• Proceedings of the KIEE Conference
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• 1999.07f
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• pp.2601-2603
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• 1999

This paper describes on the development of Controller for the Utility Car combined photovoltaic. The Utility Car is generally composed of Controller, separately excited DC motor. battery and potbox. According to using battery, Utility Car have the problem of small operation time. So operating time is expanded by using parallel operating sollar cell and battery.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.10
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• pp.1855-1860
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• 2009

This paper caused a distribution utility to generation of analysis fault several cases on the ground of substation in a energy meter three phase current, voltage data measurement to fault type and characteristics. Mother wavelet transformation of suitable to method algorithm from the distribution utility to generation of fault in image impedance etc several parameter for utility characteristics effective to probatory fault point extraction.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.9
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• pp.562-568
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• 2004

The frequency and phase angle of the utility voltage are important in many industrial systems. In the three-phase system, they can be easily known by using the utility voltage vector. However, in the case of single phase system, there are some difficulties in detecting the information of utility voltage. In conventional system, the zero-crossing detection method is widely used, but could not obtain the information of utility voltage instantaneously. In this paper, the new digital PLL control using virtual two phase detector is proposed with a detailed analysis of single-phase digital PLL control for utility connected systems. The experimental results under various utility conditions are presented and demonstrate an excellent phase tracking capability in the single-phase grid-connected operation.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2005.04a
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• pp.193-197
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• 2005

점진적 개념 학습 알고리즘인 COBWEB은 클래스 정보가 주어지지 않은 사례들(instances)을 분류하기 위하여 사례의 속성과 값에 근거하여 학습하며 각 노드가 유사한 사례들의 집합인 클래스에 해당하는 분류 트리를 생성하는 알고리즘이다. 유사한 사례들을 같은 클래스로 분류하기 위한 기준으로 category utility가 사용되며 이는 클래스 내부의 유사도와 클래스간의 차이점을 최대화하는 방향으로 클래스를 분류한다 기존의 COBWEB에 사용되는 category utility는 클래스 사이즈와 예측 정확성 사이의 tradeoff 관계로 볼 수 있으며, 이로 인하여 예측 정확성은 약간 감소하나 클래스 사이즈가 커지는 방향으로 학습이 진행 될 수 있는 편향성(bias)를 가지고 있다. 이는 분류 트리에 불필요한 클래스 노드들(spurious nodes)을 생성하게 하여 학습 결과인 클래스 개념을 이해하는뎨 어렵게 한다. 본 논문에서는 클래스와 그에 속하는 사례들의 속성-값 분포를 고려하여 클래스와 속성의 연관성에 비례한 가충치를 더한 변형된 category utility를 제안하고, dataset에 대한 실험을 통하여 제안된 category utility가 기존의 큰 클래스 사이즈를 선호하는 bias를 완화시킴을 보이고자 한다.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2004.11a
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• pp.233-235
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• 2004

This paper studies protective coordination of utility interconnected multiple distirbuted generations(DG). The study of protective coordination interconnected DG has been conducted. A protective coordination of utility disturbed by reverse current of DG. Therefore, A protetive device is not operate when reverse current flows. In this paper, we use phase difference between V and I. Also, we studied protective coordination algorithm of utility interconnected multiple DG.

• Journal of the Korean Professional Engineers Association
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• v.33 no.4
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• pp.27-32
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• 2000

The automatic utility program in electrical facilities has specially developed to fulfill the needs of electric CAD designers . Designers had separately managed the designing factors such as design, estimates and calculation sheets . However, this automatic utility program produces calculation sheets and volume reports simultaneously while designed. The program also accumulates all data automatically in database in order to be utilized as the statistics and the design data for later project management. Moreover, it is easy for new and inexperienced users to access by using the standard electric symbol libraries and utility modules.

• Journal of Power Electronics
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• v.10 no.4
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• pp.428-433
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• 2010

This paper proposes a harmonics reduction technique for the input currents of three phase PWM converters. The quality of the phase angle information on the utility voltage connected to the PWM converters affects their control performance. Under a distorted utility voltage, the extracted phase angle based on the synchronous reference frame PLL method is distorted. This causes large harmonics in the input currents of a PWM converter. In this paper, a harmonics reduction method that makes the input currents in the PWM converter sinusoidal even under distorted utility conditions is proposed. By the proposed method, without additional hardware, the THD (Total Harmonic Distortion) of the input currents can be readily limited to below 5% which is the harmonic current requirements of IEEE std. 519. Its validity is verified by simulations and experimental results.

• Journal of the Korean Solar Energy Society
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• v.25 no.4
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• pp.21-27
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• 2005

This paper summarizes the results of these efforts by offering a photovoltaic system structure in 50kW middle scale applications installed in Cho-sun University dormitory roof. The combination of photovoltaic system components are interconnected and system monitoring system will be summarized for the purpose of the increasing safety in this article. This paper describes configuration of utility interactive photovoltaic system which generated electric power supplies to dormitory. In order to installing the middle or large scale photovoltaic system, It must investigated the optimal design of system, compute quantity of power generation, economic rate of return and so on. In this paper represent 50kW utility photovoltaic system examination and developed simulation results. The performance of photovoltaic system has been evaluated and analyzed with simulation. The results obtained in this research will be much useful to prior investigation for installing utility interactive photovoltaic system.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.75-76
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• 2007

Several kinds of High Temperature Superconducting(HTS) power cables have already been developed and evaluated for use in the utility power network. HTS power cable is expected to be used as a very powerful energy delivery system supplying electric power for densely populated cities in the near future, because HTS power cable is capable of the high current density delivery with low AC loss and the size effect comparing with the conventional cable whose capacity is same. Before applying the HTS power cable to real utility network system analysis should be carried out by some simulation tools. Hereby the electrical power system analysis is very important for the practical use of HTS power devices. In this paper, authors propose a real-time simulation method which incorporates a real HTS tapes into the simulated 22.9kV utility power network system using Real Time Digital Simulator(RTDS). For the simulation analysis, a test sample of HTS tapes was actually manufactured, and the transient phenomenon of HTS power cable system was analyzed in the simulated utility power network.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.673-676
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• 2001

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 presents 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.