IEEJ Model Research Articles

A (T,ψ)‐ψe decoupled scheme for a time‐dependent multiply‐connected eddy current problem

The aim of this paper is to develop a fully discrete (T,ψ)‐ψe finite element decoupled scheme to solve time‐dependent eddy current problems with multiply‐connected conductors. By making ‘cuts’ and setting jumps of ψe across the cuts in nonconductive domain, the uniqueness of ψe is guaranteed. Distinguished from the traditional T‐ ψ method, our decoupled scheme solves the potentials T and ψ‐ ψe separately in two different simple equation systems, which avoids solving a saddle‐point equation system and leads to a remarkable reduction in computational efforts. The energy‐norm error estimate of the fully discrete decoupled scheme is provided. Finally, the scheme is applied to solve two benchmark problems—TEAM Workshop Problems 7 and IEEJ model. Copyright © 2013 John Wiley & Sons, Ltd.

Investigation of AC loss of permanent magnet of SPM motor considering hysteresis and eddy-current losses

NdFeB sintered magnets are widely used in rotating electrical machines. In order to develop an efficient rotating machine, it is important to estimate ac loss of the permanent magnet of rotor precisely. In this paper, the ac losses of the permanent magnet of IEEJ model (surface permanent-magnet motor model) are examined by using the three-dimensional finite-element method taking into account the newly measured hysteresis losses of permanent magnet. The result shows that we should consider not only the eddy-current loss but also the hysteresis loss, when the frequency of ac field due to a slot ripple is of the order of several hundred hertz.

Determination of optimal system configuration in japanese secondary power systems

In Japan, when a secondary radial power system (66 kV, 77 kV) has a number of connected feeders whose circuit breakers (CBs) can be opened or closed, the combinatorial number of possible system structures created by switching CBs becomes very large. In order to determine the optimal configuration of secondary radial power systems in both the normal state and fault state, a new computation algorithm is proposed. The proposed algorithm is based on enumeration and reduced ordered binary decision diagram (ROBDD). In order to verify the availability of the proposed approach, the authors obtain optimal configurations for normal and fault states on the IEE of Japan secondary power system model (IEEJ model) by using the proposed method. The IEEJ model has the distinctive characteristics of practical Japanese power systems, the total number of configuration candidates is the 76th power of 2 (=75 000 000 000 000 billion approximately). The optimality of the system configuration obtained by the proposed method is mathematically guaranteed.

Dynamic Available Transfer Capability Evaluation by Interior Point Nonlinear Programming

In nowadays deregulated market, available transfer capability (ATC) is a measure of the network capability for further commercial activity above the already committed uses. This paper deals with the development of an interior point nonlinear programming methodology for evaluating dynamic ATC. By establishing a novel method for integrating transient stability constraints into conventional steady-state ATC problem, the dynamic ATC problem is successfully formulated as an OPF-based optimization problem. Then, an interior point nonlinear programming algorithm is used to solve the formed dynamic ATC optimization problem. The method has been implemented and tested on two IEEJ model systems (WEST10 and WEST30). In both systems, satisfactory results are obtained.

Determination of Optimal System Confitguration in Japanese Secondary Power Systems

In Japan, when a secondary radial power system (66 kV, 77 kV) has a number of connected feeders whose circuit breakers (CB) can be opened or closed, the combinatorial number of possible system structures created by switching CBs becomes very large. In order to determine the optimal configuration of a secondary radial power system in normal state and fault state, a new computation algorithm is proposed. The algorithm is based on enumeration and reduced ordered binary decision diagram (ROBDD). In order to verify the availability of the proposed approach, the authors obtain optimal configurations for both of normal and fault states on IEE of Japan secondary power system model (IEEJ model) by using the proposed method. The IEEJ model has the distinctive characteristics of practical Japanese power systems, the total number of configuration candidates is the 76th power of 2 (= 75,000,000,000,000 billion approximately). The optimality of the system configuration obtained by the proposed method is mathematically guaranteed.

3-D finite element analysis of permanent-magnet motor excited from square pulse voltage source

This paper describes a new method for the 3D computation of a permanent magnet motor excited from a voltage source. The method has advantages that the 3D mesh as well as the circuit is changed automatically according to the movement of the armature. The method is applied to the rotating analysis of the IEEJ model excited from a square pulse voltage source. The results calculated by the 3D analysis are compared with the results by a 2D analysis. The validity of the new method is also confirmed by experiments.

Hybrid finite element-boundary element method for nonlinear electromagnetic problems

The paper deals with the application of the hybrid finite element-boundary element method in the computation of linear and nonlinear magnetostatic field with a vector potential for 2D and with a scalar potential for 3D problems. The nonlinear part of the domain is solved by finite elements, while in the linear part of the domain, the boundary elements are used. Different boundary formulations are developed to overcome the coupling problems. "Mixed" boundary elements are coupled with linear finite elements, for both 2D and 3D problems. Typical examples are presented: electrical motor and the IEEJ model.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Effects of permeability of magnetic materials on errors of the T- Omega method

The error inherent in the T- Omega method due to cancellation between the current vector potential T and grad Omega terms is investigated by solving typical models. The cancellation error is examined using not only an axisymmetric simple model but also a three-dimensional one. The effect of permeability on the error of the T- Omega method is quantitatively examined using the simple model under DC and AC excitations. The errors in single precision and double precision are also investigated, and the allowable range of permeability is discussed. The magnetic field of the IEEJ model analyzed, and the calculated results are compared with measured ones. It is concluded that, although in general the error increases with the increase in permeability, the magnitude of the error is negligibly small if the calculation is carried out in double precision.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>