• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.3
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• pp.211-218
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• 2000

The performance and dynamic characteristics of three-phase active power filter with PCC voltage compensation is presented and analyzed in this paper. The characteristics of parallel active filter are discussed when they are applied to nonlinear loads with current source and voltage source type, the characteristics of voltage compensator and comparison of two functions are discussed. The proposed scheme in this paper employs a PWM voltage-source inverter and has two operation modes. First, it operates as a conventional active filter with reactive power compensation while PCC voltage is in a certain range. Second, is operates as a voltage compensator while PCC voltage is out of range. Finally, the validity of this scheme is investigated through analysis of simulation and experimental results for a prototype active power filter system rated at 10KVA.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.5
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• pp.71-78
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• 2012

This paper presents a digital control solution to process capacitor current feedback of high performance single-phase UPS for non-linear loads. In all UPS the goal is to maintain the desired output voltage waveform and RMS value over all unknown load conditions and transient response. The proposed UPS uses instantaneous load voltage and filter capacitor current feedback, which is based on the double regulation loop such as the outer voltage control loop and inner current control loop. The proposed DSP-based digital-controlled PWM inverter system has fast dynamic response and low total harmonic distortion (THD) for nonlinear load. The control system was implemented on a 32bit Floating-point DSP controller TMS320C32 and tested on a 5[KVA] IGBT based inverter switching at 11[Khz]. The validity of the proposed scheme is investigated through simulation and experimental results.

• Proceedings of the KIEE Conference
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• summer
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• pp.1254-1256
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• 2004

This paper deals with a novel 3-phase power quality disturbance generator. The proposed generator can be applied to the performance that of custom power devices. Voltage sag, swell and outage are provided by the generator. The control scheme for the disturbance generation is simple, and hardware setup is cost effective, compared with conventional scheme. The operating principle of the generator is described and the usefulness verified through simulation with 10KVA power rating.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.5
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• pp.422-428
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• 2013

Recently, we use a static synchronous compensator(STATCOM) with cascaded H-bride topologies, because it is easy to increase capacity and to reduce total harmonic distortion(THD). When we use equipment for reactive power compensation, dc-link voltage unbalances occur from several reasons although loads are balanced. In the past, switching pattern change of single phase inverter and reference voltage magnitude change of inverter equipped with power sensor have been used for dc-link voltage balance. But previous methods are more complicated and expensive because of additional component costs. Therefore, this paper explains reasons of dc-link voltage unbalance and proposes solution. This solution is complex method that is composed of reference voltage magnitude change of inverter without additional hardware and shifted phase angle of inverter reference voltages change. It proves possibility through 1000[KVA] system simulation.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.2
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• pp.118-125
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• 2017

In this paper, we propose a smart transformer for a smart transformer miniature model, which can replace a 60 [Hz] single-phase transformer installed in an electric vehicle. The proposed smart transformer is lighter than a conventional transformer, can control instantaneous voltage, and can be expected to improve power quality through harmonic compensation. The proposed intelligent transformer consists of an incoming part, an AC/DC converter, and a dual active bridge. Only the incoming part and the AC/DC converter are described in this paper. The proposed intelligent transformer has 75 kVA 3.3 kV input and 750 V DC output, which are verified by simulation and experiment.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.999-1000
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• 2007

This paper presents the characteristic analysis of the 40 kVA high speed synchronous generator considering the power factor. The generator consist of the rotor with the short-circuited field coils connected armature coils of exciter and the stator with three-phase winding. To analyze the characteristics of the generator, the direct finite element method is applied.

• Proceedings of the KIEE Conference
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• 2005.10c
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• pp.44-46
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• 2005

대용량 유도전동기가 정지상태에서 기동할때 매우 큰 돌입전류에 의해 Voltage Sag를 유발하게 되며 유도전동기에 걸리는 기계적 토크보다 큰 전기적 토크가 가해지지 않으면 유도전동기는 기동에 실패하게 된다. 따라서 대용량 유도전동기의 기동을 위해서는 Voltage Sag를 줄이고 전동기의 가속에 필요한 기동토크를 인가할 수 있는 기동법이 필요하다. 본 논문에서는 유도전동기의 기동특성을 모의할 수 있는 모델링 기법을 제안하고 시뮬레이션에 의한 기동특성을 모의하여 적절한 기동법을 적용한다. 본 논문에서 사용한 대상 유도전동기는 한국수자원공사 취수장에서 운영하는 2500KVA 대용량 유도전동기를 사용하였으며 PSCAD/EMTDC 소프트웨어를 사용하여 시뮬레이션을 수행하였다.

• Kyungpook Mathematical Journal
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• v.58 no.4
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• pp.733-746
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• 2018

The concept of f-statistical convergence which is, in fact, a generalization of statistical convergence, has been introduced recently by Aizpuru et al. (Quaest. Math. 37: 525-530, 2014). The main object of this paper is to prove an f-statistical analog of the classical Korovkin type approximation theorem of Boyanov and Veselinov. It is shown that the f-statistical analog is intermediate between the classical theorem and its statistical analog. As an application, we estimate the rate of f-statistical convergence of the sequence of positive linear operators defined from $C^*[0,{\infty})$ into itself.

• Journal of Power Electronics
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• v.19 no.2
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• pp.413-430
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• 2019

This paper presents an optimum hybrid SVPWM technique for three-level voltage source inverters (VSIs). The proposed hybrid SVPWM technique aims to minimize total harmonic distortion (THD). A new parameter is introduced to incorporate the heterogeneous nature of switching sequences of SVPWM technique. The proposed hybrid SVPWM technique is implemented on a low-cost PIC microcontroller (PIC18F452) and verified experimentally with a 2 KVA three-phase three-level insulated gate bipolar transistor-based VSI. Optimum switching sequence results in the three-level inverter configuration are demonstrated. The proposed hybrid SVPWM technique improves the THD performance by 17.3% compared with the best available three-level SVPWM technique.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.4
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• pp.748-757
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• 2007

This paper is intended to solve the technical problem that fails in large-capacity induction motor starting due to serious voltage drop during starting period. One induction motor that is established already can reach in steady-state using reactor starting method but the voltage magnitude of PCC (point of common coupling) has dropped down a little. When the same capacity induction motor is installed additionally in the PCC, where the existing induction motor is operating, voltage drop becomes more serious by starting of additional induction motor. As a result, the additional induction motor fails in starting. Therefore, voltage compensation method is proposed so that all of two induction motors can be started completely. First, modeling technique is described in order to implement starting characteristics of large induction motor. And then, this paper proposes strategic starting scheme by proper voltage compensation that use no-load transformer tap control (NLTC) and step voltage regulator (SVR) for starting of two large induction motors successfully and improving the feeding network voltage profile during the starting period. The induction motor discussed in this paper is the pumped induction motor of 2500kVA capacity that is operating by KOWACO (Korea Water Resources Corporation). Modeling and simulation is conducted using PSCAD/EMTDC software.