Power Quality Enhancement in Grid Connected PV Systems using High Step Up DC-DC Converter

Renewable energy sources (RES) are gaining more importance in the present scenario due to the depletion of fossil fuels and increasing power demand. Solar energy is the one of the most promising as it is clean and easily available source. The voltage obtained from the PV system is low. This voltage is increased by high step up dc-dc converter which uses only one switch leads to low switching losses and hence the efficiency of this converter is high. To get the good response this converter is operated in closed loop manner. Integration of PV system with existing grid has so many issues like distorted voltage, current and reactive power control etc. This paper presents a four leg inverter which works on hysteresis current control technique to address the power quality issues like reactive power compensation, balanced load currents and compensation of neutral current. The switching to the inverter is designed in such a way that it supplies the extra current to stabilise the current of the grid that is being supplied to the loads. Finally, the proposed technique is validated by using mat lab/Simulink software and corresponding results are presented in this paper

INFLUENCE OF CARBON AND NITROGEN SOURCE ON GROWTH, DON AND NIV PRODUCTION BY TWO SPECIES OF FUSARIUM ISOLATED FROM FINGER MILLETS

Objective: Influence of different carbon [C] and nitrogen [N] source on the growth and Deoxynivalenol [DON] and Nivalenol [NIV] production by Fusarium aethiopicum and Fusarium culmorum was investigated.Methods: Seven days old monosporic cultures of F. aethiopicum strain GSKUMB [KJ21085] and F. culmorum strain GSKUMB [KJ190159] were grown in CYA broth and incubated at 27±2°C on the rotary shaker at 120 rpm for 21 days. At the end of incubation period, cultures were harvested for determination of fungal growth (biomass). The resultant culture filtrates were extracted twice with ethyl acetate and concentrated. One ml of final concentrate in methanol was employed for detection of DON and NIV with the help of RP-HPLC.Results: The highest amount of DON and NIV were produced by F. aethiopicum in the presence of D-mannose and D-galactose as C source, while the highest amount of biomass was recorded on maltose and succinic acid. F. culmorum produced maximum amount of toxins in the presence of D-glucose, D-mannitol and D-fructose. Sodium nitrate was most favorable nitrogen source as it induced maximum amount of toxins by F. aethiopicum, while L-methionine, L-asparatic acid and L-tryptophan were next preferred N source. In contrast, highest biomass of fungus was obtained with L-lysine, L-glutamine and L-tyrosine. F. culmorum produced maximum amount of toxin and biomass with potassium nitrate and L-tyrosine respectively.Conclusion: Present species of Fusarium differed varied both in toxins (DON, and NIV) and biomass production. Their response of fungi under investigation towards C and N sources is also varied.Â

PERIODATE OXIDATION OF PEG–600, AN ESSENTIAL PHARMACEUTICAL POLYMER

Objective: To study the kinetics of periodate oxidation of polyethylene glycol-600 (PEG-600), a familiar non-toxic polymer used in pharmaceutical and other fields of industry. Methods: Reactions were carried out in alkaline medium and measured the kinetics by iodometry. One oxygen atom loss or two electrons transfer was observed per each molecule of periodate i.e., the rate of reaction was measured periodate converts to iodate because the formed iodate species is unable to oxidize the substrate molecules. Results: Based on log (a-x) versus t plots, order w. r. t. oxidant (periodate) is unity. Reactions were found to be independent of substrate (PEG-600) concentration. A decrease in rate with an increase in alkali concentration [OH–] was found and order was inverse fractional. Temperature dependence of reaction rate was studied and then calculated the corresponding Arrhenius parameters. Conclusion: An appropriate rate law was proposed by considering the above experimental results

Surface morphology, electrical and optical properties of gallium antimonide layers grown by liquid phase epitaxy

Abstract Liquid phase epitaxial (LPE) growth of gallium antimonide has been carried out employing equilibrium cooling, step cooling, supercooling and two phase solution growth techniques. An optimum temperature range of 500-550°C was found to be suitable for the growth of high quality layers. The morphology of layers grown by the first three techniques improved with increase in layer thickness. In contrast, better morphology was obtained for thin layers when grown from the two phase solution technique. While the equilibrium cooling technique gave a diffuse substrate-epilayer interface, sharp interfaces were obtained by the step cooling, supercooling, and two phase solution growth techniques. Photoluminescence spectroscopy and current-voltage measurements carried out on the grown layers revealed that the layers grown from Ga-rich melts exhibit superior optical and electrical properties as compared to those grown from Sb-rich melts

Fluctuation problem in electromagnetic cascades. II

The fluctuation problem in electromagnetic cascades is examined in the light of the new approach to Cascade Theory. The moments of the number distribution of electrons produced in the entire shower (corresponding to infinite thickness) are obtained explicitly by a direct evaluation of inversion integrals. In particular, it is shown that the mean number of electrons that are produced in the shower for an energy greater than E is found to be proportional to E<SUB>0</SUB>/E, while E<SUB>0</SUB> is the energy of the primary electron. In view of this result, it has been found possible to evaluate the higher moments of the number distribution explicitly

Sequent correlations in stochastic point processes - III

Sequent correlations play a vital role in the study of stochastic point processes. In this paper we demonstrate the feasibility of defining a single characteristic functional from which various types of sequent correlations useful in braching phenomena can be obtained by appropriate functional differentiation

Effect of annealing temperature on electrical characteristics of ruthenium-based Schottky contacts on n-type GaN

The electrical properties of ruthenium (Ru) and ruthenium/gold (Ru/Au) Schottky contacts on n-type GaN are investigated as a function of annealing temperature by current--voltage (I--V) and capacitance--voltage (C--V) techniques. The Schottky barrier height of as-deposited Ru/n-GaN is found to be 0.88 eV (I--V) and 1.10 eV (C--V) respectively. However, after annealing at 500°C for 1 min in the nitrogen ambient, the decrease in barrier height is quite considerable and found to be 0.80 eV (I--V) and 0.86 eV (C--V). In the case of Ru/Au Schottky diode the measured barrier height is 0.75 eV (I--V) and 0.93 eV (C--V). In contrast to the Ru contacts, it is interesting to note that the barrier height of Ru/Au depends on the annealing temperature. Annealing at 300°C improves the barrier height and the corresponding values are 0.99 and 1.34 eV. Further increase in annealing temperature decreases the barrier height and the respective values are 0.72 and 1.08 eV at 500°C. From the above observations, it is clear that the electrical properties of annealed Ru/Au contacts are improved compared to the as-deposited films. However, Ru Schottky contacts exhibit a kind of thermal stability during annealing

Stability of quasicrystalline phase in Al-Cu-Fe, Al-Cu-Co and Al-Pd-Mn alloys during High energy ball milling

The stability of the quasicrystalline phase present in as-cast Al<SUB>65</SUB>Cu<SUB>20</SUB>Fe<SUB>15</SUB>, Al<SUB>65</SUB>Cu<SUB>20</SUB>Co<SUB>15</SUB> and Al<SUB>72</SUB>Pd<SUB>19.5</SUB>Mn<SUB>8.5</SUB> alloys during high energy ball milling and on subsequent annealing has been studied. The synthesis and stability of the quasicrystalline phase prepared by mechanical alloying of Al<SUB>65</SUB>Cu<SUB>20</SUB>Fe<SUB>15</SUB>, Al<SUB>70</SUB>Cu<SUB>20</SUB>Fe<SUB>10</SUB> and Al<SUB>65</SUB>Cu<SUB>20</SUB>Co<SUB>15</SUB> alloys has also been studied. In all the cases, the quasicrystalline phase is unstable with long hours of milling and transforms to the β-phase (bcc phase), which is stable on further milling and on subsequent annealing up to 1073 K. The quasicrystalline to β-phase transformation appears to occur for grain sizes below 20 nm

Persistent photoconductivity on ion irradiated carbon films prepared by plasma assisted chemical vapor deposition and determination of traps in the pseudo-gap region

The defects created by ion beam irradiation in disordered conducting carbon films have been studied by the photoconductivity technique. A very complex distribution of traps created mostly by random displacement of carbon atoms by energetic ion beam from its polymeric matrix showed a persistent photoconductivity at low temperature. The decay time constant estimated from the photocurrent is around 15 s at 10 K. From the time constant and the intensity of photocurrent the density of traps and the corresponding activation energies are calculated. This report shows how slow decay of photocurrent can be applied to probe distribution of traps in the amorphous carbon due to ion bombardment in the most general case