• The Transactions of the Korean Institute of Electrical Engineers B
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• v.50 no.1
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• pp.15-22
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• 2001

In this paper, a VSC(Voltage Sag Corrector) is discussed for the purpose of power quality enhancement. A fast detecting technique of voltage sag is accomplished through the detection of instantaneous value on synchronous reference frame. A robust characteristic against the noise is available by inserting the first order low pass filter in the detection circuit. The formula and the filter design process is described properly with the mathematical equations. Because the VSC system supply the active power to load, it is required to design the proper size of the energy storage system, In this paper, the capacitor bank is used as an energy storage system, and the size of the capacitor is designed from the point of view of input/output energy as the output power rating and the amplitude and duration time of the voltage sag. The simulation is accomplished by PSCAD/EMTDC.

• Proceedings of the KIEE Conference
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• 2001.04a
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• pp.191-194
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• 2001

In this paper, we propose a series active power filter control method to compensate current harmonics and unbalanced source voltage. The system is composed of series active power filter and shunt passive filer that are tuned 5th and 7th harmonics. In this conventional system, series active power filter complements drawbacks of the shunt passive filter, namely improves harmonic compensation characteristics, and compensates unbalanced source voltage. In the proposed algorithm, compensation voltage for harmonic reduction is calculated by performance function, and compensation voltage for unbalanced source voltage is calculated in based on a synchronous reference frame. So, ultimate compensation voltage is sum of those two compensation voltages. By computer simulation, we verify the excellency of proposed method.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05b
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• pp.71-74
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• 2003

The paper is proposed to position and speed control of interior permanent magnet synchronous motor(IPMSM) drive without mechanical sensor. A minimum order state observer is used for the mechanical state estimation of the motor. The observer was developed based on nonlinear model of IPMSM, that employs a d-q rotating reference frame attached to the rotor. A minimum order state observer is implemented to compute the speed and position feedback signal. The validity of the proposed sensorless scheme is confirmed by various response characteristics.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.378-379
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• 2018

본 연구는 속응형 단상 UPS(Uninterruptible Power Supply)를 위한 이상전원 검출 알고리즘에 관한 연구이다. 한국전력공사 등의 특수한 UPS 응용분야에서는 전원의 1/4주기 이내에 전원의 이상을 검출하고 UPS가 정상 기동할 필요가 있다. 본 연구에서는 가상DQ기반의 고성능 PLL(Phase Locked Loop)을 응용하여 별도의 전원검출 알고리즘 없이도 임의의 위상각에서 1/4주기이내에 전원의 크기 및 위상에 관한 오류를 검출할 수 있음을 보인다. 제시된 방법은 시뮬레이션 및 실험을 통해 검증하였다.

• Proceedings of the KIPE Conference
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• 2019.11a
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• pp.85-86
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• 2019

본 논문에서는 DQ 변환을 적용한 직렬-병렬 공진형 무선 전력 전송 시스템의 동기 좌표계 모델을 제안한다. 무선 전력 전송 시스템은 일반적으로 급전 측과 집전 측에 단상 전류가 흐르기 때문에 제어에 어려움이 있다. 따라서 정상 상태의 전압 및 전류의 수식을 이용하여 부하에 전달되는 전압 및 전류의 크기를 제어하는 경우가 많다. 따라서 과도 상태의 전압 및 전류의 동특성이 원하는 특성과 다르게 나타날 수 있다. 본 논문에서는 직렬-병렬 공진형 무선 전력 전송 시스템의 단상 전압 및 전류를 DQ 변환하여 과도 상태 및 정상 상태의 전압 및 전류의 동특성을 해석할 수 있는 등가 회로 모델을 제시한다.

• Journal of Electrical Engineering and Technology
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• v.12 no.3
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• pp.1124-1136
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• 2017

Direct Power Control technique has become popular in the grid connected Voltage Source Converter (VSC) applications due to its simplicity, direct voltage vector selection and improved dynamic performance. In this paper, a direct method to determine the effect of voltage vector on the instantaneous active and reactive power variations is developed. An alternative Look Up Table is proposed which minimizes the commutations in the converter and results in minimum reactive power variation. The application of suggested table is established for Shunt Active Power Filter (SAPF) application. The Predictive Direct Power Control method, which minimizes apparent power variation, is further investigated to reduce commutations in converters. Both the methods are validated using 2 kVA laboratory prototype of Shunt Active Power Filters (SAPF).

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.8
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• pp.60-69
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• 2011

This paper presents a power quality compensation of the autotransformer-fed railway system using Matlab/SimPowerSystem and especially investigates two installation methods of the shunt active power filter (SAPF) along the autotransformer-fed railway systems; one configuration describes the SAPF installed at the substation and the other is the SAPF at the sectioning post. Also, the novel SAPF control algorithms based on the synchronous reference frame are proposed. A comparative study on two SAPF configurations and the corresponding control algorithms is investigated comprehensively through the case study.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.319-322
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• 2001

In this paper, a 3phase-3wire series active power filter compensating current harmonics and unbalanced source voltages is presented. The system is composed of series active power filter and shunt passive filters that are tuned 5th and 7th harmonics. In this system, series active power filter improves harmonic compensation characteristics of the shunt passive filters and compensates the unbalanced source voltages. In the proposed algorithm, compensation voltage for harmonic reduction is calculated by a performance function, and compensation voltage for the unbalanced source voltage is calculated in based on the synchronous reference frame. Some results obtained from the experimental model using the proposed method are presented to demonstrate and confirm its validity.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.501-505
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• 2001

The parallel operation system of UPS is used to increase reliability of power source at critical load. But parallel UPS system has a few defects, impedance is different from each other and circulating current occurs between UPSs, due to line impedance and parameter variation, though controlled by the same synchronization signal. According to such characteristic of parallel UPS, balanced load-sharing control is the most important technique in parallel UPS operation. In this paper, a novel power deviation compensation algorithm is proposed. it is composed of voltage controller to compensate power deviation that be calculated by using active and reactive current deviation between inverters on synchronous d-q reference frame.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.4B no.3
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• pp.134-145
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• 2004

This paper presents and analyses protection schemes for a series active compensator, which consists of a Unified Power Quality Conditioner (UPQC) or a hybrid active power filter. The proposed series active compensator operates as a high impedance "k(D)" for the fundamental components of the power frequency during over current conditions in the distribution system. Two control strategies are proposed in this paper. The first strategy detects the fundamental source current using the p-q theory. The second strategy detects the fundamental component of the load current in the Synchronous Reference Frame (SRF). When over currents occur in the power distribution system momentarily, the proposed schemes protect the series active compensator without the need for additional protection circuits, and achieves excellent transient response. The validity of the proposed protection schemes is investigated through simulation and compared with experimental results using a hybrid active power filter systems.