• 전기학회논문지
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• 제62권1호
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• pp.29-36
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• 2013

This paper deals with the analysis of the customer voltage characteristic in distribution system interconnected with large scale PV system. There would be many power quality issues which are caused by reverse power flow of PV system interconnected with distribution system. In order to analyze the effect of PV system on the customer voltage, detailed modeling method of distribution system and modified modelling method of PV system are proposed using PSCAD/EMTDC in this paper. So far, less than dozens KW of PV system can be simulated with the existing modelling method. Therefore, a new modeling method which can simulate the large scale PV system is proposed by considering the relationship equation on the phase and voltage in the current control algorithm. From the simulation result of proposed modelling method, it is confirmed that an optimal operation method in distribution system is suggested by analyzing the effect of PV system on customer voltage.

• 전기학회논문지
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• 제58권12호
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• pp.2453-2461
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• 2009

Faults caused by medium-voltage customers have been increased and enlarged their portion in total distribution faults even though we have done many efforts. In the previous paper, we suggested the fault prediction model and fault prevention method for these distribution line faults. However we can't directly apply this prediction model in the field. Because we don't have an useful program to predict those customers causing distribution line faults. This paper presents the construction method of data warehouse in ERP system and the program to find customers who cause distribution line faults in medium-voltage customer's electric facility management applying data mining techniques. We expect that this data warehouse and prediction program can effectively reduce faults resulted from medium-voltage customer facility.

• Journal of Electrical Engineering and Technology
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• 제12권1호
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• pp.11-18
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• 2017

In order to maintain customer voltages within the allowable limit($220{\pm}13V$) as much as possible, tap operation strategy of SVR(Step Voltage Regulator) which is located in primary feeder, is widely used for voltage control in the utilities. However, SVR in nature has operation characteristic of the delay time ranging from 30 to 150 sec, and then the compensation of BESS (Battery Energy Storage System) during the delay time is being required because the customer voltages in distribution system may violate the allowable limit during the delay time of SVR. Furthermore, interconnection of PV(Photovoltaic) system could make a difficultly to keep customer voltage within the allowable limit. Therefore, this paper presents an optimal coordination operation algorithm between BESS and SVR based on a conventional LDC (Line Drop Compensation) method which is decided by stochastic approach. Through the modeling of SVR and BESS using the PSCAD/EMTDC, it is confirmed that customer voltages in distribution system can be maintained within the allowable limit.

• 조명전기설비학회논문지
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• 제21권3호
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• pp.117-124
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• 2007

요즈음과 같은 고유가 시대에 대두되고 있는 분야인 에너지 절감과 관련하여, 본 논문에서는 대단위 전력 수용가 내부의 저압배전 시스템을 특고압으로 변경할 때의 전기에너지의 손실절감에 대해 논하였다. 현재 대수용가에서는 특고압을 수전하여 저압으로 강압하여 각 부하에 전압선로로 전력을 공급하는데, 그 대신에 본 논문에서는 수전한 특고압을 수용가내의 개별 부하 근방까지 직접 가져오고 여기서 저압으로 변환하여 짧은 거리에 위치한 부하들에 전력을 공급할 때 소요되는 대략적인 설비비, 공사비의 증가금액과 선로의 전력손실 감소에 의한 절감 금액을 계산하였다. 또한 초기투자비의 회수 기간을 산정함으로 특고압 배전시스템의 경제성에 대하여 간략히 평가하였다.

• Journal of Electrical Engineering and Technology
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• 제4권3호
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• pp.330-336
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• 2009

This paper proposes an on-line voltage management and control solution for a distribution system which can improve the efficiency and accuracy of existing off-line work by collecting customer voltage on-line as well as the voltage compensation capability of the existing ULTC (Under Load Tap Changer) operation and control strategy by controlling the ULTC tap based on pattern clustering and recognition. The proposed solution consists of an ADVMD (Advanced Digital Voltage Management Device), a VMS (Voltage Management Solution) and an OLDUC (On-Line Digital ULTC Controller). An on-line voltage management emulator based on multi-thread programming and the shared memory method is developed to emulate on-line voltage management and digital ULTC control methodology based on the on-line collection of the customer's voltage. In addition, using this emulator, the effectiveness of the proposed pattern clustering and recognition based ULTC control strategy is proven for the worst voltage environments for three days.

• 전기학회논문지
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• 제67권8호
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• pp.1031-1039
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• 2018

If large-scale PV systems are continuously interconnected to distribution system, customer voltages could violate the allowable voltage limit($220{\pm}13V$) according to reverse power flow of PV system. In order to solve these problems, this paper proposes flexible adoption evaluation algorithm of PV system in distribution system which estimates proper introduction capacity and location of ESS(energy storage system) for keeping customer voltages within allowable voltage limit based on various operating scenarios related with connecting point and capacity of PV system. And also this paper proposes modeling of ESS, SVR(step voltage regulator) and PV system using PSCAD/EMTDC S/W and analyzes characteristics of customer voltages and the adoption ability of PV system in distribution system. From the simulation results, it is confirmed that proposed algorithm is useful for large-scale adoption of PV system in distribution system to maintain customer voltages within allowable voltage limit.

• 전기의세계
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• 제18권2호
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• pp.7-14
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• 1969

From the first customer located right at the substation to the last customer at the end of the line, voltage must be held within close limits, so the voltage regulation is more important than the thermal limit. On a typical distribution system during the peak load period, the voltage drop may be serious enough to cause unsatisfactory operation of home appliances in the residential area, and present many problems to manufacturing industries, where the voltage must be maintained within close limits to insure smooth operation. Among all the factors contributing to voltage drop in the distribution system, the voltage drop in the distribution transformer may account for 30% of this figure. If we can eliminate this factor, the power companies can provide better quality electricity to more customers with the existing distribution facilities, thus saving on initial investment costs. Taking all these problems into consideration, the author undertook the design of a capacitive transformer which would give zero voltage drop at rated load and at 80% lagging power factor while incorporating overload features to withstand 400% overload for at least 100 seconds. The following are the results obtained through design, manufacture and test of an initial experimental transformer built with these specific purposes.

• 전기학회논문지P
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• 제54권1호
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• pp.41-46
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• 2005

Most of LV customer have applied the 3-phase four wire system distribution system because it has advantage of supplying both of 1-phase & 3-phase loads simultaneously. Due to its structural simplicity, it is more convenient for use rather than the conventional separated scheme. But voltage unbalance more commonly emerges in individual customer loads due to phase load unbalance, especially where, single-phase power loads are used. Voltage unbalance factor(VUF) represents the loss of symmetry in the supply(magnitude and angle). It leads some problems such as de-rating or power losses. In this paper, voltage and current waveform in the actual fields have been measured and analyzed in relation with internationally allowable voltage unbalance limits.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.320-321
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• 2011

As the scale of industries expands, the facilities of the industrial customer become larger and more complex. When a fault occurs in the system, the circuit breakers play an important role in minimizing causalitites by quickly tripping the faulted line. Since the capacity of the receiving-end has increased in size, an examination is needed to be performed between the industrial customers and the conventional circuit breakers. The transient recovery voltage, which is the initial transient characteristics of the voltage across the breaker when tripped, is an important factor in determining the circuit breaker's performance. In this paper, a TRV analysis on the large-scale industrial customer is being performed utilizing PSCAD/EMTDC.

• 한국산학기술학회논문지
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• 제19권6호
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• pp.9-20
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• 2018

최근 국가의 3020정책에 따라 신재생에너지전원의 도입이 활발히 이루어지고 있는 상황이다. 하지만 신재생에너지전원중의 하나인 태양광전원이 대규모로 배전계통에 도입되어 운용될 경우, 태양광전원의 간헐적 특성에 의한 출력변동과 역조류에 의하여 수용가 전압은 규정범위($220V{\pm}6%$)를 벗어날 수 있는 문제점을 가지고 있다. 이를 해결하기 위한 방안 중 하나로, 배전선로에 기설된 선로전압조정장치를 이용한 수용가 전압조정 방안이 제안되고 있으나, 기계적으로 동작하는 선로 전압조정장치의 특성으로 인하여, 탭 변경 시간동안 수용가의 전압이 규정범위를 벗어날 가능성을 가지고 있다. 이에 본 논문에서는 선로전압조정장치 탭 변경시, 기계적인 특성에 의하여 탭 동작이 지연되는 시간동안 전기저장장치를 도입하여 전압 문제를 해결할 수 있는 전기저장장치의 최적운용전략을 제시하고, 파라메타 분석법을 이용하여 선로전압조정장치와 협조하여 운용되는 전기저장장치의 적정위치 및 적정용량 산정방안을 제안하였다. 본 논문에서 제안한 선로전압장치와 전기저장장치의 상호동작에 대한 최적운용 전략과 전기저장장치의 산정 알고리즘을 바탕으로 시뮬레이션을 수행한 결과, 선로전압조정 장치의 탭 변경 시간동안 수용가의 규정전압($220V{\pm}6%$) 여부를 검증함으로써, 본 논문에서 제안한 수법이 계통의 전압안정화에 기여할 수 있는 방안임을 확인하였다.