06 Electrical power supply and utilization (scientific, technical) ably reduce the complexity of the transmission and distribution networks to provide an area load model based on the load models recommended by IEEE. An improved genetic algorithm is used to estimate the model and equivalent network parameters with introduction of fictitious transmission lines and load buses. To demonstrate an application of the method, a simulation study of a S-bus power system subject to a variety of disturbances has been used to provide the source of primary data. The results show that the system behaviour can he accurately replicated by the equivalent area load model with parameters derived using the proposed methodology.
03/02301 Cool flame partial oxidation and its role in combustion and reforming of fuels for fuel cell systems
Naidja, A. et al. Program in Enrrgy mci Combustion Scienw. 2003. 29. (2) 1555191. The purpose of this review was to integrate the most recent and relevant investigations on the auto-oxidation of fuel oils and their reforming into hydrogen-rich gas that could serve as a feed for fuel cells and combustion systems. The incorporation of partial oxidation under cool flame conditions is considered to be a significant step in the reforming process for generation of hydrogen-rich gas. Therefore, particular attention has been paid to the partial oxidation of fuels at low temperature in the cool flame region. This is still not a wellunderstood feature in the oxidation of fuels and can potentially serve as a precursor to low NO, emissions and low soot formation. Pretreatment. including atomization, vaporization and burner technology are also briefly reviewed. The oxidation of reference fuels (n-heptane C7Hlr,. iso-octane CsHra and to a lesser extent cetane Cr6Hs4) in the intermediate and high temperature ranges have been studied extensively and it is examined here to show the significant progress made in modeling the kinetics and mechanisms, and in the evaluation of ignition delay times. However. due to the complex nature of real fuels such as petroleum distillates (diesel and jet fuel) and biofuels. much less is known on the kinetics and mechanisms of their oxidation. as well as on the resulting reaction products formed during partial oxidation. The rich literature on the oxidation of fuels is, hence, limited to the cited main reference fuels. Developments in the catalytic reforming of fuels are also included. In the presence of catalysts. the fuels can be reformed through partial oxidation, steam reforming and autothermal reforming (ATR) to generate hydrogen. But optimum routes to produce cost effective hydrogen fuel from conventional or derivative fuels are still debatable. It is suggested that the use of products emanating from partial oxidation of fuels under cool flame conditions could be attractive in such reforming processes. but this is as yet untested. The exploitation of developments in oxidation. combustion and reforming processes is always impacted by the resulting emission of pollutants, including NO,, SO,, CO and soot, which have an impact on the health of the fragile ecosystem. Attention is paid to the progress made in innovative techniques developed to reduce the level of pollutants resulting from oxidation and reforming processes. In the last part, the present status of the topics covered are summarized and prospects for future research presented. This information forms the basis for recommended themes that are vital in developing the next generation energy-efficient combustion and fuel cell technologies
03/02302 Dampin of multimodal power system oscillations by FA 8 TS devices using non-lmear TakagiSugeno fuzzy controller Dash, P. K. and Mishra, S. International Journal qf Electrical Power & Energy Systems, 2003, 25, (6), 481-490. The paper presents a non-linear Takagi-Sugeno fuzzy controller for flexible AC transmission system (FACTS) devices in a multi-machine power system. This controller uses a numerical consequent rule base, which can be either linear or non-linear producing control gain variations over a very wide range. This controller is expected to be more robust and effective in damping electromechanical oscillations of the power system compared to the conventional PI controller. Digital simulations of a multi-machine power system, with series connected FACTS devices like UPFC, TCSC and TCPST, etc. subjected to a wide variety of transient disturbances validate the efficiency of the new approach in damping multimodal oscillations.
03102303 Effect of iron core loss nonlinearity ferroresonance In power transformers
Al-Anbarri, K. et crl. Electric Power Systems Research, 2003, 6.5, (I). l12. This paper investigates the effect of iron core loss non-linearity on the onset of chaotic ferroresonance and duration of transient chaos in a power transformer. The transformer chosen for investigation has a rating of 50 MV A, 635.1 kV, the data for which is given by Dommel et al. (Tutorial Course on Digital Simulation of Transients in Power Systems (Chapter 14) IISc, Bangalore, 1983, pp. 17-38). The magnetization characteristics of the transformer is modelled by a single-value two-term polynomial. The core loss is modelled by a third order power series in voltage. With non-linearities in core loss 378
Fuel and Energy Abstracts
included, three eftects are clear-: (I) onset of chaos at larger values 01 open phase voltage. (ii) shorter duration of transient chaos, and (iii) less suaceptibilitv to .jump’ phcnomen:r.
03102304 Efficient segmented thermoelectric for space power applications
El-Genk. M. S. et ul. Efrcr-,q~,Co/rr.cr\i~~!! n/n/ Manuyrnrcwt, 2003, 44. (II), 17551772. This paper compares the performance of SiGe (Sit,.aGe,,,a) and skutterudite segmented thermoelectric unicouples (STUs) at a hot side temperature of 973 K and cold side temperatures of 300, 573 and 673 K and for the same total length and cross sectional dimensions of the p-leg. The area of the n-leg and lengths of and the interfacial temperatures between segments of various materials in the STU legs are determined using a global optimization methodology. Results indicate that the STUs could potentially achieve peak efficiencies of 7.8% and 14.7% when operated at a cold side temperature of 573 K, typical of that in current radioisotope thermoelectric generators (RTGs), and 300 K, respectively. These efficiencies are 55% and 99% higher. respectively, than for SiGe at the same temperatures. However, due to the higher density of skutterudite, the electrical power densities corresponding to the peak efficiencies of the STUs are 39 and 109 W,/kg versus 92 and 232 W,/kg for SiGe at cold side temperatures of S73 K and 300 K. respectively. On the other hand, the heat inputs and heat rejection powers for the STUa are 42-55%, and 39-S3%, respectively, of those for SiGe at the peak efficiency and 70-75s and h7-77% of those of SiGe. respectively. at the peak electric power density. Therefore, when used in RTGs. STUs could halve the 238PuO2 fuel mass and the radiator area, while operating at >45% higher electrical power density (>7 W,.ikg) than SiGe in current RTGs (~5.5 W,/kg).
03/02305 Enhancing small signal power system stability by coordinating unified power flow controller with power system stabilizer Fang, W. and Ngan. H. W. Electrrc Powcv Systwm R~wwd~. 2003. 65. (2). 91-99. Advancement of power electronic technologies makes ac systems to be more adaptive and flexible as new forms of power controller emerges in recent years. Though not yet well developed, underpinned research suggests that unified power flow controller (UPFC) is a promising power system controller. This paper proposes a method to coordinate UPFC with power system stabilizer (PSS) so as to damp down oscillations caused by small signal disturbance. It starts by deriving a mathematical model of UPFC, with which its linearized differential equations are integrated to design an overall control strategy for enhancing small signal stability of the so connected power systems. The approach is to identify the eigenvalue of the largest real part and then minimize it as a non-linear optimization problem. In order to ensure the robustness of the control system, different operating conditions are simultaneously considered in the parameter optimization process. Results of a case study on the New England test system show that the model is correct and the method is promising for coordinating the model parameters to enhance the small signal stability of the complex power system.
03/02306 Fault location in multi-ring using artificial neural network
Meshal, A. er al. Electric Power Systems Rrsearch, 2003, 64, (2), 87-92. This paper examines the problem of locating faults that may occur anywhere in multi-ring electrical distribution networks, which may affect the reliability of power distribution. The developed method is based on using artificial neural network techniques as the algorithm to save time in fault location. This technique is applied to an existing 33% kv distribution network, which caters to an oil production field spread over an area of 60 km-. The nature of this distribution system, which consists of multi-ring configuration, illustrates the complexity of the network. Simulation results for a case study have shown the feasibility and effectiveness of the suggested fauft location method.
03102307 Fuel cell system with devices for treating separated liquids Mack, R. and Pasera, U. Ger. Offen. DE 10,147,680 (Cl. HOlM8104). 10 Apr 2003, Appl. 10,147,680. (In German) A fuel cell system comprises a gas production system and at least a fuel cell, whereby the gas production system supplies a Hz-containing gas produced from water, and hydrocarbons. A separator, which is placed in the gas production system, and/or after the fuel cell is used for separating a liquid from media passing the fuel cell system. The separated liquid is used for the operation of the gas production system. A dosing equipment for injection the starting material (esp. methanol) into the liquid is provided between each separator and a valve mechanism for discharging the liquid from the respectively separator.