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A cascaded generalized integral control algorithm is presented in this article for a solar energy transfer system (SETS), connected to the grid. The control algorithm introduces a two part fundamental component extraction such as, primary harmonics filter with higher order harmonic reduction and dc-offset rejection, and secondary fine fundamental component tuning with fractional order and lower harmonics rejection property. This SETS transfers electrical energy converted from solar radiant energy, efficiently to the three-phase distribution grid. The two-stage system consists of a boost type dc–dc converter on the primary side. Moreover, the incremental conductance algorithm-based operation of the boost converter ensures maximum power output from the photovoltaic (PV) array. This system is designed to meet load demands and feeds remaining power to the grid. It mitigates the reactive power and harmonics requirements of the load at any irradiance level, and thereby keeps the balanced sinusoidal grid currents, in-phase with the respective grid voltages. As the PV array power and load power are varying, performance of SETS with adverse operating conditions is validated in this work. A prototype is developed and tested under varying irradiance conditions as well as nonlinear unbalanced load. The steady-state and dynamic behaviors of the system during transient operating conditions are expressed to substantiate the acceptability of the control technique for multiobjective grid-connected SETS.

In this article, a novel single-layer decoupled multiple-order generalized integral-based control algorithm is used for a single-stage solar energy grid integrator (SEGI) with maximum power extraction. The single-layer decoupled structure is used to extract the fundamental component of load current. Moreover, the online grid frequency estimation is carried out for an accurate band-pass filtering. The single-layer architecture of the control for the three-phase load current estimation, reduces the control complexity, and improves the response time. Moreover, the single-stage system is operated with the maximum power point tracking based on the residual incremental conductance algorithm. Hence, the cost of a new conversion stage and additional control are saved. This system is operated under three operating modes. In “normal-mode,” it feeds power to the load and the grid. Wherein the “sharing mode,” SEGI and grid supply the load power. During the night, SEGI functions as an active filter, which is termed as “filter-mode.” The steady-state and dynamic performances of SEGI during each operating mode and transition between the modes due to irradiation variation as well as load fluctuation are verified experimentally on a developed prototype. Moreover, test results under dynamic load variations such as nonlinear and unbalanced load conditions are presented to validate the theoretical claims.

The high power grid integrated solar energy system (GISES) prefers multilevel inverters for reduced switching losses and lower harmonics in the injected current. The integration of solar PV array with multilevel inverters (MIs) requires a proper selection of multioutput dc–dc converters. Moreover, the performance of two-stage GISES with isolated multioutput dc–dc converters and dc–ac multilevel inverters are less investigated in the literature. In this article, a cascaded H-bridge multilevel inverter with isolated multiple-output zeta converter is used. It exhibits reduced switching stresses and improved efficiency, concerning to multiple dc–dc converters fed MI. The maximum power point tracking method, based on the firefly algorithm, is implemented on the isolated multiple output zeta converter to ensure maximum power extraction at adverse irradiation conditions. The power quality improvement and active power exchange through a band stop generalized integral control, and the grid synchronization is achieved through an enhanced phase-locked loop method. The proposed system is designed and simulated in MATLAB/Simulink, and the results validate the theoretical claims. The performance of the GISES is verified using an experimental prototype developed with the help of a dSPACE Micro Lab Box and a solar PV simulator.

Organic nonlinear optical l-phenylalanine d-mandelic acid (LPDMA) single crystals have been harvested adopting slow solvent evaporation solution growth technique (SSEST) with growth period of 15 days. The XRD studies of the crystal confirm the non-centrosymmetric nature of the crystal. The presence of functional groups for the formation of the compound was confirmed by Fourier Transform Infrared (FTIR) analysis. The UV–Visible spectral studies ascertained linear optical quality and estimation of optical parameters. The nonlinear optical property was studied from Kurtz-Perry powder technique and Z-scan technique. The quantum chemical calculations such as HOMO–LUMO and Molecular Electrostatic Potential (MEP) were calculated and presented. In order to find out various mechanical parameters such as Vicker’s hardness number (Hv), Mayer’s index (n), yield strength (σy) and stiffness constant (C11), Vicker’s microhardness tester was utilized.

Glycine and its related compounds play a prominent role in the field of nonlinear optical studies and of fibre optical communication. In the present work, glycine sodium nitrate (GSN) crystal was grown using the method of slow evaporation method. The GSN crystal belongs to space group Cc in the monoclinic system. Using the FTIR spectrophotometer, the different functional groups have been qualitatively identified. A UV–Vis–NIR spectroscopy was used to record the optical absorption spectra, and the optical energy bandgap of GSN crystal is reported. The SHG conversion efficiency of GSN is determined by Kurtz and Perry technique. The Z-scan experiment was conducted to analyze GSN crystal for third-order NLO behavior and it is used to calculate the values of the nonlinear absorption coefficient, nonlinear refractive index, and third-order nonlinear susceptibility. Third-generation harmonic studies reveal that GSN is an excellent material useful in the fabrication of NLO devices due to its nonlinear response characteristics. The thermal stability of the grown crystal was determined through TG/DTA examination. Also photoconductivity studies confirm the negative photoconductive behavior of GSN and I–V characteristics measurement that have been carried out. The dielectric loss is significantly low and this supports defect-free growth of the crystal. These properties of GSN make it a good candidate in the fabrication of NLO devices.

A high gain multilevel inverter (HGMLI) based solar power transfer system (SPTS) is proposed in this paper. The five-level symmetrical source topology consists of eight semiconductor switches and two non-isolated DC sources. The HGMLI is comprised of a multilevel generator unit and a polarity alternating unit. Four switches in the circuit operate to achieve unipolar multiple levels and another four switches change the alternate polarity to get the desired five-level AC output voltage. Four switches are operated in level-shifted pulse width modulation and the other four are at the fundamental frequency. Moreover, the polarity alternating switches are operated at zero voltage levels to reduce the switching losses. A voltage booster circuit extracts maximum power from the photovoltaic (PV) array and exhibits a high gain in the voltage transformation for obtaining the desired DC-link voltage even for a low input voltage. The MLI is controlled by a second-order generalized integral-based filter to integrate active power to the grid. At the point of common coupling (PCC), a nonlinear harmonic load is connected, and its impact on grid power quality is mitigated by the SPTS operation maintaining within IEEE limits. Hence, maximum power extraction, active power injection, and power quality enhancement are the major objectives of this work. The proposed system performance is validated at different operating conditions with extensive analysis in the MATLAB/Simulink model.

The technology of electrical energy generation from the renewable energy sources is emerging as a solid solution to meet the fast-growing electrical energy demand. The dependency of the power generation with the climatic variations is challenging the reliable power supply. It also promotes the conventional fossil fuel-based power generation units in conjunction with renewable sources. This paper presents an efficient energy management system based on a pumped hydro storage power plant (PHSPP) for a high-power solar photovoltaic (PV) generation system. Pumped storage plants are being used in power systems for peak power management but the PHSPP with grid power quality improvement and renewable energy integration is reporting for the first time. Here, the system is demonstrated for supporting the grid power demand during the power fluctuations from PV power plants. It is able to satisfy the grid power demand, by absorbing excess PV power to pump the water to the reservoir when PV power is in excess of grid power demand and vice versa. Moreover, the PV inverter is controlled for power quality improvement. Variable and nonlinear substation loads are connected at the system common point. The PV power plant converter unit mitigates the load's reactive power and harmonic demands. It is presented as a promising solution for improving the power reliability of high-power PV power plants. The system is tested in the MATLAB/Simulink platform, and the theoretical claims are validated with results. Moreover, an experimental prototype is being developed, and few results are included in this manuscript, which supports the simulation results.

The fuel cell grid integration is presented in this article which is achieved using an interleaved boost bonverter with voltage multiplier cell (IBC-VMC). The converter is made up of two stages: an interleaved boost stage with inductors and switches, and a voltage multiplier stage with diodes and capacitors as the main components. The IBC-VMC offers a high gain voltage ratio with low voltage stress and inductor current are equal regardless of the number of levels. The efficiency of the interleaved stage is improved by uniform sharing of the interleaved stage, which decreases conduction losses. To suffice the requirement of fuel cell this topology is helpful. Therefore fuel cell-based interleaved boost converter with VMC for a grid is illustrated and verified with simulation results.

This paper presents a grid connected seven level multilevel inverter for Solar Photo Voltaic (SPV) application. The inverter requires eight switches and two input DC sources to generate seven levels at the output. The DC input is provided by a Single - Input Dual - Output (SIDO) boost DC to DC converter. The input of the SIDO converter is connected to a Solar PV panel. The MLI is integrated with utility grid and controlled using a Particular Resonant (PR) controller. The system is designed and implemented using Matlab\Simulink. Various waveforms have been observed and recorded. Also the THD of the output waveforms were also recorded.

A new seven-level multilevel inverter (MLI) with dual isolated input for grid-connected photovoltaic energy transfer system (PETS) is proposed in this paper. It has six unidirectional and one bidirectional semiconductor switches for realizing the seven-level output. The MLI finds application in photovoltaic (PV) energy transfer systems, where the requirement of two isolated DC sources is fulfilled by proper solar panel management. The bidirectional switch reduces the control overburden and improves circuit compactness as compared with the cascaded H-bridge MLI. The grid-connected PETS is designed to deliver the available PV power to load, connected in the distribution bus, as well as injects the remaining active power to the grid with a unity power factor (UPF). Moreover, PETS mitigates the reactive and harmonic demand of load irrespective of PV output and maintains the grid power quality within the IEEE-519 standard. The steady-state and dynamic performance of the proposed system is validated by using MATLAB/Simulink model, and the prototype for the MLI is developed and tested in the laboratory.

Hybrid systems comprising renewable energy sources based distributed energy generation connected to the grid with energy storage systems increase the cost and control complexity. But, to provide reliable power to the grid, storage systems are essential. Here, a grid-connected Photovoltaic-Fuel cell hybrid system with a fixed power dispatch to the grid using a modified least mean square control has been proposed. This has been realized to control the power flow from the sources and the load. Any variation in the photovoltaic power is balanced by power from the fuel cell by introducing a power management scheme. The change in power flow to the load arising at the transient stage due to the slow response of the fuel cell is met by power support from the grid. Moreover, the hybrid system mitigates power quality issues at the point of interconnection in the grid. The performances of the system during steady-state and transient conditions are verified by extensive simulation analysis with MATLAB with its simpower system block set.

A new single-phase multilevel inverter topology based on the trinary source is presented in this paper. The proposed inverter is capable of generating nine-level output with two sources in a 3:1 ratio. The circuit consists of six unidirectional and two bidirectional switches to produce the nine-level output voltage. The prominent advantage other than the reduced device count is that it works in four quadrants of operation with inductive loads, making it suitable for grid integration of renewable energy sources. The performance of the inverter is substantiated using Matlab/Simulink platform. The total harmonic distortion of the load current is found to be under IEEE-519 standards, and the increased output voltage level reduces the THD in the load voltage.

For power conversion in wind energy conversion systems, fast and smooth performance is essential. Here, a control system in which optimum torque control and zero d-axis current control is combined for better performance of machine side converter in terms of maximum power point tracking. Using the control discussed, the wind energy conversion system is able to extract maximum available power from wind at varying wind speeds.The synchronous reference frame theory based control is applied to grid side converter for DC-link voltage control and better grid synchronization. As a whole, the explained control system for direct driven PMSG based WECS provides better performance in machine side and grid side, at varying wind speed conditions.

A single-stage multilevel inverter (MLI) based solar energy conversion system for the grid integration is presented in this paper. An improved packed-U cell (IPUC) with asymmetrically managed DC sources, is presented for seventeen level output voltage with a minimum component count. The increased efficiency, reduced control complexity, and reduced voltage stress in MLI switches are the advantageous properties of IPUC-MLI. The asymmetrical IPUC produces 17-levels in the output voltage, using three unidentical sources of magnitudes in the ratio 1:2:5 and ten switches. The asymmetrical DC sources for an IPUC is realized using proper solar panel management, and these higher number of levels with reduced THD (Total Harmonics Distortion) ensures output power quality with low-frequency switching. This topology is tested at a nonlinear load connected distribution network, and the test results are analyzed using MATLAB software. A prototype of an IPUC-MLI is developed and the test results are produced for validating the claims.

In this paper, the performance of a modified DC-DC single-ended primary inductance converter (SEPIC) as the first stage of a grid integrated solar photovoltaic (PV) system is analysed. The incremental conductance (INC) based maximum power point tracking (MPPT) algorithm is used to control the high gain SEPIC converter while the inverter at the stage is synchronized to the grid by real time unit template monitoring. The chosen SEPIC topology provides high voltage gain at moderate duty ratios and removes the panel hotspot issues. The proposed system is designed and studied in MATLAB/Simulink platform under different test conditions. The performance of modified SEPIC converter and the overall grid tied system is found to be satisfactory under varying irradiation conditions and in terms of THD standards.

Purpose: The study aims to estimate the differences in vaginal surface, bladder, and rectal doses when adjuvant intracavitary brachytherapy is carried out with ovoids or with vaginal cylinders, in postoperative carcinoma endometrium and to assess the difference in variability in organs at risk (OAR) doses and thereby the reproducibility of application in subsequent sittings. Materials and Methods: Fifteen patients each received vaginal brachytherapy with ovoid and cylindrical applicators. The dose received by 0.1 cc, 1.0 cc, 2.0 cc, 5.0 cc, and 10.0 cc volumes of the OAR, namely, bladder, and rectum were analyzed using independent t-test. Interfractional variation in dose to OAR was evaluated using a two-way repeated ANOVA test. The dose received by the upper 2 cm of vagina was assessed using volume receiving 100% (V100) and dose received by 100% (D100) for documenting dose distribution to the target volume. Results: The mean dose to rectum and bladder were significantly lesser with ovoids (P < 0.0001). This difference was seen in all volumes analyzed. V100 (99.05% vs. 67.7%, P < 0.0001) and D100 (95.70% vs. 53.08%, P < 0.0001) were significantly better with cylinders compared to ovoids. There was no statistically significant interfractional variation between sittings with either applicator. Conclusion: The two applicators studied have different dosimetric properties conferring specific advantages and disadvantages as far as dose to OARs and target is concerned. Both applicators provide good reproducibility. The choice of applicator would ultimately depend on the clinical outcomes of these dosimetric differences which need to be prospectively analyzed.

Optically active single crystals of L -phenylalanine D -methionine (LPDM) were grown by slow evaporation technique by co-crystallization of amino acids L -phenylalanine and D -methionine in water. The unit cell dimensions have been identified from single crystal X-ray diffraction technique. The existences of various hydrocarbyls were examined by FTIR and FT-Raman spectroscopy. The carbon and hydrogen environment of the grown crystals were analyzed by FT NMR spectrum. The optical absorption studies show that the crystal is transparent in the visible region with a lower cut-off wavelength of 259 nm and there by optical band gap energy E g is calculated to be 5.35 eV. The Urbach energy, extinction coefficient, reflectance were calculated from UV-absorption data. Further, the thermal stability and accurate melting point has been investigated by TG/DSC techniques. The Kurtz powder SHG was confirmed using Nd:YAG laser with fundamental wavelength of 1064 nm. The dielectric behavior of the specimen has been determined for various temperatures (313 K, 333 K, 353 K, 373 K) at different frequencies. Fluorescence study and the time resolved decay calculation was also performed for the LPDM crystal. Optical nonlinear susceptibility was measured in LPDM and the real and imaginary part of χ 3 was evaluated by Z-scan technique using open and closed apertures.

A nonlinear optical bulk single crystal of L-methionine admixtured D-mandelic acid (LMDMA) has been grown by slow solvent evaporation technique using water as solvent at ambient temperature. The crystallized LMDMA single crystal subjected to single crystal X-ray diffraction study confirmed monoclinic system with the acentric space group P2 1 . The FTIR analysis gives information about the modes of vibration in the various functional groups present in LMDMA. The UV–visible spectral analysis assessed the optical quality and linear optical properties such as extinction coefficient, reflectance, refractive index and from which optical conductivity and electric susceptibility were also evaluated. The frequency doubling efficiency was observed using Kurtz Perry powder technique. A multiple shot laser was utilized to evaluate the laser damage threshold energy of the crystal. Discrete thermodynamic properties were carried out by TG-DTA studies. The hardness, Meyer's index, yield strength, elastic stiffness constant, Knoop hardness, fracture toughness and brittleness index were analyzed using Vickers microhardness tester. Layer growth pattern and the surface defect were examined by chemical etching studies using optical microscope. Fluorescence emission spectrum was recorded and lifetime was also studied. The electric field response of crystal was investigated from the dielectric studies at various temperatures at different frequencies. The third-order nonlinear optical response in LMDMA has been investigated using Z-scan technique with He-Ne laser at 632.8 nm and nonlinear parameters such as refractive index (n 2 ), absorption coefficient (β) and susceptibility (χ 3 ) investigated extensively for they are in optical phase conjucation, high-speed optical switches and optical dielectric devices.

An efficient nonlinear optical semiorganic material L -valinium L -valine chloride (LVVCl) was synthesized and grown-up by means of slow evaporation process. Single crystal XRD evince that LVVCl corresponds to monoclinic system having acentric space group P21. The diverse functional groups existing in LVVCl were discovered with FTIR spectral investigation. The UV-Visible and photoluminescence spectrum discloses the optical and electronic properties respectively for the grown crystal. Several optical properties specifically extinction coefficient, reflectance, linear refractive index, electrical and optical conductivity were also determined. The SEM analysis was also carried out and it portrayed the surface morphology of LVVCl. The calculated value of laser damage threshold was 2.59 GW/cm2. The mechanical and dielectric property of LVVCl was investigated employing microhardness and dielectric studies. The second and third order nonlinear optical characteristics of LVVCl was characterized utilizing Kurtz Perry and Z scan technique respectively clearly suggest its suitability in the domain of optics and photonics.

In this paper a pumped storage plant with BLDC motor drive for single stage grid connected PV system based distributed generation is proposed. Grid Synchronization is done with synchronous reference frame (SRF) based control for improving grid power quality. A brushless DC motor drive without phase current sensors is used for water pumping. Hall effect sensor control is used for the speed control of BLDC motor. During day time PV feeds the load and excess power is used to pump the water from a lower reservoir to an upper reservoir for pumped storage. At night with the pumped water head BLDC generates power, pumped storage plant can be operated to feed the load and excess power is delivered to the grid. If pumping is not required, the excess PV output can be fed to the three-phase grid. fed. The utility grid will provide supply to the load if both PV output and Pumped Storage Plant outputs are insufficient. The whole system model is simulated in MATLAB/Simulink platform. The steady-state and dynamic, performance under various operating conditions are carried out and the simulation results are produced

This paper proposes an improved H-bridge multilevel inverter in the photovoltaic power conversion system (PPCS) system which is connected to the distribution grid. The power quality is improved with the number of levels and balanced active power sharing between the sources has been achieved. The bidirectional power flow is achieved. The two-stage SPVS extracts the maximum power from the solar panels through the incremental conductance (IC) algorithm based control of the DC-DC converter. The system is designed with multi-functional objectives such as reactive power support and load harmonic mitigation in addition with the active power penetration to the grid. The system is modelled and simulated in MATLAB/Simulink platform and the laboratory prototype is developed, and test results are produced for result validation.

Background. Perchlorate is an anion that occurs as a contaminant in groundwater. It originates from the improper disposal of ammonium perchlorate, a component of rocket fuel. The objective of this study was to explore whether the exposure to perchlorate in drinking water had an impact on the thyroid function of the population residing near an ammonium perchlorate plant in Kerala. Methodology. Using an ecological study design, we compared the serum levels of thyroid-stimulating hormone, thyroxine, and thyroid peroxidase antibodies among a representative sample of 289 study subjects from the area surrounding the ammonium perchlorate enrichment plant to 281 study subjects in a control area. Results. The perchlorate concentration in the groundwater varied from 1600 ppb to 57,000 ppb in the 10 samples from the contaminated area and was below 24 ppb in all locations in the control area. No significant differences were found in the mean serum TSH concentration and mean T4 levels between the subjects from the contaminated area and the control area. On regression analysis, perchlorate contamination was not found to be a significant predictor of TSH. Conclusion. This study did not find any significant association between perchlorate in drinking water and changes in thyroid hormone levels. Our findings indicate the need for further investigation of this hypothesis using urinary perchlorate as a measure of individual exposure.

Multilevel inverters (MLI) have made a good vibe in industry and research areas. The classical MLI topologies are authenticated to be reasonable substitute in the vast range of medium and high power applications. In this paper, a new single phase five level MLI topology is proposed for renewable energy applications. The proposed inverter is derived from the classical cascaded H-bridge MLI topology with reduced component count. Hence, the voltage contrast and rating, cost, weight, and control complexity are curtailed. The topology is examined through simulations and authenticated with hardware implementation. A comprehensive comparison of proposed MLI is made against the classical MLI topologies.

Solid Oxide Fuel Cell (SOFC) based Transportation system have been reported as the future of human society. The SOFC based systems are pollution free and it converts fuel to electrical energy at high efficiency. The use of these fuel cell electric vehicle as stationary power production unit has added to the future prospects of such systems. This will help in creating a network of decentralized small scale power production units in the grid. Such power production units can be used effectively to meet the peak power demands in the grid.This paper proposes a grid tied Solid Oxide Fuel Cell (SOFC) system. The mathematical modelling of fuel cell given literature has been analysed and a Solid Oxide Fuel Cell (SOFC) model has been simulated. The SOFC has been further connected to a boost converter and an inverter to create a grid connected power generation system. Synchronous reference frame (SRF) theory has been used to syncronise the output of the proposed system to the grid. The proposed system has also been simulated using MATLAB with its Simpower system Blockset. The performance of the proposed system is found to be satisfactory.

Single crystals of L -phenylalanine dl-mandelic acid [C9H11NO2. C8H8O3], have been grown by the slow evaporation technique at room temperature using aqueous solution. The single crystal XRD study confirms monoclinic system for the grown crystal. The functional groups present in the grown crystal have been identified by FTIR and FT-Raman analyses. The optical absorption studies show that the crystal is transparent in the visible region with a lower cut-off wavelength of 257 nm and the optical band gap energy Eg is determined to be 4.62 eV. The Kurtz powder second harmonic generation was confirmed using Nd:YAG laser with fundamental wavelength of 1064 nm. Further, the thermal studies confirmed no weight loss up to 150°C for the as-grown crystal. The photoluminescence spectrum exhibited three peaks (414 nm, 519 nm, 568 nm) due to the donation of protons from carboxylic acid to amino group. Laser damage threshold value was found to be 4.98 GW/cm2. The Vickers microhardness test was carried out on the grown crystals and there by Vickers hardness number (Hv), work hardening coefficient (n), yield strength (σy), stiffness constant C11 were evaluated. The dielectric behavior of the crystal has been determined in the frequency range 50 Hz–5 MHz at various temperatures.

In this paper a two stage Solar Energy Grid Connected System (SEGCS) with Zeta converter for DC-DC and Cascaded H-bridge Multilevel Inverter (CHB-MLI) for DCAC conversions are proposed. The shunt connected SEGCS is demonstrated with a non linear unbalance reactive local load. The active power generated in the Photo Voltaic (PV) system with respect to the irradiations is shared to the load and the grid. The reactive and distortion power demand of load is continuously delivered by the SEGCS and therefore keeping the grid voltage and current sinusoidal and in phase by implementing Synchronous Reference Frame Theory-Phase Disposition PWM (SRFT-PDPWM) based control. The power sharing by the cascaded H-bridges improves the power rating. The increased number of levels and reduced switching frequency results reduction in harmonics and filter dimensions compared to two level inverters. The performance of CHB-MLI is compared with other topologies in this paper. The wide range operation of Zeta converter utilized for Maximum Power Point Tracking (MPPT) in addition with the firefly algorithm based duty ratio calculation. The Simulation analysis of the proposed work carried out with a 100 kVA capacity in MATLAB/SIMULINK model and a hardware prototype is developed. The steady state and dynamic performance of the SEGCS under various PV side and load side disturbances is carried out and results produced in this paper to validate the theory.

In this paper, a better control techniques known as wavelet modulation is proposed at the inverter side of wind energy conversion system. Permanent magnet synchronous generator is one of the generator used for integration of wind energy into power electronic topologies due to its simple construction & it provide direct coupling & number of poles can be change easily. A back to back converter topology is the most commonly used one, consist of rectifier on rotor side and inverter on grid side. Several modulation techniques are there for the control of inverter connected to load side in a wind energy conversion system. Switching pulses for inverter is generated using dSPACE1104 controller. The overall system is modelled and performance is verified in MATLAB Simulink & in hardware and obtained Low harmonic content and magnitude of fundamental component is high as compared to conventional techniques.

The design and simulations of a new five-level modular multilevel inverter based Dynamic Voltage Restorer (DVR) to enhance power quality (PQ) in distribution systems is presented in this paper. The load voltage is maintained at desired value while sag, swell, source voltage imbalances etc. occurring in the supply voltage. The proposed modular multilevel inverter topology based DVR require less number of components for the same number of-levels. The synchronous reference frame based control is used to control the DVR. The use of multilevel inverters in medium voltage DVR is a good solution as it reduces the need of filters and improves the injecting voltage quality. The proposed system is simulated in MATLAB software and the results validate the performance of the system.

This paper proposes an efficient maximum power point tracking method by using Vienna rectifier and hysteresis current controller for wind energy conversion system. It uses a permanent magnet synchronous generator without gear so as to increase the efficiency and reduce the cost of the system. From cut in speed to rated speed the maximum power point tracking is achieved by controlling the generator speed using optimal tip speed ratio and from rated speed to cut out speed a pitch angle controller is provided to make the power constant without affecting stability. By using MPPT the turbine is operated with maximum power coefficient and hence at maximum power output. The controller also ensures the unity power factor operation of generator. The wind turbine and generator, converter and controller are modeled using MATLAB simulink and performance is verified for maximum power point tracking and power factor correction.

Solar electrical energy generation and its conversion techniques gain more attention because Photo Voltaic (PV) power generation system is more attractive due to its advantages among all the RESs (Renewable Energy Sources). In this paper, Isolated SEPIC(Single-Ended Primary-Inductance Converter)converter fed grid connected Multilevel Inverter is proposed. SEPIC converter is a buck-boost derived topology gives regulated output voltage with varying solar energy by using single switch. The output of the SEPIC is regulated at a trinary ratio and the cascaded H-bridge multilevel inverter is used here for maximum levels in the output voltage with minimum number of power electronic switches. A low THD output voltage is created and fed to the grid. Proposed system is validated with MATLAB/Simulink model and the results are compared with the existing models.

A single stage three-phase four-wire grid connected Solar Photovoltaic System consisting of a Three leg Voltage Source Converter and a star/delta transformer is proposed. The performance of the system carried out with various control algorithms. In single stage grid connected photovoltaic system, maximum power point tracking is done using Voltage Source Converter unlike two-stage system that employs a DC-DC converter. Hence improvement in overall efficiency of system is achieved. The star/delta transformer mitigates zero sequence current in three phase four wire distribution system. The system not only provides injection of active power from solar panel to the electric grid but also performs harmonics elimination, load balancing, power factor correction and regulating the terminal voltage at the Point of Common Coupling. In this paper, the performance of the three-phase four-wire grid connected system with different control approaches namely Synchronous Reference Frame Theory, Instantaneous Reactive Power Theory and Least Mean Fourth is analyzed using MATLAB software with its Simulink and Power System Blockset toolboxes.

In this paper, different Distribution Static Compensators (DSTATCOMs) topologies, state of the art, their performance, design considerations, future developments, and potential applications are investigated for power quality improvement. These DSTATCOMs for three-phase three-wire systems and three-phase four-wire systems are developed and installed in the distribution system for many functions, such as reactive power compensation, harmonics elimination, load balancing, and neutral current compensation. This paper is aimed to explore a broad perspective on DSTATCOMs to researchers, engineers, and the community dealing with the power quality improvement. A classified list of some latest research publications is also provided for quick reference.

In this paper, different voltage injection schemes for dynamic voltage restorers (DVRs) are analyzed with particular focus on a new method used to minimize the rating of the voltage source converter (VSC) used in DVR. A new control technique is proposed to control the capacitor-supported DVR. The control of a DVR is demonstrated with a reduced-rating VSC. The reference load voltage is estimated using the unit vectors. The synchronous reference frame theory is used for the conversion of voltages from rotating vectors to the stationary frame. The compensation of the voltage sag, swell, and harmonics is demonstrated using a reduced-rating DVR.

Power quality is the main concern of this era and most of the power quality conditioners using the power converters as the main part. Hence performance of the converter is very important but low level converters create harmonic distortions in the output voltage and high dv/dt stresses leading to electromagnetic compatibility (EMC) issues and higher harmonic distortion results in malfunction of the device or other extra heating losses. A new approach to voltage source multilevel converter has been proposed here which creates a smoother sinusoidal output waveform reducing the THD (Total Harmonic Distortion) and hence finds a better position in the list of multilevel converters used for power quality conditioners. As the number of levels increases the number of power semiconducting devices also increased. In this paper, a new inverter is proposed with lower number of switches and sources in order to acquire maximum level. A 15 level inverter which employs three isolated sources and 7 switches has been developed. The new topology is framed out by cascading three half bridge and a single 'H-bridge configuration. The voltage level of each source is selected such that it has a binary weighted voltage level. In addition with the reduction of switches, a binary combination of the dc sources is selected for each level to reduce the THD as well as to reduce the number of DC sources. The performance of proposed converter is evaluated using MATLAB with its Simulink and Simpowersystems.

RFID is a wireless system which uses electromagnetic fields in identifying and tracking the tags attached to objects. Many researchers have proposed RFID based authentication schemes under the assumption that the back end server is trustworthy. This pre assumption is not found to be valid in cloud centered RFID scenarios where the tag data is outsourced to insecure third party cloud. In this context, in 2013, Xie et al had proposed a first of its kind of cloud based RFID authentication scheme. In 2015, Abughazalah et al has presented that Xie et al scheme is susceptible to reader impersonation attack, tag location tracking attack and proposed an improved version. After detailed analysis, we will demonstrate that Abughazalah et al scheme still lacks to accomplish tag location privacy. As a portion of our contribution, we propose a cloud centered RFID authentication scheme, which is robust and resistant to the above attacks. We formally evaluate the security strong points of our scheme using widely recognized CasperFDR tool.

In this paper, a neural-network (NN)-controlled distribution static compensator (DSTATCOM) using a dSPACE processor is implemented for power quality improvement in a three-phase four-wire distribution system. A three-leg voltage-source-converter (VSC)-based DSTATCOM with a zig-zag transformer is used for the compensation of reactive power for voltage regulation or for power factor correction along with load balancing, elimination of harmonic currents, and neutral current compensation at the point of common coupling. The Adaline (adaptive linear element)-based NN is used to implement the control scheme of the VSC. This technique gives similar performance as that of other control techniques, but it is simple to implement and has a fast response and gives nearly zero phase shift. The zig-zag transformer is used for providing a path to the zero-sequence current in a three-phase four-wire distribution system. This reduces the complexity and also the cost of the DSTATCOM system. The performance of the proposed DSTATCOM system is validated through simulations using MATLAB software with its Simulink and Power System Blockset toolboxes and hardware implementation.

A detailed investigation is made into the causes, standards, and remedies of the excessive neutral current. A reduced-rating voltage-source converter with a zig-zag transformer as a distribution static compensator is proposed for power-quality improvement in the three-phase four-wire distribution system. The proposed DSTATCOM is employed for the compensation of reactive power, harmonics currents, neutral current, load balancing and the voltage regulation at the point of common coupling. The zig-zag transformer is used for providing a path to the zero-sequence current. The performance of the DSTATCOM is validated through extensive simulations using MATLAB software with its Simulink and power system blockset toolboxes.

An organic nonlinear optical centric single crystal, sulphanilic acid monohydrate (SAM) was successfully grown by slow evaporation method. The cell parameters of the grown crystal were assessed by single crystal XRD. The UV absorption edge was found to be 249[Formula: see text]nm providing a wide optical transmittance covering the visible region. The thermal, mechanical and dielectric properties of the grown crystal were examined. Fluorescence emission spectrum was recorded and lifetime was studied. A multiple shot laser technique was adopted to investigate the surface laser damage of the crystal. The third-order nonlinear optical characteristics of the grown crystal, investigated by [Formula: see text]-scan technique attest its suitability in the field of nonlinear optical applications.

Continuous and efficient operation of a power system has become an issue of paramount importance in modern society. As such the Synchrophasor technology employing the Phasor Measurement Units (PMU) has emerged as a prime candidate for ensuring the goal of monitoring and controlling a power system in real time, which in effect ensures minimization of power system failures. But the existing network configuration which connects different PMUs to PDC (Phasor Data Concentrators) is prone to failure in the event of damage to the dedicated communication path between PMU and PDC. The system proposed in this paper aims to use GSM/GPRS (Global System for Mobile) communication between PMUs to establish alternate pathways of communication to ensure smooth operation until the original communication pathway is established. As a by-product it can also be used for dedicated monitoring of an individual PMU using a ‘Smart Phone’. This paper proposes a hybrid communication topology which can improve the reliability of PMU based monitoring system.

In this paper, an adaptive linear element (Adaline) based voltage and frequency (VF) controller is proposed for an isolated wind energy conversion system employing a permanent magnet synchronous generator (PMSG) for three-phase four-wire loads. A three-leg Voltage Source Converter (VSC) with a Scott-connected transformer is used as the VF controller. The Adaline based neural network is used to control the VSC of the proposed VF controller. The Adaline control technique is simple and has a fast response. The Scott-connected transformer is used for providing a path to the zero sequence current for three-phase four-wire loads. This reduces the complexity and also cost of the VF controller. The VF controller consists of insulated gate bipolar transistors (IGBTs) based 3-leg VSC with a battery energy storage system (BESS) at its dc link. The VF controller injects and absorbs both active power and reactive power by which it controls both frequency and voltage with varying consumer loads and wind speeds. The VF controller also functions as a harmonic compensator and a load balancer. The performance of the proposed VF controller is simulated using MATLAB software with its Simulink and Power System Blockset (PSB) toolboxes.

The protection to the sensitive loads from voltage sags, swells and harmonics can be achieved using the dynamic voltage restorer (DVR) in a cost effective manner. In this paper, a new control algorithm based on unit templates and instantaneous symmetrical component theory along with complex Fourier series is used for the generation of reference voltages for a dynamic voltage restorer (DVR). These voltages, when injected in series with a distribution feeder by a voltage source converter (VSC) with PWM control, can tightly regulate the voltage at the load terminals against any power quality problem in the source side. A capacitor supported DVR does not need any active power during steady state because the voltage injected is in quadrature with the feeder current. The control of the DVR is implemented through derived reference load terminal voltages. The proposed control strategy is validated through extensive simulation studies using MATLAB with its Simulink and Sim Power System (SPS) toolboxes. The DVR is found suitable to support its dc bus voltage through the proposed control under various power quality disturbances on source side.

In this paper, a solid state voltage and frequency (VF) controller is proposed for a standalone wind energy conversion system (WECS) employing a permanent magnet synchronous generator (PMSG). The proposed VF controller consists of IGBTs (insulated gate bipolar transistors) based three-leg voltage source converter (VSC) with a battery energy storage system (BESS) at its dc link. The Adaline (adaptive linear element) based neural network is used to control the VSC of the proposed VF controller. The Adaline control technique is simple and has a fast response. The VF controller is controlled to inject and absorb both active power and reactive power so that both frequency and the system voltage are regulated under varying consumer loads and wind speeds. The VF controller also functions as a harmonic compensator and a load balancer. The performance of the proposed VF controller is simulated using MATLAB software with its Simulink and SimPower System (SPS) toolboxes.

In this paper, a neural network controlled DSTATCOM (Distribution Static Compensator) using dSPACE processor is implemented for power quality improvement in a three-phase four-wire distribution system. A three-leg VSC (Voltage Source Converter) based DSTATCOM with a zig-zag transformer is used for the compensation of reactive power for voltage regulation or for power factor correction along with load balancing, elimination of harmonics currents and neutral current compensation at the point of common coupling (PCC). The Adaline (adaptive linear element) based neural network is used to implement the control scheme of the VSC. This technique gives similar performance as that of other control techniques, but it is simple to implement and has a fast response and gives nearly zero phase shift. The zig-zag transformer is used for providing a path to the zero sequence current in a three-phase four-wire distribution system. This reduces the complexity and also cost of the DSTATCOM system. The performance of the proposed DSTATCOM system is validated through simulations using MATLAB software with its Simulink and Power System Blockset (PSB) toolboxes and hardware implementation.

Precocious puberty in a child less than 3 years of age is usually gonadotropin dependent and is often associated with extrasellar central nervous system disorders. The present report describes the case of a 2½-year-old girl who presented with gonadotropin-independent precocious puberty and had a sellar mass. She was referred for neurosurgical intervention to our institute. On investigation, she was found to have primary hypothyroidism of autoimmune aetiology, which is rarely associated with precocious puberty and sellar mass due to thyrotroph hyperplasia. She was successfully treated with levothyroxine, and with this secondary sexual characteristics progressively regressed and the sellar mass disappeared.

Aim To gain insight into the prevalence of peripheral neuropathy, foot care practices, foot at risk and foot ulcers in patients with diabetes mellitus at a tertiary care centre. Methods A prospective case study involving 1044 patients with diabetes mellitus attending the diabetes clinic of a tertiary care centre in north India from January 2007 to May 2008. All subjects underwent a detailed clinical assessment including vibration perception threshold (VPT) and ankle brachial pressure index (ABI), along with metabolic parameters, and were categorized into ulcer, foot at risk and patients with no risk factors. Foot care practices were assessed with a questionnaire. Peripheral neuropathy was defined as VPT score ≥ 25 V. Peripheral vascular disease (PVD) was defined as ABI