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03367 Dynamic ratings boost transmission margins
06 Electrical power supply and utilizabon (scientific, technical)
trial iterations is used for identifying an accurate set of active inequality constraints. The 265-bus Taipower system is used to serve as an example for illustrating the performance of the proposed method in studying the imbalance problem caused by the upcoming high-speed electric railway load in Taiwan. 00/03366 Diffusion layer parameters influencing optimal fuel cell performance Jordan, L. R. Journal of Poitser Sources, 2000, 86, (l-2), 250-254. The performance of polymer electrolyte fuel cells (PEFCs) is substantially influenced by the morphology of the gas diffusion layer. Cells utilizing sintered gas diffusion layers made with a low pore volume Acetylene Black carbon, at an optimized thickness, showed better performance compared with cells containing Vulcan XC-72R carbon. The cells were optimized using both oxygen and air as oxidants showing that different conditions were required in each case to achieve optimum cell performance. A model, in which the hydrophohicity and porosity of the diffusion layer affect water impregnation and gas diffusion through the gas diffusion layer, is presented to explain the influence of the diffusion layer morphology on cell performance. 00/03367 Dynamic ratings boost transmission margins Moore, T. EPRI journal, 2000, 25, (I), 18-25. Dynamic thermal ratings for power equipment make it possible to increase the loading of transmission circuits under most weather and system conditions and to reduce the risk of failure under favourahle conditions. Powerful software now available from EPRI incorporates real-time load and weather data from relatively inexpensive monitoring technology to calculate such dynamic ratings, which are far more realistic than the conservative static ratings normally used. By revealing a circuit’s true thermal limit, the software lets system operators move more power with little additional investment in equipment: they not only can seize opportunities to deliver more electricity during high-demand periods hut also can avoid unnecessary load shedding when contingencies arise. The software’s current version, which incorporates application knowledge developed since 1992, has been verified in extensive fields testing by six member companies. 00103368 Dynamic stability improvement of multi-machine power system with UPFC Sreenivasachar, K. Electric Power Sysrems Research, 2000, 55. (I), 27-37. This paper presents a procedure leading to the formulation of the state matrix to study the dynamic stability of multi-machine power system in the presence of a unified power flow controller (UPFC). The dynamics of the dc link capacitor of the UPFC have been taken into account while evaluating system stability. Two different control structures have been evaluated for closed loop stability. The improvement in dynamic stability with the different control structures has been presented for a multi-machine multi-UPFC power system. Also the effect of different d.c. capacitor ratings on the dynamic stability has been evaluated. 00103369 Effect of the specific consumption of blowing components, the temperature in the reaction zone,, and the duration of the process on semicoke gasification Indexes Kruvshinov, V. E. er ul. Koks Khim., 1999, 5, 17-20. (In Russian) The operation conditions of the gasification stage for an experimental plant (10,000 t coal/year) for low-rank coal thermolysis were studied experimentally in the laboratory. The conditions were: 700 kg steam/t semicoke; 3000 m3 air/t semicoke; and 900°C gasification temperature. The residence time of the carbonaceous material in the reaction zone was calculated to he 250 min. OOlO3370 Effects of flow rate and starvation of reactant gases on the performance of phosphoric acid fuel cells Song, R.-H. el ~1. Journal of Power Sources, 2000, 86, (i-2), 2899293. Effects of reactant gas flow rates and starvation on the performance of phosphoric acid fuel cells were studied using single cells. As the reactant gas flow rates of single cell increased, the performance of the cell increased, and then remained constant. The optimum flow rates of hydrogen, oxygen and air under cell operating condition of 150 mA/cm’ at 190°C were found to he 5 cm3/mincm2, 5 cm3/mincm2, and 15 cm3/mincm2 at 7 atm. and room temperature, respectively. The open circuit voltage of the single cell decreased with increasing oxygen flow rate at constant hydrogen flow rate, which is attributed to the increased gas cross-over rate. When the reactant gases were again supplied to the cell after gas starvation, the cell voltage losses were found to he about 5 mV in the case of hydrogen starvation and about 1 mV for oxygen starvation, and the voltage loss was independent of gas starvation time. These results were discussed from the electrochemical viewpoint of the cell. tfJfz371
Electric
field analysis
of hybrid acldc transmission
Ismail, H. M. Znr. J. Energy Res., 2000, 24, (7), 641-653. In recent years, the possibility for a.c. and d.c. transmission lines running parallel to each other, sharing the same right-of-way (ROW) or even the same tower has been increased. Design of such hybrid ac/dc networks requires a precise calculation of the electric field around and under them. This paper presents a quantitative analysis of the electric field at 1 m height above ground surface for different hybrid acidc transmission lines. Lateral
profiles for typical Egyptian 500, 220 and I32 kV after adding bipolar dc lines are presented. The paper also considers reconfiguration of a typical 220 kV Egyptian double-circuit ac transmission line, in which one of the circuits is converted into f220 kV bipolar dc line. Different reconfiguration alternatives are studied to choose the optimum arrangement. The charge simulation method (CSM) employing the superposition principle is used to calculate the RMS value of the electric field generated by hybrid acldc lines at any point in the space. The RMS values of the field are determined directly without dividing the ac supply cycle into a sufficient number of subintervals as it has been done before. Satisfactory agreement with the results measured and calculated before by other techniques, for some typical acidc lines, has been obtained.
00103372 Electricity generation from solid biomass via co-combustion with coal energy and emission balances from a German case study Hartmann, D. and Kaltschmitt, M. Biomuss Biocner~,, 1999, 16, (6) 397406. The environmental effects of electricity production from different hiofuels via co-combustion with hard coal in existing coal-fired power plants were analysed and compared to electricity production from hard coal alone based on life cycle analysis (LCA). Using straw and residual wood at a 10% blend with coal in an existing power plant in southern Germany showed that all investigated environmental effects are significantly lower if biomass is used versus coal. Thus, based on the available. proven technology of cocombustion of hard coal and biomass in existing power plants, a significant contribution could be made to a more environmentally sound energy system versus the use of coal alone.
00103373 Electrode R&D, stack design and performance of biomass-based alkaline fuel cell module Kiros, Y. el (II. Ini. J. Hydrogen Energy, 1999, 24, (6) 549-564. The stability and activity of electrode formulations in long-term operations was tested electrochemically with different materials and manufacturing techniques. Cathode electrocatalysts, such as CoTPP, Caa’, Lae.,MnOs and platinum-cobalt alloys were incorporated in high surface area carbons and operated at a constant load of 100 mA/cm-, 80°C and an electrolyte concentration of 6 M KOH. Similarly, anode catalysts with platinumpalladium bimetallic combinations were also tested and ascertained in halfcell measurements. Surface area measurements and transmission electron microscopy (TEM) analyses were carried out both before and after the electrochemical test procedures. The electrodes were incorporated into a seven and two cell module design of the external and internal manifolding types and the experiences gained from these design principles are described, respectively. Furthermore, a hiomass fed AFC module with all the system descriptions, steps, and a demonstration layout of producer gas to alkali fuel cell are examined and discussed. Wood charcoal and agroresidues were used as feedstock and as a primary fuel. Power output of the different feedstocks in a producer gas fed alkali fuel cell has shown the potential and efficiency to be applied as a stand-alone power generator.
00103374 Electrooxidation of methanol on Pt-Flu catalysts supported by basal plane graphite in phosphoric acid solution Lee, C. H. et (II. Journd ofPower Sources. 2000, 86, (I-2), 478481. The electro-oxidation of methanol on platinum-ruthenium catalyst supported by basal plane graphite was investigated in phosphoric acid solution by cyclic voltammetry, X-ray diffraction I(XRD) and scanning electron microscope (SEM). Platinum-ruthenium catalysts were prepared by applying a potential of 0.0 V in chloroplatimc acid solution of various ruthenium chloride concentrations. The peak potential of methanol oxidation is shifted to a lower potential as the concentration ratio of ruthenium/platinum in the electro-deposition solution. Shifts of peak potential are due to the difference of the oxidation pathway of CO adsorbed on the surface of platinum-ruthemum catalyst. For methanol oxidation in phosphoric acid solution, the electro-catalytic activity of the catalyst prepared in ruthenium chloride solutions of chloroplatinic acid solution (1:l) was better than that of catalysts prepared in different concentrations of ruthenium chloride solution. 00103375 Evaluation and modeling of performance of anodesupported solid oxide fuel cell Yakahe, H. er al. Journal of Power Source.?. 2000. X6, (l-2), 423-431. For an anode-supported planar SOFC. a single-unit with double channels was modelled for a counter-flow pattern, and the concentration polarization at the anode was estimated. The flow phenomena were simulated using the finite volume method and the distribution of the gaseous species was calculated. In the model, it was assumed that the gas flow in the porous anode is governed by Darcy’s Law, and the reactant species are transported to the electrolyte/anode interface mainly by diffusion in a multi-component mixture system. For binary Hz-Ha0 and CO-CO2 systems, the calculated concentration polarization was found comparable to the experimental results. As an example for a multi-component system, a model using steamreformed methane as a fuel was employed to simulate the concentration polarization at a high fuel utilization. From the simulated results, it was evident that the shift reaction effectively reduces the concentration polarization when the fuel utilization is high.
Fuel and Energy Abstracts
November 2000
379
trial iterations is used for identifying an accurate set of active inequality constraints. The 265-bus Taipower system is used to serve as an example for illustrating the performance of the proposed method in studying the imbalance problem caused by the upcoming high-speed electric railway load in Taiwan. 00/03366 Diffusion layer parameters influencing optimal fuel cell performance Jordan, L. R. Journal of Poitser Sources, 2000, 86, (l-2), 250-254. The performance of polymer electrolyte fuel cells (PEFCs) is substantially influenced by the morphology of the gas diffusion layer. Cells utilizing sintered gas diffusion layers made with a low pore volume Acetylene Black carbon, at an optimized thickness, showed better performance compared with cells containing Vulcan XC-72R carbon. The cells were optimized using both oxygen and air as oxidants showing that different conditions were required in each case to achieve optimum cell performance. A model, in which the hydrophohicity and porosity of the diffusion layer affect water impregnation and gas diffusion through the gas diffusion layer, is presented to explain the influence of the diffusion layer morphology on cell performance. 00/03367 Dynamic ratings boost transmission margins Moore, T. EPRI journal, 2000, 25, (I), 18-25. Dynamic thermal ratings for power equipment make it possible to increase the loading of transmission circuits under most weather and system conditions and to reduce the risk of failure under favourahle conditions. Powerful software now available from EPRI incorporates real-time load and weather data from relatively inexpensive monitoring technology to calculate such dynamic ratings, which are far more realistic than the conservative static ratings normally used. By revealing a circuit’s true thermal limit, the software lets system operators move more power with little additional investment in equipment: they not only can seize opportunities to deliver more electricity during high-demand periods hut also can avoid unnecessary load shedding when contingencies arise. The software’s current version, which incorporates application knowledge developed since 1992, has been verified in extensive fields testing by six member companies. 00103368 Dynamic stability improvement of multi-machine power system with UPFC Sreenivasachar, K. Electric Power Sysrems Research, 2000, 55. (I), 27-37. This paper presents a procedure leading to the formulation of the state matrix to study the dynamic stability of multi-machine power system in the presence of a unified power flow controller (UPFC). The dynamics of the dc link capacitor of the UPFC have been taken into account while evaluating system stability. Two different control structures have been evaluated for closed loop stability. The improvement in dynamic stability with the different control structures has been presented for a multi-machine multi-UPFC power system. Also the effect of different d.c. capacitor ratings on the dynamic stability has been evaluated. 00103369 Effect of the specific consumption of blowing components, the temperature in the reaction zone,, and the duration of the process on semicoke gasification Indexes Kruvshinov, V. E. er ul. Koks Khim., 1999, 5, 17-20. (In Russian) The operation conditions of the gasification stage for an experimental plant (10,000 t coal/year) for low-rank coal thermolysis were studied experimentally in the laboratory. The conditions were: 700 kg steam/t semicoke; 3000 m3 air/t semicoke; and 900°C gasification temperature. The residence time of the carbonaceous material in the reaction zone was calculated to he 250 min. OOlO3370 Effects of flow rate and starvation of reactant gases on the performance of phosphoric acid fuel cells Song, R.-H. el ~1. Journal of Power Sources, 2000, 86, (i-2), 2899293. Effects of reactant gas flow rates and starvation on the performance of phosphoric acid fuel cells were studied using single cells. As the reactant gas flow rates of single cell increased, the performance of the cell increased, and then remained constant. The optimum flow rates of hydrogen, oxygen and air under cell operating condition of 150 mA/cm’ at 190°C were found to he 5 cm3/mincm2, 5 cm3/mincm2, and 15 cm3/mincm2 at 7 atm. and room temperature, respectively. The open circuit voltage of the single cell decreased with increasing oxygen flow rate at constant hydrogen flow rate, which is attributed to the increased gas cross-over rate. When the reactant gases were again supplied to the cell after gas starvation, the cell voltage losses were found to he about 5 mV in the case of hydrogen starvation and about 1 mV for oxygen starvation, and the voltage loss was independent of gas starvation time. These results were discussed from the electrochemical viewpoint of the cell. tfJfz371
Electric
field analysis
of hybrid acldc transmission
Ismail, H. M. Znr. J. Energy Res., 2000, 24, (7), 641-653. In recent years, the possibility for a.c. and d.c. transmission lines running parallel to each other, sharing the same right-of-way (ROW) or even the same tower has been increased. Design of such hybrid ac/dc networks requires a precise calculation of the electric field around and under them. This paper presents a quantitative analysis of the electric field at 1 m height above ground surface for different hybrid acidc transmission lines. Lateral
profiles for typical Egyptian 500, 220 and I32 kV after adding bipolar dc lines are presented. The paper also considers reconfiguration of a typical 220 kV Egyptian double-circuit ac transmission line, in which one of the circuits is converted into f220 kV bipolar dc line. Different reconfiguration alternatives are studied to choose the optimum arrangement. The charge simulation method (CSM) employing the superposition principle is used to calculate the RMS value of the electric field generated by hybrid acldc lines at any point in the space. The RMS values of the field are determined directly without dividing the ac supply cycle into a sufficient number of subintervals as it has been done before. Satisfactory agreement with the results measured and calculated before by other techniques, for some typical acidc lines, has been obtained.
00103372 Electricity generation from solid biomass via co-combustion with coal energy and emission balances from a German case study Hartmann, D. and Kaltschmitt, M. Biomuss Biocner~,, 1999, 16, (6) 397406. The environmental effects of electricity production from different hiofuels via co-combustion with hard coal in existing coal-fired power plants were analysed and compared to electricity production from hard coal alone based on life cycle analysis (LCA). Using straw and residual wood at a 10% blend with coal in an existing power plant in southern Germany showed that all investigated environmental effects are significantly lower if biomass is used versus coal. Thus, based on the available. proven technology of cocombustion of hard coal and biomass in existing power plants, a significant contribution could be made to a more environmentally sound energy system versus the use of coal alone.
00103373 Electrode R&D, stack design and performance of biomass-based alkaline fuel cell module Kiros, Y. el (II. Ini. J. Hydrogen Energy, 1999, 24, (6) 549-564. The stability and activity of electrode formulations in long-term operations was tested electrochemically with different materials and manufacturing techniques. Cathode electrocatalysts, such as CoTPP, Caa’, Lae.,MnOs and platinum-cobalt alloys were incorporated in high surface area carbons and operated at a constant load of 100 mA/cm-, 80°C and an electrolyte concentration of 6 M KOH. Similarly, anode catalysts with platinumpalladium bimetallic combinations were also tested and ascertained in halfcell measurements. Surface area measurements and transmission electron microscopy (TEM) analyses were carried out both before and after the electrochemical test procedures. The electrodes were incorporated into a seven and two cell module design of the external and internal manifolding types and the experiences gained from these design principles are described, respectively. Furthermore, a hiomass fed AFC module with all the system descriptions, steps, and a demonstration layout of producer gas to alkali fuel cell are examined and discussed. Wood charcoal and agroresidues were used as feedstock and as a primary fuel. Power output of the different feedstocks in a producer gas fed alkali fuel cell has shown the potential and efficiency to be applied as a stand-alone power generator.
00103374 Electrooxidation of methanol on Pt-Flu catalysts supported by basal plane graphite in phosphoric acid solution Lee, C. H. et (II. Journd ofPower Sources. 2000, 86, (I-2), 478481. The electro-oxidation of methanol on platinum-ruthenium catalyst supported by basal plane graphite was investigated in phosphoric acid solution by cyclic voltammetry, X-ray diffraction I(XRD) and scanning electron microscope (SEM). Platinum-ruthenium catalysts were prepared by applying a potential of 0.0 V in chloroplatimc acid solution of various ruthenium chloride concentrations. The peak potential of methanol oxidation is shifted to a lower potential as the concentration ratio of ruthenium/platinum in the electro-deposition solution. Shifts of peak potential are due to the difference of the oxidation pathway of CO adsorbed on the surface of platinum-ruthemum catalyst. For methanol oxidation in phosphoric acid solution, the electro-catalytic activity of the catalyst prepared in ruthenium chloride solutions of chloroplatinic acid solution (1:l) was better than that of catalysts prepared in different concentrations of ruthenium chloride solution. 00103375 Evaluation and modeling of performance of anodesupported solid oxide fuel cell Yakahe, H. er al. Journal of Power Source.?. 2000. X6, (l-2), 423-431. For an anode-supported planar SOFC. a single-unit with double channels was modelled for a counter-flow pattern, and the concentration polarization at the anode was estimated. The flow phenomena were simulated using the finite volume method and the distribution of the gaseous species was calculated. In the model, it was assumed that the gas flow in the porous anode is governed by Darcy’s Law, and the reactant species are transported to the electrolyte/anode interface mainly by diffusion in a multi-component mixture system. For binary Hz-Ha0 and CO-CO2 systems, the calculated concentration polarization was found comparable to the experimental results. As an example for a multi-component system, a model using steamreformed methane as a fuel was employed to simulate the concentration polarization at a high fuel utilization. From the simulated results, it was evident that the shift reaction effectively reduces the concentration polarization when the fuel utilization is high.
Fuel and Energy Abstracts
November 2000
379