• Journal of the Korean Society for Railway
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• v.12 no.5
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• pp.694-699
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• 2009

This paper presents a synchronous-reference-frame-based control of single-phase UPQC(Unified Power Quality Conditioner) to improve power quality in ac electrified railway systems. The proposed synchronous-reference-frame-based UPQC can compensate the voltage distortion, the voltage sag, the harmonic currents, and the reactive power instantaneously. The simulation results show that the UPQC can compensate the harmonic supply voltages, the voltage sag, the harmonic load currents, and the reactive power in electrified railway systems. Validity and effectiveness of the proposed UPQC control method based on the synchronous-reference-frame is illustrated through the simulation results.

• Journal of IKEEE
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• v.23 no.1
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• pp.99-106
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• 2019

This paper propose a new form of UPQC (Unified Power Quality Compensator) to compensate the current and voltage quality problems of nonlinear loads. The conventional UPQC system consists of a series inverter, a parallel inverter, and a common DC link. A new type of UPQC proposed is a parallel compensator with SVC (Static Var Compensator) added to compensate for the wide compensation range and low DC link voltage. The parallel inverter compensates the reactive power generated by the nonlinear load, and the series inverter compensates the sag and swell generated at the power supply side.

• Journal of Electrical Engineering and Technology
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• v.10 no.3
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• pp.1015-1024
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• 2015

This paper introduces a low cost, high efficiency, high performance three-phase unified power quality conditioner (UPQC) by using four-switch three-phase inverters (FSTPIs) and an extra capacitor in the shunt active power filter (APF) side of the UPQC. In the proposed UPQC, both shunt and series APFs are developed by using FSTPIs so that the number of switching devices is reduced from twelve to eight devices. In addition, by inserting an additional capacitor in series with the shunt APF, the DC-link voltage in the proposed UPQC can also be greatly reduced. As a result, the system cost and power loss of the proposed UPQC is significantly minimized thanks to the use of a smaller number of power switches with a lower rating voltage without degrading the compensation performance of the UPQC. Design of passive components for the proposed UPQC to achieve a good performance is presented in detail. In addition, comparisons on power loss, overall system efficiency, compensation performance between the proposed UPQC and the traditional one are also determined in this paper. Simulation and experimental studies are performed to verify the validity of the proposed topology.

• Proceedings of the KIEE Conference
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• 2007.04c
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• pp.211-214
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• 2007

본 논문은 다계 H-브리지와 다권선 변압기를 이용하여 22.9kV 배전계통에 직접결합하여 전력품질을 보상하는 UPQC(Unified Power Quality Conditioner)를 제안하고 그 동작을 분석한 내용을 기술하고 있다. 제안하는 UPQC는 스위칭소자를 직결한 방식대신 H-브리지로 구성된 인버터모듈을 직결하는 방식으로 동작전압을 증가시켜 배전전압 22.9kV에서 동작할 수 있도록 고안되어 있다. 제안하는 시스템의 기술적 타당성을 입중하기 위해 EMTDC 소프트웨어에 의한 시뮬레이션을 통한 분석을 실시하였으며 또한 하드웨어 축소모형을 제작하여 실험을 통한 분석을 실시하였다. 이러한 검증을 통하여 제안하는 UPQC는 실제규모로 용량을 확대하여 배전계통에 결합할 경우 동작이 가능할 것으로 보인다. 제안하는 UPQC는 배전전압에 따라 H-브리지 모듈의 수를 가감하여 설계의 유연성을 확보할 수 있고 직렬주입변압기가 없이 동작이 가능하여 기존 UPQC의 직렬주입변압기에 의한 제반 취약점을 제거할 수 있다.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.1951-1958
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• 2009

This paper presents a synchronous-rotating-frame-based control of single-phase UPQC(Unified Power Quality Conditioner) to improve power quality in ac electrified railway systems. The simulation results show that the UPQC can compensate the harmonic supply voltages, the harmonic load currents, and the reactive power in electrified railway systems. Validity of the proposed UPQC control method based on the synchronous rotating frame is illustrated through the simulation results.

• Proceedings of the KIPE Conference
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• 2019.11a
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• pp.142-143
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• 2019

본 논문은 계통과 연계하여 운전하거나 계통사고시나 의도적인 단독 운전이 필요한 경우 계통과 분리하여 운전하기 위한 UPQC(Unified Power Quality Conditioner)를 기반으로 하는 인버터를 제안한다. UPQC 기반의 인버터는 계통 연계시에 과전압, 저전압 등의 계통 전압의 변동이 발생 했을 시 이를 보상하여 부하에 전달되는 전력의 품질을 유지 할수 있다. UPQC의 개념에 대하여 설명하고, 계통 연계시의 전압 보상, 단독 운전시의 시퀀스에 대하여 설명하고, 이를 시뮬레이션을 통해 검증한다.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.5
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• pp.279-286
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• 2003

A new UPQC(unified power quality conditioner), which consists of series inverter, shunt inverter, dc/dc converter, and energy storage, is proposed. The proposing UPQC can compensate reactive power, harmonics, voltage sag and swell, voltage unbalance, and voltage interruption. The control strategy for the proposing UPWQC was derived using the instantaneous power method. The performance of proposing system was analyzed by means of the EMTDC/PSCAD simulation and the experimental work with the hardware prototype. The proposing UPQC has the ultimate capability of improving power quality at the point of installation on power distribution systems or industrial power systems and can be utilized for the custom power device in the future distribution system.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.251-255
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• 2003

This paper proposes a novel UPQC(unified power quality conditioner) based on H-bridge modules, isolated through single-phase multi-winding transformers. The dynamic performance of proposed system was analyzed by simulation with EMTDC/PSCAD, assuming that the UPQC is connected with the 22.9kV distribution line. The proposed system can be directly connected to the transmission line without series injection transformers. It has flexibility in expanding the operation voltage by increasing the number of H-bridge modules and can compensate reactive power, harmonics, voltage sag and swell, voltage unbalance. The control strategy for the proposing UPQC was derived using the instantaneous power method. The proposing UPQC has the ultimate capability of improving power quality at the point of installation on power distribution systems and can be utilized for the future distribution system.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.54 no.1
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• pp.1-7
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• 2005

This paper proposes a novel UPQC(unified power quality conditioner) based on H-bridge modules, isolated through single-phase multi-winding transformers. The dynamic performance of proposed system was analyzed by simulation with PSCAD/EMTDC, assuming that the UPQC is connected with the 22.9kV distribution line. The proposed system can be directly connected to the transmission line without series injection transformers. It has flexibility in expanding the operation voltage by increasing the number of H-bridge modules and can compensate reactive power, harmonics, voltage sag and swell, voltage unbalance. The proposing UPQC has the ultimate capability of improving power quality at the point of installation on power distribution systems.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1483-1485
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• 2005

In recent years, customers and power supplies are interested in power quality. Demands of customers are change from standard quality of distribution power system to various high quality of distribution power system. so, it is necessary to apply power quality compensator. in our project, we develop the UPQC(Unfied Power Quality Compensator of 45kVA which compensates power factor and voltage sag, interruption. it is very frequently occurred power quality problems. As a series and shunt compensator, UPQC consists of two inverters with common dc link capacitor bank. It compensates the current quality in the shunt part and the voltage quality in the series part. In this paper, we present simulation and test result of developed UPQC system. Test for UPQC are performed at voltage sag, flickers and non-linear load conditions. For voltage sag and ficker generation, we use RTDS(Real Time Digital Simulator) and power amplifier system.