Showing papers in "Universal Journal of Electrical and Electronic Engineering in 2017"

Role of Dopants on Ceria-based Anodes for IT-SOFCs Powered by Hydrocarbon Fuels

Abstract: The direct use of hydrocarbon or hydrocarbon-derived fuels to generate electrical power has the potential to accelerate substantially the use of fuel cells in transportation and distributed-power applications. Most fuel-cell research has involved the use of hydrogen as the fuel, although the practical generation and storage of hydrogen remains an important technological hurdle. Although hydrocarbon fuels have been successfully oxidised or reformed electrochemically, the susceptibility to carbon formation or poor power densities has prevented the application of these fuels in practical applications. In this manuscript, the effect of different dopants on the properties of Cu-ceria based anodes for IT-SOFCs powered by hydrocarbon fuels has been explored. Four dopants atoms (Co, Ca, Ag and Rh) with different properties and concomitant varied effects on properties of the final material are studied. They have been selected in order to improve the electrical and textural properties of anode material as well as the catalytic activity for hydrocarbon oxidation. Results revealed a strong dependence of the final properties of the anode formulation and mechanism involved in the electro-oxidation of the different fuels. Different doping successfully improves the behaviour of anode material for IT-SOFCs powered by hydrocarbon fuels and reasonable power densities can be achieved.

Design of a Broadband Planar RF Structure for a 0.22 THz Travelling Wave Tube

Abstract: Planar broadband THz travelling wave tube is being designed for ultra broadband high speed data rate communication and imaging. A simplified analytical approach is developed for designing of a planar staggered double vane rectangular waveguide slow-wave structure (SDVSWS) for a broadband 0.22 THz 100W TWT. The structure is inherently compatible for sheet beam operation, and it is designed for an electron beam of voltage 20 kV and current 50 mA. 3D e.m. field simulator code CST-MWS was used for simulating the SDVSWS using the analytical design parameters. It is found that the dispersion characteristic by the analytical method matches well within 5% with the simulated dispersion characteristic of the structure. Effects of various parameters of a double-vane SWS on dispersion and impedance characteristics are evaluated for achieving a planar TWT of bandwidth more than 40 GHz with high gain. It is shown that pitch and vane height are most significant parameters and half-period staggering of double vanes in the structure provides wider bandwidth, high impedance and high symmetric RF electric field for efficient beam-wave interaction.

An Investigation of Grounding Resistance Estimation of Human Body by Attenuation Coefficient

Abstract: It is dangerous when human are working in and around the high voltage environments. The safety of personnel in and around electric power the installations has been a prime concern. Specifically, this safety is generally in terms of the allowable touch and step voltages. These voltages are related to the ground resistance of human foot. In order to increase the safety of personnel, a high resistivity surface layer of gravel is normally existed in the substation switchyards or other high voltage areas. The thickness of this layer will affect the calculation of the ground resistance of human foot. Among them, the electromagnetic field factors are also considered in this paper. As a result, the surface layer of gravel can be used to reduce the ground resistance of human foot. The equivalent model of human foot was modeled by the circular plate conductor in the past. This paper investigates the present methods for estimating the ground resistance of human foot and proposes an equivalent model for calculating the ground resistance of human foot. A comparison of the proposed model and present methods is also shown in this paper.

Approximate Analysis of Transient Heat Conduction in the Stator of an Induction Motor during Auto-transformer Starting

Abstract: For the development of electric machines, particularly induction machines, temperature limit is a key factor affecting the efficiency of the overall design during transient state. Since conventional loading of induction motors is often expensive, the estimation of temperature rise by tools of mathematical modeling becomes increasingly important and as a result of which computational methods are widely used for estimation of temperature rise in electrical machines. This paper describes the problem of two dimensional transient state heat flow in the stator of induction motor during auto-transformer starting. The stator being static is prone to high temperature and the study of thermal behavior in the stator is useful to identify the causes of failure in induction machines. The temperature distribution is obtained using finite element formulation and employing arch shaped elements in the r-θ plane of the cylindrical co-ordinate system. This model is applied to one 3-phase squirrel cage induction motor of 7.5 kW rating.

Energy Yield and Economic Analysis of Tracker Controlled and Fixed Angle Photovoltaic Solar Power System

Abstract: The efficiency of the solar system is affected by the angle between a photovoltaic (PV) panel and sun. More direct sun light on PV modules leads to enhanced energy yield. Therefore, tracking systems are implemented to improve the performance of PV system by tracking sun trajectory. With the advent of different applications of PV solar power, system planners have been implementing different strategies and techniques to maximize the output of solar system with commonly available technology in market. The foremost purpose of this study was to provide comparison of energy yield for timer based tracker controlled PV system and fixed angle PV system. Furthermore, implementation cost and payback analysis for both types of systems have also been done. This study is performed to find the feasibility of tracker system installation based on energy generation over sizable period of time. The base line results of this study were obtained via software based simulation techniques as well as physical implementation of simulated system to analyze the various parameters. Various simulation software (mainly PVsyst and Meteonorm) are used. Tracker based PV system and fixed angle PV system were designed and simulated via PVsyst 5.61 software. Both the simulated systems were practically installed and analyzed in real time conditions. Additionally, various mathematical techniques were utilized to analyze the results gathered from simulations and physical implementation. Results of this study are based on two types of analysis. First, comparison of simulated with real time measured values for the systems. Secondly, cost benefit analysis of both technologies is done in terms of payback period. This work differs from the rest as both PV systems were simulated and practically implemented to get appropriate results and mainly all the equipment and services utilized in installation are widely available in local market. As tracker based PV systems seem less viable in market due to the recent cost reduction of PV modules, so in this study the feasibility of tracker based PV systems is analyzed.

VLSI Implementation of 8051 MCU with Decoupling Capacitor for IC-EMC

Abstract: In recent years, several new methods for IC-level electromagnetic compatibility (EMC) testing have been introduced. Therefore, a handy vehicle for IC-EMC testing is required to validate the effectiveness of the new IC-EMC testing methods. This paper proposes an 8051 MCU for IC-EMC testing platform with in-system programming (ISP) and decoupling capacitor (decap) functions. In order to reduce the EMI and improve the EMC properties for the 8051 MCU, decoupling capacitors (decaps) are added to the integrated circuit (IC) design flow. Chip-level design and fabrication technology are fundamental and cost-effective solutions to this issue. A cell-based design flow is used for chip implementation; specifically, TSMC 90-nm technology is used to implement the present chip via the National Chip Implementation Center. This study will implement two 8051 MCU chips: one that internally comprises a large number of decaps, and another that comprises no decaps. We also implemented an IC-EMC testing platform composed of a multifunction test board and several off-board probes that were fabricated according to IEC 61967 and IEC 62132 standards. The platform demonstrates a method for using the proposed two 8051 chips in EMC testing, and we reveal the results of its EMC performance. Finally, this study simulates the EMC properties, compares the two 8051 MCU chips, conducts static or dynamic analyses for the chips in a power network, and measures the EMC improvements.

Multi-Terminal VSC-HVDC for Wind Power in Thailand

Abstract: This paper presents an application of an asynchronous back to back VSC-HVDC system, which uses multilevel converter, which uses two-level series voltage connection SPWM converter topology technique. The control strategy is design and implementation of Multi-Terminal on a VSC-HVDC network, representing the future transnational network in Thailand with rated 300MVA (±300kV). The capability to dispatch the offshore wind power as well as the traded power among the onshore grids is explored under wind speed changes. The controller of an asynchronous back to back VSC-HVDC system, the process PQ controller can realize the designated control of active power (P) and reactive power (Q) strategy. The PQ power can exchange controlled independently, the experimental in laboratory tests, and simulation results got from MATLAB/Simulink program software, The Simulation results, the PQ-controller results consist of PMSG rotational speed, voltages and currents, the active and reactive power, DC-bus (kVDC), DC-power (Pdc) and step response command active power, the control of DC-bus voltage is assured by regulation of the active and reactive power. The control strategy of PQ-control to the two-level SPWM converters topology technique for the realization of HVDC system, and to confirm the control strategy provides satisfactory response and strong stability. The system of wind power application is used as a guideline for analyzing and design of the data process control with the PQ-control HVDC system.