• Proceedings of the KIEE Conference
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• summer
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• pp.351-353
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• 2004

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 $problems^{[1-3]}$ As a series and shunt compensator, UPQC consists of two inverters with common do 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 the design and control algorithm for 4SkVA UPQC system. As a control algorithm is implemented by digital controller, we consider sample-and-hold of signals. In this simulation, we use EMTDC/PSCAD V3.0 software which can simulate instantaneous voltage and current.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.54 no.7
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• pp.328-336
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• 2005

Power quality has become concern both utilities and their customers with wide spread use of electronic and power electronic equipment. The poor quality of electric power causes malfunctions, instabilities and shorter lifetime of the load. In power system operation, power system disturbances such as faults, overvoltage, capacitor switching transients, harmonic distortion and impulses affects power quality. For diagnosing power quality problem, the causes of the disturbances should be understood before appropriate actions can be taken. In this paper we present a new approach to detect, localize, and investigate the feasibility of classifying various types of power quality disturbances. This paper deals with the use of a multi-resolution analysis by a discrete wavelet transform to detect power system disturbances such as interruption, sag, swell, transients, etc. We also proposed do-noising and threshold technique to detect power system disturbances in a noisy environment. To find the better mother wavelet for detecting disturbances, we compared the performance of the disturbance detection with the several mother wavelets such as Daubechies, Symlets, Coiflets and Biorthogonals wavelets. In our analysis, we adopt db4 wavelet as mother wavelet because it shows better results for detecting several disturbances than other mother wavelets. To show the effectiveness of the proposed method, a various case studies are simulated for the example system which is constructed by using PSCAD/EMTDC. From the simulation results. proposed method detects time Points of the start and end time of the disturbances.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.6
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• pp.220-229
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• 2004

The AC railway system is quite differing from the general electric power system because it is single- phase and intermittently heavy loads. Thus, inevitably power quality problems are occurred in the AC railway system, i.e. voltage regulation voltage sags, voltage imbalance, and harmonic distortion. Recently, the power quality of the AC railway system becoming a hot issue because it is affect the control and safety of high-speed traction. In addition it is also affect the power quality of the electric power system. In this paper, single-phase Unified Power Quality Conditioner(UPQS) for the AC railway system is proposed to compensate the voltage sags and harmonic distortion. The configurations and control schemes of the proposed single-phase UPQC are presented. The effectiveness of the proposed single-phase UPQC application is verified by the PSCAD/EMTDC simulation works. It can be shown that the application of UPQC in the AC railway system is very useful to compensate the voltage sags and harmonic distortion from the results of related simulation works.

• Journal of Power System Engineering
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• v.19 no.2
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• pp.84-89
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• 2015

The occurrence of algae caused by eutrophication of fresh water is a pollution source to destroy the aquatic environment. When the high voltage electric field is applied in the water, When a high voltage is applied to the electric field in the water, the algae can be broken the balance of cell membranes, and is dead. In this paper, we develop a water quality improvement system for generating an electric field having a higher energy than the zeta potential when a high voltage is applied to 4,000V. To ensure the mobility of the water quality improvement system, we designed the PV generation system using the optimal size technique that is based on the model of power lack ratio. By evaluating the output characteristics of the water quality improvement system, power generation characteristics of the PV generation system, and battery charging characteristics, we can show that the proposed system can be applicable to the water quality improvement system inhibiting the growth rate of the algae in the fresh water.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.6
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• pp.147-153
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• 2010

When small scale wind and solar power generation systems are connected to conventional power distribution system. It is worried that it can affect the quality of electricity such as voltage variation, power factor, frequency, harmonics and flicker. Therefore, in this research, in order to investigate the effects of wind power generation equipments(AC link method) on electrical power quality, when they are connected to distribution system. Power quality analyzer was installed respectively at the front side of power conversion system of conventional wind generation system and secondary side of consumer's power supply at distribution line. Measurements on power quality were performed and the effects of the wind generation system on distribution system were analyzed when it was and was not operated. The results show that 0.34[%] increase on voltage variation, 0.145 increase on current crest factor and 0.6[$^{\circ}$] deviation on phase difference when the power generation system was operated.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.56 no.1
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• pp.13-18
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• 2007

In this paper, authors deal with an application of power quality monitoring using the Sampled Value which is described in the IEC61850 International Standard for substation communication. Firstly, while Merging Unit is designed as a process level device transmitting sensor data, the practical problems such as time delay compensation and optical fiber communication are issued. Secondly, the Sampled Value message which is proper to a power quality monitoring system is presented. Because the power quality monitoring system requests non time critical service comparing to protection and control applications, the Sampled Value service message structure is introduced to improve efficiency. At last, the power quality monitoring server having various power quality analysis functions is suggested to verify the performance of Merging Unit. With the diverse experiments, it is proved that the process bus distributed solution is flexible and economic for the power quality monitoring.

• Proceedings of the KIEE Conference
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• 2005.05a
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• pp.96-98
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• 2005

This paper describes a monitoring system that monitors power quality and undesirable accidents when distributed generations are connected to the power grid. Prior to develop and operate a physical monitoring system, we constitute a simulation device to simulate the monitoring processes for the situations. The simulation system consists of the server and the client that connected by communication line. This system has various functions to monitor the power quality and the connection situation. Those functions are generation, transmission, acquisition and analysis of the simulated power data. This research seems very important to get the reliable and intelligent connection algorithm through the result of simulated monitoring system. Also hereafter, as this system uses the remote monitoring system through network and constitute the data base(DB), it will play an important role in building the automation of power system efficiently and systematically.

• Proceedings of the KIEE Conference
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• 2002.11b
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• pp.127-130
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• 2002

Recently, with the increasing use of power semiconductors and microprocessors which are very sensitive to little change of power quality and for coping positively with anticipating power quality disputes between power providers and consumers which are possible to occur by of power market being formed, the power quality problem has gained preponderance among the contemporary research areas. To serve these purposes, the integrated system has been researched and developed for power quality analysis and monitoring, which provides speedy and powerful functions by the growth of computer hardware and information technology. But the advent of fast and lower price hardware make little difference in an application on many systems. As a result, the key issues of constructing power quality monitoring system are in the management of data obtained, accurate algorithms, graphic representation and user-friendly-environment for easy and clear analysis results. So, in this paper it will be introduced that the standard of user-friendly-GUI(Graphic User Interface) and analysis graphic representation for intuitive understanding of results from power quality analysis based on consideration of several systems currently being in use.

• Proceedings of the KIEE Conference
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• 1999.11b
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• pp.229-231
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• 1999

This paper deals with electromagnetic transient modelling of wind power system embedded in distribution networks. Wind power system consists of induction generator link reactor, distribution line, and controlled load unit. The introduction of embedded wind power system presents a new set of conditions to networks both with respect to power quantify needed to be transported and power quality such as sag swell, very short interruption, and flicker. This paper investigates the transient behavior of voltage, frequency, and load flow in wind driven induction generation system embedded in distribution networks.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.192-193
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• 2006

An AC electrical railroad system has rapidly changing dynamic single-phase load, and at a feeding substation, three-phase electric power is transformed to the paired directional single-phase electric power. There is a great difference in electrical phenomenon between the load of AC electrical railroad system and that of general power system. Electric characteristics of AC electrical railroad's trainload are changed continuously according to the traction, operating characteristic, operating schedule, track slope, etc. Because of the long feeding distance of the dynamic trainload, power quality problems such as voltage drop, voltage imbalance and harmonic distortion may also occur to AC electrical railroad system. These problems affect not only power system stability. but also power quality deterioration in AC electrical railroad system. The dynamic simulation model of AC electrical railroad system presented by PSCAD/EMTDC is modeled in this paper, and then, it is analyzed voltage drop and power quality for AC electrical railroad system both with single-Phase distributed STATCOM(Static Synchronous Compensator) installed at SP(Sectioning Post) and without.