• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.1
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• pp.26-34
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• 1999

According to increase of nonlinear power electronics equipment, active power filters have been researched and developed for many years to compensate harmonic disturbances and reactive power. However the commercial of active power filter is being proceeded slowly, because the cost of active power filter compared to the passive filter for harmonic and reactive power compensation is expensive. Especially, the use of DSP (Digital Signal Processing) chip, which is frequently used to control 3-phase active power filter, is a factor of increasing the cost of active power filters. On the other hand, the use of only analog controller makes the controller's circuits much more complicate and depreciates the flexibilities of controller. In this paper, a controller with low cost for 5[kVA] 3-phase active power filter system is designed. To reduce the expense of active filter system, the presented controller is composed of digital control part using Intel 80C196KC $\mu$P and analog control part using hysteresis controller for current control. Characteristic analysis of designed controller for active filter system is performed by computer simulation and compensating characteristics of the designed controller are verified by experiment.tegy can apply to the vector control, leading to better output torque capability in the ac motor drive system. This strategy is that in the overmodulation range, the d-axis output current is given a priority to regulate the flux well, instead the q-axis output curent is sacrificed. Therefore, the vector control even in the overmodulation PWM operation can be achieved well. For this purpose, the d-axis output voltage of a current controller to control the flux is conserved. the q-axis output voltage to control the torque is controlled to place the reference voltage vector on the hexagon boundary in case of the overmodulation. The validity of the proposed overall scheme is confirmed by simulation and experiments for a 22[kW] induction motor drive system.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.49 no.5
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• pp.212-219
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• 2000

This paper deals with a systematic approach to GA-PI controller design for static VAR compensator(SVC) using genetic algorithms(GAs) which are search algorithms based on the mechanics of natural of natural selection and natural genetics, to improve system stability. A SVC, one of the Flexible AC Transmission System(FACTS), constructed by a fixed capacitor(FC) and a thyristor controlled reactor(TCR), is designed and implemented to improve the damping of a synchronous generator, as well as controlling the system voltage. To verify the robustness of the proposed method, considered dynamic response of generator used deviation and generator terminal voltage by applying a power fluctuation and three-phase fault at heavy load, normal load and light load. Thus, we proved usefulness of GA-PI controller design to improve the stability of single machine-infinite bus with SVC system.

• KIEE International Transactions on Power Engineering
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• v.4A no.3
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• pp.129-133
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• 2004

This paper deals with the design and implementation of a TCSC (Thyristor Controlled Series Capacitor) simulator, which is a module for an analog type power system simulator. Principally, it presents configuration of controller hardware/software and its experimental results. An analog type power system simulator consists of numerous power system components, such as various types of generator models, scale-downed transmission line modules, transformer models, switches and FACTS (Flexible AC Transmission System) devices. It has been utilized for the verification of the control algorithm and the study of system characteristics analysis. This TCSC simulator is designed for 50% line compensation rate and considered for damping resister characteristic analysis. Its power rate is three phase 380V 20kVA. For hardware extendibility, its controller is designed with VMEBUS and its main CPU is TMS320C32 DSP (Digital Signal Processor). For real time control and communications, its controller is applied to the RTOS (Real Time Operation System) for multi-tasking. This RTOS is uC/OS-II. The experimental results of capacitive mode and inductive mode operations verify the fundamental operations of the TCSC.

• The Transactions of the Korean Institute of Power Electronics
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• v.26 no.5
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• pp.315-324
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• 2021

A solid state transformer (SST) that can interface an MVAC of three-phase 13.2 kV and a 1.5 kV DC distribution. SST consists of an AC/DC converter and a DC/DC converter with a high-frequency isolation transformer (HFIT). The AC/DC converter consists of cascaded NPC full-bridge to cope with the MVAC. The DC/DC converter applies a quad active bridge (QAB) topology to reduce the number of the HFIT. Topology analysis and controller design for this specific structure are discussed. In addition, the insulation of HFIT used in DC/DC converters is considered. The discussion is validated using a 300 kVA three-phase SST prototype.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.998-998
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• 2008

It is difficult to find for analysis solution of the synchronous generator exciter system. Recently, it had good performance UPS converter system using CRA method. The single converter of synchronous generator excitor system under considerations : (i) the overall system shall keep very low AC-voltage tracking error as well as no phase delay over different load condition, and (ii) the digital controller shall be employed at a fixed sampling. It is shown that the synchronous exciter system can be achieved by the proposed controller using Characteristic Ratio Assignment.

• Proceedings of the KIPE Conference
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• 2003.07b
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• pp.540-543
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• 2003

This paper presents a method for increasing controller performance through multirate state estimation for ac machines at a low velocity. The multirate controller outputs control desired speed at each measurement Instant. The simulation results show that the performance of multirate velocity estimation and control at low velocity is improved than single rate one.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2001.11a
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• pp.47-50
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• 2001

In order for effective operation of existing power systems, introduction of the so-called FACTS(Flexible AC Transmission System) such as SVC and UPFC etc, is unavoidable. The UPFC(Unified Power Flow Controller) is composed of STATCOM(Static Compensator) and SSSC(Static Synchronous Series Compensator), and is used to control the magnitude and phase angle of injected sources which are connected bothin series and in parallel with the transmission line to control the power flow and bus voltages. This paper presents a UPFC simulation on RTDS. The voltage and phase angle of a system have been analyzed by regulating the firing angle inside the UPFC.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.8
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• pp.536-543
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• 2000

The photovoltaic power generation system has a great future as clean energy instead of fossil fuel which has many environmental problems such as exhausted gas or air pollution. In a utility interactive photovoltaic generation system, a three-phase inverter is used for the connection between the photovoltaic array and the utility. This paper present a three phase inverter for photovoltaic power system with current controller, voltage controller, PLL Control system and the Phase detector of Interactive Voltage by using dq transformation. The proposed inverter system provides a sinusoidal ac current for domestic loads and the utility line with unity power factor.

• Proceedings of the KIPE Conference
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• 2017.11a
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• pp.121-122
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• 2017

ITER AC/DC 컨버터(Converter)는 핵융합 발생을 위해 토카막의 초전도코일에 제어된 전류를 공급하여 플라즈마 발생, 형상 유지, 소멸하는 기능을 한다. 만일 컨버터 또는 초전도코일에 이상이 발생하면 즉시 보호동작이 실행되어야 한다. 이를 위해 설계된 F-LIC(Fast Local Interlock Controller)은 즉시 작동하여 Bypass 및 Make Switch 트리거, 차단기 작동 등을 순차적으로 수행한다. ITER Interlock System의 기기는 중요성이 고려되어 높은 신뢰도가 요구된다. 본 논문에서는 F-LIC 회로분석과 Telcordia SR-332 Standard에 의한 부품고장률 산출방법을 사용하여 FMEDA를 분석하고, 이를 통하여 회로구성 부품의 고장이 미치는 영향과 F-LIC 제어모듈의 SIL-2 등급의 적합성을 분석하였다.

• Journal of Electrical Engineering and Technology
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• v.8 no.5
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• pp.1138-1145
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• 2013

A novel predictive current control strategy for a sparse matrix converter is presented. The sparse matrix converter is functionally-equivalent to the direct matrix converter but has a reduced number of switches. The predictive current control uses a model of the system to predict the future value of the load current and generates the reference voltage vector that minimizes a given cost function so that space vector modulation is achieved. The results show that the proposed controller for sparse matrix converters controls the load current very effectively and performs very well through simulation and experimental results.