• Title/Summary/Keyword: Symmetrical components

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Voltage Sag Detection Algorithm for Instantaneous Voltage Sag Corrector

  • Lee, Sang-Hoon;Choi, Jae-Ho
    • Journal of Power Electronics
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    • v.2 no.3
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    • pp.162-170
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    • 2002
  • Voltage sag detection algorithm for voltage sag corrector is proposed in this paper. To quantify the standard of voltage unbalance under the faulted conditions, the 3-phase unbalanced voltages are decomposed into two balanced 3-phase symmetrical components of the positive and negative sequence voltages, which is defined by the magnitude factor (MF) and unbalance factor (UF). It is analyzed that MWF and UF values are given as the dc constant values even though under the voltage unbalance condition. This paper also proposes the control scheme of the instantaneous voltage sag corrector based on this detection algorithm. The validity of the proposed algorithm is verified through the EMTDC simulation and experiments.

Modified Capacitor-Assisted Z-Source Inverter Topology with Enhanced Boost Ability

  • Ho, Anh-Vu;Chun, Tae-Won
    • Journal of Power Electronics
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    • v.17 no.5
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    • pp.1195-1202
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    • 2017
  • This paper presents a novel topology named a modified capacitor-assisted Z-source inverter (MCA-ZSI) based on the traditional ZSI. The impedance network of the proposed MCA-ZSI consists of two symmetrical cells coupled with two capacitors with an X-shape structure, and each cell has two inductors, two capacitors, and one diode. Compared with other topologies based on switched ZSI with the same number of components used at impedance network, the proposed topology provides higher boost ability, lower voltage stress across inverter switching devices, and lower capacitor voltage stress. The improved performances of the proposed topology are demonstrated in the simulation and experimental results.

Starting Characteristic Analysis of Single-Phase Line-Start Permanent Magnet Synchronous Motor (단상 직립기동 영구자석 동기전동기의 기동특성 해석)

  • Gang, Gyu-Hong;Hong, Jeong-Pyo
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.50 no.12
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    • pp.592-600
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    • 2001
  • This Paper presents the transient analysis of the single-phase line-start permanent magnet synchronous motor. To analyse the starting characteristics, the dynamic equation which is combined electric dynamic equations with mechanical dynamic equation is used. The electric dynamics are derived from the d-q axis voltages of stator and rotor respectively. Especially, symmetrical components transformation is used to consider unbalanced magnetic field which is produced by single-phase input. Non-linear d-q axis inductances according to current amplitude and current phase angle are calculated by Finite Element Method and applied to lumped parameter circuit. The analysis methods are validated by comparing simulated and experimental results.

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Optimal Selection of Capacitor for a Capacitor Run Single-Phase Induction Motor (콘덴서 단상 유도전동기의 콘덴서 용량의 최적 선정에 관한 연구)

  • Lee, Byung-Sam;Kim, Kyung-Ho;Heo, Du-Suck;Cho, Yun-Hyun
    • Proceedings of the KIEE Conference
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    • 2002.11d
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    • pp.24-26
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    • 2002
  • The recent emphasis on energy conservation demands an improvement of the efficiency of single-phase induction motors. To take the efficiency operation of the capacitor run single-phase induction motor with auxiliary and main winding, it is very important to select the capacitance value. This paper describes the theoretical analysis method of a single-phase induction motor which is based on the rotating field theory, using the method of symmetrical components. The optimal selection method of capacitance is proposed.

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Characteristic Analysis of Single-Phase Line-Start Permanent Magnet Synchronous Motors (단상 영구자석형 유도동기기의 특성해석)

  • Kang, Gyu-Hong;Lee, Sun-Kwon;Hong, Jung-Pyo;Kim, Gyu-Tak
    • Proceedings of the KIEE Conference
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    • 2001.04a
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    • pp.144-146
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    • 2001
  • This paper deals with analysis method of single-phase line-start permanent magnet motors. Unbalanced magnetic fields produced by single-phase input make analysis difficult. To solve this unbalanced magnetic fields, this paper proposed symmetrical components transformations as well as d-q axis ones. Parameters in d-q voltage equations were calculated by Finite Element Analysis.

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Nonlinear Tolerance Allocation for Assembly Components (조립품을 위한 비선형 공차할당)

  • Kim, Kwang-Soo;Choi, Hoo-Gon
    • IE interfaces
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    • v.16 no.spc
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    • pp.39-44
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    • 2003
  • As one of many design variables, the role of dimension tolerances is to restrict the amount of size variation in a manufactured feature while ensuring functionality. In this study, a nonlinear integer model has been modeled to allocate the optimal tolerance to each individual feature at a minimum manufacturing cost. While a normal distribution determines statistically worst tolerances with its symmetrical property in many previous tolerance allocation studies, a asymmetrical distribution is more realistic because its mean is not always coincident with a process center. A nonlinear integer model is modeled to allocate the optimal tolerance to a feature based on a beta distribution at a minimum total cost. The total cost as a function of tolerances is defined by machining cost and quality loss. After the convexity of manufacturing cost is checked by the Hessian matrix, the model is solved by the Complex Method. Finally, a numerical example is presented demonstrating successful model implementation for a nonlinear design case.

An algorithm for faster symmetrical components separation (대칭좌표 분리 고속화 알고리즘)

  • Kim, Sun-Tae;Jung, Seung-Ki;Song, Seung-Ho;Kim, Young-Rea
    • Proceedings of the KIPE Conference
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    • 2018.07a
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    • pp.147-149
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    • 2018
  • 비대칭 부하 전류를 평형 상태로 만들기 위한 보상장치는 3상변수를 대칭좌표로 분리해야한다. 통상 전대역필터를 이용한 정상분, 역상분 분리 방식이 사용되는데 제어기 최하위단에서 동작하는 전대역필터의 대역폭이 전체 제어시스템의 대역폭을 제한한다. 따라서 보상장치의 제어성능을 향상시키기 위해서는 정역분리에 사용하는 필터의 대역폭을 넓혀야 한다. 본 논문에서는 대역폭이 조절가능한 고속화된 대칭좌표 분리 알고리즘을 제안한다. 이를 MATLAB/SIMULINK를 이용하여 시뮬레이션을 진행하였으며, TMS320F28335를 이용하여 실험을 진행하였다.

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Extended Wing Technique Approach for the Detection of Winding Interturn Faults in Three-phase Transformers

  • Balla, Makarand Sudhakar;Suryawanshi, Hiralal Murlidhar;Choudhari, Bhupesh Nemichand
    • Journal of Power Electronics
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    • v.15 no.1
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    • pp.288-297
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    • 2015
  • This paper presents a novel approach to diagnose interturn insulation faults in three-phase transformers that operate at different loading conditions. This approach is based on the loci of instantaneous symmetrical components and requires the measurement of three input primary winding currents and voltages to diagnose faults in the transformer. The effect of unbalance supply conditions, load variations, constructional imbalance, and measurement errors when this methodology is used is also investigated. Wing size or length determines the loading on the transformer. Wing travel and area determine the degree of severity of fault. Experimental results are presented for a 400/200 V, 7.5 kVA transformer to validate this method.

Analysis of Operating Characteristic of Self Excited Induction Generator with Steinmetz Connection (스타인메츠결선 자기여자 유도발전기의 운전특성 분석)

  • Kang, Sang-Su;Jwa, Chong-Keun
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.57 no.4
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    • pp.383-387
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    • 2008
  • This paper analyzes the operation characteristics of a self excited induction generator with Steinmetz connection. For this analysis, the symmetrical components analysis is used to obtain the related expressions and the excitation capacitance and the magnetizing reactance are determined in turn by the condition of self excitation which includes the input impedance of the generator as viewed across load terminals. Two simultaneous equations of the condition of self excitation itself are solved by using the real and imaginary function in an application software. This method is applied to simulate the operation characteristics when the generator is driven at rated speed and the specified excitation capacitor is connected across the lagging phase. The results show that better operation characteristics except generated frequency are obtained by using relatively large excitation capacitance and resistive load.

Evolution of strain states during Cross-roll rolling in AA 5052 sheet using Finite Element Method (유한요소 해석을 통한 AA 5052 판재의 Cross-roll 압연시 변형율 상태의 변화)

  • Kim, S.H.;Kim, D.G.;Park, E.S.;Lee, J.S.;Huh, M.Y.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2008.05a
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    • pp.404-407
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    • 2008
  • In the present work, cross-roll rolling was carried out using a rolling mill in which the roll axis is tilted by $7.5^{\circ}$ towards the transverse direction of the rolled sample. The evolution of strain states during cross-roll rolling was investigated by three-dimensional finite element method (FEM) simulation. Parallel to cross-roll rolling, normal-rolling using a conventional rolling mill was also carried out in the same rolling condition for clarifying the effect of cross-roll rolling. It turned out that three shear rate components were all introduced to the rolled sample by the cross-roll rolling process, while only one shear rate component operated during normal-rolling.

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