• 조명전기설비학회논문지
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• 제29권12호
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• pp.88-96
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• 2015

This paper describes a new method for enhancing the accuracy of network analysis applications in energy management systems. Topology processing, state estimation, power flow analysis, and contingency analysis play a key factor in the stable and reliable operation of power systems. In this respect, the aim of topology processing is to provide the electrical buses and the electrical islands with the actual state of the power system as input data. The results of topology processing is used to input of other applications. New method, which includes the topology error analysis based on inconsistency check, coherency check, bus mismatch check, and outaged device check is proposed to enhance the accuracy of network analysis. The proposed methodology is conducted by energy management systems and the Korean power systems have been utilized for the test systems.

• 전기학회논문지
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• 제65권8호
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• pp.1400-1406
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• 2016

This paper presents a new adaptive converter control approach for electric motor systems whose voltage source is excited from photovoltaic (PV) power generators. First, an electric model is represented with dynamic states and output velocity of such DC motor systems. We propose a hybrid converter control law in which a state feedback control is applied as an auxiliary control framework. Moreover, control parameter estimation is derived to realize adaptive converter systems for effective control performance against stochastic PV power excitation in practice. We carry out stability analysis for such converter system by using a well-known eigenvalue theory. Lastly, numerical simulation is conducted to test reliability of the proposed converter control approach and prove its superiority in the control point of view.

• 전력전자학회논문지
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• 제25권5호
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• pp.376-384
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• 2020

An energy storage system is composed of lithium-ion batteries in modern applications. Batteries are regarded as storage devices for renewable and residual energy. The failure of batteries can cause the performance reduction and explosion of battery systems. High maintenance cost is essential when dealing with the problem of battery safety. Therefore an accurate health diagnosis is required to ensure the high reliability of battery systems. A battery pack is a combination of single cells in series and parallel connections. A battery pack has to consider various factors to assess battery health. Battery health involves conventional factors and additional factors, such as cell-to-cell imbalance. For large applications, state-of-health (SOH) can be inaccurate because of the lack of factors that indicate the state of the battery pack. In this study, six characterization factors are proposed for improving the SOH estimation of battery packs. The six proposed characterization factors can be regarded as health indicators (HIs). The six HIs are applied to the principal component analysis (PCA) algorithm. To reflect information regarding capacity, voltage, and temperature, the PCA algorithm extracts new degradation factors by using the six HIs. The new degradation factors are applied to a multiple regression model. Results show the advancement and improvement of SOH estimation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 추계학술대회 논문집 학회본부
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• pp.523-526
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• 1995

This paper presents an improved algorithm of optimal measurement system design with a reliability evaluation method for a large power system. The proposed algorithm is developed to cosider the observability and to achieve highest accuracy of the state estimator as well with the limited investment cost. When the effect on these dummy bus measurements is considered in the proposed algorithm the other errors in the power system is also detected and then analyzed until to achieve the limited values. By taking advantage of the matrix sparsity and the optimal bus ordering the memory and the time are successfully reduced in the P/C's and workstation's model. The improved program is successfully tested for IEEK sample system and KEPCO system with PSS/E lineflow calculated data package.

• Journal of electromagnetic engineering and science
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• 제6권4호
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• pp.203-208
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• 2006

Channel estimation and data detection for OFDM systems over time- and frequency-selective channels are investigated. Relying on the complex exponential basis expansion channel model, a pilot-embedded channel estimation scheme with low computational complexity and spectral efficiency is proposed. A periodic pilot sequence is superimposed at a low power on information bearing sequence at the transmitter before modulation and transmission. The channel state information(CSI) can be estimated using the first-order statistics of the received data. In order to enhance the performance of channel estimation, we recover the transmitted data which can be exploited to estimate CSI iteratively. Simulation results show that the proposed method is suitable for doubly-selective channel estimation for the OFDM systems and the performance of the proposed method can be better than that of the Wiener filter method under some conditions. Through simulations, we also analyze the factors which can affect the system performances.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 1995년도 춘계학술발표회 초록집
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• pp.113-116
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• 1995

Simplified approach has been adopted for the prediction of the thermal behavior of CANDU reactor core during power transients. Based on the assumption that the ratio of mass flow rate for each core channel does not vary during the transient, quasy-steady state analysis technique is applied with predicted core inlet boundary conditions(total mass flow rate and specific enthalpy). For restricted transient case, the presented method shows functionally reasonable estimation of core thermal behavior which could be implemented in the fast running reactor simulation program.

• 아태비즈니스연구
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• 제13권1호
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• pp.263-275
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• 2022

Purpose - This study estimated the non-market value of pumped storage power generation using the contingent valuation method(CVM). Design/methodology/approach - CVM, a non-market value estimation method, was used. The perception of pumped storage power generation and the willingness to pay(WTP) for pumped storage power generation were investigated among 612 randomly selected households. Findings - It was analyzed that the average value per household was 7309.99 won/month, and the sources of these benefits were 1819.37 won due to the improvement of power generation efficiency, 1320.48 won due to the improvement of power system reliability, 2359.24 won due to the stabilization of electricity rates, 2110.89 won due to water resource management It was assumed that a circle occurred. If the average monthly benefit per household is expanded to cover countries across the country, it is estimated that the annual value to our society from pumped storage power generation will be KRW 1.796.6 trillion. Research implications or Originality - It is necessary to consider the operation of pumped-water power generation by reflecting the value of pumped-up power generation that is not evaluated in the market. Since Korea's electricity market is isolated in a state where it is impossible to connect with other countries, it may be vulnerable to a stable electricity operation system. Therefore, there is a need for a facility that can stably secure reserve power and produce power quickly when necessary. If pumped-water power generation is actively used for power operation, a more stable power system can be secured.

• 전기학회논문지
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• 제67권4호
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• pp.491-497
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• 2018

Most of the applications for distribution system operation highly rely on the voltage and current managements from the field devices. Voltage from the remote controlled switch contains unacceptably large measurement error due to the nonlinear characteristics of the bushing potential transformer. This paper proposes a new voltage magnitude estimation method by calculating voltage drop using current measurement, line impedance and loads deployment data. Contract demand power and pole transformer capacity managed by NDIS are used as a key element to improve accuracy of the proposed method. Various case studies using Matlab simulation have been performed to verify feasibility of the propose voltage estimation method.

• 한국산학기술학회논문지
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• 제5권6호
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• pp.533-538
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• 2004

전력 소비자 근처에 설치, 운영하는 소규모 발전 형태인 분산형 전원에 대한 관심이 최근 들어 커지고 있다. 전력산업 구조개편이 진행되고 있는 현 상황에서 분산형 전원을 배전계통 내에 설치하고, 배전계통의 상태추정 기법을 적용하여 배전계통 운영을 안정적이고 신뢰성 높게 하려는 시도가 이루어지고 있다. 본 논문에서는 배전계통에 분산형 전원을 추가하였을 때 계통 손실에 미치는 영향을 분석하여 분산형 전원의 최적위치를 선정하고, 분산형 전원이 포함된 배전계통을 위한 상태추정 기법을 개발하였다. 불량데이터에 대한 강건성이 뛰어난 WLAV 상태추정기를 구현하였으며, 단일, 다중, 상호작용 불량 데이터에 대한 테스트를 실시하였다. IEEE 34 모선 수지상 계통을 사용하여 사례연구를 수행함으로써 제안한 알고리즘의 타당성을 확인하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 A
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• pp.325-327
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• 2000

This paper addresses the issues of the external system modeling and power system state estimation with the external model. A set of significant branches is identified in the external system based on their branch outage sensitivities on the tie-lines. Measurements on these branches are transffered to internal system and updated in real-time. The state estimator is run for different loading conditions by using the actual measurements for the internal system and selected significant external system measurements while keeping the rest of the external system measurements at their base case values. Simulation results are presented using the IEEE 118 bus system as an example.