An optimal power routing (OPR) scheme between and within interlinking converters (ICs) in unbalanced hybrid AC–DC microgrids to minimise the power imbalance factor at the point of common coupling, ...active power losses, and voltage deviation indices for microgrids in grid-connected operating mode is proposed in this study. These goals are achieved through a multi-objective optimisation model by optimal distributing of mobile loads between available charging stations and at the same time, OPR within three phases of three-phase four-lag AC/DC converters. Numerical results obtained from implementing the proposed method on the modified IEEE 13-bus system, as an unbalanced hybrid microgrid, and IEEE 34-bus test system, as an unbalanced distribution system, demonstrate that proposed OPR algorithm is successful to satisfy the optimisation goals. For this purpose, four case studies are defined and studied to demonstrate the unique features of the proposed OPR comparing with other power routing schemes. In addition to simulation results, the OPR scheme between ICs is realistically implemented at Florida International University smart grid testbed to show the effect of the power routing on energy losses reduction.
The climate changes that are becoming visible today are a challenge for the global research community. In this context, renewable energy sources, fuel cell systems, and other energy generating ...sources must be optimally combined and connected to the grid system using advanced energy transaction methods. As this reprint presents the latest solutions in the implementation of fuel cell and renewable energy in mobile and stationary applications, such as hybrid and microgrid power systems based on the Energy Internet, Blockchain technology, and smart contracts, we hope that they will be of interest to readers working in the related fields mentioned above.
This reprint is a collection of research that contributes to a better understanding of energy transfer related to alternative vehicles. The hybridization of power units and alternative propulsion ...systems are the mainly developed technology in the automotive field today. The modernization of conventional propulsion sources is justified by the increasingly stringent economic, ecological, and comfort requirements. The common link in any renewable energy source or propulsion system today is electric motors. Their correct use in propulsion offers the possibility of reducing or eliminating harmful emissions both in the form of toxic compounds and noise or unwanted vibrations. The research works were related to energy transfer in both hybrid and electric vehicles, and conversion of energy from renewable sources such as photovoltaic installations to power alternative vehicles. However, you will also find in this reprint papers that are related to modules of alternative propulsion such as drivetrain efficiency analysis, ways of energy accumulation in batteries, and influence of the charging method on the energy consumption of a vehicle during its life cycle.
The electrical distribution network is undergoing tremendous modifications with the introduction of distributed generation technologies which have led to an increase in fault current levels in the ...distribution network. Fault current limiters have been developed as a promising technology to limit fault current levels in power systems. Though, quite a number of fault current limiters have been developed; the most common are the superconducting fault current limiters, solid-state fault current limiters, and saturated core fault current limiters. These fault current limiters present potential fault current limiting solutions in power systems. Nevertheless, they encounter various challenges hindering their deployment and commercialization. This research aimed at designing a bridge-type nonsuperconducting fault current limiter with a novel topology for distribution network applications. The proposed bridge-type nonsuperconducting fault current limiter was designed and simulated using PSCAD/EMTDC. Simulation results showed the effectiveness of the proposed design in fault current limiting, voltage sag compensation during fault conditions, and its ability not to affect the load voltage and current during normal conditions as well as in suppressing the source powers during fault conditions. Simulation results also showed very minimal power loss by the fault current limiter during normal conditions.
Emission reduction targets in both highway trucks and off-road vehicles have turned the electrification focus into vehicle mountable equipment such as loader cranes and tail lifts. Nowadays, these ...devices are powered by hydraulic linear actuators, which provide cost-efficient and robust solutions that also fulfill lifting device safety standards. However, lifting device electrification has the potential to offer several advances, such as efficient utilization of on-board battery with fewer components and energy conversions. In order to contribute to the electrification trend, different aspects of substituting those conventional actuators with the almost new electromechanical linear actuators (EMLA) technology need to be investigated. This paper studies the different energy conversion processes in the EMLA for a heavy-duty mechanism and estimates the loss in each component. The investigation of energy conversion processes in EMLA paves the way for obtaining the efficiency map of the system and its power flow with the purpose of performance analysis. To this end, all the mentioned energy conversions are categorized into desirable and power loss categories. Subsequently, the dynamic model of one degree of freedom (DOF) parallel-serial mechanism is exerted in a trajectory optimization framework. Objectives such as minimum effort, energy expenditure, and delivered power are selected to generate optimal trajectories that feed the efficiency algorithms and examine the EMLA performance. The results show the efficacy of the above-mentioned trajectories concerning the criteria costs, total time, and efficiency of the whole system.
Solution processed flexible organic solar cells (OSCs) are of interest due to their potential use as environmentally friendly, shapeable, or wearable energy. Such flexible devices require compatible ...transparent conducting electrodes (TCEs). The use of three‐layer graphene as a useful TCE for flexible OSCs is reported. The conformal coating of the graphene‐based TCE with good retention of performance was achieved using a bulk heterojunction (BHJ) active layer comprised of the non‐polymeric molecular (5Z,5′Z)‐5,5′‐(5‴,5‴‴′‐{4,8‐bis5‐(2‐ethylhexyl)‐4‐n‐hexylthiophen‐2‐ylbenzo1,2‐b:4,5‐b′dithiophene‐2,6‐diyl}bis{3′,3″,3‴‐tri‐n‐hexyl‐2,2′:5′,2″:5″,2‴‐quaterthiophene‐5‴,5‐diyl})bis(methanylylidene)bis3‐n‐hexyl‐2‐thioxothiazolidin‐4‐one (BQR) donor and 6,6‐phenyl‐C71‐butyric acid methyl ester (PC71BM) as the acceptor. This material combination enables thick BHJ junctions to be used so that the roughness of the graphene surface did not lead to shorted devices. The best graphene/poly(ethylene terephthalate) (PET) devices (PET/graphene/molybdenum oxide/BHJ/calcium/aluminum) show a photoconversion efficiency (PCE) of 5.8%, which while excellent was lower than that of a similar device architecture that used ITO/glass as the anode. The power losses of the graphene/PET‐based cells mainly resulted from absorption losses caused by the optical profile distribution in the device and the relatively high sheet resistance of the anode, leading to an 18% decrease in the short‐circuit current and lower fill factor, respectively.
Three‐layer graphene is used as the transparent conducting electrode for flexible organic solar cells. A thick bulk heterojunction active layer comprised of a blend of the non‐polymeric molecular donor BQR and PC71BM enables coverage of the rough graphene surface so as to avoid shorted devices. The best devices (PET/graphene/molybdenum oxide/BHJ/calcium/aluminum) have a photoconversion efficiency of 5.8%.
A new thermal model, which allows temperature distribution determination inside a supercapacitor cell, is developed. The model is tested for a supercapacitor based on the activated carbon and organic ...electrolyte technology. In hybrid vehicle applications, supercapacitors are used as energy-storage devices, offering the possibility of providing the peak-power requirement. They are charged and discharged at a high current rate. The problem with this operating mode is the large amount of heat produced in the device which can lead to its destruction. An accurate thermal modeling of the internal temperature is required to design a cooling system for supercapacitor module, meeting the safety and reliability of the power systems. The purpose of this paper is to study the supercapacitor temperature distribution in steady and transient states. A thermal model is developed; it is based on the finite-differential method which allows for the supercapacitor thermal resistance determination. The originality of this paper is in the fact that a thermocouple (type K) was placed inside the supercapacitor from Maxwell Technologies. A test bench is realized. The cases of supercapacitor thermal distribution using natural and forced convection are studied. Simulations and experimental results are reported to validate the proposed model. The results obtained with this model may be used to determine the cooling system required for actual supercapacitor applications.
Reducing ripples on the capacitor voltage has two benefits: improved output waveform quality and accurate converter size. During the generation of a given output voltage level, the factor "Inherent ...Redundant Paths (IRPs)" has a considerable impact on the characteristics of multilevel inverter design. The consistent distribution of power loss derives from the Active Neutral Point-Clamed Inverter's intrinsic redundant route at zero-voltage level generation. Even though it has been claimed that adding intrinsically redundant routes might give fault-tolerance capabilities to MLI topologies, the utilization of these pathways at intermediate voltage levels has not yet been studied. Based on this, the current research provides a unique charging and discharging technique is known as the alternating charging and discharging approach, which reduces capacitor voltage ripple. In addition, the suggested technique permits the inherent voltage balancing of capacitors without the need for supplemental components. The suggested alternative charging and discharging approach is implemented under both healthy and varied switch failure circumstances. In a laboratory prototype, the efficacy of the suggested alternative charging and discharging technique has been empirically tested.
Electricity losses are an important problem worldwide that shuld be mitigated, since they generate an impact on CO2 emissions and drive a possible rate increase. The benefits of the reduction of such ...losses are savings, a better environment and less infrastructure needs, amongst others. However, in order to generate reductions, it is imperative to measure the factors associated with such losses. Thus, the objective of this study is to explore the factors associated with electricity losses in the world. A database of 91 countries and 10 years of available data, from 2005 to 2014, was built, with variables taken according to our literature review and obtaind from different publicly available sources. A panel data model with international information was then tested in order to find the determinants of power losses. The model with the best fit was one with random effects. Our results show that the variables unemployment and crime were significant and positive at one percent, while urbanization and education were significant and negative also at one percent. Finally, we provide some policy implications on the evidence of how electricity losses are associated with low education, high unemployment, high homicide rates, and less urbanization.
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