Battery Hybrid System Research Articles

A transformerless single-phase multilevel converter for grid-tie renewable energy systems

A multilevel converter produces a high quality output voltage waveform therefore requires less filtering in grid-tie systems. Cascaded H-bridge converter is a favourable topology for a hybrid renewable and storage system due to isolated DC source requirement. This converter is designed to interface a hybrid photovoltaic and battery system to the utility grid, making DC sources more accessible. In this study, a nine-level cascaded H-bridge converter is presented. A closed loop controller implemented in synchronous rotating frame is used to control active and reactive power independently. The control strategy is implemented in a simulation environment and then validated with experimental results. The generated output current waveforms are analysed when operated with various sinusoidal pulse width modulation techniques such as phase disposition pulse width modulation. It is found that the converter has a low total harmonic distortion that conforms to IEEE 1547 standard.

A Ternary Hybrid-Cation Room-Temperature Liquid Metal Battery and Interfacial Selection Mechanism Study.

The dendrite-free sodium-potassium (Na-K) liquid alloy composed of two alkali metals is one of the ideal alternatives for Li metal as an anode material while maintaining large capacity, low potential, and high abundance. However, Na- or K-ion batteries have limited cathode materials that can deliver stably large capacity. Combining advantages of both, a hybrid-cation liquid metal battery is designed for a Li-ion-insertion-based cathode to deliver stable high capacity using a Na-K liquid anode to avoid dendrites. The mechanical property of the Na-K alloy is confirmed by simulation and experimental characterization, which leads to stable cycling performance. The charge carrier selection principle in this ternary hybrid-cation system is investigated, showing consistency with the proposed interfacial layer formation and ion distribution mechanism for the electrochemical process as well as the good stability. With Li ions contributing stable cycling as the cathode charge carrier, the K ion working as charge carrier on the anode, and Na as the medium to liquefy K metal, such a ternary hybrid battery system not only inherits the rich battery chemistry of Li-insertion cathodes but also broadens the understanding of alkali metal alloys and hybrid-ion battery chemistry.

Model Predictive for Reactive Power Scheduling Control Strategy for PV–Battery Hybrid System in Competitive Energy Market

This article presents an optimal control scheme based on model predictive control (MPC) strategy for a photovoltaic (PV)/battery hybrid system. By considering various trading scenarios of electricity markets in order to maximize profits, an objective function is formulated using variable electricity tariff (VET), battery state of charge (SoC), and availability of solar insolation. The proposed optimal scheme is designed with a two-stage control algorithm based on VET, forecasted solar insolation, and SoC to easily cope with the load demand variation between low and high prices. In this case, the MPC is implemented to predict the SoC in the PV–battery hybrid system by directly calculating it in the first stage while predicting the values of solar irradiance, load consumption, and electricity price. Furthermore, the proposed MPC is used to account for forecasting errors and acts under the given limits to minimize errors and compensate reactive power during the scheduling process. To validate the performance of the proposed control scheme, the PV/battery system is modeled and implemented in MATLAB/Simulink package. Simulation results demonstrate that the proposed optimal control scheme has better performances under various scenarios such as parameter uncertainties and sudden changes.

Switched Energy Management Strategy for Fuel Cell Hybrid Vehicle Based on Switch Network

Environmentally friendly and pollution-free fuel cell/lithium battery hybrid vehicles have received the attention of the community in recent years. It is imperative for fuel cell/lithium battery hybrid vehicles to use the energy management strategy (EMS) to distribute the output power of each power source to improve fuel economy and system life. In practical application, inconsistency of battery pack will lead to security hazard and capacity degradation. However, few EMS take the inconsistency of battery pack into account. Also, the current battery equalization strategy rarely discusses how to perform the equilibrium process while meeting the power demand of vehicle. To solve these issues, a novel equalization energy management strategy (EEMS) based on the switch network is proposed at first. Then, a switched energy management strategy (SEMS) that switches between the EEMS and the equivalent consumption minimization strategy (ECMS) is proposed and implemented in the fuel cell/lithium battery hybrid system to validate its effectiveness. The results show that the proposed SEMS can ameliorate the inconsistency of series lithium battery pack while meeting the power demand of vehicle’s normal operation. It can improve the safety and durability of the system and reduce the equalization time. Besides, it has good expansibility and no energy waste.

NiMOF-derived oxygen vacancy rich NiO with excellent capacitance and ORR/OER activities as a cathode material for Zn-based hybrid batteries.

An Ni-Zn battery is a distinguished member in the family of closed Zn-based batteries due to its ideal power density and voltage. However, when it is employed as a power supply for electric vehicles, its defects in terms of specific capacitance and energy density become obvious. Herein, to resolve this problem, a hybrid battery system was created through a combination of Ni-Zn and Zn-air batteries at the cell level. In a hybrid battery system, oxygen vacancy rich NiO with S,N co-modified mesoporous carbon as a matrix was used as the cathode material. This cathode material showed a high specific capacitance of 202.1 mA h g-1 at 1.0 A g-1. When the current density reduces to 20 A g-1, this value decreases to 130.2 mA h g-1, which implies that 64.4% of specific capacitance was retained. It also exhibits excellent OER and ORR activities. For the hybrid battery system, when the discharge process was carried out at 1 mA cm-2, there were two voltage plateaus at 1.72 and 1.12 V, which originated from Ni-Zn and Zn-air, respectively. In this case, its specific capacitance and energy density reaches 800.3 mA h g-1 and 961 W h kg-1, respectively. The hybrid battery also possesses perfect stability during multi-cycle charge-discharge tests. The construction of this hybrid battery system develops a new road to prepare a power supply device with high performance.

Speed Racer

Electric motorbikes are becoming a booming business. To showcase where they could be heading is the Nawa Racer, a concept e-bike with a world first hybrid battery system using ultracapacitor technology

The potential for grid defection of small and medium sized enterprises using solar photovoltaic, battery and generator hybrid systems

Grid-tied solar photovoltaic (PV) systems enable lowercost electricity for small and medium size enterprises (SMEs) than current many providers of grid electricity in the U.S. These economic realities threaten conventional electric utilities, which have begun manipulating rate structures to reduce the profitability of distributed generation (DG), as well as putting arbitrary caps on DG in their service territories. SMEs may still reduce electricity costs, if they can grid defect with hybrid captive power systems made up of solar PV, battery and generator subsystems. This paper analyzes the technical and economic viability for hybrid solar systems deployed in the commercial sector to enable self-generation. Specifically, for the first time, the economics of grid defection are analyzed for three case studies of SMEs in the northern U.S., which represent a challenging technical case because of long dark winters, but also have high utility costs. The results of the simulations make it clear that grid defection is already viable for SMEs with the current prices for all components in the solar hybrid system. These results were consistent across scale, load-profile, and utility rate. These economic projections included no government incentives or subsidies and can thus be considered extremely conservative for the specific case studies. Policy changes are discussed for electric utilities to avoid the potential of a utility death spiral in this and similar performing locations.

Coordinated Power Management for Variable Speed Diesel Generator and Lithium-ion Battery Hybrid System

This paper presents coordinated operation of power management strategies for a hybrid system. This hybrid system is modeled based on dynamic variation of load power and its effective distribution strategy. The proposed hybrid system consists of variable speed diesel generator (VSDG) and lithium-ion battery which is able to supply electric power for Power, Water and Communication (PWC) economically and efficiently in rural areas. The variation of power demand in PWC load is highlighted in load profile. The total PWC load is effectively shared by two VSDGs and one Lithium-Ion battery bank. The use of advanced VSDG helps hybrid system to reduce fuel consumption as its speed varies with load demand. The proposed segmentation of high frequency and low frequency components of load currents and their assignation to suitable source helps to reduce the transients during load variations. Also, one of the generators will be switched off when the total power demand goes below specified level and hence significant fuel savings can be achieved. The execution of proposed system is assessed through MATLAB/Simulink model and its validation by experimental test bench.

Design and environmental sustainability assessment of small-scale off-grid energy systems for remote rural communities

Small-scale off-grid renewable energy systems are being increasingly used for rural electrification, commonly as stand-alone home systems or community micro-grids. With the variety of technologies and configurations available, it is not clear which options are sustainable for remote communities. This study investigates the life cycle environmental sustainability of both home and community installations, designed as part of this work, which utilise diesel, solar, and wind resources coupled with battery storage. A total of 21 system configurations (six home systems and 15 micro-grids) have been designed and optimised for a prototypical rural community in the Philippines, considering both stand-alone and hybrid systems. Life cycle assessment (LCA) considering 18 potential impact categories has been carried out to compare the environmental impacts associated with electricity production of each option. At the household level, hybrid solar photovoltaics (PV)-wind systems with storage have 17–40% lower impacts than the equivalent stand-alone installations per kWh generated. Batteries are a major environmental hotspot, causing up to 88% of the life cycle impacts of a home energy system. Among the community micro-grid options, the PV-wind-lead acid battery hybrid system has the lowest impacts in many categories, including climate change, ozone depletion, and acidification. Comparing equivalent architectures for single-household and community-scale installations, PV systems are environmentally more sustainable if installed individually in households, while larger turbines in community micro-grids are environmentally better for wind utilisation. The results suggest that a household-scale PV system integrated within a micro-grid with community-scale wind turbines and Li-ion batteries is environmentally the most sustainable configuration.

High-performance Energy Storage System Using Low-cost Sensors for a Photovoltaic and Battery Hybrid System

High-performance Energy Storage System Using Low-cost Sensors for a Photovoltaic and Battery Hybrid System

Comparison of semi-active hybrid battery system configurations for electric taxis application

This paper proposes two semi-active configurations for hybrid battery system (HBS) in which LiFePO4 (LFP) and Li4Ti5O12 (LTO) batteries are combined to prolong the life span of LFP batteries used in electric vehicles (EVs). To protect the LFP batteries from frequent peak power demands, the first configuration (HBS #1) uses diodes and switches, while the second (HBS #2) adopts a bidirectional DC/DC convertor to decouple various batteries. To make a fair comparison of the two configurations, their component sizes are firstly determined using brute-force search considering energy capacity and cost. Then, a unified fuzzy-logic energy management strategy was designed and optimized for each configuration to mitigate LFP battery degradation. Simulated implementation of HBSs #1 and 2 in an electric taxi with standard daily operation (driving nearly 400 km per day) and charging patterns revealed that both have longer LFP lifespans (44.4% and 45.4% improvement, respectively), lower annual costs (12.49% and 11.52% reduction, respectively) and reduced distance-based costs (39.41% and 39.18% reduction, respectively) than a single-LFP battery configuration. Although HBS #2 demonstrated more battery life improvement, HBS #1 was found to be cheaper in EV application from the perspectives of total and distance-based cost.

Multiobjective Scheduling-based Energy Management System Considering Renewable Energy and Energy Storage Systems: A Case Study and Experimental Result

The fast-growing development of smart grid and renewable energy increases the challenge in balancing the production on local energy consumption. The power scheduling of energy storage has directed to growing interests in energy storage system to increase the use of renewables. In this study, a practical laboratory energy management system considering renewable energy and battery is established. Besides, two control strategies including ‘scheduling’ and ‘ON/OFF’ operation of the grid in the photovoltaic–wind–battery hybrid systems are modeled. This paper proposes a day-ahead optimizing planning using mixed-integer linear programming, aiming to achieve economic benefit by reducing operational costs of the grid. Related to demand-side management, a control technique is developed for a proper scheduling of the power from the hybrid system. The ultimate objective of the aimed strategy is to maximize the advantages of renewable energy in different running conditions such as weather fluctuation and grid support. In addition, a day-ahead optimization for operational costs, as well as a prediction model for PV and WT, is used. The data of renewable productions and load demand are used. The obtained results prove that applying the scheduling strategy for PV–WT–battery and grid operation control models, significant grid decreasing can be achieved related to the case where the grid is managed alone to satisfy the same load demand.

Integration and energy management of a hybrid Li-VRB battery for renewable applications

Energy storage systems are becoming more and more important for integrating higher levels of varying and intermittent renewable power into the grid. As we have energy storages with different characteristics and applications, hybrid storage solutions combining various technologies to meet different applications are fast developing. In this paper, an efficient energy management strategy is proposed for a VRB and Li-ion hybrid battery system to be integrated with a grid-connected wind-PV Hybrid Renewable Energy System (HRES). The operation of the generating system and the storage batteries are evaluated using Matlab/Simulink and techno-economic analysis is carried out. The results demonstrated successful implementation of the hybrid system with improved deliver ability and storage lifetime.

Vanadium redox flow batteries application to electric buses propulsion: Performance analysis of hybrid energy storage system

Abstract This paper presents a comparison between different battery energy storage systems (ESS) suitable for an urban electric bus. The investigation starts from a daily energy consumption analysis of a bus route in term of batteries state of charge (SOC). Specifically, three different ESS configurations are modelled basing on experimental data: LiFePO4 battery pack, LiFePO4 battery coupled with PEM fuel cell stack and a hybrid battery system composed by LiFePO4 and vanadium redox flow batteries (VRFBs). Moreover, authors provide an evaluation about the battery life through the application of the rainflow-counting algorithm on the yearly SOC trends of each system. As result, the proposed analysis highlights the favorable effect on the ESS due to the introduction of VRFB in the system. The improvements are found both on the net daily operating hours (one hour longer than the conventional case) and on the life expectancy of the LiFePO4 battery (over 9 years, with a gain factor of 5). The obtained results can be considered as a starting point for a wider study focused both on the ESS sizing and on the routes planning of a city buses fleet.

A Stand-Alone Hybrid Photovoltaic, Fuel Cell, and Battery System: Case Studies in Jordan

The main purpose of this study is to investigate the feasibility of using a hybrid photovoltaic (PV), fuel cell (FC), and battery system to power different load cases, which are intended to be used at the Al-Zarqa governorate in Jordan. All aspects related to the potentials of solar energy in the Al-Hashemeya area were studied. The irradiation levels were carefully identified and analyzed and found to range between 4.1 and 7.6 kWh/m2/day; these values represented an excellent opportunity for the photovoltaic solar system. homer (Hybrid Optimization model for Multiple Energy Resources) software is used as an optimization and sizing tool to discuss several renewable and nonrenewable energy sources, energy storage methods, and their applicability regarding cost and performance. Different scenarios with photovoltaic slope, diesel price, and fuel cell cost were done. A remote residential building, school, and factory having an energy consumption of 31 kWh/day with a peak of 5.3 kW, 529 kWh/day with a maximum of 123 kW and 608 kWh/day with a maximum of 67 kW, respectively, were considered as the case studies' loads. It was found that the PV-diesel generator system with battery is the most suitable solution at present for the residential building case, while the PV-FC-diesel generator-electrolyzer hybrid system with battery suites best both the school and factory cases. The load profile for each case was found to have a substantial effect on how the system's power produced a scheme. For the residential building, PV panels contributed by about 75% of the total power production, the contribution increased for the school case study to 96% and dropped for the factory case to almost 50%.

Dynamic modeling and verification of a proton exchange membrane fuel cell-battery hybrid system to power servers in data centers

Dynamic performance of a 10-kW proton exchange membrane fuel cell (PEMFC)–battery hybrid system to power servers in data centers has been experimentally evaluated in our previous work [1]. The present work is a numerical study based on the previous work to identify the dynamic characteristics and present basic insights for the system control strategy during transients. The hybrid system dynamic model has been developed using the MATLAB–Simulink®, which consists of a one-dimensional, two-phase dynamic model of the PEMFC, lumped dynamic model of an air blower and a battery. The system model is verified by comparing the dynamic behavior of the power generated by the PEMFC and battery with the experimental data at the step change of the system demand power between 0 and 1.5, 3.0, 4.5, 6.0, 7.5, and 9.0 kW. During the step load increases, the system instantly obtained the total amount of external load power from the battery within 0.1 s in every case and gradually decreased until approximately 4 s or 6 s as the power generated by the fuel cell is gradually increased. The dynamic response of the system model is compared with the experimental data at various load profiles of three, six, and nine servers.

Development of low-cost sodium-aqueous polysulfide hybrid batteries

There has been increasing interest in sodium-sulfur (Na-S) batteries as an option for low-cost grid-scale energy storage. However, traditional Na-S batteries operate at high temperatures, raising concerns about long-term maintenance costs and safety. On the other hand, room-temperature Na-S batteries have their own limitations, including Na dendrite formation, polysulfide shuttling, and low utilization of active material. To overcome these issues, we present here a novel low-cost room-temperature sodium-aqueous polysulfide (Na-APS) hybrid battery system with a Na-metal anode, Na+-ion solid electrolyte separator, and an aqueous polysulfide catholyte. The solid electrolyte blocks Na dendrites and polysulfide shuttling while simultaneously protecting the reactive Na metal anode from the aqueous catholyte. The redox kinetics of the APS catholyte is improved with a rational development of a freestanding CuS-CNT catalytic electrode. The improvements with the Na-APS hybrid battery compared to the traditional Na-S battery systems are discussed. The Na-APS hybrid battery displays excellent performance under a 418 mA h g−1 of sulfur capacity-restricted cycling. The battery achieves an energy efficiency of 90% over 100 cycles at 0.5 mA cm−2 current density.

Efficient dynamic performance of brushless DC motor using soft computing approaches

A novel attempt to employ moth swarm algorithm (MSA) to generate the optimal gains of a proportional–integral (PI) speed controller of brushless DC (BLDC) motor is addressed to assure its satisfactory dynamic performance. For torque ripples minimization, a dual-loop speed controller is adapted. The agreed objective function is formulated to minimize the integral time absolute speed error (ITAE) subjects to set of constraints. The effectiveness of the MSA is verified through many test cases along with the detailed comparisons to those obtained by well known genetic algorithm and particle swarm optimization. At this stage, the numerical results of the MSA are used to train and test an artificial neural network which shall be used as an adaptive controller to give the optimal PI gains under different operating conditions. At final stage, the performance of the BLDC motor powered from photovoltaic (PV)–battery hybrid system with the proposed controller is demonstrated. A Landsman converter is controlled by an incremental conductance technique to maximize the extracted PV array power. A bidirectional converter is used to control battery charging/discharging states. Various demonstrated case studies indicate that the MSA is effective in generating the optimal gains of the PI controller.

Experimental Test Results of Nine Scheduling Operational Modes of PV and Battery Hybrid System for the Development of Automatic Control Algorithm for Continual Operation without being shut-downed

Experimental Test Results of Nine Scheduling Operational Modes of PV and Battery Hybrid System for the Development of Automatic Control Algorithm for Continual Operation without being shut-downed

Dynamic vulnerability in standalone hybrid renewable energy system

Ensuring continuous power supply in the hybrid renewable energy and battery system is important because power utilization is fundamental to economy and human well-being. Earlier studies have been concerned with the ability to supply a desired amount of power in a long-term static condition in the context of system reliability. Meanwhile, short-term dynamic behavior and its relevant vulnerability in a hybrid system associated with a continuous power supply has been given less attention due to the modeling complexity of the problem. This study uses a parametric approach to assess the dynamic transition of vulnerabilities potentially leading to disruptions in electricity supply throughout a given day to identify a specific vulnerable time. The methodology of quantifying the dynamic vulnerability of power source components during a given day in a hybrid system is developed. Then, the temporal dynamic vulnerability and overall vulnerability in the system are presented by changing the capacity size in the case of a fictitious standalone house. Through the analysis, the approach developed in this study would potentially highlight the greater contribution of the battery to continuous power supply, compared with the solar PV in the hybrid system.