Search

This study explores the impact of end electric current on the performance of a marine magnetohydrodynamic (MHD) propulsion motor or thruster using a comprehensive 3D numerical simulation. The investigation focuses on various operating parameters, such as electromagnetic and drag forces, efficiency, losses, current, and different pressure components. To validate the numerical findings, a scaled-down experimental setup is utilised. The results demonstrate that certain operating parameters of MHD motors are not affected by the three-dimensional characteristics of their channels. These parameters, including fluid velocity, can be accurately calculated using the analytical model based on the effective electric current of the motor. Conversely, other operating parameters of MHD motors are significantly influenced by the end effects in their channels. For example, the overall efficiency, which depends on the total electric current of the motor, should be calculated using a more precise simulation method. [ABSTRACT FROM AUTHOR]

In this study, the effect of the channel dimensions on the performance of a marine MHD thruster is investigated using a fully three-dimensional numerical model. In this model, all electric, magnetic and fluid flow fields are considered in three dimensions. In addition, a simple analytical model is developed for comparison purpose and an optimisation method is proposed for the channel design to achieve the maximum efficiency and power density. The results show that at a specific output power and flow rate, the channel dimensions can be optimised to achieve the maximum efficiency or output power density, but not both. [ABSTRACT FROM AUTHOR]

This study presents a new three-dimensional (3D) analytical method for no-load magnetic flux density computation of axial-flux permanent-magnet synchronous machines. In the method suggested, at first the machine's cylindrical coordinates are converted to the Cartesian coordinates using conformal mapping, and then Laplace's equation is solved in Cartesian coordinates in 3D to give the scalar magnetic potential. Finally, the magnetic flux density is computed using the scalar magnetic potential. Use of the analytical method takes much less computational time than 3D finite element method does, and is, thus, useful for designing and optimisation purposes. Validation of this method is performed through the 3D finite element analysis and experimental results. [ABSTRACT FROM AUTHOR]

This paper presents an advanced optimization technique to solve unit commitment problems and reliability issues simultaneously for thermal generating units. To solve unit commitment, generalized benders decomposition along with genetic algorithm to include minimum up/down time constraints are proposed, and for reliability issues consideration, a fuzzy stochastic-based technique is presented. To implement the problem into an optimization program, the MATLAB software, and CPLEX and KNITRO solvers are used. To verify the proposed technique and algorithm, two case studies that are IEEE 14 and 118 bus systems are implemented for optimal generation scheduling, and reliability issues. Finally, a comparison with other solution techniques has been given. [ABSTRACT FROM AUTHOR]

This paper presents an advanced optimization technique to solve unit commitment problems and reliability issues simultaneously for thermal generating units. To solve unit commitment, generalized benders decomposition along with genetic algorithm to include minimum up/down time constraints are proposed, and for reliability issues consideration, a fuzzy stochastic-based technique is presented. To implement the problem into an optimization program, the MATLAB software, and CPLEX and KNITRO solvers are used. To verify the proposed technique and algorithm, two case studies that are IEEE 14 and 118 bus systems are implemented for optimal generation scheduling, and reliability issues. Finally, a comparison with other solution techniques has been given. [ABSTRACT FROM AUTHOR]

In this paper, transient stability improvement of power system using fault current limiter (FCL) based on superconducting magnetic energy storage (SMES) is proposed. SMES technology is capable to make dc reactors with large values because of its superconducting property. Using such dc reactors in FCL structure can effectively limit the fault current during short circuits in power lines. To show the additional merits of such FCL structure, it is applied to transient stability of single machine infinite bus (SMIB) system with a double circuit transmission line. Analytical analysis including transient stability study is presented. In addition, simulation results using EMTDC/PSCAD software are included to confirm the analytical analysis accuracy. [ABSTRACT FROM AUTHOR]

Summary: This paper presents a novel feeding system based on matrix converter power supply for DC electric arc furnaces. This recommended topology possesses many promising features like overcoming the disadvantages of conventional DC power supply systems, improving the efficiency of feeding system, and power quality indices improvement in the grid side. It comprises a matrix converter controlled by space vector modulation (SVM) strategy with a single‐sided switching pattern and a six‐pulse diode rectifier. The primary function of this topology is to regulate the rms value of fixed input voltage of AC source to the proper value utilizing matrix converter, and then a six‐pulse diode rectifier can be applied to provide the required DC voltage for supplying DC arc furnace. The selection of matrix converter has been made because of particular advantages such as controllable input power factor, mitigation of input current harmonics, and controllable output frequency. The suggested configuration predominates because of the lower number of rectifier units and smoothing reactors. Moreover, the suggested feeding system does not have any current or power‐sharing problems, and only one proportional‐integral (PI) controller is adequate to control the DC arc current or its power. Note that the matrix converter used in this topology is three‐phase to three‐phase and utilized an improved passive filter (IPF) at the input side. [ABSTRACT FROM AUTHOR]