Gregory Su

ECS Meeting Abstracts • 2021

The performance of electrochemically active materials, for example, ion-conducting polymer membranes, is defined by their unique molecular architecture and resulting hierarchical morphology across length scales that controls functional properties such as transport. Synchrotron X-ray probes have proven invaluable to reveal details into the chemistry and structure of electrochemical systems. Nevertheless, opportunities remain to uncover new structure-property insights with emerging synchrotron tools. Energy-resolved X-ray absorption spectroscopy coupled with resonant X-ray scattering can elucidate morphology with chemical sensitivity in heterogeneous polymer-based systems. These techniques are amenable to in situ and operando studies. Moreover, they are well-suited to probe thin films, enabling detailed interrogation of relevant interfaces, for example, membrane-electrode interfaces, and how interfacial molecular assembly impacts charge transport and overall electrochemical performance. Herein, we present examples of polymer morphology evolution, including perfluorinated ionomers with unique side chain architectures, leveraging the sensitivity of energy-resolved scattering to reveal detailed aspects of membrane phase separation. These studies highlight opportunities in synchrotron-based resonant scattering coupled with spectroscopy and other techniques to achieve new insights into the bulk and interfacial structure of membranes and other complex electrochemical materials.

Abinaya Kamaraj, Johann Wilhelm Erning, Stefan Reimann et al.

CORROSION 2019 • 2019

Abstract The generation of active disinfectants by electrochemical processes gains market share due to the lack of need for transportation and storage of dangerous goods as well as the ease of operation. Usually, the process involves the use of specific electrodes for electrolysis of water to produce active chlorine species, sometimes supported by the addition of chlorides to the process water. Thus, the influence on the corrosion behavior can vary widely. The susceptibility of AISI 304 stainless steel to crevice corrosion on the effect of contact with electrochemically active fluids was investigated using exposure and stepwise potentiostatic polarisation. Crevice materials made up of 304 SS and Polyether ether ketone (PEEK) forming two kinds of crevices including 304 SS-to-PEEK and 304 SS-to-304 SS were tested, and results indicate that 304 SS specimen is strongly susceptible to crevice corrosion in 304 SS crevice former assembly. The combination of the influence of oxidant and chloride concentration were examined in detail, and results indicate a strong influence of free chlorine and chloride concentration to crevice corrosion. The corroded surface morphology was investigated using scanning electron microscope(SEM), Energy Dispersive X-ray (EDX) and Confocal microscope.

Vitor Silva Liduino, Magali Christe Cammarota, Eliana Flávia Camporese Sérvulo

LatinCORR 2023 • 2023

Electroactive biofilms provide environments conducive to the occurrence of microbiologically influenced corrosion (MIC) in several industrial sectors. There are many distinct MIC mechanisms associated with different microbial groups and metabolism types. Most published research studies on MIC focus on bacteria, where sulfate-reducing bacteria (SRB) have the largest impact on corrosion because sulfate is widely distributed in anoxic environments, such as offshore oil reservoirs. This study investigated the role of an oilfield SRB-consortium in the AISI 1020 carbon steel corrosion immersed in hypersaline seawater (10% NaCl w/m) with low dissolved oxygen (>2 mg/L). This steel is globally used to build oil and gas industry facilities exposed to both onshore and offshore sites due to its low cost and good corrosion resistance. Each microcosm consisted of 100 mL seawater and one suspended metallic coupon of 6 cm2 total surface area. Three identical microcosms were performed. Simultaneously, abiotic control assays without microbial consortium were also executed. The assays were analysed by weight loss method and scanning electron microscopy (SEM) after 10 days at 40°C. Additionally, SRB counts in the hypersaline seawater at diferent times are done. The planktonic population increased slow and its peak at 9.5× 106 MPN/mL appeared at day 10. This result suggest that the increased salt content was not an inhibiting factor since the SRB consortia grew well and remained metabolically active throughout the assay. Corrosion rates are shown in Table 1. The abiotic condition must have improved the corrosion rate because of the large amount of chloride ions (Cl−) in the hypersaline seawater (10% w/v salinity). Cl− enhances the electrical conductivity of aqueous solutions and consequently boosts the velocity of oxidation and reduction reactions of the corrosive process. Thus, it proceeds an homogeneous degradation over the entire surface area causing signifcant mass loss and well-proportioned corrosion rate. On the other hand, SRB-MIC consumes only a relatively small amount (mass) of material due to the localized corrosion (pits), corroborating the low corrosion rate. Many pits were detected in the steel surface with a maximum depth of 33 μm; it was 86% deeper than the maximum pit depth in abiotic condition.

Ana Sanz Matias, Fabrice Roncoroni, Siddharth Sundararaman et al.

Research Square • 2023

Abstract Divalent ions, such as Mg, Ca, and Zn, are being considered as competitive, safe, and earth-abundant alternatives to Li-ion electrochemistry. However, the challenge remains to match elec- trode and electrolyte materials that stably cycle with these new formulations, based primarily on controlling interfacial phenomena. We explore the formation of electroactive species in the electrolyte Ca(BH 4 ) 2 in THF through molecular dynamics simulation. Free-energy analysis indicates that this electrolyte has a majority population of neutral Ca dimers and monomers, albeit with diverse molecular conformations as revealed by unsupervised learning techniques, but with an order of magnitude lower concentration of possibly electroactive charged species, such as the monocation, CaBH 4 + , which we show is produced via disproportionation of neutral Ca(BH 4 ) 2 complexes. Dense layering of THF molecules within 1 nm of the electrode surface (modeled here using graphite) hinders the approach of reducible species to within 0.6 nm and instead enhances the local concentration of species in a narrow intermediate-density layer from 0.7-0.9 nm. A dramatic increase in the monocation population in this intermediate layer is induced at negative bias, supplied by local dimer disproportionation. We see no evidence to support any functional role of fully-solvated Ca 2+ in the electrochemical activity of this electrolyte. The consequences for performance and alternative formulations are discussed in light of this molecular-scale insight.

Shoji Hall

ECS Meeting Abstracts • 2020

The conversion of O2 to H2O is an important fuel cell reaction for the recovery of renewable electricity from chemical fuels. Alloys of Pt-group metals (PGMs) with transition metals have emerged as catalysts with enhanced activity and durability for the oxygen reduction reaction (ORR). To date, most studies focus exclusively on alloys that adopt a Face-centered cubic (FCC) or Face-centered tetragonal (FCT) crystal lattice. Under ORR operating conditions, these materials evolve from alloys to Pt core-alloy shell materials, in this case both the alloy core and Pt shell retains the CCP type crystal structure; indicating that materials can dynamically change during catalysis. Here we present the synthesis of Pd-Bi based ordered intermetallics by partial dealloying of a Bi rich alloy. We found that under ORR operation conditions, ß-PdBi2 which adopts a tetragonal lattice, transforms to Pd3B orthorhombic crystal structure; this transformation is mediated by oxidative Bi corrosion under potential cycling, and reconstruction of the atoms in the bulk. To the best of our knowledge, this is the first report of a material that exhibits an electrochemically driven, non-congruent phase transition among materials with different crystal structures. The resulting phase-converted Pd3Bi is stable and exhibits high performance for ORR. Phase-converted Pd3Bi outperform Pt and Pd metal, reaching mass activities of 2.6 A/mgPd, which is nearly 10X higher than Pt/C (~0.3 A/mgPt) and Pd/C (~0.2 A/mg) at 0.9 V vs the Real Hydrogen Electrode (RHE). The mass activity of Pd3Bi decreases by ~38% after 10,000 cycles, indicating that it is stable. Activation energy (Ea) determined by temperature dependent electro-kinetic measurements indicates that the activity enhancement on phase-converted Pd3Bi originates from anion-poisoning resistant behavior. These results establish that PGMs-based ordered intermetallics with low-symmetry crystal structures can be highly active and durable electrocatalysts.

Dina Fattakhova, Petr Krtil

MRS Proceedings • 2001

ABSTRACT Nanocrystalline Li-Ti-O spinel samples were prepared by solvothermal reaction of TiO 2 with lithium hydroxide in water and ethanol. The hydrothermal reaction proceeds at temperature higher than 130 °C. The reaction proceeds via dissolution-precipitation mechanism and its course is not sensitive to titanium dioxide polymorph used in the reaction. Product of the reaction in water has cubic rock salt type structure. It converts, however, to spinel if annealed to temperatures exceeding 250 °C. The re-crystallization is accompanied with water removal from the structure. Solvothermal reaction in ethanol leads directly to a product with spinel structure without need for annealing. Both products are active for Li insertion; theelectrochemical activity. The specific capacity ranges between 100 and 160 mAh/g depending on the annealing temperature.

Haluk Beyenal, Jerome T. Babauta

ECS Meeting Abstracts • 2016

Almost a decade has passed since the rediscovery of microbial fuel cell research, yet the power generation of these devices has not advanced. This is mainly due to the research being focused solely on the improvement of power generation rather than on a fundamental understanding of electron transfer processes and their limitations in the biofilms grown on the anode and cathode. The chemical and electrochemical gradients in these biofilms play a critical role in electron transfer rates between cells and a solid electron acceptor or donor. Our research group has developed and used novel microelectrodes and in situ Nuclear Magnetic Resonance (NMR) imaging techniques to investigate electron transfer mechanisms in biofilms. The newly developed microelectrodes were successfully operated on polarized surfaces. Both NMR and microelectrode technologies allowed us to quantify metabolic and chemical variations in biofilms while the cells respired on polarized electrode surfaces. We combined our techniques with two new techniques – rotating disk electrode (RDE) and electrochemical quartz crystal balance (eQCM). The addition of both these techniques allowed us to differentiate mass transfer limitations from intra-biofilm electron transfer processes. When we attempted to identify limitations in anodic biofilms, first, we addressed the importance of local acetate concentrations within G. sulfurreducens biofilms using a novel acetate microelectrode which has better resolution than NMR. The microelectrode work confirmed our previous NMR findings and generated profiles on the order of µM. We should note that the microelectrode method developed is significantly more economical to use than NMR and can facilitate rapid in situ measurements of acetate in anoxic biofilms. Second, we integrated our previous RDE method with our eQCM methods to show that, on both a per current basis and a per mass basis, biofilm capacitance is a better indicator of biofilm performance than conductance.In particular, we compared the capacitance/conductance relationship of G. sulfurreducens biofilms to those of both polyaniline films and diffusing flavin systems. The results indicated that the tandem increase in capacitance and conductance is unique to the extracellular electron transfer mechanisms operating in G. sulfurreducens biofilms. Our local potential and current measurements indicated that the upper layers of the biofilms are always under a reducing condition. This knowledge also confirmed that the amount of cytochromes in the biofilm is not high enough or the biofilm conductivity is not sufficient to generate an oxidizing condition near the top of a biofilm. Finally, we extended the role of excess surface area in the scale-up of bioelectrochemical systems by examining biomass accumulation under this condition. We found that biomass continues to accumulate on the excess surface area electrodes with net arithmetic growth rates and acetate consumption during steady-state current. The linear growth rates constrained by ion transport limitations that we found may be important factors in understanding the current generation using high-surface-area 3D electrodes with advection. In conclusion, we demonstrated the importance of the metabolic inactivity of layers within G. sulfurreducens biofilms using microelectrodes and NMR. In addition, we verified these findings using electrochemical impedance spectroscopy (EIS) by demonstrating the pseudocapacitive behavior of biofilm impedance. We also demonstrated the feasibility of directly measuring biofilm inefficiencies via intra-biofilm electron transfer rates and local current depth profiles.

Haisheng Fang, Liping Li, Guangshe Li

Chemistry Letters • 2007

Abstract Highly crystalline olivine-structured LiMnPO4 was prepared by a simple hydrothermal method in a basic aqueous medium at 200 °C for 10 h. The particle shape of the as-prepared LiMnPO4 was plate-like with the thickness of 100–200 nm. A capacity of 68 mA h g−1 was reversibly achieved between 3 and 4.5 V vs. Li+/Li.

Po-Chun Hsu

Advanced Photonics Congress 2024 • 2024

The combination of reversible electrochemical reaction and metasurface allows multifunctional and multispectral light and heat management. This talk will introduce two examples, conjugated polymers and metal, and the design principle to accomplish various dynamic thermoregulation applications. Full-text article not available; see video presentation

, Chatthai Kaewtong

• 2007

Hexahomotriaza-p-chlorocalix[3]arene (L1) was successfully by synthesized and functionalized to provide two novel heteroditopic sensors. From complexation studies, the hexahomotriaza-p-chlorocalix[3]arene could be used as a selective chromogenic sensor for F[superscript -] and H[subscript 2]PO[subscript 4][superscript -]. The partial-cone hexahomotriaza-p-chlorocalix[3]-trinaphthylamide (L2) synthesized from both cone and partial cone triester derivatives exhibited a selective fluorescent sensor for Cd[superscript 2+], Pb[superscript 2+] and F[superscript -]. Hexahomotriaza-p-chlorocalix[3]-cryptand (L3) which is fixed in cone conformation and possesses a close well-defined cavity showed a high selectivity for Cl[superscript -] ion. Tuning this ligand by complexing with Zn[superscript 2+] on hexahomotriaza-p-chlorocalix[3]arene framework, its anion binding selectivity changed to Br[superscript -] ion. Moreover, a new class of chemosensor recognition elements based on conjugated polymer network ultra-thin films from electrochemical cross-linking of hexahomotriaza-p-chlorocalix[3]arene-carbazole (L4) was successfully realized. Its demonstrated high selectivity and sensitivity towards Zn[superscript 2+] was observed. A self-assembly between polyamidoamine (PAMAM) dendrimer and dendron surfmers (G[subscript 0]COOH, G[subscript 1]COOH and G[subscript 1]COOH) was prepared through an efficient supramolecular interaction. The electrochemical cross-linking of dendrimer complexes (PAMAM-G[subscript 1]COOH) provided thin films which have a ring-like or donut structure most likely composed of the PAMAM-core and dendron-carbazole shell. In addition, [pi]-conjugated dendrimer-protected gold nanoparticles in a stable colloidal form have been successfully prepared via simultaneous reduction of AuCl[subscript 3] with terthiophene (PT) and carbazole (PC) peripheral functionalized PAMAM dendrimers.

V. N. Nwigwe, B. O. Uba

Journal of Applied Sciences and Environmental Management • 2022

In this study, piggery and poultry wastewaters were used as agro-based industrial wastewaters to evaluate the role of electrochemically active bacteria in an anodic chamber of microbial fuel cell (MFC) with 0.1M potassium permanganate cathodic cell using salt bridge preparation. The BOD5, COD, TDS, TSS, nitrogen, phosphates, pH and conductivity served as indicative parameters for determining the wastewater treatment efficiencies (WWTE) of the MFCs. Results obtained from the WWTE reveal that the MFCs were able to reduce the piggery wastewater parameters, BOD, COD, TDS, TSS, nitrogen, phosphate, pH, conductivity by 89.66, 69.57, 52.20, 69.04, 70.27, 59.57, - 4.41 and 0.99 %, respectively while the same parameters for the poultry wastewater were reduced by 82.61, 78.59, 58.03, 67.13, 70.49, 64.52, 2.70 and 28.04 %, respectively. Statistically, there were significant differences before and after treatments and between wastewater samples revealing that that the effect of treatment before and after on physicochemical parameters were different for piggery wastewater than they were for poultry wastewater. Microbes in the biofilms on the electrodes (potential exoelectrogens) include Staphylococcus aureus, Bacillus cereus, Micrococcus luteus, Corynebacterium sp., Enterococcus sp., Pseudomonas aeruginosa, Escherichia coli, Klebsiella sp., Salmonella sp. and Shigella sp. while the fungal isolates include Mucor sp., Saccharomyces sp. and Aspergillus sp. in both piggery and poultry wastewaters. Thus, microbial fuel cell bacteria oxidize the organic matter leading to decontamination of the wastewater – a significant approach in addressing the public health threats of these wastes in our country.

Kaitlyn Dwelle, Adam Willard

ChemRxiv • 2019

This manuscript presents a theoretical model for simulating molecular dynamics at electrode-electrolyte interfaces. The novelty of the model is that it combines a method for simulating constant potential electrodes and a method for simulating stochastic interfacial charge transfer. We combine these methods to simulate model electrochemical systems under driven conditions, where charge is flowing across the electrode-electrolyte interface. The manuscript describes the theoretical formalism and applies it to a model battery system. We highlight the ability of the model to support the formation of electrical double-layers and to provide microscopic physical insight the results of potential jump experiments.

, Jutatip Kongpeth

• 2013

DNA sensors are useful in various applications including medical diagnosis, environmental monitoring, food quality control, and forensic science. The sensor usually consists of a sensing element known as a “probe” that can bind specifically with the DNA target. The binding between the probe and the target creates a should allow rapid detection, provide high specificity and sensitivity, require small sample volumes and require low cost instrumentation. Electrochemical DN sensors are one type of DNA sensors that meet all the above requirements. Peptide nucleic acid or PNA is a unique DNA analogue that is often employed as the sensing element in DNA sensors due to its superior affinity and specificity in recognition of DNA than natural DNA or other DNA analogues. To combine the advantages of PNA and electrochemistry in DNA sensing, an electrochemical DNA sensor based on pyrrolidinyl peptide nucleic acid (acpcPNA) probe that does not require probe immobilization was developed. Various kinds of redox-active redox reporters including anthraquinone and methylene blue were synthesized and introduced onto acpcPNA via acylation chemistry. The redox-active acpcPNA were purified by reverse phase HPLC and characterized by MALDI – TOF MS. The labeled acpcPNA formed hybrids to DNA with high thermal stability and specificity according to UV melting experiments. The immobilization-free electrochemical DNA detection platform was next developed on an inexpensive screen-printed carbon electrode (SPCE) by using a square-wave voltammetric (SWV) technique. Electrostatic interactions between the acpcPNA probe, the acpcPNA hybrid and the electrode surface modulate the electron transfer between the labeled acpcPNA probe and the electrode, providing the basis of the signal transduction. As an example, a highly specific signal-on detection of DNA by SWV with LOD and LOQ in the low nanomolar range was achieved using anthraquinone-labeled acpcPNA probes on PQDMAEMA-modified SPCE electrodes. Applications of the technique for analysis of real DNA samples that had been amplified by LAMP or PCR were demonstrated. Furthermore, the effects of the charges on the surface of the electrode and on the acpcPNA probe were studied to obtain further insights into the mechanism of the signal transduction. Accordingly, a novel and highly promising immobilization-free electrochemical DNA sensor based on redox-active acpcPNA prode on SPCE was successfully developed.

Gang Fan

ECS Meeting Abstracts • 2024

Bacteria produce a variety of soft materials, but they are limited in their structure and function. A synthetic system in which the power of bacterial engineering is combined with traditional organometallic catalysis could pave new avenues to polymer synthesis. Here we demonstrate that the electroactive bacteria Shewanella oneidensis can control the activity of a transitional-metal catalyst in atom-transfer radical polymerization (ATRP) through extracellular electron transport (EET) machinery. This polymerization features characteristics of controlled radical polymerization, such as first-order kinetics, narrow molecular weight distribution and block-polymer synthesis. Catalyst performance and polymer microstructure were a strong function of bacterial metabolism, specific electron transport machinery, and catalyst design. Moreover, different bio-renewable and bio-friendly energy sources, such as lactate, glucose, pyruvate and xylose, could be utilized to control the rate of polymerization process. Overall, our results demonstrate that targeting biological electron transport pathways may combine the advantages of metabolic engineering with traditional polymer synthesis.

Fitria Nur Laily, Sri Rachmania Juliastuti, Raden Darmawan

Journal of Advanced Research in Fluid Mechanics and Thermal Sciences • 2024

Microbial Fuel Cell (MFC) are the one of utilization of waste for renewable energy continues to be developed. According to the FAO, 32% of all food for human consumption is discarded about 1.3 billion tonnes per year. In this study, Microbial Fuel Cells used an organic source in the form of food waste that had been hydrolyzed by Aspergillus oryzae, Aspergillus aculeatus, and Candida rugosa. The results of the hydrolysis are entered into the MFC system. In the MFC system it is mixed with Sidoarjo mud and Shewanella oneidensis MR-1, then put into a Single Chamber microbial fuel cell (SC-MFC) to generate electricity. In this research, also added micronutrients (Mg2+, Ni2+, Cu2+, Ca2+, Pb2+, Co2+, Cd2+, Cr2+, and Zn2+) to increase the metabolic of Shewanella oneidensis MR-1 bacteria, so can elevate electric currents. electrons and protons are produced by microorganisms by changing organic compounds in the substrate. The results showed that the best power density was 6.652 W/m2 with BOD 89.362% and COD removal 77.273% achieved with a ratio of food waste to water of 2:1 M. Food hydrolysis is capable of hydrolyzing 40% food waste into glucose within 24 hours. The greatest percentage of glucose decreased was achieved by Cobalt micronutrient addition with 77% of glucose decreased. Therefore, MFC can be greatly enhance food waste degradation to become a carbon source in a microbial fuel cell for electricity production.

Karnapa Ajit, Juliana John, Haribabu Krishnan

Research Square • 2023

Abstract It becomes important to simultaneously focus on the development of cost-effective electrode materials and catalysts as well as evaluating their performance on stacked systems in order to create scalable bio electrochemical systems for waste water treatment. Platinum group metal free biomass derived cathode catalysts have been observed to improve the microbial fuel cell performance in recent years. But their performance in scalable systems using Natural clay membrane – SS mesh electrode MEA needs to be evaluated for applying to real time systems. In the current work, a catalyst with intrinsic Fe-N-C coordination could be synthesised from the seedpods of biomass Bauhinia Accuminata. The elemental analysis and XPS results confirmed the intrinsic doping of heteroatoms N and P in the catalyst with atomic weight percentages of 4.5 and 3.5, respectively. The deconvolution of N1 and Fe2p spectra confirmed Fe-N-C coordination in the catalyst with pyridinic N and graphitic N content of 17.3% and 34.1%, favouring the ORR activity. The catalyst when coated on SS mesh and used in an MFC system with natural clay membrane - modified SS mesh electrode MEA, the maximum power density was 0.91 W/m 3 compared to 0.02 W/m 3 in plain SS electrode cell with COD removal efficiency of 93.3%. The study also demonstrated the stepping up of voltage, current and power achieved while stacking such single MFCs in series, parallel, parallel - series and fluidically connected configurations. Parallelly connected system outperformed other systems with a maximum power density of 1.54 W/m 3 despite a high OCV of 4.15V attained in series connection. It was also notable that the fluidically connected parallel system achieved better power and current density (0.84W/m 3 and 1.97A/m 3 ) than the mixed parallel series circuitry (0.7W/m 3 and 0.57A/m 3 ).

Alberto Mur-Gorgas, Antonio V. García-Triviño, R. Mateos et al.

Applied Sciences • 2024

This study explores the impact of incorporating conductive materials and bioelectrochemical systems (BES) on the efficiency of anaerobic digestion (AD) of sewage sludge. The research consists of two phases: biodegradability tests using 3D-printed polylactic acid-based conductive fillers (PLA/Carbon Black and PLA/Graphene) and semi-continuous assays integrating an external BES into the AD process. Results from biodegradability tests indicate that conductive fillers enhance around 50% methane production during the start-up phase, with microbial communities adapting over time to reduce variability in methane yields. Moreover, as the experiment progressed, the methane yields of the digesters with and without fillers became equal. Semi-continuous experiments demonstrate that BES integration improves process stability and methane production by achieving a 5–10% improvement in the amount of methane in the biogas throughout the entire operation, even under high organic loads, by facilitating diverse electron transfer pathways. The challenges of BES operation highlight the need for optimized designs to ensure scalability. Microbial analyses reveal that BES application shifts methanogenic pathways, favouring acetoclastic methanogenesis. Overall, the findings underscore the potential of conductive materials and BES to improve biogas quality and production, contributing to sustainable wastewater management and renewable energy generation.

W. Houf, S. Bashir, J. Liu

ECS Meeting Abstracts • 2022

The microbial fuel cells (MFCs) are bioelectrochemical devices to convert chemical energy into electricity using a microorganism, without relying on abiotic catalysts and fossil fuels. The microbes enable proton production and electron transfer by oxidizing organic matters, which can be from wastewater, biomass, and other feedstocks. The electrons flow will produce a direct electrical current, causing the potential differences between the anode and cathode compartments. The aromatic sulfonation of membrane may result in acidity changes in the anode, causing microbe inhibitions. The PVA based novel membrane was developed and used as the electrolyte to overcome the above problems. The brewer’s yeast (S. cerevisiae) as a biocatalyst was used in MFCs due to the resilience to environmental changes and simple mechanism of electron transfer. The S. cerevisiae an eukaryote was found to easily retrofit into ethanol plants for in situ power generation, which were found improve the microbial fuel cell performance by our study. This study indicated that anodic biofilm modification using nanoparticles is an effective approach to improve electrochemical activities due to their high surface area and high electronic conductivity. The red-light facilitates the efficient electron transfer through mediated redox couples within the anodic biota-anchored films. These redox mediators may represent an electronic network permeating the biofilm that can promote long-range electrical transfer in an energy-efficient manner, as a result of increasing MFC electricity production. As society migrates from consumption of gasoline to low carbon-based fuels, the MFCs becomes important to produce electrical energy with near zero net emission. Figure 1

M. Moqsud, Yuichiro Kanehagi

Japanese Geotechnical Society Special Publication • 2016

In this study, a microbial fuel cell has been designed for the marine sediment to generate bio-electricity and to improve the geo-environmental condition simultaneously. Four different kinds of sediments were used in the laboratory tests to generate the bio-electricity. The acid volatile sulfide (AVS) was measured to verify the improvement of the geo-environment of the marine sediment. The effects of temperature, number of anode and the different conditions of the circuit were evaluated to observe the bio-electricity generation. The amount of voltage value showed almost twice when two anodes were used compared with single anode. Higher temperature showed the higher voltage due to enhanced activity of the bacteria in the higher temperature. Acid volatile sulfide values reduced quickly when the circuit was completed. All the samples showed the decreasing trend of AVS value with time and reached at the 0.2 mg/g dry mud indicating the geo-environmental improvement of the marine sediments.

, Phuwadon Bunlengsuwan

• 2015

The proton exchange membranes (PEMs) are being developed intensively due to their great potential as a promising power source for transportation, residential, and portable applications. In this work, the novel PEMs consisting of inorganic fillers embedded in sulfonated polysulfone (S-PSF) were fabricated. The effect of zeolite Y and sulfonated graphene oxide (S-GO) was investigated on the thermal and mechanical stability, water uptake, proton conductivity, and methanol permeability. The proton conductivity of S-PSF/zeolite Y membrane increased with increasing zeolite Y content, in parallel with the methanol permeability. It was due to its water retention property. The highest proton conductivity was found at 3 % v/v of S-GO because of the increment of sulfonic acid groups by incorporating of S-GO. The S-GO particles positively affected for blocking water and methanol molecules, caused by the increasing of interfacial interaction between S-PSF and S-GO, leading to the decreases in the water uptake and methanol permeability. Besides, the hybrid membranes, which were S-PSF membrane mixing with both zeolite Y and S-GO, were investigated. They also showed better performance than the pristine S-PSF and Nafion 117 membrane. Therefore, all composite membranes are a potential candidate for being used in DMFC applications.

Franz Clementschitsch, Karl Bayer

Microbial Cell Factories • 2006

Abstract The advancement of bioprocess monitoring will play a crucial role to meet the future requirements of bioprocess technology. Major issues are the acceleration of process development to reduce the time to the market and to ensure optimal exploitation of the cell factory and further to cope with the requirements of the Process Analytical Technology initiative. Due to the enormous complexity of cellular systems and lack of appropriate sensor systems microbial production processes are still poorly understood. This holds generally true for the most microbial production processes, in particular for the recombinant protein production due to strong interaction between recombinant gene expression and host cell metabolism. Therefore, it is necessary to scrutinise the role of the different cellular compartments in the biosynthesis process in order to develop comprehensive process monitoring concepts by involving the most significant process variables and their interconnections. Although research for the development of novel sensor systems is progressing their applicability in bioprocessing is very limited with respect to on-line and in-situ measurement due to specific requirements of aseptic conditions, high number of analytes, drift, and often rather low physiological relevance. A comprehensive survey of the state of the art of bioprocess monitoring reveals that only a limited number of metabolic variables show a close correlation to the currently explored chemical/physical principles. In order to circumvent this unsatisfying situation mathematical methods are applied to uncover "hidden" information contained in the on-line data and thereby creating correlations to the multitude of highly specific biochemical off-line data. Modelling enables the continuous prediction of otherwise discrete off-line data whereby critical process states can be more easily detected. The challenging issue of this concept is to establish significant on-line and off-line data sets. In this context, online sensor systems are reviewed with respect to commercial availability in combination with the suitability of offline analytical measurement methods. In a case study, the aptitude of the concept to exploit easily available online data for prediction of complex process variables in a recombinant E. coli fed-batch cultivation aiming at the improvement of monitoring capabilities is demonstrated. In addition, the perspectives for model-based process supervision and process control are outlined.

, Vorachatra Sukwattanajaroon

• 2010

This research investigated the performance improvement of bioethanol-fuelled Solid Oxide Fuel Cell (SOFC) system with pervaporation. Two types of membrane, hydrophilic and hydrophobic were employed in a pervaporation integrated with SOFC system and their corresponding overall electrical efficiencies were compared. The results indicated that the system with hydrophobic membrane required much less thermal energy about 1/4 times and offered a higher overall electrical efficiency compared to the system with hydrophilic membrane. High ethanol separation factor values of hydrophobic membrane were required when the purification system was operated at higher ethanol recovery to achieve more overall efficiency. However, the real membranes which had high enough separation factor values of the hydrophobic type were limited. Afterwards, vapor permeation was proposed to be further installed after a hydrophobic pervaporation (hybrid vapor permeation-pervaporation) to solve the previous problem. Based on energy self-sufficient condition and PTMSP membrane regarded as the poorest separation performance, the simulation results showed that it could offer the overall electrical efficiency of about 2.4 times when installing a hydrophilic vapor permeation compared with the case of using the pervaporation alone. Among the different purification processes at base case, the overall electrical efficiency can be ranked by the following order: Hybrid vapor permeation-pervaporation > pervaporation > distillation column, respectively.

, Nattaphol Ruangrassamee

• 2006

This study was carried out to investigate the possible improvement of SOFC performance by using multiple stacks arranged in series in which the operating voltages were allowed to vary among the different stacks. The comparative study on the operation in conventional SOFC configuration in which multiple stacks are typically arranged in parallel and the alternative ones in which stacks are networked in series is considered in both case i.e with and without considering the effect of pressure drop. By connected the stacks in series instead of in parallel, the power and electrical efficiency improvement as high as 5.0% can be achieved. Moreover, the improvement by the arrangement in series becomes less significant after the number of stacks more than 2. The configuration in series with one compressor installed only at the inlets of the first stack is the best option when taking into account the pressure drop. However, the pressure drops are about 4.7 and 3.75 times in the anodic and cathodic channels, respectively, compared with those from the case with stack arrangement in parallel. Therefore it requires higher consumption of compression power. It was suggested that, to compensate a part of power consumption from installed compressors, the heat recovery system should be installed to offer the practical operation.

, Supawat Vivanpatarakij

• 2007

The research focuses on the improvement of methane-fuelled solid oxide fuel cell system. Three improvements of the system were considered: 1) Operating under a non-uniform potential operation (SOFC-NUP), 2) Implementing a membrane reactor to the SOFC system (SOFC-MR) and 3) Integrating a CaO-CO₂ acceptor with the SOFC system (SOFC-CaO). For SOFC-NUP, the optimum split ratios of Sp,1 = 0.55 and Sp,2 = 0.45 was found to improve power density as high as 9.2%. In addition, the increase in the number of separated section (n) of the cell could increase the achieved maximum power density but less pronounced after n > 3. For SOFC-MR, an SOFC system integrated with a palladium membrane reactor operating at different modes; i.e., high pressure compressor (MR-HPC), vacuum pump (MR-V) and combined high pressure compressor and vacuum pump (MR-HPC-V) was considered. The power density of the SOFC was improved, depending on the increasing hydrogen recovery (). At high electrical efficiency, the SOFC-MR system became more attractive than the conventional system. It was found that the MR-HPC-V was the best operation mode among MR-SOFC systems. For the CaO-CO₂ acceptor SOFC systems, the CO₂ capture efficiency (Ec) depends on fresh feed CaO (F0), recycled CaO (FR) and amount of CO₂ ¬fed through. The CaO-CO₂ SOFC systems (i.e. CaO-After-Burner, CaO-After-SOFC and CaO-Before-SOFC) were compared with the conventional SOFC. Only CaO-Before-SOFC can improve SOFC performance which depends on both CO2 capture efficiency (Ec) and fuel utilization (Uf). The CaO-SOFC system can operate at lower cost than the conventional SOFC. The total added cost/reduced CO2 ($.mol-1) are in the sequence of the CaO-After-Burner > CaO-After-SOFC > CaO-Before-SOFC. Unfortunately, CaO-Before-SOFC can not reduce CO2 more than 40%. When the CO₂ reduction was required more than 40%, the CaO-After-SOFC was a suitable choice for the SOFC-CaO system.

Mukul Chankaya, Aijaz Ahmad, Ikhlaq Hussain et al.

IEEE Transactions on Industry Applications • 2022

This article presents a photovoltaic (PV)–battery energy storage (BES) system functioning in both grid-tied and standalone modes while performing multifunctional operations, including reactive power compensation, power balancing, and power quality enhancement. The PV–BES system ensures uninterrupted power supply to the critical loads even during seamless transitions from grid-tied mode to islanded mode, and vice versa. The incremental conductance technique controls the boost converter and confirms maximum PV power extraction. The bidirectional converter connects BES to the dc bus. The dc bus voltage $({{V}_{dc}})$ is regulated by a slime mold optimized proportional-integral controller to limit the dynamic state variation and improve stability. The voltage-source converter (VSC) is controlled by a minimum kernel-risk-sensitive mean p-power loss algorithm during the grid-synchronization mode. In contrast, the voltage control algorithm executes islanded control of VSC. The VSC control transition is achieved seamlessly without any significant disturbance at the point of common coupling. The hardware test results demonstrate that the present system remains stable during dynamic conditions and performs adequately as per the IEEE 519-2014 standard.

Y. Singh, Bhim Singh, S. Mishra

IEEE Transactions on Industrial Electronics • 2022

This article aims to develop a solar- battery energy storage (BES) based system, which ensures an uninterruptable supply to loads irrespective of availability of the grid. This system comprises of a solar photovoltaic (PV) array, a BES, the grid and local residential loads. A new control is implemented such that the active power demand of residential loads, is fed from the PV array, a BES unit and the utility grid. In this system, the power control operates in different power modes, which delivers the benefits to the end users with an integration of BES and an excess of PV array power, which is sold back to the grid. For this, an effective control logic is developed for the grid tied voltage source converter. Moreover, this system deals with the issue of an integrating power quality enhancement along with the power generation from the solar PV source. The cascaded delayed signal cancellation based phase locked loop is implemented for grid synchronization during the grid voltage distortion. The developed control is easily implemented in a real time controller (dSPACE-1202). Test results validate the performance of the implemented control in different operating conditions such as varying solar power generation, load variations and unavailability of the grid.

R. Bès, G. Gas, J. Molinier et al.

Ozone: Science & Engineering • 1989

Abstract Treatment of poplar sawdust with ozone in a fixed bed reactor results in greatly enhanced susceptibility to cellulase enzyme hydrolysis. Ozone attacks lignin and hemicellulose in preference to cellulose giving water soluble products.

V. Yadav, A. Verma, Bhim Singh et al.

2020 International Conference on Power, Instrumentation, Control and Computing (PICC) • 2020

The non conventional energy generation is a cleaner alternative of greener AC microgrid. This paper presents the performance enhancement of a non conventional energy based microgrid for the seamless grid synchronization. A robust control strategy is used for wind energy conversion system (WECS) and battery energy storage (BES) based nonconventional energy system (NCES) with seamless changeover proficiency from an islanded (IL) mode to the grid-connected (GC) mode and grid reconnected (GR) mode. The NCES has a capability to feed the load both in GC and IL modes and it operates smoothly during mode shifting from IL to GC and GC to IL. The unknown disturbances and ambiguity of NCES in GC mode are taken care by multilayer harmonic decoupling network based quadrature fourth order complex filter (MHDN-QFOCF). The issues like fluctuation in power, DC offset, voltage unbalance, swell/sag produced by WECS, are successfully taken care by MHDN- QFOCF. . With the help of this algorithm, the l quadrature sinusoidal fundamental component (Q-SFC) is extracted. It improves overall system capability of power flow. To control the NCES in an IL mode, the proportional plus resonant (P+R) based control algorithm is used. A dual fourth order complex filter (DFOCF) is combining to phase locked loop (PLL) and develops DFOCF-PLL for precise and smooth synchronization and resynchronization of grid. DFOCF-PLL improves system performance without affecting the stability. During frequency variation, it effectively follows the voltages of the grid and the load and it is adjustable to different conditions of grid. Moreover, total harmonic distortions (THDs) of the load and grid parameters are in the limits of the IEEE-519 standard.

J. Bai, Y. Ban, J. Bian et al.

30 Years of BES Physics • 2020

(BES Collaboration) J. Z. Bai, Y. Ban, J. G. Bian, X. Cai, J. F. Chang, H. F. Chen, H. S. Chen, J. Chen, Jie Chen, J. C. Chen, Y. B. Chen, S. P. Chi, Y. P. Chu, X. Z. Cui, Y. M. Dai, Y. S. Dai, L. Y. Dong, S. X. Du, Z. Z. Du, W. Dunwoodie, J. Fang, S. S. Fang, C. D. Fu, H. Y. Fu, L. P. Fu, C. S. Gao, M. L. Gao, Y. N. Gao, M. Y. Gong, W. X. Gong, S. D. Gu, Y. N. Guo, Y. Q. Guo, Z. J. Guo, S. W. Han, F. A. Harris, J. He, K. L. He, M. He, X. He, Y. K. Heng, T. Hong, H. M. Hu, T. Hu, G. S. Huang, L. Huang, X. P. Huang, J. M. Izen, X. B. Ji, C. H. Jiang, X. S. Jiang, D. P. Jin, S. Jin, Y. Jin, B. D. Jones, Z. J. Ke, D. Kong, Y. F. Lai, F. Li, G. Li, H. H. Li, J. Li, J. C. Li, K. Li, Q. J. Li, R. B. Li, R. Y. Li, W. Li, W. G. Li, X. Q. Li, X. S. Li, C. F. Liu, C. X. Liu, Fang Liu, F. Liu, H. M. Liu, J. B. Liu, J. P. Liu, R. G. Liu, Y. Liu, Z. A. Liu, Z. X. Liu, X. C. Lou, G. R. Lu, F. Lu, H. J. Lu, J. G. Lu, Z. J. Lu, X. L. Luo, E. C. Ma, F. C. Ma, J. M. Ma, R. Malchow, Z. P. Mao, X. C. Meng, X. H. Mo, J. Nie, Z. D. Nie, S. L. Olsen, D. Paluselli, H. P. Peng, N. D. Qi, C. D. Qian, J. F. Qiu, G. Rong, D. L. Shen, H. Shen, X. Y. Shen, H. Y. Sheng, F. Shi, L. W. Song, H. S. Sun, S. S. Sun, Y. Z. Sun, Z. J. Sun, S. Q. Tang, X. Tang, D. Tian, Y. R. Tian, W. Toki, G. L. Tong, G. S. Varner, J. Wang, J. Z. Wang, L. Wang, L. S. Wang, M. Wang, Meng Wang, P. Wang, P. L. Wang, W. F. Wang, Y. F. Wang, Zhe Wang, Z. Wang, Zheng Wang, Z. Y. Wang, C. L. Wei, N. Wu, X. M. Xia, X. X. Xie, G. F. Xu, Y. Xu, S. T. Xue, M. L. Yan, W. B. Yan, G. A. Yang, H. X. Yang, J. Yang, S. D. Yang, M. H. Ye, Y. X. Ye, J. Ying, C. S. Yu, G. W. Yu, C. Z. Yuan, J. M. Yuan, Y. Yuan, Q. Yue, S. L. Zang, Y. Zeng, B. X. Zhang, B. Y. Zhang, C. C. Zhang, D. H. Zhang, H. Y. Zhang, J. Zhang, J. M. Zhang, J. W. Zhang, L. S. Zhang, Q. J. Zhang, S. Q. Zhang, X. Y. Zhang, Y. J. Zhang, Yiyun Zhang, Y. Y. Zhang, Z. P. Zhang, D. X. Zhao, Jiawei Zhao, J. W. Zhao, P. P. Zhao, W. R. Zhao, Y. B. Zhao, Z. G. Zhao, J. P. Zheng, L. S. Zheng, Z. P. Zheng, X. C. Zhong, B. Q. Zhou, G. M. Zhou, L. Zhou, N. F. Zhou, K. J. Zhu, Q. M. Zhu, Yingchun Zhu, Y. C. Zhu, Y. S. Zhu, Z. A. Zhu, B. A. Zhuang, B. S. Zou. 1 Institute of High Energy Physics, Beijing 100039, People’s Republic of China 2 China Center of Advanced Science and Technology, Beijing 100080, People’s Republic of China 3 Colorado State University, Fort Collins, Colorado 80523 4 Henan Normal University, Xinxiang 453002, People’s Republic of China 5 Huazhong Normal University, Wuhan 430079, People’s Republic of China 6 Hunan University, Changsha 410082, People’s Republic of China 7 Liaoning University, Shenyang 110036, People’s Republic of China 8 Nankai University, Tianjin 300071, People’s Republic of China 9 Peking University, Beijing 100871, People’s Republic of China 10 Shandong University, Jinan 250100, People’s Republic of China 11 Shanghai Jiaotong University, Shanghai 200030, People’s Republic of China 12 Sichuan University, Chengdu 610064, People’s Republic of China 13 Stanford Linear Accelerator Center, Stanford, California 94309 14 Tsinghua University, Beijing 100084, People’s Republic of China 15 University of Hawaii, Honolulu, Hawaii 96822 16 University of Science and Technology of China, Hefei 230026, People’s Republic of China 17 University of Texas at Dallas, Richardson, Texas 75083-0688 18 Wuhan University, Wuhan 430072, People’s Republic of China 19 Zhejiang University, Hangzhou 310028, People’s Republic of China ∗ Visiting professor at the University of Michigan, Ann Arbor, MI 48109 (March 7, 2003)

Gaurav Modi, Bhim Singh

2021 IEEE 6th International Conference on Computing, Communication and Automation (ICCCA) • 2021

In this work, a control algorithm is implemented for power quality enhancement in the grid-interactive micro grid, operating with nonlinear/unbalanced loads. The microgrid consists of the solar photovoltaic array (SPVA) and battery energy storage (BES), and a synchronous reluctance generator (SyRG) based wind energy system (WES). Both energy sources interact with the AC grid at PCC through a single voltage source converter (VSC) and the back-to-back VSCs, respectively. This work implements the improved multi-layer generalized integrator (GI)- quadrature signal generator (QSG) to separate the positive and negative sequence components (PNSC) for the sensed load currents fundamental component (FC) and the harmonics components (HC). These estimated components are practiced to control the grid side VSC's currents for both the energy sources to eliminate the harmonics and negative sequence currents from the injected grid currents and adhere to the IEEE std 519 at the PCC. Moreover, the SPVA-BES system currents are controlled so that no negative sequence currents flow in its VSC, eliminating the requirement of an additional converter to protect the BES from the second harmonic current. The same algorithm is exercised to evaluate the PNSC for the AC grid voltages and in the sensorless field-oriented control (FOC) of the SyRG in the WECS. Further, in the FOC, the SyRG direct axis current is controlled to minimize the winding losses to acquire maximum efficiency. Performance of the control algorithm is corroborated on a microgrid model, developed using MATLAB /Simulink and subjected to the nonlinear/unbalanced loads, varied solar insolation, and wind speed conditions.

M. Hariprabhu, M. Sarankumar, S. Sharansharvesh et al.

2023 5th International Conference on Smart Systems and Inventive Technology (ICSSIT) • 2023

This paper presents an innovative concept of photovoltaic system which includes the voltage quality issue that is rectified by active power filter. This method is useful for electric vehicle charging by using boost converter. The concepts like performance analysis of battery, increasing the efficiency of a non-linear loads and improving the power quality by using the boost converter algorithm is proposed. A Constant charging is required for EV charging which is achieved by the combination of solar PV array, Lithium Ferro Phosphate battery as battery energy storage (BES) and boost converter. By using Maximum Power Point Tracking (MPPT), the effective battery charging is executed. The threephase pulse width modulation inverter helps in maintaining the power quality enhancement and also used to charge the electric vehicle in AC supply. This work is carried out by the matlab Simulink. And also, with the execution of THD analysis, the harmonic distortion is reduced.

C. Shen, Abel Noble, J. Paquet et al.

Proceedings of 11th International Conference on Hard and Elecctromagnetic Probes of High-Energy Nuclear Collisions — PoS(HardProbes2023) • 2023

Heavy-ion collisions at $\sqrt{s_\mathrm{NN}} \sim 10$ GeV probe the QCD phase diagram at large baryon densities. Because the longitudinal Lorentz contraction is small at these collision energies, understanding the dynamics during the early phase of the collision is essential for the subsequent modeling of the system evolution and for constraining the QGP transport properties at finite baryon densities. Direct photons provide undistorted information on early-stage dynamics. We model relativistic heavy-ion collisions at RHIC Beam Energy Scan energies with a hybrid dynamical approach consisting of a 3D-Glauber initial state followed by viscous hydrodynamics and hadronic transport (MUSIC + UrQMD). The implemented thermal photon emission takes into account the enhancement from finite baryon chemical potentials. We show that direct photon spectra and their anisotropic flow coefficients have a strong sensitivity to the early stage of heavy-ion collisions. Thus, they provide constraints on QGP dynamics complementary to those obtained from hadronic observables.

Subhadip Chakraborty, Gaurav Modi, Bhim Singh et al.

2023 IEEE International Conference on Power Electronics, Smart Grid, and Renewable Energy (PESGRE) • 2023

With the reduced response time and power levelling feature of the battery energy storage (BES), it supports the power variability experienced by the grid during variability of renewable sources and load fluctuations. Moreover, the increased distortion factor of load currents contaminates the grid currents by degrading the overall system power quality and increased system losses. Therefore, there is a need for proper energy management solutions with improved converter control to regulate the BES power as well as to improve the system power quality. Hence, this work presents a solar photovoltaic array (SPVA) with a battery energy storage (BES) based grid tied microgrid. To control the microgrid, a comb filter derived mixed second-third order generalized integrator with normalized frequency locked loop (Comb-MSTOGI-NFLL) based control is deployed into SPVA converter to achieve power quality enhancement features by elimination of dominant harmonic components and DC offset from the grid currents. The control technique also involves power levelling features, with support from BES, without using an additional converter for BES. The system response with proposed control is demonstrated through simulation results.

Subhadip Chakraborty, Gaurav Modi, Bhim Singh

IEEE Transactions on Power Delivery • 2023

The local nonlinear loads impact performance of a microgrid (MG), as they degrade the system power quality (PQ). This degradation is more in a diesel generator (DG) based standalone MG than grid-connected MG. Therefore, this article introduces an enhanced adaptive multilayer complex coefficient filter (EAMCCF) control for PQ enhancement of a MG comprising a solar photovoltaic (SPV) array, battery energy storage (BES) with a synchronous reluctance type DG (SyRG). The EAMCCF removes dominant third, fifth, seventh harmonics during unbalanced/distorted load and eliminates DC offset without compromising the dynamic response. The control runs the DG set in its fuel economic zone (FEZ). EAMCCF performance is compared with existing controls like multilayer second-order generalized integrator (MSOGI), CCF, and its modified version. MG performance with EAMCCF control is verified experimentally at its steady state and during situations like varying solar irradiance and load unbalance.

Ch. Naga Sai Kalyan, Anuradha Devi Tellapati, Thalanki Venkata Sai Kalyani et al.

2024 International Conference on Distributed Computing and Optimization Techniques (ICDCOT) • 2024

This paper develops the tilt-integral-derivative (TID) plus filter (F) based on the fruit fly optimization (FFO) algorithm for the stability of the interconnected power system (IPS). The dynamic behavior of considered IPS is analyzed by laying the step load disturbance (SLD) of 10% in area-1 under the FFO-based TIDF controller. However, the efficacy of TIDF is revealed with other available controller performances in the literature. Moreover, the time delays (TDs) are believed with the IPS network to conduct the dynamic analysis near to practicality, and their significance on the system performance is revealed. Further, the system is integrated with the supplementary control mechanism of battery energy storage (BES) and static synchronous series compensator (SSSC) for performance enhancement. Simulation results reveal the improvement in system dynamic behavior with the implementation of the BES-SSSC strategy as a supplementary controller.

Syed Bilal Qaiser Naqvi, Bhim Singh

2020 International Conference on Power, Instrumentation, Control and Computing (PICC) • 2020

This work presents a grid interactive photovoltaic (PV) array generation unit, with the PV array (PVA) supplying the power directly at the DC link. The PVA power is maximized by keeping the DC link voltage at the maximum power point of the PVA. The system considers light single phase loads, as well as three phase loads, used in the distribution network, to be the local loads. During grid fault, the control detects the anomaly on the grid side. The system is decoupled and isolated from the utility, and the local loads are energized in an islanded mode. In case PVA power is insufficient, the integrated battery energy system (BES) is utilized. Thus, optimum PVA power utilization and robust supply to the local loads, is realized. After fault clearing, the on-line resynchronization of the system takes place, without disturbance to the local loads. The effect of various dynamic scenarios on the system is minimized, by the fast and continuous estimation of the load current weights, and the rapid update of grid currents, in the event of changing PVA power. Moreover, the grid power quality enhancement is realized by the implemented control strategy.

Amirullah Amirullah, Adiananda Adiananda, O. Penangsang et al.

International Journal of Intelligent Engineering and Systems • 2020

This paper presents enhancement of load active power transfer using Unified Power Quality ConditionerPhotovoltaic-Battery Energy Storage (UPQC-PV-BES) system. This system is connected to a three phase three wire (3P3W) system with a voltage of 380 V (line to line) and 50 hertz. The proposed model is also compared with UPQC and UPQC-PV respectively. The parameters investigated are load voltage, load current, load active power, and efficiency. BES functions to save excess energy generated by PV, distribute it to the load, avoid interruption voltage, and regulate the charging process and energy utilization. The fuzzy logic controller (FLC) is proposed and compared with proportional integral (PI) method to control DC voltage variable and input DC reference voltage, to produce a reference current source on hysteresis current controller on shunt active filter in 12 disturbance scenarios (scns). In Scenario (Scn) 1 to 5, the 3P3W system uses three combinations of UPQC with PI controller and FLC, still keeps load voltage and load current above 300 V and 8 A. Whereas in Scn 6, only the UPQC-PV-BES with FLC is able to maintain load voltage and load current higher compared to UPQC and UPQC-PV combinations as 304.1 V and 8.421 A, respectively. In Scn 1 to 5, the 3P3W system uses three combinations of UPQC with PI controller and FLC, capable of producing load active power above 3600 W. Whereas in Scn 6, only a combination of UPQC-PV-BES with PI controller and FLC is able to produce a load voltage of 3720 W and 3700 W, respectively. In Scn 1 to 6, UPQC-PV-BES results in lower efficiency compared to using UPQC and UPQC-PV. However, in Scn 6, UPQC-PVBES with FLC is able to produce load voltage, load current, and load active power higher than UPQC-PV and UPQC. Thus, the UPQC-PV-BES model using FLC is able to compensate load voltage and load current, as well as to enhance load active power, especially for an interruption on source bus. This research is simulated using Matlab/Simulink.

Subhadip Chakraborty, Gaurav Modi, Bhim Singh et al.

IEEE Transactions on Industry Applications • 2025

Variability of power generated by renewable energy sources and load power fluctuations reflect as grid power ramps. These power ramps monitored at point of common coupling (PCC) of individual microgrids may lead to penalties imposed by grid operator for violating grid power ramp rates specified by the IEEE std. 1547-2018. Since grid is dominated by alternators having high mechanical time constant, it imposes power ramp limit to utility grid, violating which, may lead to grid instability issues. During daytime, high solar generation leads to a rapid reduction in grid side demand curve resembling a duck shaped curve. Evening peak load situation results into a sudden ramp in grid demand curve. Variability in generation and demand lead to rapid grid power ramps. Therefore, in this work, a battery interfaced to a solar photovoltaic (SPV) array-based grid connected microgrid. Novel contributions of this work include power coordination maintaining grid side ramp rate within standard limits, prevention of duck curve formation and providing peak load shaving features using battery satisfying its constraints. These enhancements are embedded within solar inverter control without any additional cost of power electronics. Distribution static compensator (DSTATCOM) features are incorporated into the control for load harmonic, DC offset and reactive current compensation. A novel third order generalized integrator with frequency locked loop (NTOGI-FLL) control is used with improved filtering ability, DC rejection, low computational burden, and improved dynamics, comparable to advanced filters, for rapid and accurate actuation. System operation is validated through simulation and hardware results.

Subhadip Chakraborty, Gaurav Modi, Bhim Singh

2022 IEEE Energy Conversion Congress and Exposition (ECCE) • 2022

This paper focuses on the power quality improvement of a diesel generator (DG) in a standalone microgrid, in presence of local nonlinear loads that draw nonlinear currents. A standalone system comprising of a dual-stage solar photovoltaic (SPV) array, battery energy storage (BES) interfaced with a bidirectional converter (BDC), and a synchronous reluctance DG set is considered in this work. An improved mixed fifth-order generalized integrator (IMFOGI) based control algorithm is presented for control of the voltage source converter (VSC) of the SPV array. The IMFOGI control has enhanced filtering ability and it eliminates the dominant harmonic components and DC offsets from the load currents and point of common coupling (PCC) voltages and makes the DG set currents and voltages sinusoidal, even in the presence of nonlinear three-phase and single-phase loads. To extract maximum power from the SPV array, it is controlled by the incremental conductance (INC) algorithm. The DG set is run in the fuel economy zone (FEZ) for maximum fuel efficiency. The system performance with the presented IMFOGI control is analyzed in steady-state and dynamic conditions, in both simulation and hardware, using a Simulink model and experimental setup of the system prototype, respectively.

Yu Pan, Xinyu Da, Hang Hu et al.

IET Communications • 2020

: Mobile edge computing (MEC) has been envisaged as a promising technique in fifth generation (5G) and beyond wireless networks. In order to alleviate the explosive growth of computation and spectrum demand, cognitive radio (CR) and unmanned aerial vehicles (UAV) are studied in MEC-aware networks. In this study, considering a local computation and partial offloading scheme, a UAV-enabled CR-MEC framework is proposed and the authors' aim is to maximise the energy efficiency (EE) of the wireless devices (WDs). The formulated optimisation problem is not convex and challenging to be solved. To deal with it, an equivalent reformulation of this EE maximisation problem is introduced, and the authors decompose the original problem into two sub-problems, wherein the sub-problems become tractable and can be solved by jointly optimising sensing time, offloading power and WD-UAV scheduling. Numerical results highlight the EE enhancement with various system parameters and reveal the superiority of the proposed algorithm than other schemes with low computational complexity.