the focus of research in countries around the world, especially in the electric transportation field. This paper mainly studies the modeling of fuel cell hybrid locomotives (FCHL) including fuel cells, batteries, motors, and energy management systems. To increase the operating efficiency and improve the performance of FCHL, a modified fuzzy logic-based energy management system (MFL-EMS) is proposed and compared with the traditional power flow energy management system (PF-EMS). Meanwhile, a modified fuel cell hybrid power system model for locomotives is proposed, taking into account the traction motor features that, compared with a simplified controlled source load, can directly reflect the status of the locomotive running speed and the output power of the traction motor load. The proposed system parameters and configurations are determined by combining the characteristics of power and energy density, response characteristics, and charging/discharging characteristics of fuel cells and batteries. The precise simulation results revealed that adopting the proposed MFL-EMS in comparison to the traditional PF-EMS, reduced the hydrogen consumption by 2.943%. Comparing the battery output voltage, it is confirmed that with MFL-EMS it tends to be steeper than the one with PF-EMS, showing the proposed strategy’s robustness. Overall, the obtained results revealed an improved performance in terms of power distribution as well as SOC, which means less hydrogen consumption and therefore a more economical solution.

Novel extraction method of working condition spectrum for the lifetime prediction and energy management strategy evaluation of automotive fuel cells

Lifetime is a major bottleneck for the commercialization of fuel cells. A quick evaluating method for fuel cell lifetime can assist in immediately assessing technology progress, predicting lifetime in real-time, and extending durability. Among the existing methods, the lifetime prediction method based on working conditions is a cost-effective, time-saving, and realistic method. However, there are no methods and clear standards for extracting the time and frequency of working conditions in test protocols used in this method. In this study, the working condition spectrum extraction method is proposed and used to extract the working condition spectra of commonly used durability test protocols. The lifetime prediction of fuel cells operating under different specific test protocols based on the working condition spectrum extraction method is performed and verified to demonstrate its reliability. Furthermore, the proposed method is used to extract the working condition spectra and predict the lifetime of fuel cells in hybrid power systems with different energy management strategies (EMSs). The results show that the extraction method can provide an evaluation method for developing EMSs of fuel cell hybrid power systems from the lifetime perspective, which is useful for fuel cell durability research.

Energy economy optimization and comprehensive performance improvement for PEMFC/LIB hybrid system based on hierarchical optimization

In order to improve the motion range of mobile welding robot, energy management strategy of fuel cell hybrid power system were studied, which involves energy economy optimization and comprehensive performance improvement. The energy management strategy adopts hierarchical optimization control. Inner layer realizes power distribution and energy optimization, using the maximum power point tracking control (MPPT) based on hybrid algorithm and an improved equivalent consumption minimization strategy (ECMS) to optimize the output power distribution. MPPT allows fuel cell to output maximum power stably and maximize the fuel cell utilization. The improved ECMS optimizes the equivalence factor by fuzzy logic control to increase the calculation accuracy. This strategy improves the economy of system energy consumption. The outer layer uses state machine control to switch the control strategy according to the operating state of the system. When the SOC of the battery is lower than the set threshold, MPPT control is used. And when the SOC is higher than the set threshold, ECMS is used. Experimental results show that the rationality of PEMFC output power and battery charge-discharge has been improved, and the economy of hybrid power system has also been improved.

An Improved Energy Management Strategy for Fuel Cell Hybrid Vehicles Based on Pontryagin's Minimum Principle

For finding a balance between fuel economy and durability of fuel cell hybrid power systems, this article proposes an improved real-time energy management strategy (EMS) based on Pontryagin's minimum principle (IM-PMP). We introduce the fuel cell output change rate with weighted coefficient into the Hamiltonian function to limit frequent power fluctuations so as to improve the durability of the fuel cell. In addition, a real-time costate updating method is proposed for unknown driving conditions. This method determines the optimal value of costate according to the real-time state of charge (SOC), which can ensure the online implementation of the EMS and control the SOC of the lithium battery within a certain range. By constructing the hardware-in-the-loop experimental platform, the proposed strategy is compared with the finite state machine (FSM) strategy. Compared with FSM, the hydrogen consumption of the IM-PMP strategy is reduced by 10.1%, and the fuel cell operating stress is reduced by 38.3%. The SOC of the lithium battery is maintained at around 0.6. The experimental results verify the superiority of the proposed EMS.

Multi-scale assessment and multi-objective optimization of a novel solid oxide fuel cell hybrid power system fed by bio-syngas

Nowadays, thermal power generation using fossil fuels is still the main way for electricity supply, resulting in serious environmental pollution and energy consumption. The research on new power generation and alternative energy is urgently needed to conduct. In this paper, a new power supply system combined biomass and fuel cell with waste heat recovery is proposed and analyzed. The system uses agricultural waste as energy source, providing gas fuel for solid oxide fuel cell through the biomass gasification. In addition, the homogeneous charge compression ignition engine can utilize unreacted fuel, and the waste heat energy in flue gas is recovered by the combination of supercritical carbon dioxide cycle and absorption refrigeration cycle. Under selecting working condition, the engine and bottom cycles brings an improvement of 11.10% in thermal efficiency, and the total fuel efficiency can reach 59.35%. Besides, the payback time of this system is nearly 60% shorter than the traditional system, with a minimum of 1.77 years. The whole system realizes the energy cascade utilization, being more efficient and cleaner, and has satisfactory performance.

Effects of temperature on the performance of fuel cell hybrid electric vehicles: A review

Fuel cell hybrid electric vehicles powered by fuel cell and lithium-ion battery have been considered as an attractive and potential candidate in place of internal combustion vehicles with the advantage of high energy density and energy conversion efficiency, and have become a configuration of interest of many researchers in recent years. Energy management and thermal management are critical issues for steady output power of fuel cell hybrid power system. However, most of the research on energy management and temperature control of fuel cell hybrid electric vehicles is mutually independent. From the literatures, it is observed that existing energy management strategies without integration of fuel cell or battery’s temperature dimension are more or less incapable to perform very well. This paper focuses on reviewing the temperature effects on energy management strategies for fuel cell hybrid electric vehicles. To do this, temperature effects on the performance of lithium-ion battery and proton exchange membrane fuel cell are summarized respectively at first. Then, energy management in combination with thermal management of hybrid electric vehicles and fuel cell hybrid electric vehicles are analyzed and summarized in detail. It is indicated that the solution of power distribution considering temperature effects is a significant way to improve the efficiency and service life of fuel cell hybrid electric vehicles compared to the energy management strategy without considering temperature effects. Based on the above analysis, future suggestions of EMS designing are prospected in order to achieve better performance for fuel cell hybrid electric vehicles.

Research on ADHDP energy management strategy for fuel cell hybrid power system

Fuel cell hybrid power system is a prospective power source for electrical vehicles. To reduce hydrogen consumption and enhance dynamic performance of the system, Action Dependent Heuristic Dynamic Programming (ADHDP) energy management strategy for the fuel cell hybrid power system was proposed. Firstly, topology of the system was analyzed and mathematical model was established through mechanism analysis. Secondly, framework of the ADHDP algorithm was presented, and it was followed by training algorithm for evaluating network and executing network of ADHDP based on Back Propagation (BP) algorithm. Finally, hardware-in-the-loop (HIL) simulation of the fuel cell hybrid power system was carried out to demonstrate the proposed ADHDP algorithm under real operating conditions. The results show that evaluating network and executing network of ADHDP have good convergence performance under different operating conditions. Compared with the other algorithms, the proposed ADHDP energy management strategy has better fuel economy and dynamic performance.

Energy Management Strategies for Hybrid Power Systems Considering Dynamic Characteristics of Power Sources

Due to the rising concern of environmental problems, fuel cell hybrid power systems have been proposed to be an ideal substitution to diesel engines. However, the hybrid power system has brought many challenges, one of which is the power splitting among different power generation technologies. In this paper, a wavelet transform and fuzzy logic based energy management strategy is proposed for a fuel cell/battery/ultra-capacitor hybrid power cruiser considering their dynamic characteristics. The energy demand of the cruiser is decoupled into different frequencies by wavelet transform and distributed to different energy sources according to their dynamic characteristics. To ensure long-term reliable operation of the hybrid power system, fuzzy logic is proposed to keep the state of charges of the battery and ultra-capacitor within safe range. The proposed energy management strategy is applied to a hybrid power cruiser in MATLAB/Simulink and two cases are studied considering different initial states of charge of the energy storage system. The results show that the proposed energy management strategy enables the fuel cell to supply about 50% of the high frequency power and reduce the peak power supplied by the fuel cell by 80% - 100% when the initial state of charge of the ultra-capacitor is low, and the fuel cell supplies around 400% higher than the low peak power and 20% of the high peak power when the initial state of charge of the battery is low.

Development of optimal energy management for a residential fuel cell hybrid power system with heat recovery

Integration of heat recovery with proton exchange membrane fuel cell/battery-based hybrid power system, which is also known as a micro-combined heat and power (CHP) system, is a promising method to achieve higher output efficiency. The developed hybrid power system for a micro-CHP is applied to a residential house by supplying electric power and hot water simultaneously. When the fuel cell generates heat and electricity via the oxidation reaction of hydrogen with a working temperature of 70 °C, heat recovery is provided through internal cooling system. Energy management system (EMS) plays a crucial role in obtaining optimal fuel economy and promising the running stability. Optimal Pontryagin minimum principle is used as a real-time EMS by splitting the hybrid power (i.e., power between fuel cell and battery) to realize fuel minimization, battery protection, and hot water supply. Optimal energy management is achieved by considering the external load demand, state charge of a battery, and temperature of the thermal storage system. Simulation model is developed, and real experiments are performed to prove that the EMS can effectuate high efficiency and safe operation of a hybrid power system through optimal power split between fuel cell and battery powers.

Convex multi‐objective optimization for a hybrid fuel cell power system of more electric aircraft

Convex <scp>multi‐objective</scp> optimization for a hybrid fuel cell power system of more electric aircraft

Variable structure battery-based fuel cell hybrid power system and its incremental fuzzy logic energy management strategy

A hybrid power system consists of a fuel cell and an energy storage device like a battery and/or a supercapacitor possessing high energy and power density that beneficially drives electric vehicle motor. The structures of the fuel cell-based power system are complicated and costly, and in energy management strategies (EMSs), the fuel cell's characteristics are usually neglected. In this study, a variable structure battery (VSB) scheme is proposed to enhance the hybrid power system, and an incremental fuzzy logic method is developed by considering the efficiency and power change rate of fuel cell to balance the power system load. The principle of VSB is firstly introduced and validated by discharge and charge experiments. Subsequently, parameters matching of the fuel cell hybrid power system according to the proposed VSB are designed and modeled. To protect the fuel cell as well as ensure the efficiency, a fuzzy logic EMS is formulated via setting the fuel cell operating in a high efficiency and generating an incremental power output within the affordable power slope. The comparison between a traditional deterministic rules-based EMS and the designed fuzzy logic was implemented by numerical simulation in three different operation conditions: NEDC, UDDS, and user-defined driving cycle. The results indicated that the incremental fuzzy logic EMS smoothed the fuel cell power and kept the high efficiency. The proposed VSB and incremental fuzzy logic EMS may have a potential application in fuel cell vehicles.

Model Predictive Control With Lifetime Constraints Based Energy Management Strategy for Proton Exchange Membrane Fuel Cell Hybrid Power Systems

In this article, a model predictive control (MPC) energy management strategy is proposed to distribute power flows of proton exchange membrane fuel cell (PEMFC)-based hybrid power systems consisting of PEMFC, battery, and waste heat recovery system such as TEG and CHP. To optimally meet the demand of load power balancing as well as protect PEMFC from lifetime degradation, a novel objective function by considering fuel consumption, state-of-charge (SOC) of battery, as well as power slope and temperature of PEMFC is constructed and solved in the states prediction horizon within the defined lifetime constraints and SOC limitations. In particular, temperature effects are newly introduced by adding a state-variable to the energy management model and formulating a penalty function. Simulations with mobility and stationary application scenarios are presented. In the automobile case, the hydrogen consumption of the constraints MPC is reduced by 9.98% compared with the rule-based strategy, and the same results can be achieved in the household application. A hardware in the loop experiment was carried out to verify the real-time performance of the MPC strategy which occupied a 2.21% average CPU load rate. The proposed MPC strategy has a promising fuel consumption optimization, lifetime extension, and real-time capability.

Surge and Stall Detection Using Acoustic Analysis for Gas Turbine Hybrid Cycles

Abstract Compressor dynamics were studied in a gas turbine—fuel cell hybrid power system having a larger compressor volume than traditionally found in gas turbine systems. This larger compressor volume adversely affects the surge margin of the gas turbine. Industrial acoustic sensors were placed near the compressor to identify when the equipment was getting close to the surge line. Fast Fourier transform (FFT) mathematical analysis was used to obtain spectra representing the probability density across the frequency range (0–5000 Hz). Comparison between FFT spectra for nominal and transient operations revealed that higher amplitude spikes were observed during incipient stall at three different frequencies, 900, 1020, and 1800 Hz. These frequencies were compared to the natural frequencies of the equipment and the frequency for the rotating turbomachinery to identify more general nature of the acoustic signal typical of the onset of compressor surge. The primary goal of this acoustic analysis was to establish an online methodology to monitor compressor stability that can be anticipated and avoided.

Techno-economic evaluation and technology roadmap of the MWe-scale SOFC-PEMFC hybrid fuel cell system for clean power generation

This paper proposes a novel hybrid fuel cell power generation system with high efficiency. The thermo-economic modeling of the MWe-scale systems using different fuels is conducted to evaluate the economic feasibility under the subsidy policy of Eastern China. This work aims to develop the technology roadmap for this kind of clean power system. It is found that the energy efficiency of the natural gas and biogas fed systems could reach up to 64% and 63.5% respectively, thus they are efficient and cost-optimal for the hybrid system while liquefied petroleum gas and water gas yield low efficiency and high electricity cost. Moreover, under the subsidy policy, the biogas-fed hybrid system is more suitable for a small-scale power system, while the natural gas-fed system is preferable for the large-scale case. The specific electricity cost of small-scale biogas hybrid fuel cell power plant is 0.365 CNY/kWh, lower than the present feed-in-tariff price 0.475–0.704 CNY/kWh of other biogas plants in China. Also, the cost of 0.345–0.347 CNY/kWh of large-scale natural gas-fed hybrid system is much lower than the on-grid electricity price 0.7655 CNY/kWh in Shanghai. These results reveal that the proposed hybrid fuel cell power system is efficient and economically feasible. The payback period and annual return on investment are 0.8–1.2 year and 11–12%, respectively.

An optimized energy management strategy for fuel cell hybrid power system based on maximum efficiency range identification

This study proposes an optimized energy management strategy (EMS) based on maximum efficiency range (MER) identification for a fuel cell/battery hybrid sightseeing car. And the aim of this study is to optimize hydrogen consumption of hybrid system and make sure that the power distribution between the fuel cell (FC) system and battery is optimal. FC system has the MER and is also a strongly coupled system. The MER of FC system will move with the change of operating conditions, and consequently, a parameter identification technique is needed to estimate the boundary powers of MER. This goal is achieved in this paper by using a forgetting factor recursive least square (FFRLS) online identification approach. Then the sequential quadratic programming (SQP) algorithm is used to solve the majorization problem of equivalent consumption minimum strategy (ECMS) so that the FC system operates as much as possible in the MER, while ensuring that the battery state of charge (SOC) fluctuates within the limited range. This helps to improve the efficiency, performance, and durability of the FC system and reduce the equivalent hydrogen consumption of the battery. A reduce-scale test platform is designed to verify the feasibility of the proposed optimized ECMS (OECMS). In addition, the conventional ECMS and rule-based state machine control (SMC) strategy are utilized in this paper to highlight the advantages of the proposed strategy. The experiment results show that the proposed OECMS helps to improve FC performance and optimize system hydrogen consumption.

Energy optimization of logistics transport vehicle driven by fuel cell hybrid power system

To reduce the transportation cost of logistics industry and realize the cleanliness and environmental protection of transportation process, the energy management of logistics transportation vehicles driven by proton exchange membrane fuel cell/Li-ion hybrid power system was studied. Based on the high repeatability of vehicle routing, an energy management strategy is proposed to optimize hydrogen consumption on the premise of ensuring the stability of operation process. To improve the proton exchange membrane fuel cell output characteristics, the maximum power point tracking method based on conductance increment is used, and then the maximum power point, which is seared at the first time, is corrected again by simulated annealing algorithm. The power output control system of Li-ion battery pack based on dynamic programming is also designed. The state variables, control variables, constraint functions, objective functions and cost functions of the drive system are designed according to the related parameters such as vehicle gear change, demand torque and state-of-charge of Li-ion battery pack. The principle of equivalent hydrogen consumption is used to measure the energy output of Li-ion battery, and the fuzzy logic controller is used to simplify the expression of system state and control variables. Finally, the optimal output power sequence of Li-ion battery is calculated. And the experimental results show that after dynamic programming optimization, the driving system can ensure the stable operation of logistics vehicles and greatly reduce the consumption of hydrogen. These results can provide reference for energy management of other types of vehicles driven by proton exchange membrane fuel cell hybrid power system.

Status evaluation of mobile welding robot driven by fuel cell hybrid power system based on cloud model

The comprehensive evaluation of the performance parameters of the mobile welding robot driven by the fuel cell hybrid power system is beneficial to optimizing the energy efficiency and control performance of the system. However, few studies have paid attention to this aspect. Rough analytic hierarchy process and entropy weight method are used to calculate the weight of the evaluation index. Cloud model is used to synthesize all evaluation indicators to determine the status level. First, the golden section method is used to determine the evaluation criteria, and through cloud model, the evaluation criteria and measured parameters of the single evaluation index are transformed into corresponding evaluation reference clouds and evaluation clouds. Second, the weight of the evaluation index is determined by the method of the rough analytic hierarchy process, and the method of the entropy weight is used to revise the method of the rough analytic hierarchy process. The single evaluation reference cloud and evaluation cloud are aggregated to get the comprehensive evaluation reference cloud, and the comprehensive evaluation of the reference cloud is carried out. The evaluation cloud for each evaluation cycle. Finally, according to the correlation between the comprehensive evaluation cloud and the comprehensive evaluation standard cloud, the performance level of each evaluation cycle is determined. In this paper, the randomness and fuzziness of the qualitative concepts are solved by using the characteristics of the cloud model. Combined with rough analytic hierarchy process, the objectivity of the data is maintained and the advantages of the expert evaluation are enhanced. The validity of the model is verified by comparing the existing methods. These studies evaluate and classify the real-time status of the fuel cell robot, and provide a basis for the performance optimization and energy optimization of the hybrid power system controllers.

Sensitivity analysis of the fuel economy strategy based on load-following control of the fuel cell hybrid power system

In this paper, a real-time strategy for a fuel cell hybrid power system based on fuel optimization and load-following is analyzed to identify the critical parameters of the optimization problem. Because the dither’s frequency dictates the searching speed of the optimum in the perturbed extremum seeking algorithm, this parameter has been selected from multiple parameters involved in the optimization problem to improve the fuel economy based on sensitivity analysis. The sensitivity analysis reveals the multimodal behavior of the fuel economy, but also the best choice for the dither. The fuel cell hybrid power system is a highly dynamic system, so the optimization and control loops have been designed for a robust but efficient operation of the system based on new perturbed extremum seeking algorithm to track the optimum. Considering the recommended 100 Hz sinusoidal dither, the improvement in fuel economy is of 47.9 L for an 8 kW/12 s load cycle. Also, the electrical efficiency of the fuel cell system increases with 7.83%. Both improvements were estimated compared to a commercial strategy, called in the literature as static feed-forward strategy.