• The Transactions of the Korean Institute of Electrical Engineers
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• v.34 no.5
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• pp.201-209
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• 1985

This paper describes a method for the state estimation by a modified fast decoupled estimation method and system decomposition. The state values are gained by using the weighted least square estimation method, fast decoupled estimation method, and modified fast decoupled estimation method. The estimated values of each method were compared about effectiveness of state values, respectively. This paper investigated the effects of impedance of well-condition or ill-condition into lines. The characteristics of state estimation were gained through hierarchical state estimation. Each method was applied to three model power systems, and, the results of test for the proposed method are given.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.35 no.4
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• pp.148-155
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• 1986

This paper presents a new decoupled power system state estimation method. The decoupling is achieved via simple linear transformation on power measurements in contrast with the modified fast decoupled state estimation method which assumes decoupling by direct negligence of the off-diagonal blocks of the observation functions. The new estimation method is compared with the modified decoupled state estimation method against IEEE-14 bus model power system and 25 bus model power system in several system conditions. It is observed that the proposed method shows better convergence performance and filtering performance than a modified fast decoupled state estimation.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.46-48
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• 2000

Continuation power flow has been developed to remove the ill-condition problem caused by singularity of power flow Jacobian at and near steady-state voltage instability point in conventional power flow. When solving large-scale power transmission systems, an alternative strategy for improving computational efficiency and reducing computer storage requirements is the decoupled power flow method, which makes use of an approximate version of the Newton-Raphson procedure. This paper presents a technique to improve the speed of continuation power flow system using decoupled power flow method.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.12
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• pp.1514-1519
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• 1999

This paper presents two flexible alternatives to the decoupled load flow(DCL) method. The proposed load flow methods can improve the convergence profiles of the DCL by reflecting in part the effects of the off-diagonal terms in the Jacobian at minimal costs. They can improve the convergence characteristics especially when the power system operating states deviate from the conditions required for stable convergence of the DCL and the P-Q coupling becomes significant. Two algorithms are obtained from the expression of the full Newton-Raphson load flow (NRL) method by successively diminishing the effects of the off-diagonal submatrices in the Jacobian. In the process of simplification, the Neuman series expansion is utilized. Test results show promising performances of the proposed algorithms in their convergence characteristics both in number of iterations and overall convergence speeds. Proposed algorithms are expected to provide flexible alternatives to the NRL when the DCL experiences convergence problems.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.5
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• pp.403-408
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• 2012

In this paper, we propose useful load flow algorithms called FEDL (fast enhanced decoupled load flow). The proposed load flow method can improve the convergence characteristics particularly when the P-Q coupling becomes significant and the power system operating states deviate from the conditions required for stable convergence of the FDL by reflecting in part the effects of the off-diagonal terms in the Jacobian. In our test with IEEE AEP-30 bus system and RTS-96 73-bus system, it converge even when the fast decoupled load flow (FDL) and its variations keeping load flow matrices constant experience convergence problems. Test results show promising performances of the proposed algorithms in their convergence characteristics both in number of iterations and overall convergence speeds.

• Journal of Power Electronics
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• v.18 no.5
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• pp.1424-1433
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• 2018

This paper presents a novel space vector pulse-width modulation (SVPWM) to synthesize an arbitrary non-sinusoidal phase voltage. The key of the proposed method is that the switching vectors used to comprise the reference vectors in the ${\alpha}_1-{\beta}_1$ frame and the ${\alpha}_3-{\beta}_3$ frame are decoupled. In the ${\alpha}_1-{\beta}_1$ frame, the reference vector is comprised by near two large vectors. The corresponding vector comprised by the two vectors in the ${\alpha}_3-{\beta}_3$ frame is considered as a disturbance, which is restrained by close-loop control. In the ${\alpha}_3-{\beta}_3$ frame, there are two methods to comprise the reference vector. Method I is a near two middle vectors method. Method II uses near four vectors (two middle and two little vectors). The proposed SVPWM using decoupled switching vectors can guarantee a maximum modulation index in the ${\alpha}_1-{\beta}_1$ frame. The effectiveness of the proposed method is verified by simulated and experimental results under various operation conditions.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.12
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• pp.1053-1060
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• 2000

In this paper, a discrete-time variable structure control method using recursively defined switching function and a decoupled variable structure disturbance compensator is used to achieve high performance circular motion control of a CNC machining center. The discrete-time variable structure control with the decoupled disturbance compensator method developed in this paper uses a recursive switching function defined as the sum of the current tracking error vector and the previous value of the switching function multiplied by a positive constant less than one. This recursive switching function provides much improved performance compared to the method that uses a switching function defined only as a linear combination of the current tracking error. Enhancements in tracking performance are demonstrated in the circular motion control using a CNC milling machine.

• Structural Engineering and Mechanics
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• v.46 no.6
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• pp.775-790
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• 2013

Deformation analysis is a major concern in many geotechnical applications. In this paper, the deformation behavior of a geocell mattress subjected to symmetric loads was studied. The mattress was idealized as an elastic foundation beam. The horizontal beam-soil interfacial shear resistances at the beam top and bottom sides were taken into account by assuming the resistances to be linear with the relative horizontal displacements. A decoupled iterative method was employed to solve the differential displacement equations derived from the force analysis of a beam element and to obtain the solutions for the deformations and internal forces of the geocell reinforcement. The validity of the present solutions was verified by the existing finite element method and power-series solutions.

• Proceedings of the KIEE Conference
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• 2000.11a
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• pp.13-16
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• 2000

Continuation power flow has been developed to remove the ill-condition problem caused by singularity of power flow Jacobian at and near steady-state voltage instability point in conventional power flow. When solving large-scale power transmission systems, continuation power flow require large computational costs. Therefore, technique to improve the speed of continuation power flow system was required. In this paper Decoupled Power Flow Method (DPFM), Enhanced Decoupled Power Flow Method (EDPFM), Robust Fast Decoupled Power Flow Method (RFDPFM) are applied to continuation power flow algorithm to improve the speed of continuation power flow system.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.21 no.1
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• pp.23-29
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• 2013

This paper presents a tracking filter of radar beacon system (RBS) for automatic takeoff and landing of an unmanned aerial vehicle. The proposed tracking filter is designed as the decoupled tracking filter to reduce the computational burden. Also, an adaptive estimation method of the measurement error covariance is proposed to provide an improved tracking performance compared to the conventional decoupled tracking filter whenever the accuracy of RBS observations is degraded. 100 times Monte Carlo runs performed to analyze the performance of the proposed tracking filter in case of normal operation and degraded operations, respectively. The simulation results show that the proposed tracking filter provides the improved tracking accuracy in comparison with the conventional decoupled tracking filter.