• KIEE International Transactions on Power Engineering
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• 제5A권3호
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• pp.260-268
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• 2005

This paper proposes an improved investment pnonty decision method of facilities considering the reliability of distribution networks. The proposed method decides an investment order of the facilities combining, by fuzzy rules, the investment priority decision by KEPCO and that by reliability evaluation indices. The reliability evaluation indices are SAIFI (System Average Interruption Frequency Index) and SAIDI (System Average Interruption Duration Index). The reliability analysis method of distribution networks applied in this paper utilizes the analytic method, where the used reliability data is the historical data of KEPCO. Particularly, we assumed that the failure rate increases as the equipment ages. To verify the performance of the proposed method, we applied it with the planned projects to reinforce the weak electrical facilities in KEPCO in 2004. The evaluation result showed that, under a limited budget, the reliability of KEPCO in the Busan region using the proposed method could be enhanced if used rather than the conventional method typically in place. Therefore, the results verify that the proposed method can be efficiently used in the actual priorities method for investing in the electrical facilities.

• Journal of Communications and Networks
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• 제13권4호
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• pp.319-326
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• 2011

Beamforming techniques have been successfully utilized for traffic channels in order to solve the interference problem. However, their use for control channels has not been sufficiently investigated. In this paper, a (semi-) centralized beamforming strategy that adaptively changes beam patterns and controls the total transmit power of cells is proposed for the performance enhancement of the common channel in hierarchical cell structure (HCS) networks. In addition, some examples of its practical implementation with low complexity are presented for two-tier HCS networks consisting of macro and pico cells. The performance of the proposed scheme has been evaluated through multi-cell system-level simulations under optimistic and pessimistic interference scenarios. The cumulative distribution function of user geometry or channel quality has been used as a performance metric since in the case of common control channel the number of outage users is more important than the sum rate. Simulation results confirm that the proposed scheme provides a significant gain compared to the random beamforming scheme as well as conventional systems that do not use the proposed algorithm. Finally, the proposed scheme can be applied simultaneously to several adjacent macro and pico cells even if it is designed primarily for the pico cell within macro cells.

• 전기학회논문지
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• 제57권4호
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• pp.582-588
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• 2008

Microgrids are new distribution level power networks that consist of various electronically-interlaced generators and sensitive loads. The important control object of Microgrids is to supply reliable and high-quality power even during the faults or loss of mains(islanding) cases. This paper presents power control methods to coordinate multiple distributed generators(DGs) against abnormal cases such as islanding and load power variations. Using speed-droop and voltage-droop characteristics, multiple distributed generators can share the load power based on locally measured signals without any communications between them. This paper adopts the droop controllers for multiple DG control and improved them by considering the generation speed of distribution level generators. Dynamic response of the proposed control scheme has been investigated under severe operation cases such as islanding and abrupt load changes through PSCAD/EMTDC simulations.

• 조명전기설비학회논문지
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• 제21권9호
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• pp.81-86
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• 2007

Electric utility companies have the responsibility of providing good electricity for their customers. They have introduced the DAS(Distribution Automation System) to automate the power distribution networks. DAS engineers require state-of-the-art applications, such as a way to actively manage the distribution system and gain economic benefits from a flexible DAS architectural design. The existing DAS is not capable of handling these needs. It requires operator intervention whenever feeder overloading is detected while operator error could cause the feeder overload area to be extended. It also utilizes a closed architecture and it is therefore difficult to meet the system migration and future enhancement requirements. This paper represents a web based, platform-independent, flexible DAS architectural design and active database application. Recent advanced Internet technologies are fully utilized in this new DAS architecture allowing it to meet the system migration and future enhancement requirements. By using an active database, the DAS can minimize the feeder overloading area in the distribution system without operator intervention, thereby minimizing mistakes due to operator error.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 A
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• pp.102-104
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• 2005

This paper describes the model of the distribution grid for the broadband power line communication based on lumped-element circuits. In addition, this paper discusses various configurations of the MV distribution network in PLC. The distribution grid is not designed for communication so that it involves unfriendly conditions for PLC. The characterization of the MV distribution grid for PLC should be determined such as noise, attenuation, and mismatched impedance. For theses reasons, the PLC networks is described in using the scattering parameters. Finally, the n-port network is explained.

• 조명전기설비학회논문지
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• 제16권3호
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• pp.61-66
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• 2002

배전시스템은 고 신뢰도가 요구되는 사례시스템이다. 신뢰도는 정해진 기간과 운전 조건하에서 설비나 시스템이 적절히 자기 기능을 할 수 있는 확률로 정의된다 수용가에서 배전시스템의 성능을 예측하고 검증하기 위한 기본적인 신뢰지수는 평균고장률, 평균고장기간, 평균 활용률 등이 포함된다 본 논문에서는 EDSA의 배전계통 신뢰도 평가 프로그램을 이용하여 배전 시스템의 기본적인 신뢰도 평가지수를 구하고, 수지식 사례 배전시스템을 개선시키기 위한 방법으로 환상식 시스템으로 구성을 변경시켜 수치적으로 얼마나 높은 신뢰도가 얻어졌는지를 보여준다.

• 드라이브 ㆍ 컨트롤
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• 제17권1호
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• pp.13-20
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• 2020

Adaptive neural networks based lateral controller is presented to guarantee path following performance for vehicle lane keeping in the presence of parameter time-varying characteristics of the vehicle lateral dynamics due to the road surface condition, load distribution, tire pressure and so on. The proposed adaptive controller could compensate vehicle lateral dynamics deviated from nominal dynamics resulting from parameter variations by incorporating it with neural networks that have the ability to approximate any given nonlinear function by adjusting weighting matrices. The controller is derived by using Lyapunov-based approach, which provides adaptive update rules for weighting matrices of neural networks. To show the superiority of the presented adaptive neural networks controller, the simulation results are given while comparing with backstepping controller chosen as the baseline controller. According to the simulation results, it is shown that the proposed controller can effectively keep the vehicle tracking the pre-given trajectory in high velocity and curvature with much accuracy under parameter variations.

• Journal of Communications and Networks
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• 제16권6호
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• pp.600-612
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• 2014

In this paper, we consider the problem of spectrum sensing for advanced television systems committee (ATSC) digital television (DTV) signal detection. To exploit the cyclostationarity of the ATSC DTV signals, we employ spectral correlation density (SCD) as the decision statistic and propose an optimal detection algorithm. The major difficulty is in obtaining the probability distribution functions of the SCD. To overcome the difficulty, we probabilistically model the pilot frequency location and employ Gaussian approximation for the SCD distribution. Then, we obtain a practically implementable detection algorithm that outperforms the industry leading systems by 2-3 dB. We also propose various techniques that greatly reduce the system complexity with performance degradation by only a few tenths of decibels. Finally, we show how robust the system is to the estimation errors of the noise power spectral density level and the probability distribution of the pilot frequency location.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 C
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• pp.1114-1117
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• 1998

Recent applications of neural networks to power system fault diagnosis have provided positive results and have shown advantages in process speed over conventional approaches. This paper describes the application of neural network to fault detection and classification in distribution lines using the fundamental component, 2-5th harmonics index, even and odd harmonics index, and zero phase current. The Electromagnetic Transients Program (EMTP) is used to obtain fault patterns for the training and testing of neural networks. The proposed fault detection and classification method in distribution lines is obtained by analysing the difference among normal, HIF, ground fault, short circuit fault condition.

• 조명전기설비학회논문지
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• 제24권10호
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• pp.49-57
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• 2010

In order to provide electricity to users economically and safely, distribution automation systems (DASs) monitor and operate components of distribution systems remotely through communication networks. The fiber optic communication network has been mainly installed for the DAS of Korea Electric Power Corporation (KEPCO) because of its huge bandwidth and dielectric noise immunity. However, the fiber optic communication network has some shortcomings that its installation cost and communication fee are expensive. This paper proposes a complex network where WLANs are combined with conventional fiber optic communication networks in order to expand DAS easily and inexpensively. A fixed wireless bridge communication unit (FWB-CU) for the proposed complex network is implemented using IEEE 802.11a WLAN technology. The proposed complex network is built actually to verify its feasibility experimentally as a DAS communication network.