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00373 Bundled conductor configuration optimization for compact transmission lines incorporating electromagnetic fields management
06
preparation of more intensified use of nuclear energy in the next century. The NHR has applications as an energy source for district heating, air conditioning and seawater desalination as well as other low temperature process heat applications, while with the HTGR, nuclear energy can be used to generate electricity with high efficiency and to provide process heat for a variety of industrial applications covering a wide range of temperature levels, such as heavy oil recovery, oil refinement, coal liquefaction and gasification. Taking into account of the features of the energy market in China at present and in the future, nuclear energy utilization both for power generation and for heat supply purposes is of great significance. It is required to fill the gap between energy supply and demand, to improve the energy mix and to mitigate the environmental pollution.
06
ELECTRICAL POWER SUPPLY AND UTILIZATION Scientific,
Technical
Assessment of coal-water slurry fuels for electric 98199372 power generation in Southern Indiana. Part 1. Detailed resource characterization Daniel, D. ef al. Proc. Int. Tech. Conf. Coal Util. Fuel Syst., 1997, 22, 149158. Due to their abundance and characteristics when burned as a coal-water slurry fuel (CWSF), impounded coal fines, a by-product of wet coal preparation techniques, are a potential fuel resource for electrical power generation. Recent work by the Pennsylvania Electricity Company, and others, has shown that co-firing CWSF composed of cleaned material from slurry impoundments can reduce nitrogen oxides emissions by as much as 20%. Detailed characterization of two inactive impoundments highlighted the differences between coal fines in an older impoundment and one filled in the last ten years. The calorific value of the composite, as received product from an older impoundment is 10,578 Btuilb; the ash content is 23.88%; and the sulfur content is 4.06%. The calorific value of the composite, as received product from twelve cores taken along the centreline of an impoundment filled in 1995 is lower at 8252 Btu/lb. The ash content is higher at 38.47% and the average sulfur content is slightly lower at 3.45%. Pyritic sulfur deposited near the input point of this impoundment causes the sulfur content in the first 300 feed to exceed 8%. The ash and sulfur contents remain near 40% and 4% respectively between 600-3000 ft from the input. Bundled conductor configuration optimization for 98109373 compact transmission lines incorporating electromagnetic fields management Farag, A. S. et al. Elec. Power Syst. Res., 1997, 43, (3), 157-167. An optimization calculation procedure used for bundled conductor configuration of compact transmission lines to improve certain operating performance and electromagnetic fields (EMF) management techniques is introduced. Its objective function is to allow as equal and balanced charges and surface maximum gradients on all sub-conductors as possible. As a result three optimum schemes are induced in this paper for 220 kV transmission lines. Parameters of compact lines and their unbalance, surge impedance electric field distribution under the line corona loss and radio noise level are also evaluated. EMF management and field minimization over the right-of-way (ROW) of the optimum schemes are also presented. The paper analyses EMF fields and compares them to attainable fields of standard compact and conventional lines. 9at99374 Carbon dioxide capture in molten carbonate fuel cell power plants fueled with coal and natural gas Reimer, P. et al. Proc. Intersoc. Energy Comers. Eng. Conf. 1997, 32, 805810. An IEA sponsored study to assess fuel cell power generation configurations that could be adopted if climate change considerations lead to a need to reduce emissions of COs to the atmosphere was presented. Comparisons were made of performance, CO? emission, capital cost, cost of electricity, and cost of avoiding COz emission among four atmospheric, or near atmospheric, molten carbonate fuel cell/COz capturing plants. Each fuel cell combined cycle plant with CO2 capture was compared with a similarlysized reference combined cycle plant without CO2 capture to develop comparison characteristics. The first reference plant was a coal-fuelled integrated gasification combined cycle (IGCC) featuring an oxygen-blown, entrained-bed gasifier providing fuel gas to a commercially available gas turbine. Waste heat is recovered and utilized in a steam turbine bottoming cycle. The second reference plant was a typical natural gas-fuelled gas turbine combined cycle.
Electrical power supply and utilization (scientific, technical)
9at99375 A combination of the genetic algorithm and Lagrangian relaxation decomposition techniques for the generation unit commitment problem Orero, S. 0. and Irving, M. R. Elec. Power Sysr. Res., 1997, 43, (3). 149156. The scheduling of generators in a power system to meet the requirements of a given load profile is involved in unit commitment. The basis for combining the genetic algorithm (GA) and Lagrangian relaxation (LR) methods for the unit commitment problem was analysed. It is shown that a robust unit commitment algorithm can be obtained by combining the global search property of the genetic algorithm with the ability of the Lagrangian decomposition technique to handle all kinds of constraints such as pollution unit ramping and transmission security. 98100376 Contingency ranking for voltage stability using a genetic algorithm Nims, J. W. et al. Electric Power Systems Research, 1997, 43, (1) 69-76. Based on genetic algorithms, a new contingency ranking approach is introduced. It formulates contingency ranking as an optimization. The genetic algorithm was selected as the search method due to its ability to find the optimal, or near optimal, solution while only evaluating a small percent of the problem space. In addition to limiting the number of evaluated contingencies, this approach can encompass other techniques to reduce the computational burden of analysing each contingency. Each contingency is measured by the minimum singular value of the power flow Jacobian to determine its severity. Testing validated the effectiveness of the proposed approach on two test systems. 98lQQ377 Design of reactive current and voltage controller of static condenser Padiyar, K. R. and Kulkarni, A. M. Electrical Power and Energy Systems, 1997, 19, (6) 397410. The paper describes the Static Condenser (STATCON), a shunt connected voltage source converter using self-commutating devices like GTOs for reactive power control. Their operation principle resembles that of a synchronous condenser. A typical application of a STATCON is for voltage regulation at the mid-point of a long transmission line. A two-stage structure for the control of voltage was investigated, which uses a closed loop reactive current controller whose reference is set by an outer voltage controller. For reactive current control, the use of a PI controller and a fuzzy logic PI controller was investigated; the fuzzy logic controller overcomes the problem of oscillatory instability encountered when a conventional PI controller is used. Notably, the plant transfer function for voltage control is generally of the non-minimum phase type, which precludes the use of large gains in a PI controller as there is a risk of instability of an oscillatory mode. Eigenvalue analysis using a linearized model was completed to aid the design of a compensator in cascade with an integral controller as a solution to this problem. 98iQQ378 Dynamic load dispatch with voltage security and environmental constraints Song, Y. H. and Yu, I.-K. Electric Power Systems Research, 1997, 43, (l), 53-60.
The authors applied a linear programming (LP)-based approach to dynamic load dispatch of electric power systems, taking security and environment constraints into consideration. In addition to the basic constraints, a comprehensive set of constraints are considered including transmission line capacity limits, generators dynamic ramp rate, voltage security margin and environmental issues. Calculated using the modified N-R continuation method, the voltage security margins considered heuristically through the control of transmission line capacity limits during the solution process by the LP. The environmental issue is considered as an operating constraint which has restrictions on hourly SO2 emission allowances. Application results of the proposed algorithm to the New England test system are presented to illustrate the effectiveness of the approach numerically. 98100379 Effects of non-linear protective devices in cable systems under energisation conditions Abdel-Gawad, N. M. K. Energy Cowers. Mgmt, 1997, 38, (18). 1647-1867. The transient performance of cable systems under energization conditions is discussed, including the non-linear effects of surge divertors which are used as sheath voltage limiters. The method developed and used is based on the modified Fourier transform technique in conjunction with modal analysis. The non-linear effects of surge divertors are included by the use of Duhamel’s integral. Mathematical formulations of the transient responses are also given. Both the cross-bonded and single-point bonded electrical power cable systems were considered. In obtaining the transient solutions, the frequency-dependent characteristics of system parameters were taken into account. Particular attention is given to systems which include crossbonded cables. The effects of various system parameters on the transient performance of the systems, as well as on the surge divertor responses, were investigated. 98/0038Q Enhancement of steady-state voltage stability by static VAR compensators El-Sadek, M. Z. et al. Elec. Power Syst. Res., 1997, 43, (3), 179-185. Static VAR compensators can enhance steady-state voltage instability, as they can hold certain nude voltages constant and create infinite buses within the system nodes. Static VAR compensator parameters needed for
Fuel and Energy
Abstracts
January 1999
31
preparation of more intensified use of nuclear energy in the next century. The NHR has applications as an energy source for district heating, air conditioning and seawater desalination as well as other low temperature process heat applications, while with the HTGR, nuclear energy can be used to generate electricity with high efficiency and to provide process heat for a variety of industrial applications covering a wide range of temperature levels, such as heavy oil recovery, oil refinement, coal liquefaction and gasification. Taking into account of the features of the energy market in China at present and in the future, nuclear energy utilization both for power generation and for heat supply purposes is of great significance. It is required to fill the gap between energy supply and demand, to improve the energy mix and to mitigate the environmental pollution.
06
ELECTRICAL POWER SUPPLY AND UTILIZATION Scientific,
Technical
Assessment of coal-water slurry fuels for electric 98199372 power generation in Southern Indiana. Part 1. Detailed resource characterization Daniel, D. ef al. Proc. Int. Tech. Conf. Coal Util. Fuel Syst., 1997, 22, 149158. Due to their abundance and characteristics when burned as a coal-water slurry fuel (CWSF), impounded coal fines, a by-product of wet coal preparation techniques, are a potential fuel resource for electrical power generation. Recent work by the Pennsylvania Electricity Company, and others, has shown that co-firing CWSF composed of cleaned material from slurry impoundments can reduce nitrogen oxides emissions by as much as 20%. Detailed characterization of two inactive impoundments highlighted the differences between coal fines in an older impoundment and one filled in the last ten years. The calorific value of the composite, as received product from an older impoundment is 10,578 Btuilb; the ash content is 23.88%; and the sulfur content is 4.06%. The calorific value of the composite, as received product from twelve cores taken along the centreline of an impoundment filled in 1995 is lower at 8252 Btu/lb. The ash content is higher at 38.47% and the average sulfur content is slightly lower at 3.45%. Pyritic sulfur deposited near the input point of this impoundment causes the sulfur content in the first 300 feed to exceed 8%. The ash and sulfur contents remain near 40% and 4% respectively between 600-3000 ft from the input. Bundled conductor configuration optimization for 98109373 compact transmission lines incorporating electromagnetic fields management Farag, A. S. et al. Elec. Power Syst. Res., 1997, 43, (3), 157-167. An optimization calculation procedure used for bundled conductor configuration of compact transmission lines to improve certain operating performance and electromagnetic fields (EMF) management techniques is introduced. Its objective function is to allow as equal and balanced charges and surface maximum gradients on all sub-conductors as possible. As a result three optimum schemes are induced in this paper for 220 kV transmission lines. Parameters of compact lines and their unbalance, surge impedance electric field distribution under the line corona loss and radio noise level are also evaluated. EMF management and field minimization over the right-of-way (ROW) of the optimum schemes are also presented. The paper analyses EMF fields and compares them to attainable fields of standard compact and conventional lines. 9at99374 Carbon dioxide capture in molten carbonate fuel cell power plants fueled with coal and natural gas Reimer, P. et al. Proc. Intersoc. Energy Comers. Eng. Conf. 1997, 32, 805810. An IEA sponsored study to assess fuel cell power generation configurations that could be adopted if climate change considerations lead to a need to reduce emissions of COs to the atmosphere was presented. Comparisons were made of performance, CO? emission, capital cost, cost of electricity, and cost of avoiding COz emission among four atmospheric, or near atmospheric, molten carbonate fuel cell/COz capturing plants. Each fuel cell combined cycle plant with CO2 capture was compared with a similarlysized reference combined cycle plant without CO2 capture to develop comparison characteristics. The first reference plant was a coal-fuelled integrated gasification combined cycle (IGCC) featuring an oxygen-blown, entrained-bed gasifier providing fuel gas to a commercially available gas turbine. Waste heat is recovered and utilized in a steam turbine bottoming cycle. The second reference plant was a typical natural gas-fuelled gas turbine combined cycle.
Electrical power supply and utilization (scientific, technical)
9at99375 A combination of the genetic algorithm and Lagrangian relaxation decomposition techniques for the generation unit commitment problem Orero, S. 0. and Irving, M. R. Elec. Power Sysr. Res., 1997, 43, (3). 149156. The scheduling of generators in a power system to meet the requirements of a given load profile is involved in unit commitment. The basis for combining the genetic algorithm (GA) and Lagrangian relaxation (LR) methods for the unit commitment problem was analysed. It is shown that a robust unit commitment algorithm can be obtained by combining the global search property of the genetic algorithm with the ability of the Lagrangian decomposition technique to handle all kinds of constraints such as pollution unit ramping and transmission security. 98100376 Contingency ranking for voltage stability using a genetic algorithm Nims, J. W. et al. Electric Power Systems Research, 1997, 43, (1) 69-76. Based on genetic algorithms, a new contingency ranking approach is introduced. It formulates contingency ranking as an optimization. The genetic algorithm was selected as the search method due to its ability to find the optimal, or near optimal, solution while only evaluating a small percent of the problem space. In addition to limiting the number of evaluated contingencies, this approach can encompass other techniques to reduce the computational burden of analysing each contingency. Each contingency is measured by the minimum singular value of the power flow Jacobian to determine its severity. Testing validated the effectiveness of the proposed approach on two test systems. 98lQQ377 Design of reactive current and voltage controller of static condenser Padiyar, K. R. and Kulkarni, A. M. Electrical Power and Energy Systems, 1997, 19, (6) 397410. The paper describes the Static Condenser (STATCON), a shunt connected voltage source converter using self-commutating devices like GTOs for reactive power control. Their operation principle resembles that of a synchronous condenser. A typical application of a STATCON is for voltage regulation at the mid-point of a long transmission line. A two-stage structure for the control of voltage was investigated, which uses a closed loop reactive current controller whose reference is set by an outer voltage controller. For reactive current control, the use of a PI controller and a fuzzy logic PI controller was investigated; the fuzzy logic controller overcomes the problem of oscillatory instability encountered when a conventional PI controller is used. Notably, the plant transfer function for voltage control is generally of the non-minimum phase type, which precludes the use of large gains in a PI controller as there is a risk of instability of an oscillatory mode. Eigenvalue analysis using a linearized model was completed to aid the design of a compensator in cascade with an integral controller as a solution to this problem. 98iQQ378 Dynamic load dispatch with voltage security and environmental constraints Song, Y. H. and Yu, I.-K. Electric Power Systems Research, 1997, 43, (l), 53-60.
The authors applied a linear programming (LP)-based approach to dynamic load dispatch of electric power systems, taking security and environment constraints into consideration. In addition to the basic constraints, a comprehensive set of constraints are considered including transmission line capacity limits, generators dynamic ramp rate, voltage security margin and environmental issues. Calculated using the modified N-R continuation method, the voltage security margins considered heuristically through the control of transmission line capacity limits during the solution process by the LP. The environmental issue is considered as an operating constraint which has restrictions on hourly SO2 emission allowances. Application results of the proposed algorithm to the New England test system are presented to illustrate the effectiveness of the approach numerically. 98100379 Effects of non-linear protective devices in cable systems under energisation conditions Abdel-Gawad, N. M. K. Energy Cowers. Mgmt, 1997, 38, (18). 1647-1867. The transient performance of cable systems under energization conditions is discussed, including the non-linear effects of surge divertors which are used as sheath voltage limiters. The method developed and used is based on the modified Fourier transform technique in conjunction with modal analysis. The non-linear effects of surge divertors are included by the use of Duhamel’s integral. Mathematical formulations of the transient responses are also given. Both the cross-bonded and single-point bonded electrical power cable systems were considered. In obtaining the transient solutions, the frequency-dependent characteristics of system parameters were taken into account. Particular attention is given to systems which include crossbonded cables. The effects of various system parameters on the transient performance of the systems, as well as on the surge divertor responses, were investigated. 98/0038Q Enhancement of steady-state voltage stability by static VAR compensators El-Sadek, M. Z. et al. Elec. Power Syst. Res., 1997, 43, (3), 179-185. Static VAR compensators can enhance steady-state voltage instability, as they can hold certain nude voltages constant and create infinite buses within the system nodes. Static VAR compensator parameters needed for
Fuel and Energy
Abstracts
January 1999
31