• Proceedings of the KIEE Conference
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• 2001.11b
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• pp.305-307
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• 2001

This paper deals with single-phase unified power quality conditioner(UPQC), which aims at the integration of series-active and shunt-active filter. The series filter is used to compensate for the voltage distortions and the shunt filter is used to provide reactive power and counteract the harmonic current injected by the load. Also, the voltage of the DC link capacitor is controlled to a desired value by the shunt active filter. The performance of UPQC under load nonlinearities conditions is investigated using simulation as well as experimental results.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.5B no.4
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• pp.382-391
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• 2005

Increasing of the nonlinear type power electronics equipment, power conditioning systems (PCS) have been researched and developed for many years in order to compensate for harmonic disturbances and reactive power. PCS's not only improve harmonic current and power factor in the ac grid line but also achieves energy saving used by the renewable energy source (RES). In this paper, the implementation of a current controlled voltage source inverter (CCVSI) using RES for PCS is presented. The basic principle and control algorithm is theoretically analyzed and the design methodology of the system is discussed. The proposed system could achieve power quality control (PQC) to reduce harmonic current and improve power factor, and demand side management (DSM) to supply active power simultaneously, which are both operated by the polarized ramp time (PRT) current control algorithm and the grid-interactive current control algorithm. A 1KVA test model of the CCVSI has been built using IGBT controlled by a digital signal processor (DSP). To verify the proposed system, a comprehensive evaluation with theoretical analysis, simulation and experimental results is presented.

• Proceedings of the KIPE Conference
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• 2004.07b
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• pp.515-518
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• 2004

Increasing of the nonlinear power electronics equipments, power conditioning systems have been researched and developed for many years to compensate the harmonic disturbances and the reactive power. The main function of power conditioning systems is to reduce harmonic distortions, since extensive surveys quantify the problems associated with electric networks having non-linear loads. The main function of power conditioner compensates the current instead of the voltage. Therefore the inverter used in power conditioner is mostly the current controlled type. In this paper, we propose the power conditioner using photovoltaic system, which is operated by the PRT(Polarized Ramp Time) current control algorithm. The proposed system could also achieve Demand Side Management's function and Uninterruptible Power Supply's function simultaneously. To verify the proposed current controlled inverter for improved quality of the grid, the detail simulation and experiment results indicate that operation PCS, DSM and UPS can be achieved.

• Journal of Power Electronics
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• v.9 no.3
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• pp.403-409
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• 2009

Automatically tuned passive filters can improve power quality to a great extent in power systems. A novel three-phase shunt auto-tuned filter is designed to effectively compensate source current harmonics and to provide reactive power required by the non-linear load, which draws a highly reactive, harmonic-rich current from the supply. An artificial neural network (ANN) based controller selects filter component values in accordance with reactive power requirement and harmonic compensation. Traditional passive filters are permanently connected to the system and draw large amounts of source current even under light load conditions. By using auto-tuned filters, the passive filter components can be controlled according to load variations and, hence, draw only required source currents. The selection is done by the ANN with the help of a properly tuned knowledge base to provide instantaneous compensation using a digital controller.

• Journal of Power Electronics
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• v.16 no.6
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• pp.2284-2293
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• 2016

With the rapid development of clean energy, photovoltaic (PV) generation has been utilized in the harmonic compensation of power systems. This paper presents a novel multi-function PV micro-inverter with three stages (pseudo-two-stage). It can inject active power and compensate harmonic currents in the power grid at the same time. In order to keep the micro-inverter working under the maximum allowable output power, an optimized capacity limitation strategy is presented. Moreover, the harmonic compensation can be adjusted according to the customized requirements of power quality. Additionally, a phase shedding strategy in the DC/DC stage is introduced to improve the efficiency of parallel Boost converters in a wide range. Compared with existing capacity limitation methods, the proposed strategy shows better performance and energy efficiency. Simulations and experiments verify the feasibility of the micro-inverter and the effectiveness of the strategy.

• Journal of Electrical Engineering and Technology
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• v.12 no.1
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• pp.207-216
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• 2017

Wind energy conversion systems (WECS) which consist of wind turbines with permanent magnet synchronous generator (PMSG) and full-power converters have become widespread in the field of renewable power systems. Generally, conventional diode bridge rectifiers have used to obtain a constant DC bus voltage from output of PMSG based wind generator. In recent years, together advanced power electronics technology, Pulse Width Modulation (PWM) rectifiers have used in WECS. PWM rectifiers are used in many applications thanks to their characteristics such as high power factor and low harmonic distortion. In general, L, LC and LCL-type filter configurations are used in these rectifiers. These filter configurations are not exactly compensate current and voltage harmonics. This study proposes a hybrid passive filter configuration for PWM rectifiers instead of existing filters. The performance of hybrid passive filter was tested via MATLAB/Simulink environment under various operational conditions and was compared with LCL filter structure. In addition, neuro-fuzzy controller (NFC) was preferred to increase the performance of PWM rectifier in DC bus voltage control against disturbances because of its robust and nonlinear structure. The study demonstrates that the hybrid passive filter configuration proposed in this study successfully compensates current and voltage harmonics, and improves total harmonic distortion and true power factor.

• Proceedings of the KIPE Conference
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• 2017.11a
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• pp.141-142
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• 2017

In this paper, integrated series and shunt inverter is presented to solve power quality problems in distribution line system. In this configuration consists of series inverter and shunt inverter. Series inverter acts as DVR to compensate voltage during sagging occurred and shunt inverter optimize to inject balance active power from distributed power source like PV system with Maximum Power Point Tracing (MPPT). Finally, the proposed configuration is verified through the PSiM simulation.

• Journal of Electrical Engineering and Technology
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• v.10 no.1
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• pp.379-387
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• 2015

A custom power device provides an integrated solution to the present problems that are faced by the utilities and power distribution. In this paper, a new controller is designed which is connected to a multiconverter unified power quality conditioner (MC-UPQC) for improving the power quality issues adopted modified synchronous reference frame (MSRF) theory with Fuzzy logic control (FLC) technique. This newly designed controller is connected to a source in order to compensate voltage and current in two feeders. The expanded concept of UPQC is multi converter-UPQC; this system has a two-series voltage source inverter and one shunt voltage source inverter connected back to back. This configuration will helps mitigate any type of voltage / current fluctuations and power factor correction in power distribution network to improve power quality issues. In the proposed system the power can be conveyed from one feeder to another in order to mitigate the voltage sag, swell, interruption and transient response of the system. The control strategies of multi converter- UPQC are designed based on the modified synchronous reference frame theory with fuzzy logic controller. The fast dynamics response of dc link capacitor is achieved with the help of Fuzzy logic controller. Different types of fault conditions are taken and simulated for the analysis and the results are compared with the conventional method. The relevant simulation and compensation performance analysis of the proposed multi converter-UPQC with fuzzy logic controller is performed.

• Journal of KIISE:Information Networking
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• v.37 no.5
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• pp.403-408
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• 2010

The sensor nodes can be installed in the environment in which the temperature change is considerable, such as desert, urban, and data center. Particularly, because the output power becomes less than the targeted power if a temperature is increasing, link quality is degraded and packet losses are occurred. In order to compensate the temperature changes, existing schemes detect the change of the link quality between nodes and control transmission power through a series of feedback process. However, these approaches can cause heavy overhead by additional control packets. In this paper, we propose the T2PC(Temperature-aware Transmission Power Control) to keep up the link quality despite temperature variation. At each node, T2PC compensates the attenuated link quality by controlling the transmission power based on the local temperature measurement. In addition, the packet reception ratio can be improved with less control packets than ones required in existing transmission power control methods based on the feedback control.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.151-153
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• 2008

This paper deals with the electric energy saving system for lighting with power conditioning, which aims at the integration of power quality improvement and energy saving. The system consists of a CCVSI(Current-Controlled Voltage Source Inverter) and VCVSI(Voltage-Controlled Voltage Source Inverter). The CCVSI is connected in parallel to a grid, which can be operated to compensate the reactive power demanded by nonlinear and variation loads. The VCVSI is connected to the CCVSI through the DC capacitor (DC side) and in series on the AC side(lighting load), which can perform the energy saving. The operation of the proposed system is confirmed through the simulation and its usefulness is discussed.