Classical controller for coordination of wind-solar-hydro energy conversion systems in isolated region

This paper proposes a control strategy for accomplishing reliable coordination of wind-solar-hydro energy conversion systems in islanded mode of operation. With this integrated scheme, it is viable to generate electrical power from inexhaustible resources in regions having favourable meteorological conditions with limited or no connectivity to grid. In this work, the control technique is formulated to utilize the available renewable energy sources in an efficacious manner to render power at almost constant voltage and frequency to the isolated load. The control strategy of hybrid scheme is implemented and its effectiveness is demonstrated through simulation results.by Ram J. Prabhakar, and K. Ragava

STATCOM-Based Wind-Solar-Hydro Electric Power System with Modified Real and Reactive Power Controls

This paper presents a control of distributed generation (DG) system subjected to sudden rise in demand, faults on the distribution feeder and unbalanced load condition. The effects of line to ground faults on the system are investigated and control measures are taken to stabilize the generator speed and to improve voltage quality at the point of common coupling (PCC). The static shunt compensator (STATCOM) is connected at PCC to provide voltage support during sudden demand rise and fault on feeder. Moreover, the STATCOM control is devised such that even during unbalanced load condition the converter current and hydro-turbine–driven induction generator current is balanced. Owing to this, the double power frequency oscillations in the dc-link voltage and torque pulsations in generator can be averted. The STATCOM also supplies reactive power to the load. In addition to this, generation-demand mismatch is moderated using real and reactive power controllers. To demonstrate the performance of the DG system with the said control approach, model of system is simulated in Matlab–Simulink environment and the results are presented.by J. Ram Prabhakar and K. Ragava

Power Management Based Current Control Technique for Photovoltaic-Battery Assisted Wind–Hydro Hybrid System

This article proposes new power management based current control strategy for integrated wind–solar–hydro system equipped with battery storage mechanism. In this control technique, an indirect estimation of load current is done, through energy balance model, DC-link voltage control and droop control. This system features simpler energy management strategy and necessitates few power electronic converters, thereby minimizing the cost of the system. The generation–demand (G–D) management diagram is formulated based on the stochastic weather conditions and demand, which would likely moderate the gap between both. The features of management strategy deploying energy balance model include (1) regulating DC-link voltage within specified tolerances, (2) isolated operation without relying on external electric power transmission network, (3) indirect current control of hydro turbine driven induction generator and (4) seamless transition between grid-connected and off-grid operation modes. Furthermore, structuring of the hybrid system with appropriate selection of control variables enables power sharing among each energy conversion systems and battery storage mechanism. By addressing these intricacies, it is viable to regulate the frequency and voltage of the remote network at load end. The performance of the proposed composite scheme is demonstrated through time-domain simulation in MATLAB/Simulink environment.by J. Ram Prabhakar and K. Ragava

Unified controller for reliable coordination of wind-solar-hydro energy conversion systems

by Ram J. Prabhakar and K. Ragava

Theoretical Insights into the Functioning of Metallopeptidases and Their Synthetic Analogues

Conspectus The selective hydrolysis of a peptide or amide bond (−(O)­C–NH−) by a synthetic metallopeptidase is required in a wide range of biological, biotechnological, and industrial applications. In nature, highly specialized enzymes known as proteases and peptidases are used to accomplish this daunting task. Currently, many peptide bond cleaving enzymes and synthetic reagents have been utilized to achieve efficient peptide hydrolysis. However, they possess some serious limitations. To overcome these inadequacies, a variety of metal complexes have been developed that mimic the activities of natural enzymes (metallopeptidases). However, in comparison to metallopeptidases, the hydrolytic reactions facilitated by their existing synthetic analogues are considerably slower and occur with lower catalytic turnover. This could be due to the following reasons: (1) they lack chemical properties of amino acid residues found within enzyme active sites; (2) they contain a higher metal coordination number compared with naturally occurring enzymes; and (3) they do not have access to second coordination shell residues that provide substantial rate enhancements in enzymes. Additionally, the critical structural and mechanistic information required for the development of the next generation of synthetic metallopeptidases cannot be readily obtained through existing experimental techniques. This is because most experimental techniques cannot follow the individual chemical steps in the catalytic cycle due to the fast rate of enzymes. They are also limited by the fact that the diamagnetic d10 Zn­(II) center is silent to electronic, electron spin resonance, and 67Zn NMR spectroscopies. Therefore, we have employed molecular dynamics (MD), quantum mechanics (QM), and hybrid quantum mechanics/molecular mechanics (QM/MM) techniques to derive this information. In particular, the role of the metal ions, ligands, and microenvironment in the functioning of mono- and binuclear metal center containing enzymes such as insulin degrading enzyme (IDE) and bovine lens leucine aminopeptidase (BILAP), respectively, and their synthetic analogues have been investigated. Our results suggested that in the functioning of IDE, the chemical nature of the peptide bond played a role in the energetics of the reaction and the peptide bond cleavage occurred in the rate-limiting step of the mechanism. In the cocatalytic mechanism used by BILAP, one metal center polarized the scissile peptide bond through the formation of a bond between the metal and the carbonyl group of the substrate, while the second metal center delivered the hydroxyl nucleophile. The Zn­(N3) [Zn­(His, His, His)] core of matrix metalloproteinase was better than the Zn­(N2O) [Zn­(His, His, Glu)] core of IDE for peptide hydrolysis. Due to the synergistic interaction between the two metal centers, the binuclear metal center containing Pd2(μ-OH)­([18]­aneN6)]4+ complex was found to be ∼100 times faster than the mononuclear [Pd­(H2O)4]2+ complex. A successful small-molecule synthetic analogue of a mononuclear metallopeptidase must contain a metal with a strong Lewis acidity capable of reducing the pK a of its water ligand to less than 7. Ideally, the metal center should include three ligands with low basicity. The steric effects or strain exerted by the microenvironment could be used to weaken the metal–ligand interactions and increase the activity of the metallopeptidase

Mechanisms of peptide hydrolysis by aspartyl and metalloproteases

#nofulltext# --- Özbil, Mehmet (Arel Author)Peptide hydrolysis has been involved in a wide range of biological, biotechnological, and industrial applications. In this perspective, the mechanisms of three distinct peptide bond cleaving enzymes, beta secretase (BACE1), insulin degrading enzyme (IDE), and bovine lens leucine aminopeptidase (BILAP), have been discussed. BACE1 is a catalytic Asp dyad [Asp, Asp-] containing aspartyl protease, while IDE and BILAP are mononuclear [Zn(His, His, Glu)] and binuclear [Zn1(Asp, Glu, Asp)-Zn2(Lys, Glu, Asp, Asp)] core possessing metallopeptidases, respectively. Specifically, enzyme-substrate interactions and the roles of metal ion(s), the ligand environment, second coordination shell residues, and the protein environment in the functioning of these enzymes have been elucidated. This information will be useful to design small inhibitors, activators, and synthetic analogues of these enzymes for biomedical, biotechnological, and industrial applications

The structure of Chondroitin B Lyase Complexed with Glycosaminoglycan Oligosaccharides Unravels a Calcium-Dependent Catalytic Machinery

NRC publication: Ye

The Catalytic Machinery of Chondroitinase ABC I Utilizes a Calcium Coordination

The chondroitinases are bacterial lyases that specifically cleave chondroitin sulfate and/or dermatan sulfate glycosaminoglycans. One of these enzymes, chondroitinase ABC I from Proteus Vulgaris, has the broadest substrate specificity and has been widely used to depolymerize these glycosaminoglycans

Not Available

Not AvailableFood security of the country has been improved due to green revolution and enhancement of cereal production. However, recent surveys showed 35.8% of children suffer from malnutrition in India. The Indian Council of Agricultural Research has taken lead for the biofortification of cereal crops based on earlier national and international research efforts, targeting the enhancement of nutrients in staple food crops. In this article, the significant progress made in rice, wheat, maize and millets for identification of genotypes, development, evaluation and release of the varieties with high nutrient contents and their bioavailability studies is discussed.Not Availabl