• Title/Summary/Keyword: power estimation

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Development of Current Harmonics Estimation Method by Considering the Characteristics of Input Voltage (인가전압의 특성을 고려한 주거용 부하의 전류성분 추정기법 개발)

  • Ji, Pyeong-Shik
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.60 no.4
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    • pp.181-185
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    • 2011
  • Due to the increasing of nonlinear loads such as converters and inverters connected to the electric power distribution system, and extensive application of harmonic generation sources with power electronic devices, disturbance of the electric power system and its influences on industries have been continuously increasing. Thus, it is difficult to construct accurate load model for active and reactive power in environments with harmonics. In this research, we develop current harmonics estimation method based on Extreme Learning Machine (ELM) with fast learning procedure for residential loads. Using data sets acquired from various residential loads, the proposed method has been intensively tested. As the experimental results, we confirm that the proposed method makes it possible to effective estimate current harmonics for various input voltage.

DFT-based Power System Frequency Estimation using Two Digital Filters for Noise Effect Reduction (잡음영향의 저감을 위한 두 디지털 필터들의 사용에 의한 DFT 기반의 계통주파수 추정)

  • Hwang, Jin Kwon
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.62 no.7
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    • pp.891-897
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    • 2013
  • The power system frequency plays an important role in monitoring and controlling the power system. The frequency can be measured through discrete Fourier transform (DFT) coefficients of its positive fundamental frequency. The accuracy of the frequency estimate is severely affected by noise in the power system signal and the leakage effect of the negative fundamental frequency in DFT. This paper proposes a DFT-based frequency estimation algorithm to cope with the noise as well as the leakage effect. In this algorithm, two suitable digital filters are introduced to reduce efficiently frequency estimate error due to the noise. These filters are designed to use a digital bandpass filter and a second-degree integrator. The effectiveness of the proposed algorithm in reduction of frequency estimate error is verified through simulations on noise, harmonics and frequency deviation.

Critical Current Estimation of HTS Magnets by using Field Dependent E-J Relation (전계를 이용한 팬케이크 권선으로 제작되는 마그넷의 임계전류 산정)

  • Kang, Myung-Hun;Koo, Myung-Hwan;Lee, Hee-Joon;Cha, Guee-Soo
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.58 no.3
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    • pp.502-508
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    • 2009
  • The method to determine the operating current of HTS magnets needs to be different from that of LTS magnets. This paper presented estimation of the critical current of pancake windings. The pancake windings can be excited by a single power source or by multiple power sources. Critical currents were determined by using field dependent E-J relation. For the better estimation of the critical current, a new method to define the magnetic field of the HTS wire has been proposed. Calculated critical currents of pancake windings were compared with measured ones of the HTS BSCCO magnet consisting of 10 pancake windings. According to the test results, the estimated critical currents of pancake windings agreed well with that of measured ones. Effects of the single and multiple power source excitation on the critical currents have been also examined.

A Study on the Validation Methodology of Network Analysis Applications in Energy Management Systems (계통운영시스템 계통해석 프로그램 검증 방안에 관한 연구)

  • Cho, Yoon-Sung
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.28 no.10
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    • pp.27-36
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    • 2014
  • Network analysis applications in energy management systems play a key role in the economic and reliable operation of power systems. In order to provide operators with useful network information, the accurate results of topology processing, state estimation, power flow, and contingency analysis must be simulated. This paper proposes a validation methodology of network analysis applications in energy management systems. The energy management systems was checked to ensure that it meets the originally specified functions based on the proposed methodology. In addition, the performance of state estimation is evaluated with the reference of the proposed methodology. The proposed methodology is being conducted by energy management systems and the Korean power systems have been utilized for the test systems.

Distribution Load Forecasting based with Land-use Estimation (토지용도 추정을 기반으로 한 배전계통 부하예측)

  • Kwon, Seong-Chul;Lee, Hak-Joo;Choi, Byoung-Youn
    • Proceedings of the KIEE Conference
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    • 1999.07c
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    • pp.1481-1483
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    • 1999
  • Power distribution system planning for maximum customer satisfaction and system efficiency requires accurate forecast of future demand in service area. Spatial load forecasting method provides a more accurate estimation of both magnitudes and location of future electrical load. This method considers the causes of load growth due to addition of customers and per capita consumption among customers by land use (residential, commercial and industrial). So the land-use study and it's preference for small area is quite important. This paper proposes land-use preference estimation method based on fuzzy logic. Fuzzy logic is applied to computing preference scores for each land-use and by these scores the customer growth is allocated in service area. An simulation example is used to illustrate the proposed method.

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Harmonic and Interhamonic Detection and Estimation of Power Signal using Subband MUSIC/ESPRIT (부밴드 MUSIC/ESPRIT를 이용한 전력신호 고조파 및 중간고조파 검출 및 추정)

  • Choi, Hun;Bae, Hyeon-Deok
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.64 no.1
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    • pp.149-158
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    • 2015
  • This paper proposes a subband filtering technique to the MUSIC and the ESPRIT algorithm for estimating the magnitude and frequency of the harmonics of power signal. In proposed method, the input power signal is decomposed to the odd harmonics and the even harmonics respectively by the filter bank system. The amplitude and the frequency estimation of the decomposed harmonics are carried out using the MUSIC and the ESPRIT method. Subband filtering can reduce the autocorrelation matrix size of input data, and spectrum leakage between adjacent harmonics. Therefore, this subband technique has advantage in computational cost and estimation accuracy compared to fullband MUSIC and ESPRIT. To demonstrate the performance of the method, computer simulations are performed to the synthesized input signal, and experiment results are compared in subband and fullband cases.

A Comparison of C/No Estimation Techniques for Commercial GPS Receivers under Jamming Environments (전파방해환경에서 상용 GPS 수신기의 C/No 추정기법 성능분석)

  • Baek, Jeehyeon;Yoo, Seungsoo;Kim, Sun Yong
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.38A no.11
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    • pp.973-975
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    • 2013
  • In this paper, the carrier-to-noise power ratio estimation performances for commercial GPS receiver are shown by simulation and are analyzed under weak signal reception, high sensitivity signal reception, and the matched spectrum jamming signal reception environments.

A Study on Indirect Estimating Methods for Yearly Maximum Cooling Load (연 최대 냉방부하의 간접추정 방법론에 관한 연구)

  • Yang, Moon-Hee
    • IE interfaces
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    • v.16 no.1
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    • pp.16-26
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    • 2003
  • In Korea, cooling power load, which occupies about 20% of peak load in 2000 and fluctuates depending on the popular usage of air conditioning systems, has been recently the focus of the load management. The first work of KEPCO (Korea Electric Power Corporation) to regulate cooling load as low as possible was to estimate its approximate scale and to develop the indirect methods to estimate it from the available time series data for the average hourly loads. However, KEPCO would like to have their methods improved both theoretically and practically. In this paper, we analyze their current indirect methods and detect their faults to design better indirect estimation methods. Under one of the assumptions of "no cooling load in April or May", the linear relationship between basic loads and GDP's, and the normalized seasonal factors of the Winters' multiplicative seasonal model, we provide ten indirect estimation methods in total and suggest the estimated cooling load(1988-1999) based on our various indirect methods.

A New Low Power High Level Synthesis for DSP (DSP를 위한 새로운 저전력 상위 레벨 합성)

  • 한태희;김영숙;인치호;김희석
    • Proceedings of the IEEK Conference
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    • 2002.06b
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    • pp.101-104
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    • 2002
  • This paper propose that is algorithm of power dissipation reduction in the high level synthesis design for DSP(Digital Signal Processor), as the portable terminal system recently demand high power dissipation. This paper obtain effect of power dissipation reduction and switching activity that increase correlation of operands as input data of function unit. The algorithm search loop or repeatedly data to the input operands of function unit. That can be reduce the power dissipation using the new low power high level synthesis algorithm. In this Paper, scheduling operation search same nodes from input DFG(Data Flow Graph) with correlation coefficient of first input node and among nodes. Function units consist a multiplier, an adder and a register. The power estimation method is added switching activity for each bits of nodes. The power estimation have good efficient using proposed algorithm. This paper result obtain more Power reduction of fifty percents after using a new low power algorithm in a function unit as multiplier.

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A Maximum Power Point Tracking Control for Photovoltaic Array without Voltage Sensor

  • Senjyu, Tomonobu;Shirasawa, Tomiyuki;Uezato, Katsumi
    • Journal of Power Electronics
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    • v.2 no.3
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    • pp.155-161
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    • 2002
  • This paper presents a maximum power point tracking algorithm for Photovoltaic array using only instantaneous output current information. The conventional Hill climbing method of peak power tracking has a disadvantage of oscillations about the maximum power point. To overcome this problem, we have developed an algorithm that will estimate the duty ratio corresponding to maximum power operation of solar cell. The estimation of the optimal duty ratio involves, finding the duty ratio at which integral value of output current is maximum. For the estimation, we have used the well know Lagrange's interpolation method. This method can track maximum power point quickly even for changing solar isolation and avoids oscillations after reaching the maximum power point.