• Title/Summary/Keyword: Load power factor

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Study on grid-connected photovoltaic 3 kW Inverter (3kW급 계통 연계형 태양광 인버터에 관한 연구)

  • Song, S.G.;Lee, S.H.;Park, S.J.
    • Proceedings of the KIPE Conference
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    • 2005.07a
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    • pp.707-710
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    • 2005
  • This paper presents a 3kW grid-connection photovoltaic power generation system and its topology. Photovoltaic system must provide the sinusoidal output voltage wave for unity power factor High frequency switching converters are becoming more popular because of several benefits which are essential in power conversion system. This paper introduces a high speed digital controller using TMS320F2812 DSP chip which can be used for high frequency switching converters. The experimental results of the proposed PWM Inverter demonstrates its high performance with unity input power factor having very low distorsion in input current waveforms and good dynamic characteristics at full load.

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Effects of Imperfect Sinusoidal Input Currents on the Performance of a Boost PFC Pre-Regulator

  • Cheung, Martin K.H.;Chow, Martin H.L.;Lai, Y.M.;Loo, K.H.
    • Journal of Power Electronics
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    • v.12 no.5
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    • pp.689-698
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    • 2012
  • This paper investigates the effects of applying different input current waveshapes on the performance of a continuous-conduction-mode (CCM) power-factor-correction (PFC) boost pre-regulator. It is found that the output voltage ripple of the pre-regulator can be reduced if the input current is modified to include controlled amount of higher order harmonics. This finding allows us to balance the performance of output regulation and the harmonic current emission when coming to the design of the pre-regulator. An experimental PFC boost pre-regulator prototype is constructed to verify the analysis and show the benefit of the pre-regulator operating with input current containing higher order harmonics.

Recommended Practice for Demand Factor/Diversity Factor with respect to Power Consumption Characteristics in Commercial Buildings (업무용 빌딩의 전력소비 특성을 고려한 수용률/부등률의 적용에 관한 연구)

  • 김세동
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.16 no.6
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    • pp.74-79
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    • 2002
  • This paper shows a reasonable design standard factor in commercial buildings, that was made by the systematic and statistical way considering actual conditions, such as investigated electric equipment capacity, electric power consumption, load characteristic, etc., for 23 commercial buildings. With a rapid growth of national economics with the development of intelligence society , electrical energy consumption markedly increased Expecially, it is increased electrical energy consumption in the commercial buildings and thus an energy conservation through efficient use of electricity became more important In our country, the estimation of demand factor and electric equipment capacity are not properly and thus the application of these factors are confusing and different in each electric design of the field.

The Developed Study for SMPS to Protect the Noise and Inrush Current at LED Lighting Source (LED 광원에서 잡음 및 돌입전류 방지를 위한 스위칭모드 전원공급 장치 (SMPS) 개발 연구)

  • Chung, Chansoo;Hong, Gyujang;We, Sungbok;Yu, Geonsu;Kim, Mijin
    • KEPCO Journal on Electric Power and Energy
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    • v.2 no.4
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    • pp.577-582
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    • 2016
  • This Study focused on the development of SMPS (Switching Mode Power Supply) to supply the constant votage and current nevertheless LED fluorescent Light generated the electric noise (with Harmonics) and Inrush current at instant time of turn-on and off. Recently, according to the Green policy in government, the LED fluorescent Lighter showed the rapidly increasing tend as indoor and outdoor Lighter. But, because of costs, LED fluorescent Light not considered and neglected the following items; power factor, efficiency, Harmonics and Inrush current. So, we are developed the SMPS about 3 key issues as follows: 1st, power factor and efficiency is 85%. 2nd, the switching noisy by harmonic is minimized. 3rd, the Inrush current at turn on and off time is reduced the minimum 0.3 A after $100{\mu}sec$ on turnon time. The proposed SMPS adjusted by LNK 409 driver (included the high frequency modulation function). Although, the developed SMPS maintained the about 85% of power factor and efficiency. but, the SMPS must be generated low heat by the variation of minute load current at switching timing. To improve the above weak point, the developed SMPS have the feedback monitoring circuit between input side and output side to maintain the power factor and efficiency. Also, we are studied the time-constant of control circuit to output the constant voltage and current nevertheless the load disturbance of LED lighting. The LED fluorescent Light of 46W is checked the above items.

The Optimal Volt/Var Control Algorithm with Distributed Generation of Distribution System (분산전원이 연계된 배전계통의 최적 전압/무효전력 제어 알고리즘)

  • Kim, Young-In;Lim, Il-Hyung;Choi, Myeon-Song;Lee, Seung-Jae;Lee, Sung-Woo;Ha, Bok-Nam
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.59 no.2
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    • pp.298-305
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    • 2010
  • In this paper, a new algorithm of optimal Volt/Var Control is proposed using Volt/Var control for the Distribution Automation System (DAS) with Distributed Generation (DG) based on the modeling of the distributed load and the distributed current. In the proposed, algorithm based on the modeling of the distributed load and the distributed current are estimated from constants of four terminals using the measurement of the current and power factor from a Feeder Remote Terminal Unit (FRTU) and DG data from RTU for DG. For the optimal Volt/Var Control, the gradient method is applied to find optimal solution for tap, capacity and power control of OLTC (On-Load Tap Changers), SVR (Step Voltage Regulator), PC (Power Condenser) and DG (Distributed Generation). In the case studies, the estimation and control of the voltages have been testified in a radial distribution system with DG using matlab program.

A Study on the Characteristics of Refrigerating System according to the Condensation and Evaporation Load (응축 및 증발 부하에 따른 냉동시스템 특성에 관한 연구)

  • Choi, Seung-Il;Ji, Myoung-Kuk;Lee, Dae-Chul;Jeong, Hyo-Min;Chung, Han-Shik
    • Journal of Power System Engineering
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    • v.17 no.3
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    • pp.44-49
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    • 2013
  • The refrigerating system are high efficiency and comfortable due to the automation of the system as well as enhance energy saving are contributing to driving system. Previous study the rotational frequency of the compressor was confined to the fixed condition have changed load of evaporator and condenser related about the refrigerator performance characteristic according to the evaporation load and condensation load change tries to be analyze through the experiment. The useful data for the economic driving of the freezing apparatus tries to be drawn. Consequently, it confirmed that refrigerant in the compressor overheated and as the evaporation load increased the specific volume was increased and the coolant circulation rate decreased. In confirmed that condensation load increased the compression ratio and discharge gas temperature increased. It reduced the low-temperature efficiency and condensation calorie and the quality factor was decreased.

Integrated Volt/Var Control Algorithm based on the Distributed Load Modeling of Distribution Network (배전계통의 분포 부하 모델링을 통한 최적화 IVVC 알고리즘)

  • Kim, Young-In;Lim, Il-Hyung;Choi, Myeon-Song;Lee, Seung-Jae;Lee, Sung-Woo;Kwon, Sung-Chul
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.58 no.8
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    • pp.1463-1471
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    • 2009
  • In this paper, a new algorithm of Integrated Volt/Var Control (IVVC) is proposed using Volt/Var control for the Distribution Automation System (DAS) based on the modeling of the distributed load and the distributed current. In the proposed, the load flow based on the modeling of the distributed load and the distributed current are estimated from constants of four terminals using the measurement of the current and power factor from a Feeder Remote Terminal Unit (FRTU). For Integrated Volt/Var Control (IVVC), the gradient method is applied to find optimal solution for tap and capacity control of OLTC (On-Load Tap Changers), SVR (Step Voltage Regulator), and SC (Shunt Condenser). What is more Volt/Var control method is proposed using moving the tie switch as well as IVVC algorithm using power utility control. In the case studies, the estimation and simulation network have been testified in Matlab Simulink.

A Study on the Effective Utilization Plan through Field Investigation and Analysis with Power Transformers in Domestic Areas

  • Shin, Heung-Sik;Lee, Jae-Cheon;Bai, Seok-Myung;Kim, Seon-Gu;Kim, Jin-Tae;Kim, Gi-Hyeon;Jeong, Jong-Wook;Bang, Seon-Bae
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.21 no.4
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    • pp.88-95
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    • 2007
  • Korea is highly dependent on foreign countries for energy while at the same time having a high energy-consumption industrial structure. Therefore, logical improvements in energy use efficiency and nationwide energy saving are becoming more and more important in coping with the worldwidehigh oil prices and environmental issues such as listed in the Kyoto Protocol to the United Nations Framework Convention on Climate Change. Consequently, a study was conducted on the average annual load factor in domestic areas to set a reasonable and reliable technology standard plan for high-efficiency transformers. The average annual load factor in Korea was discovered to be 18.4[%] classified by industry. This factor is expected to be used in arranging a domestic standard for a minimum efficiency system for transformers, and in reviewing and supplementing the standard transformers plan for the High Energy-Efficiency Appliance Certification. The expected effect from the establishment of the technology standards plan for highly efficient transformers is the expansion of the manufacturing and distribution of highly efficient transformers that are suitable for domestic use. These will lead to electricity cost savings for users, strengthening the related industries' market competitive powers and the effective reduction of greenhouse gases on a national level by drastically reducing loss from transformers, which accounts for a large portion of the total electric supply losses.

Optimal design of the suspension stiffness in HDD for improving the load/unload performance (램프 로드-언로드 특성 향상을 위한 서스펜션강성 최적설계)

  • 강태식;김태수;이철우
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2003.11a
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    • pp.898-901
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    • 2003
  • In order to get the drive reliability and low Power-consumption characteristics, most of small form factor HDD has und the load/unload mechanism instead of CSS type. Compared with CSS mechanism, the load/unload system has little opportunity of head/media contact during the disk spin-up and down. However, the load/unload mechanism needs the precise integration technology with slider, suspension, ramp and load/unload velocity, and all of these component s should be designed simultaneously, not an individually. In this paper, we focus the design of the suspension stiffness using the specified ABS design. We use the CML software to calculate the load/unload dynamic and use the RSM(Response surface method) to get the optimal condition of the suspension stiffness.

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Analysis of the Utilization Characteristics of Electrical Power and Equipments on the Farms (농촌의 전력및 전기기기의 이용특성분석)

  • 박승우;류한열
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.17 no.4
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    • pp.3943-3955
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    • 1975
  • The purposes of this study are to evaluate the utilization characteristics of electrical power consumption, to grasp the present trends in the use of electrical equipments, to estimate the demand factor and load factor being held, and to evaluate the efficiency of electical uses for the recently electrified farms cultivating paddy rice. For the purposes, 109 sample farms located in eleven villiages electrified in six different years from 1968 to 1973, were chosen at random and investigated on 35 items concerning to electrical uses and wiring systems. The survey was carried out in 1975, in the vinicity of Suweon city. The results are summarized as follows: i) The average annual power consumption on sample farms is considered to be low, being 242.9 Kwh. in 1974, and varied according to the different electrified year and size of cultivated land, respectively. It has significant positive correlation to the area of farm, too. ii) Between the number of year of electrical uses and the power consumption, there is very significant positive correlation, which could be expressed as Y=43.041+16.108 X, where X represents the number of years of electrical uses. The annual increment of power consumption is much greater at the beginning of the electrification than that at the later years, its average being approximately 20 percent. However, it is recommended that any estimation of long-term increments should be carefully investigated. iii) The monthly power consumption varies considerably throughout a year, in which the heaviest farm load occurs in November. Observing the seasonal variation of consumption, the winter-time is the heaviest season while the summer is the lowest. The result implies house lighting is chief contribution to the present electrical consumption on the farms. Comparing the variation of monthly consumption ratios between the sample farms and industries, the electrical uses on the farms are independant of the industrial uses, and further, the agricultural uses are of inverse pattern to the farms from the results that there is negative correlationship between them, iv) The number of electrical equipments used on the farms are occupied chiefly by lighting sources. Next to the lighting sources, household appliances of small quantity and some motors are used. The mean electrical quantity is about 1, 127.4 watt, which corresponds to about 37.6 per cent to the contracted quantity. The composition of quantity is chiefly occupied by the electrical motor of about 1.5 hp., single-phased. The number of the annual utilization hours of each equipment is tabulated in Table IV-5. In contradiction to the high utilization of lighting sources and small household appliances, the motor is poorly used for approximately 22 hours in a year. v) More than 55 per cent of farms want to purchase new electrical equipments such as small household appliances and electrical motors in their number. The impulse of purchasing such items is stimulated by the contacts to the mass media and their knowledge on such equipments. Consequently, the increase of electrical uses could be prompted by such trials as education and demonstration. vi) The demand and load factors on the farms vary considerably according to the greater variation of the power consumption, daily or monthly. The daily demand factor is 22.4 per cent and load factor 18.6 per cent, while the annual demand factor is 1.3 per cent and load factor 70 per cent approximately. Therefore, the low efficiency of construction cost requires re-evaluation of the present contracted quantity of 3 Kw. or increase of electrical uses. vii) The electrical energy on the farms devoted chiefly to lighten the farm residences does not contribute to the farm incomes. Consequently, the cost of electrical consumption presses considerably upon the farm economy. Therefore, there is great need to build up the electrical uses on the farms through the development of new works and techinques to utilize any electrical equipments on the production of farm products. Further more, such the development should be related to increase the actual income of the farm consumers.

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