The Experts below are selected from a list of 300 Experts worldwide ranked by ideXlab platform

D. Hoadley - One of the best experts on this subject based on the ideXlab platform.

  • A New Phase-Coordinate Transformer Model for y Bus Analysis
    IEEE Transactions on Power Systems, 2002
    Co-Authors: S. S. Moorthy, D. Hoadley
    Abstract:

    A new method of modeling three-Phase transformers has been developed. The method can represent transformers with two or more windings and can incorporate the effects of interPhase coupling, particularly the lowered impedance of three-Phase units to zero-sequence magnetizing currents. For two-winding transformers, the model requires only four data items per transformer and can still be used even in the absence of some of them, in which case, it simplifies to existing well-established modeling techniques.

  • Steady-state Phase-Coordinate model for induction machines
    Electric Power Systems Research, 2001
    Co-Authors: D. Hoadley, S. Moorthy, Majid Al-dabbagh
    Abstract:

    Abstract A Phase-Coordinate model for induction machines is developed, to facilitate load-flow studies of small hydro- or wind generators connected to distribution systems. The Phase-Coordinate method allows ready analysis of system unbalance, and the model is applicable to both induction motors and generators under these conditions.

Lv Ming - One of the best experts on this subject based on the ideXlab platform.

Junji Tamura - One of the best experts on this subject based on the ideXlab platform.

  • Unbalanced power flow calculation of a power system containing a variable‐speed generator
    Electrical Engineering in Japan, 2000
    Co-Authors: Junji Tamura, Masahiro Kubo, Toshiyuki Nagano
    Abstract:

    There are some factors that render a power system network unbalanced: UHV transmission lines in which three-Phase transmission lines are not transposed, an unbalanced transformer, unbalanced load as well as sustained unbalanced faults. On the other hand, the number of variable-speed generators used in pumping-up power stations has recently been increasing in Japan. This paper presents a new means of calculating unbalanced power flow of a power system which contains variable-speed pumping-up generators. This new technique is based on the Phase Coordinate method, because a power system which has elements of unsymmetrical impedance can easily be analyzed by using it. In this paper, Phase Coordinate models of the variable-speed generator and its secondary exciting circuit, composed of a GTO converter/inverter, are analyzed first. Procedures of power flow calculation of unbalanced power systems follow. © 2000 Scripta Technica, Electr Eng Jpn, 134(3): 34–43, 2001

  • A method of transient stability simulation of unbalanced power system
    PowerTech Budapest 99. Abstract Records. (Cat. No.99EX376), 1999
    Co-Authors: Junji Tamura, M. Kubo, T. Nagano
    Abstract:

    This paper presents a new simulation method to analyze the transient stability of a power system including three Phase unbalanced impedances. The method is based on the Phase Coordinate method, because it is easy to analyze the power system which has elements of unbalanced three Phase impedances by the Phase Coordinate method. This paper consists of two main parts: unbalanced power flow calculation to determine the initial conditions, and the transient stability simulation of power system following faults.

  • A synchronous machine model for unbalanced analyses
    Electrical Engineering in Japan, 1997
    Co-Authors: Junji Tamura, Ikuo Takeda, Mitsugu Kimura, Masahiro Ueno, Shigeru Yonaga
    Abstract:

    This paper presents a new asymmetrical model of synchronous generators for power system transient stability simulations. The symmetrical component method has been used traditionally in the analysis of unbalanced faults in power systems. This is mainly because the synchronous generators, which play an important role in the power system, can be easily treated by the method. However, when analyzing a system that has elements with asymmetrical impedance, it may not be easy to use the symmetrical component method. In such cases, the simulations can be easily executed by using the Phase Coordinate method. However, there are few papers that derive a Phase Coordinate model of synchronous machines. This paper analyzes synchronous generators under asymmetrical conditions in detail by using the symmetrical component method, then derives a model of synchronous generators for the Phase Coordinate method. © 1997 Scripta Technica, Inc. Electr Eng Jpn 119(2): 46–59, 1997

G. Švenda - One of the best experts on this subject based on the ideXlab platform.

  • Power and earthing system modeling in natural Coordinates
    International Journal of Electrical Power & Energy Systems, 2002
    Co-Authors: J. Nahman, G. Švenda
    Abstract:

    A power system model in natural Coordinates is developed for an efficient analysis of the currents and voltages in complex earthing systems caused by Phase-to-earth faults. The approach suggested makes it possible to consider in a general and comparatively simple manner, the structural asymmetry of power and earthing system components and the multiple system failures. Phase Coordinate models for transformer stations with auto- and separate multiple winding transformers are extended in a way to enable a proper interconnection with associated earth electrodes. Illustrative examples from practice are included.

Naoyuki Uchida - One of the best experts on this subject based on the ideXlab platform.

  • Fast computation and stable convergence technique for unbalanced load flow calculation in large‐scale systems
    Electrical Engineering in Japan, 2010
    Co-Authors: Keisuke Shirasaki, Naoyuki Uchida
    Abstract:

    This paper presents a new method of unbalanced load flow calculation to improve complexity by the method of advanced symmetrical Coordinates. Usually, the electric power system has been calculated only by the positive Phase sequence component on the assumption that three-Phase transmission lines and loads are balanced. However, many ultrahigh-voltage transmission lines are not transposed, and therefore mutual inductances cause negative sequence currents in the trunk transmission system. Negative sequence currents cause heating of generators and transformers, and therefore the three-Phase sequence component should be calculated accurately. We examined the fast computation and good convergence performance of unbalanced load flow calculation by models of three-Phase transmission lines, transformers, and loads. The proposed method is not the Phase Coordinate system but the method of symmetrical Coordinates. This technique decreases numerical complexity by the use of a simplified Jacobian matrix. The convergence performance of this method is inferior to that of the usual Newton–Raphson method. As a consequence, the problem of poor convergence performance is alleviated by a technique for the newly developed deceleration Newton method. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 174(1): 17–24, 2011; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.21034

  • Fast Computation and Stable Convergence Technique for Unbalanced Load Flow Calculation in the Large Scale System
    IEEJ Transactions on Power and Energy, 2008
    Co-Authors: Keisuke Shirasaki, Naoyuki Uchida
    Abstract:

    This paper presents a new method of unbalanced load flow calculation to improve complexity by the method of advanced symmetrical Coordinates. Usually, the electric power system has been calculated only by positive Phase sequence component on the assumption that three Phase transmission lines and loads are balanced. However, many ultra high voltage transmission lines are not transposed, therefore mutual inductances cause negative sequence current in trunk transmission system. Negative sequence current causes the heating of the generators and transformers. Therefore, the three Phase sequence component should be calculated accurately.We examined fast computation and good convergence performance of unbalanced load flow calculation by the models of three Phase transmission lines, transformers and loads. The proposed method is not the Phase Coordinate system but the method of symmetrical Coordinates. This technique decreases numerical complexity by the use of simplified jacobian matrix. The convergence performance of this method is inferior to usual Newton-Raphson method. In consequence, the problem of poor convergence performance is improved by the technique for newly developed deceleration Newton method.