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This paper proposes a new kind of multifunctional energy system (MES) using natural gas and coal to more efficiently and more economically produce methanol and power. Traditional chemical processes pursue high conversion ratios of chemical energy o f fuels. The new MES focuses on the moderate conversion of the chemical energy of fuels. To do this, about 50% of the coal is partially gasified with pure oxygen and steam as oxidant, and then the unconverted residuals (char) and natural gas are utilized synthetically by char-fired reforming to generate syngas. The combustion of char drives the methane/ steam-reforming reaction. Here, the reforming reaction is also moderately converted, and the reforming temperature is decreased 100-150[degrees]C compared with that of the conventional method. The carbon-rich syngas from the partial gasifier of coal and hydrogen-rich syngas from char-fired reformer are mixed together and converted into methanol at a proper conversion ratio (lower than that of the conventional chemical process). Finally, the unconverted syngas is used in a combined cycle as fuel for power generation. As a result, the total exergy efficiency of the new system is 55-60%. Comparing to individual systems, including the integrated gasification combined cycle and the natural gas-based methanol synthesis plants, this new system can generate 10-20% more electricity with the same quantity of fossil fuel input and methanol output. In addition, the possibility of reducing the size of gasifier, reformer, and methanol synthesis reactor may reduce investment costs accordingly. These results may provide a new way to use coal and natural gas more efficiently and economically. [DOI: 10.1115/1.3205025]

Fuel Cell/Gas Turbine (FC/GT) hybrid technology is promising, but introduces challenges in system operation and control For base-load applications, changes in ambient conditions perturb the system and it becomes difficult to maintain constant power production by the FC/GT system. If the FC/GT hybrid system is load-following, then the problem becomes even more complex. In the current study, a dynamic model of a FC/GT power plant is developed with system controls. Two cases are evaluated: (1) system controls are developed to maintain constant power and process control within acceptable constraints and (2) the FC/GT power plant is set in power following mode connected in parallel to the grid for a daily load profile scenario. Changing ambient conditions are employed in the dynamic analysis for both cases. With appropriate attention to design of the system itself and the control logic, the challenges for dynamic system operation and control can be addressed. [DOI: 10.1115/1.2833489] Keywords: fuel cell, gas turbine, hybrid, controls, dynamic simulation, base-load

As energy demands increase and the associated costs increase with that demand, newer energy alternatives are becoming more important to society. Although not new, fuel cell technology is taking a lead role in the quest for a cleaner and competitive power generation system. High efficiencies on the order of 50% are now possible with stand-alone fuel cells. When coupled with a gas turbine, efficiencies of around 70% may be expected. However, the fuel cell/gas turbine hybrid has inherent problems of stability and unpredictable response to adverse transients that first must be addressed to make this technology viable. The National Energy Technology Laboratories (NETL) in Morgantown is involved in the development of such hybrid technology. This study details a process modeling approach based on a commercial modeling package, and is associated specifically with the NETL Hybrid Performance (HYPER) research effort. Simulation versus experimental test data are presented to validate the process model during the cold flow startup phase. The results provide insight into the transients of the system built at NETL. [DOI: 10.1115/1.2830551]

This paper presents a fast hardware-efficient logic for fault detection and classification in transmission lines, implemented using a field-programmable gate array (FPGA). The general-purpose SPARTAN3E FPGA was employed for developing the prototype, with all the coding done using a hardware description language (HDL) called very high speed integrated circuit (VHDL). The proposed logic employs only one-terminal current samples and is based on wavelet analysis. Depending on the amount of high frequency components in the current signals after processing, the faults are classified into ten types. The Real Time Windows Target Toolbox of MATLAB was used to apply the current signal inputs to the prototype in real time. An adaptive threshold value is chosen, rather than a fixed threshold in the case of faults involving the ground, to make the classification reliable and accurate. The fault classification time is 6 ms, which is about 1/3 of the power frequency cycle (20 ms). A high level of computational efficiency is achieved as compared to the other wavelet-transform-based algorithms, since only the high frequency details at first level are employed in this algorithm. The validity of the proposed logic was exhaustively tested by simulating various types of faults on a system modeled in the Electromagnetic Transients Program/Alternative Transients Program. The proposed logic was found to be highly reliable and accurate, even in the presence of fault resistance. Index Terms--Fault classification, field-programmable gate array (FPGA) implementation, transmission line protection, wavelet transform.

Among the several components of distribution systems, protection devices present a fundamental importance, since they aim at keeping the physical integrity not only of the system equipment, but also of the electricians team and the population in general. The existing tools today in the market that carry out the making of protection studies basically draw curves, and need direct user's interference for the protection devices adjustment and coordination analyses of selectivity, being susceptible to the user's mistakes and not always considering the best technical and economical application. In Brazil, the correct application of the protection devices demand a high amount of time, being extremely laborious due to the great number of devices (around 200 devices), besides the very dynamic behavior of distribution networks and the need for constant system expansion. This paper presents a computational tool developed with the objective of automatically determining the adjustments of all protection devices in the distribution networks to obtain the best technical application, optimizing its performance and making easier protection studies. Index Terms--Optimization, protection coordination and distribution networks, protection devices.

In this paper, extended research upon the potentials of implementing distributed artificial intelligence technology to achieve high degrees of independency in distribution network protection and restoration processes is presented. The work that has already been done in the area of agent-based and/or knowledge-based applications and expert systems is briefly reviewed. The authors justify the need to distribute activities in contradiction to the centralized methodologies. A proper model of the real environment is introduced in order to define the designing parameters of a prototype agent entity, which is the part of a cooperative network-management system. The system's goal is to autonomously perform effective fault management upon medium-voltage power distribution lines. The structure of the agent entity is then described by means of the agent behaviors being implemented. The cooperative operations of the proposed system and its computer simulation are presented. Simulation results are being evaluated. Finally, general conclusive remarks are made. Index Terms--Artificial intelligence, cooperative systems, power distribution protection, underground power distribution lines.