06 Electma/ power supply and utilization (scientific, technical)

97102869 A general-purpose transmission line model and its interface with an electromagnetic transients programme Correia dc Barros. M. T. el N/. Electrical POWI. & Energy Sysfems, 1997, 19, (4) 249-254. The paper claims the transmission line models generally used in electromagnetic transients analysis in power systems arc not adequate for directly taking into account (a) distributed non-uniform parameters, (b) distributed non-linear parameters or (c) distributed sources. However, these features are important in the analysis of many electromagnetic transient problems in power systems. A multlphase transmission line model adequate for taking into account rhe above-mentioned parameters has been developed. In this paper. application examples of this multi-purpose line model are presented, illustrating the solution of various electromagnetic transient problems in power systems. This model provides a simple and efficient method for including frequency-dependent effects in transmission line transient analysis.

97102870 Hopf bifurcation control in power systems with static var compensators Laufenberg, M. J. et a/. Electrical Power & Energy Systems, 1997, 19. (S), X39-347. A proposal for a flexible modular approach for incorporating FACTS devices into the small-signal analysis framework of a power system is outlined. In particular, static var compensators (SVCs) with auxiliary controllers are illustrated. The effect of adding SVCs on the Hopf bifurcation is an increase in dynamic stability range.

97102871 Impact of electromagnetic field management on the design of 500 kV transmission lines Farag, A. S. et al. Ekctric Power Systen~s Research, 1997, 203-238. The siting and construction of new, and the upgrading of existing electric facilities has become a subject of public concern. The information concerning the possible health effects of electric and magnetic fields has not been interpreted conclusively. There remains uncertainty as to whether exposure to EMF can cause human health effects. The strength of electric and magnetic fields should be considered when planning and designing a transmission system. Other issues such as safety, environmental concerns, reliability, insulation and electrical clearance requirements, aesthetics, cost, operations and maintenance also need to he taken into account. The field reduction techniques described in this paper are proven methods, and the new techniques are explained thoroughly and incorporated taking into consideration the percentage field reduction, maintenance, and operational reliability. Systematic comparisons of the effectiveness of different line designs in reducing the EMF are included.

97102872 Impacts of pertinent factors on reliability worth indices in an electric power system Gael, L. and Billinton, R. Electric Power Systems Research, 1997, 41, (2), 151-158. This paper presents the system customer load point reliability worth factors designated in interrupted energy assessment rates (IEAR) at the overall systems level, i.e. considering failures in generation, transmission and the associated s&transmission and distribution systems. The basic objective of the paper is to assess the impacts on the IEAR of the pertinent factors such as load curtailment philosophy, contingency level, additional generation and/or transmission facilities and/or distribution system reinforcements, etc. The reliability worth assessment of the power system is illustrated by a practical reliability test system.

97102873 The implementation and effectiveness of linear interpolation within digital simulation Kuffel, P. et al. Ekctrical Power & Energy Systems, 1997, 19, (4), 221-227. A need to re-examine the ability of digital computations performed at finite time intervals has arisen in order to accurately represent the actual system. This is due to a greater use of detailed models and the increasing size and complexity of system studies in power system digital simulation. These concerns are manifested in two distinct areas. The first is the ability to switch elements at a specific point in time. The second is in the ability to accurately represent detailed control systems. These concerns are of particular importance in simulations containing a large number of controlled switching devices, such as HVd.c. systems or a.c. systems containing FACT5 devices. A discussion of the implementation and effectiveness of linear interpolation techniques in a digital simulation program is presented, addressing the interpolation in both the network solution and the control system.

97102874 Improved genetic algorithms for optimal power flow under both normal and contingent operation states Lai, L. L. et al. Electrical Power & Energy Systems, 1997, 19, (4), 287-292. In an attempt to solve the problem of optimal power flow, an improved genetic algorithm (IGA) has been derived. The GA has the ability to code a large number of control variables in a practical system within a reasonable length string. It is, therefore, able to regulate the active power outputs of generators, bus voltages, shunt capacitors reactors and transformer tap- settings to minimize the fuel costs. Two cases in the IEEE .?O-bus system for both normal and contingent operation states have been studied. The IGA always finds the best results and eliminates operational and insecure violations.

97102875 Independent steam-electric power plants in the Anthracite region, NE Pennsylvania: site geology, coal-refuse bank utilization, and environmental benefits Inners, J. D. rf al. Proc. Annu. Int. Pittshqh Cod Cmf.. 1996. 1.i. (2). 813-818. Small independent, coal-refuse burning, steam-electric stations in Pennsyl- vania appeared during the 1980s and 1990s as a result of the economic incentives of Public Utility Regulatory Policies Act of lY78. Eight such plants, ranging from 18 to 83 MW in net power output. have been operating for several years within the Anthracite region of north-eastern Penn+- nia. A ninth (having a net output of 108 MW) has recently come on line in the Lehigh Valley just to the south. Circulating fluidized-bed combustion boilers are implemented in all the sites. in which finely crushed limestone i\ burned along with pulverized coal-refuse fuel. Detailed sampling and studb of historic air photos are necessary to evaluate the economic potential & each individual hank. EnvIronmental benefits of the Anthracite region’s independent power plants include: (I) removal of many black. barren pilca of colliery refuse which contribute to acid-pollution and siltation of streams and (2) reclamation of strip-mined lands through disposal, compaction and grading of the alkali ash generated hy the fluidized bed boiler\.

97102876 Inside cable tray-Part IV Valvoda, F. R. and Farrell, G. W. Coilsrrl. Specif. Eqqr.. Dccemhcr I9Oh. 20, (h), X-52. Thi< paper addresses the requirements of the National Elrctrlcal C‘otlc (NEC) of the USA for the grounding of metal trays. It also supplies a glossary of terms associated with cable trays and illustrates the features of typical underfloor cable trays for a computer room. Finally. sample calculations for six combination7 of cable and tray recogniscd hy the NEC are presented.

97102877 Loop testing in the presence of RCDs Jones D. Wiring Matters. Autumn 1996, 11-12. The residual current devices’ (RCDs) design requirements and those of the instruments to test electrical installations which incorporate them are incompatible. Using a reduced test current (15 mA) instead of the traditional heavy (25 mA) current, a method of measuring the loop impedance without cutting off the power supply is proposed. The author summarizes the practical requirements for testing the loop resistance of circuits protected by fuses or RCDs.

97102878 Networking in harmony Forrester, W. Elect. Contractor, November/December 19Yh, 3X.39. The paper considers distortion in the waveform of the supply voltage, examining its causes and its effects. The effects of loads with high crest factors on supply voltage waveform, voltage drops in the distribution system and the effect of third harmonics are investigated and four possible remedies are assessed.

97102879 Numerical analysis of molten carbonate fuel cell systems He, W. Int. .I. Energy Rex., 1997, 21, (l), h9-76. A high level integration of various components can often he seen in a molten carbonate fuel cell system (MCFCs). A simulation tool is therefore highly desirable for the investigation of such a complex system operating in load-following modes: thus, the theoretical modelling of a complete MCFCs has been presented in this paper. Moreover, the approach is hased on the modularity concept and the techniques dealing with the bilateral coupling of various component modules are emphasized. The usefulness of the MCFCs model developed is demonstrated by applying it to simulate a practical I MW MCFCs. The energy halances have been illustrated at system level, and the calculated results show reasonable agreement with the design data.

97102880 An optimal real-time short term operation of independent hydro generator company in the open electricity market Tufegdzic, N. and Hyslop, P. Ekctric Power Sy.stemr Re.wur-(,/I, 41, (I). 5- 11. An approach to short-term hydro scheduling and dispatch for the independent hydro generator in the Open Electricity Market (OEM) environment is reported. The paper discusses optimal operation of hydra electric power plants and possible control arrangements in the OEM environment. The algorithm currently used by the Hydro Electric Commission, which operates as an isolated purely hydro system, has been modified to suit any independent hydro generation company. It also provides a different perspective for operation of hydro power plants as part of a hydrothermal system and can also be used for hydro optimization in hydrothermal systems. The concept is developed for a decentralized market (as in Australia), hut the concept can be used in a centralized dispatched market or centrally planned systems for the optimization of hydro resources.

236 Fuel and Energy Abstracts July 1997