02986 Development of power system control facilities in China

06 9WO2980 Compacted carbon for batteries Greinke, R. A. and Lewis, I. C. U.S. US 5,677,082 (Cl. 429-194; HOlMlO/ 40), 14 Ott 1997, Appl. 654,644, 29 May 1996, 16 pp. In the anode of an alkali metal/carbon battery of improved capacity compacted carbon is selected from the coke having an X-ray density of 12.00 g/cm’, a closed porosity of 55% and an open porosity of 547%; and from graphite having an X-ray density of 22.20 g/cm*, a closed porosity of 55% and an open porosity of ~25%. The anode for an alkali metal/carbon battery comprises compacted carbon and a binder. The alkali metal/carbon battery comprises the anode, a non-aqueous electrolyte of an organic aprotic solvent and an electrolytically conductive salt of an alkali metal, and a counter-electrode. 98102981 A comparative study of sliding mode and model reference adaptive speed observers for induction motor drive Lin, F.-J. ef al. Electric Power Systems Research, 1998, 44, (3). 163-174. This paper introduces a comparative study of sliding mode and model reference adaptive speed observers for a speed sensorless induction motor (IM) drive A speed observer is proposed on the basis of the sliding mode control theory and compared with the speed estimation algorithm based on model reference adaptive system (MRAS) theory to verify its robustness (IP) speed controller against parametervariations. An integral proportional using the estimated speed signal was designed to stabilize the speed loop. In order to increase the accuracy of the estimated speed, the speed estimation algorithms were implemented using a digital signal processor (DSP). Simulation and experimental results are cited to demonstrate the effectiveness of the proposed sliding mode speed observer. 98102982 Comparison of power densities and chemical potential variation in solid oxide fuel ceils with multilayer and single-layer oxide electrolytes Soral, P. et al. J. Electrochem. Sot., 1998, 145, (I), 99-106. Regarding their use as electrolytes in solid oxide fuel cells, several multilayer and single-layer mixed conducting oxide structures are compared. Detailed calculations of the power density characteristics and the variation of the oxygen chemistry potential gradient as a function of the external load and thickness of the oxide layers are provided. Also provided are engineering implications of the analysis in terms of designing efficient as well as mechanically and chemically stable fuel cells with a layered electrolyte structure. Construction of maximal steady-state security 99102983 regions of power systems using optimization method Zhu, J. et nl. Electric Power Sysfems Research, 44, (2). 101-105. For the construction of the maximal steady-state security regions of power systems using optimization a new approach is detailed. Based on dc. load flow, the method, for the first time, directly computes the maximal steadystate security region-hyperbox through a linear programming (LP) model, in which the upper and lower limits of each component forming hyperbox are taken as unknown variables. The objective is to maximize the sum of each generator’s power adjustment range. The IEEE six-bus and 30.bus systems have been used to test the new concept. The calculation results and comparison show that the new method is superior to the extending method which is the conventional means for constructing maximal steady-state security regions. Degradation mechanism due to decomposition of 98102904 organic electrolyte in LilMoS2 ceils during long cycling Kumai, K. cr al. J. Power Sources, 1998, 70, (2) 235-239. An investigation into the degradation mechanism during charge and discharge cycling of Li/MoSz cells due to the decomposition of organic electrolytes. Gas chromatography (GC) was used to measure the gas products of the electrolyte decomposition during long cycling and the changes in electrolyte composition were measured by gas chromatography/ mass spectrometry (GCIMS). Two types of electrolyte decomposition produced the gases: the electrochemical reaction, which was dependent on the charge and discharge voltage, and the chemical reaction, which was independent of the discharge voltage. This decomposition of electrolytes occurred under a discharge voltage lower than 1.4 V. Electrochemical decomposition was accelerated under operating conditions with a lower discharge rate and a deeper depth of discharge (DOD). The rate of gas production by chemical decomposition, which is independent of the discharge condition, was estimated to be about 0.1 ml/h. Development of a 1000 kW class MCFC pilot plant in 98102905 Japan Yasue, H. er al. J. Power Sources, 1998, 71, (l/2), 89-94. in Japan, the development of a molten carbonate fuel cell (MCFC) began in 1981, as part of the former Moonlight Programme, promoted by the Agency of Industrial Science and Technology of the Ministry of International Trade and Industry. After the basic research, plans to develop a 1000 kW class MCFC pilot plant began in 1987 with the development of 100 kW class stacks and components. Results from the first developments were applied to the next stage of the project, the operating test of a 1000 kW class pilot plant. The main objective of this pilot plant is to verify the system connected stacks and components. At present, the building work, component fabrication and installation are complete and component adjustments have been carried out. The process and control test will commence in 1998. The operation will come to an end in fiscal year 1999. A

Electrical power supply and utilization (scientific, technical)

test on longer

lifetime stacks will follow the operation tests and the development of a demonstration plant. The possibility of several MW to several tens of MW output, for this future demonstration plant will be seriously investigated.

Development of power system control facilities in :iion2a986 Zhang, B. M. Electric Power Systems Research, 27-33. The paper addresses the development of Chinese power system control facilities. Automation facilities in power system dispatching centres are particularly emphasized. Firstly, the dispatching centre hierarchy in China is introduced and then the development of energy management system (EMS) and distribution management system (DMS) in China is reported. The development of integrated substation automation and feeder automation is also presented. 99102987 Development of second generation direct internal reforming molten carbonate fuel ceil stack technology for cogeneration application Kraaij, G. J. J. Power Sources, 1998, 71, (l/2), 215-217. The basis for second generation direct internal reforming molten carbonate fuel cell (DIR-MCFC) stack development is a system-dedicated stack. An internally manifolded, co-flow stack with robust sealing properties and lifetime ~25,000 h is therefore being developed. Stack design, validation of design tools and obtaining the specifications for full size stack components are the prime objectives. 98102988 Dynamic model for molten carbonate fuel-ceil power-generation systems He, W. Energy Convers. Mgmt, 1998, 39, (8) 775-783. A simulation model for investigating the dynamic performance of molten carbonate fuel-cell power-generation systems is introduced. It consists of nine types of component models: fuel cell, external reformer, steam generator, water separator, rotation equipment, heat exchanger, DC/AC inventer, pipeline and control valve. The model is applied to the calculation of the load-following capability of the system under various step changes and to identify the potential component operation problems at loadfollowing modes. 96102999 A dynamic simulator for a 250 kW class ER-MCFC system Kortbeek, P. J. et al. J. Power Sources, 1998, 71, (l/2), 278-280. In order to study the controllability of the system, a dynamic simulator has been built for a 250 kW ER-molten carbonate fuel cell (MCFC) system. The tool has a modular set-up and will be used for designing the control system of more advanced MCFC systems, such as the SMARTER system or can be adapted for systems based on other types of fuel cell, such as phosphoric acid fuel cell (PAFC), solid polymer fuel cell (SPFC) or solid oxide fuel cell (SOFC). 9ato2990 Effect of operating pressure on the system efficiency of a methane-fueiied solid polymer fuel cell power source Virji, M. B. V. et al. J. Power Sources, 1998, 71, (l/2), 337-347. A fuel cell’s energy conversion efficiency is directly related to its operating voltage. Increasing the fuel and oxidant pressure generally increases the cell potential. However, additional energy is required to compress the gases in order to raise the pressure, negating the efficiency gains achieved in the cells. System designers seek to balance complexity, cost and system efficiency. The overall system efficiency is highly dependent on the interaction and interconnection of the components. An analysis has been carried out for a system which includes a solid polymer fuel cell (SPFC) stack, a methane fuel processor and a compressor/expander to assess the functional relationship between the operating pressure and efficiency. For a system configuration which includes a high-temperature fuel processor and a 40 kW, stack, an 8% improvement in efficiency was predicted for the higher operating pressure. 96102991 Effects of Nb and Pd on the electrochemical properties of a Ti-Ni hydrogen-storage electrode Wang, C. S. et al. J. Power Sources, 1998, 70, (2) 222-227. The paper examines the effects of niobium and palladium on the electrochemical properties of a titanium-nickel hydrogen-storage electrode. The results show that palladium or niobium addition to the alloy can decrease the rate of decay of the exchange current during charge-discharge cycling and is also useful in increasing the discharge capacity and cycle life of titanium-nickel electrodes. 98102992 EMTP models for simulation of shunt reactor switching transients Prikier, L. et al. Electrical Power & Energy Systems, 1997, 19, (4), 235-240. Shunt reactor sets are generally used to compensate long EHV transmission lines. Reactor failures have directed attention to the transient overvoltages generated by reactor switching. Measurements from a 750 kV site have shown that arrester operations or breaker restrikes could cause particularly dangerous steep reactor voltages. The paper introduces a comprehensive EMTP-type model of the reactor and the surrounding system. The computer model has been tested by field experiments. For the study of transients, a similar computer model has been elaborated caused by

Fuel and Energy Abstracts

July 1998

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