- Email: [email protected]
01911 Damping of subsynchronous resonance oscillations with TCSC and PSS and their control interaction
06 Electricalpower generation and utilization (scientific, technical) ization. A calculated discharge curve algorithm (CDCA) was used to generate calculated discharge curves. The algorithm procedure is presented. Alkaline manganese cell LR 20.VARTA, load 10 f2, was used for demonstration of the method.
00/01905 Characterizing wastewater streams at electric utility power plants-collecting accurate data and developing predictive relationships Chu, P. Q[fi Proc. I,?[. Wr/rc~r COU/:. 1998 59th. 228-235. In 1988, the Electric Power Research Institute (EPRI) initiated the Power Plant Integrated Systems: Chemical Emissions Studies (PISCES) program to characterize the dispersal of trace substances from fossil-fuel-fired electric utility power plants in water, air and solid waste streams. In 1990 the Clean Air Act amendments were passed, which resulted in the EPRI focusing on the PISCES field studies on flue gas stack emissions, with only limited water and solids sampling. With the completion of the trace substances synthesis report. which summarized EPRT’s air toxics research, EPRI is expanding its focus to complete the multimedia assessment of water and solid streams. At five coal-fired utility power plants, EPRI has initiated water toxics field studies. The research programme is described in this paper and the results from these ongoing studies are presented.
00101906 Cobalt doped chromium oxides as cathode materials for secondary lithium batteries Zhang, D. J. POIUY Sorrrce.\. 1999, 83, (I-2) 121-127. Cobalt doped chromium oxides were synthesized and characterized as cathode materials for secondary lithium batteries. A small amount of Co as dopant in the chromium oxides provides greater stability to the structure of CrO, and helps in improving the high-rate behaviour of these oxides. Optimized Co,,?CrO, exhibited an initial capacity of 290 mA h;g with an average discharge voltage of 3.0 V versus Li;Li ‘ . The lithiated Co,, :CrO, exhibited an initial capacity of 220 mA h/g. Both lithiated and non-lithiated Co,, ?CrO, were found to be reversible in the entire intercalation range (2.04.2 V versus Li/Li’. Compared with pure CrO,, Co doped CrO, > is characterized by better high-rate behaviour ( > 85% capacity for Co,,.?CrO,. and > 75”/0 capacity for LiCo,, ZCrO, at 0.65 C discharge rate).
OOIO1907 Coke versus graphite as fast charging anodes for lithium ion batteries Shi. H. and Brodd, R. flog. Borrc~rie.~ Botfer~, Marrr.. 1998, 17, 21-38. The capabilities of both graphite and coke for use in lithium-ion electrochemical cells were investigated. Lithium-ion cells with graphite anodes showed a poor ability to be rapidly charged due to the nature of the lithium intercalation process associated with graphite. By contrast, lithiumion cells with coke anodes showed a much better quick-charge capability compared to that of graphite cells. A series of experiments were performed in order to characterize the difference in quick-charge capability between graphite and coke anode cells. The cathode material used was lithium manganese oxide. Newman or c/l. has developed a mathematical simulation model that was also used in order to explore the change of lithium distribution in the anode as the cells were charged and discharged. The experimental observation that coke has a superior ability to quickly distribute the lithium into the anode during high-rate charging, was supported by the simulation results.
00/01906 Comparison of feature selection techniques for ANNbased voltage estimation Srivastava, L. E/~~rric, Power Sr.r/nrr.v Re.~rtr/d~. 2000. 53. (3). 187-195. Fast estimation of bus voltage magnitude is essential for security monitoring and analysis of power system. An approach based on a parallel self-organising hierarchical neural network (PSHNN) is proposed to estimate bus voltage magnitudes at all the PQ buses of a power system in an efficient manner. PSHNN is a multi-stage neural network in which stages operate in parallel rather than in series during testing. The revised backpropagation algorithm is used for learning input non-linearities along with forward-backward training of stage neural networks. A method based on Euclidean distance clustering is proposed for feature selection. Effectiveness of the proposed method is compared with two existing methods of feature-selection entropy based and angular distance based clustering methods for bus voltage magnitude estimation at different loading conditions in the IEEE 30-bus system and a practical 7S-bus Indian system. The PSHNN based on Euclidean distance based clustering method is found to be superior in terms of training time and error performance.
00/01909 Corrosion behavlour of sensitized AISI-type 316L stainless steel In molten carbonate fuel cell in cathode-gas environment Lee, K. S. J. Powr .Soww.r. 1999. 83, (l-2). 32-40. Corrosion of the cell components is a major problem in the development of the molten carbonate fuel cell (MCFC). This study describes the effect of sensitization on the corrosion characteristics of AISI-type 316L stainless steel in a 62138 lithium-potassium carbonate eutectic melt in the cathodegas environment. After solution treatment at 1200°C for 4 hours followed by sensitization treatment at 650°C for predetermined time, the corrosion behaviour of the sensitized sample is analysed electrochemically by a potentiodynamic method. The sensitized sample displays behaviour that is typical of active-passive transition. Increasing the time of the sensitization treatment causes the corrosion potential to shift in the cathodic direction. In addition. the passive film becomes unstable and supports a high passive
214
Fuel and Energy Abstracts July
2000
current, i.e. the substrate is more susceptible to intergranular corrosion (IGC). Morphological observation of samples immersed in a carbonate melt reveals a change in corrosion mechanism from initial IGC to localized corrosion. Huge cavities develop from grooves after 200 hours of immersion in a carbonate melt. A combination of a Cr-depleted region due to sensitization and decreasing oxygen concentration from top to bottom of the oxide layer, is considered to be the main reason for the change in corrosion morphology.
00/01910 Cycle life and utilization studies on cobalt microencapsulated ABs type metal hydride Durirajan. A. J. Power .Sorwc~,.v. 1999. X3. (l-2). I 14-120. LaNij 2$n,, 24 alloy was microencapsulated with cobalt by electroless deposition. The coated material has a higher capacity compared to the bare alloy due to the faradaic reaction of cobalt during discharge. This additional capacity has been studied using various material and electrochemical characterization techniques. The capacity due to cobalt varies depending on the amount of active material available for reaction. An increase in utilization is seen with decrease in thickness of the coating. Active surface area and the transport process within the film control the amount of cobalt utilized. Finally, cobalt coated alloys are seen to cycle ten times more than bare LaNil &n,, 2, with constant capacity.
00/01911 Dampin of subsynchronous resonance oscillations with TCSC and PS8 and their control interaction Jayaram Kumar, S. V. E/c P~IIYV S~,.Y/. Re.v.. 2000. 54, (I). 29-36. Typically the control systems of a thyristor-controlled series compensator (TCSC) employ a conventional type controller to obtain a reactance order. As the characteristic of a TCSC is non-linear in nature, this becomes necessary. The reactance order is then converted into the corresponding firing angle of the TCSC through a look-up table. The main drawback of this approach is the absence of a closed-loop model through which the stability of the system can be analysed. To alleviate this problem a linear, discrete-time state space model of a TCSC compensated transmission line in the t/-c/ domain is proposed in P.C. Srivastava, A. Ghosh. S.V. Jayaram Kumar. Model-based control design of a TCSC compensated power system. Elecrr. Power Dwr,q,~ Srtr. (submitted for publication). This paper uses this discrete-time model for studying the control interaction between a TCSC and a power system stabilizer (PSS) in damping torsional oscillations arising due to subsynchronous resonance (SSR). To do this. an overall system model in the linearized domain is developed first for eigenvalue analysis of the IEEE first benchmark model (IEEE-FBM) for SSR analysis IEEE SSR Tusk Force. ‘First benchmark model for computer simulation of subsynchronous resonance.’ IEEE T~OIIS. Power /Q/w. Srs/.. 96 (5) I56S1572 (1979). Through this eigenvalue analysis. the controller parameters are chosen, which are then used in PSCADiEMTDC simulation studies.
00/01912 Demonstration of coal gas run molten carbonate fuel cell concept Mathur, A. /~lt. J. of Dw,:q~~ Ra.. 1999, 23. (13). 1177-l 185. Integrated gasifier-molten carbonate fuel cell (IG-MCFC) offers a clean and efficient route for power generation from coal. A molten carbonate fuel cell (MCFC) was assembled and its performance was tested with simulated coal gas. The output and the stability was found to he comparable to that with conventional feed gas. It was also observed that switching from one type of feed gas to another had only a marginal effect on the cell performance.
00/01913 cycling
Deterioration of Laves phase alloy electrode during
Gao, X.-P J. Pon~cr .Sorwc~. 1999. 83. (I 2). lOO&lO7. A study is made of the deterioration mechanism of a Laves phase alloy electrode without addition of nickle powder by means of electrochemical impedance spectra (EIS). X-ray diffraction (XRD), inductively coupled plasma (ICP) and X-ray photoelectron spectroscopy (XPS). The XRD analysis shows that after cycling, the alloy bulk still has the capability to store hydrogen. The deterioration mechanism is considered to be mainly a surface process. In particular, particle pulverization (increased specific surface area and reduced the particle size) is the main reason for electrode deterioration. Dissolution of V and Mn increases gradually during cycling. On the other hand, particle pulverization increases further the dissolution rates of V and Mn. which are proportional to the specific surface area due to the generation of a new, fresh surface. In addition, it is demonstrated by XPS that the depth oxide of layers of Zr and Mn increases with cycling and results in an increase in the reaction impedance and a decrease in the surface electronic conductivity. Therefore, a change in the structure of the particle surface layer, due to particle pulverization and dissolution of V and Mn, contributes to the deterioration of the Laves phase electrode.
00/01914 Development of LiNIOp positive active materials for lithium-ion batteries Nagata. M. GS NUS T&l. Rc,/>.. 1998. 57. (2). 15. 19. (In Japanese) This paper presents an investigation of the effect of partial substitution of Ni in LiNiOz for cobalt and aluminium on the basis of its electrochemical characteristics. The cobalt 20% substitution improved cycle life. X-ray diffraction analvsls indicates that this was due to the alleviation of the structural deterioration at 4.2 V [versus Li/Li+]. The exothermic reaction peak of Li(Ni,,HJCo,, 1,,)I_2-AlzOz in differential scanning calorimetry measurement became broader with increase of the amount of substituted
00/01905 Characterizing wastewater streams at electric utility power plants-collecting accurate data and developing predictive relationships Chu, P. Q[fi Proc. I,?[. Wr/rc~r COU/:. 1998 59th. 228-235. In 1988, the Electric Power Research Institute (EPRI) initiated the Power Plant Integrated Systems: Chemical Emissions Studies (PISCES) program to characterize the dispersal of trace substances from fossil-fuel-fired electric utility power plants in water, air and solid waste streams. In 1990 the Clean Air Act amendments were passed, which resulted in the EPRI focusing on the PISCES field studies on flue gas stack emissions, with only limited water and solids sampling. With the completion of the trace substances synthesis report. which summarized EPRT’s air toxics research, EPRI is expanding its focus to complete the multimedia assessment of water and solid streams. At five coal-fired utility power plants, EPRI has initiated water toxics field studies. The research programme is described in this paper and the results from these ongoing studies are presented.
00101906 Cobalt doped chromium oxides as cathode materials for secondary lithium batteries Zhang, D. J. POIUY Sorrrce.\. 1999, 83, (I-2) 121-127. Cobalt doped chromium oxides were synthesized and characterized as cathode materials for secondary lithium batteries. A small amount of Co as dopant in the chromium oxides provides greater stability to the structure of CrO, and helps in improving the high-rate behaviour of these oxides. Optimized Co,,?CrO, exhibited an initial capacity of 290 mA h;g with an average discharge voltage of 3.0 V versus Li;Li ‘ . The lithiated Co,, :CrO, exhibited an initial capacity of 220 mA h/g. Both lithiated and non-lithiated Co,, ?CrO, were found to be reversible in the entire intercalation range (2.04.2 V versus Li/Li’. Compared with pure CrO,, Co doped CrO, > is characterized by better high-rate behaviour ( > 85% capacity for Co,,.?CrO,. and > 75”/0 capacity for LiCo,, ZCrO, at 0.65 C discharge rate).
OOIO1907 Coke versus graphite as fast charging anodes for lithium ion batteries Shi. H. and Brodd, R. flog. Borrc~rie.~ Botfer~, Marrr.. 1998, 17, 21-38. The capabilities of both graphite and coke for use in lithium-ion electrochemical cells were investigated. Lithium-ion cells with graphite anodes showed a poor ability to be rapidly charged due to the nature of the lithium intercalation process associated with graphite. By contrast, lithiumion cells with coke anodes showed a much better quick-charge capability compared to that of graphite cells. A series of experiments were performed in order to characterize the difference in quick-charge capability between graphite and coke anode cells. The cathode material used was lithium manganese oxide. Newman or c/l. has developed a mathematical simulation model that was also used in order to explore the change of lithium distribution in the anode as the cells were charged and discharged. The experimental observation that coke has a superior ability to quickly distribute the lithium into the anode during high-rate charging, was supported by the simulation results.
00/01906 Comparison of feature selection techniques for ANNbased voltage estimation Srivastava, L. E/~~rric, Power Sr.r/nrr.v Re.~rtr/d~. 2000. 53. (3). 187-195. Fast estimation of bus voltage magnitude is essential for security monitoring and analysis of power system. An approach based on a parallel self-organising hierarchical neural network (PSHNN) is proposed to estimate bus voltage magnitudes at all the PQ buses of a power system in an efficient manner. PSHNN is a multi-stage neural network in which stages operate in parallel rather than in series during testing. The revised backpropagation algorithm is used for learning input non-linearities along with forward-backward training of stage neural networks. A method based on Euclidean distance clustering is proposed for feature selection. Effectiveness of the proposed method is compared with two existing methods of feature-selection entropy based and angular distance based clustering methods for bus voltage magnitude estimation at different loading conditions in the IEEE 30-bus system and a practical 7S-bus Indian system. The PSHNN based on Euclidean distance based clustering method is found to be superior in terms of training time and error performance.
00/01909 Corrosion behavlour of sensitized AISI-type 316L stainless steel In molten carbonate fuel cell in cathode-gas environment Lee, K. S. J. Powr .Soww.r. 1999. 83, (l-2). 32-40. Corrosion of the cell components is a major problem in the development of the molten carbonate fuel cell (MCFC). This study describes the effect of sensitization on the corrosion characteristics of AISI-type 316L stainless steel in a 62138 lithium-potassium carbonate eutectic melt in the cathodegas environment. After solution treatment at 1200°C for 4 hours followed by sensitization treatment at 650°C for predetermined time, the corrosion behaviour of the sensitized sample is analysed electrochemically by a potentiodynamic method. The sensitized sample displays behaviour that is typical of active-passive transition. Increasing the time of the sensitization treatment causes the corrosion potential to shift in the cathodic direction. In addition. the passive film becomes unstable and supports a high passive
214
Fuel and Energy Abstracts July
2000
current, i.e. the substrate is more susceptible to intergranular corrosion (IGC). Morphological observation of samples immersed in a carbonate melt reveals a change in corrosion mechanism from initial IGC to localized corrosion. Huge cavities develop from grooves after 200 hours of immersion in a carbonate melt. A combination of a Cr-depleted region due to sensitization and decreasing oxygen concentration from top to bottom of the oxide layer, is considered to be the main reason for the change in corrosion morphology.
00/01910 Cycle life and utilization studies on cobalt microencapsulated ABs type metal hydride Durirajan. A. J. Power .Sorwc~,.v. 1999. X3. (l-2). I 14-120. LaNij 2$n,, 24 alloy was microencapsulated with cobalt by electroless deposition. The coated material has a higher capacity compared to the bare alloy due to the faradaic reaction of cobalt during discharge. This additional capacity has been studied using various material and electrochemical characterization techniques. The capacity due to cobalt varies depending on the amount of active material available for reaction. An increase in utilization is seen with decrease in thickness of the coating. Active surface area and the transport process within the film control the amount of cobalt utilized. Finally, cobalt coated alloys are seen to cycle ten times more than bare LaNil &n,, 2, with constant capacity.
00/01911 Dampin of subsynchronous resonance oscillations with TCSC and PS8 and their control interaction Jayaram Kumar, S. V. E/c P~IIYV S~,.Y/. Re.v.. 2000. 54, (I). 29-36. Typically the control systems of a thyristor-controlled series compensator (TCSC) employ a conventional type controller to obtain a reactance order. As the characteristic of a TCSC is non-linear in nature, this becomes necessary. The reactance order is then converted into the corresponding firing angle of the TCSC through a look-up table. The main drawback of this approach is the absence of a closed-loop model through which the stability of the system can be analysed. To alleviate this problem a linear, discrete-time state space model of a TCSC compensated transmission line in the t/-c/ domain is proposed in P.C. Srivastava, A. Ghosh. S.V. Jayaram Kumar. Model-based control design of a TCSC compensated power system. Elecrr. Power Dwr,q,~ Srtr. (submitted for publication). This paper uses this discrete-time model for studying the control interaction between a TCSC and a power system stabilizer (PSS) in damping torsional oscillations arising due to subsynchronous resonance (SSR). To do this. an overall system model in the linearized domain is developed first for eigenvalue analysis of the IEEE first benchmark model (IEEE-FBM) for SSR analysis IEEE SSR Tusk Force. ‘First benchmark model for computer simulation of subsynchronous resonance.’ IEEE T~OIIS. Power /Q/w. Srs/.. 96 (5) I56S1572 (1979). Through this eigenvalue analysis. the controller parameters are chosen, which are then used in PSCADiEMTDC simulation studies.
00/01912 Demonstration of coal gas run molten carbonate fuel cell concept Mathur, A. /~lt. J. of Dw,:q~~ Ra.. 1999, 23. (13). 1177-l 185. Integrated gasifier-molten carbonate fuel cell (IG-MCFC) offers a clean and efficient route for power generation from coal. A molten carbonate fuel cell (MCFC) was assembled and its performance was tested with simulated coal gas. The output and the stability was found to he comparable to that with conventional feed gas. It was also observed that switching from one type of feed gas to another had only a marginal effect on the cell performance.
00/01913 cycling
Deterioration of Laves phase alloy electrode during
Gao, X.-P J. Pon~cr .Sorwc~. 1999. 83. (I 2). lOO&lO7. A study is made of the deterioration mechanism of a Laves phase alloy electrode without addition of nickle powder by means of electrochemical impedance spectra (EIS). X-ray diffraction (XRD), inductively coupled plasma (ICP) and X-ray photoelectron spectroscopy (XPS). The XRD analysis shows that after cycling, the alloy bulk still has the capability to store hydrogen. The deterioration mechanism is considered to be mainly a surface process. In particular, particle pulverization (increased specific surface area and reduced the particle size) is the main reason for electrode deterioration. Dissolution of V and Mn increases gradually during cycling. On the other hand, particle pulverization increases further the dissolution rates of V and Mn. which are proportional to the specific surface area due to the generation of a new, fresh surface. In addition, it is demonstrated by XPS that the depth oxide of layers of Zr and Mn increases with cycling and results in an increase in the reaction impedance and a decrease in the surface electronic conductivity. Therefore, a change in the structure of the particle surface layer, due to particle pulverization and dissolution of V and Mn, contributes to the deterioration of the Laves phase electrode.
00/01914 Development of LiNIOp positive active materials for lithium-ion batteries Nagata. M. GS NUS T&l. Rc,/>.. 1998. 57. (2). 15. 19. (In Japanese) This paper presents an investigation of the effect of partial substitution of Ni in LiNiOz for cobalt and aluminium on the basis of its electrochemical characteristics. The cobalt 20% substitution improved cycle life. X-ray diffraction analvsls indicates that this was due to the alleviation of the structural deterioration at 4.2 V [versus Li/Li+]. The exothermic reaction peak of Li(Ni,,HJCo,, 1,,)I_2-AlzOz in differential scanning calorimetry measurement became broader with increase of the amount of substituted