• Title/Summary/Keyword: Load Leveling

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A Comparative Study of Maintenance Scheduling Methods for Small Utilities

  • Ong, H.L.;Goh, T.N.;Eu, P.S.
    • International Journal of Reliability and Applications
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    • v.4 no.1
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    • pp.13-26
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    • 2003
  • This paper presents a comparative study of a few commonly used maintenance scheduling methods for small utilities that consists solely of thermal generating plants. Two deterministic methods and a stochastic method are examined. The deterministic methods employ the leveling of reserve capacity criterion, of which one uses a heuristic rule to level the deterministic equivalent load obtained by using the product of the unit capacity and its corresponding forced outage rate. The stochastic method simulates the leveling of risk criterion by using the peak load carry capacity of available units. The results indicate that for the size and type of the maintenance scheduling problem described In this study, the stochastic method does not produce a schedule which is significantly better than the deterministic methods.

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Effect of Friction on the Hysteresis of the Thrust Forces Acting on Auto Leveling Devices in Vehicle Head Lamps (헤드 램프 빛의 각도 자동 조절 장치에 작용하는 추력의 히스테리시스에 대한 마찰의 영향)

  • Baek, Hong;Kim, Jae-Hoon;Nam, Jin-Sik;Park, Sang-Shin
    • Tribology and Lubricants
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    • v.35 no.6
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    • pp.369-375
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    • 2019
  • This paper presents a new method on how to calculate the thrust forces acting on an auto-leveling device in headlamps for passenger vehicles. The leveling device is used to lower the angle of lights when a load in the trunk of the vehicle lifts it. In the process of the headlamp design, it is imperative to predict the external forces so that the designers can decide whether to proceed or not. The device is composed of three pivot joints with no reaction moment, a plate that holds the lamp, and a leveling motor that changes rotation to linear motion. In this study, force balance, moment balance, and geometric compatibility are applied to the leveling device system so that a nonlinear system of equations can be derived; the multi-dimensional Newton-Raphson algorithm is then used to solve these. A sensitivity analysis is carried out to verify which design variables affect the system the most: the mass of the lamp and the height between the pivot and leveling device affect the thrust forces the most. Then, considering the friction forces between the moving parts, the hysteresis of the forces are derived. An experimental apparatus, designed and developed in this study, is used to verify the exactness of the derived equations. The results from experiments coincide well with the calculated results. The friction hysteresis, in particular, proves this upon analysis.

Erection Process Planning & Scheduling using Genetic Algorithm (유전 알고리즘을 이용한 탑재 공정과 일정 계획)

  • J.W. Lee;H.J. Kim
    • Journal of the Society of Naval Architects of Korea
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    • v.32 no.1
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    • pp.9-16
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    • 1995
  • The erection process planning is to decide erection strategy and sequence that satisfies dock duration. The erection scheduling is to decide erection date of each block. The load profile varies according to scheduling and it is related to building cost. It must be possible to simulate the various combinations of process plan and schedule for optimal planning. To develop the process planning system for optimal planning, the system that generate the sequence of erection automatically and the load leveling system are required. This paper suggests the method that generates the erection sequence. The load leveling should be done to all the ships in the same dock batch to get reliable results. In this case since the search space is very large, efficient optimization method is needed Our research achieved the load leveling system using Genetic Algorithm. This system made it possible to simulate various process plans to which schedule is considered.

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A Study on the Decision of Appropriate Subsidy Levels for Energy Storage Systems Considering Load Leveling in Smart Place (부하평준화 기능을 고려한 주택용 ESS의 적정 지원금 산정에 관한 연구)

  • Kim, Jung-Hoon;Hwang, Sung-Wook;Lee, Hak-Ju
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.63 no.2
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    • pp.211-216
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    • 2014
  • Construction of power plants and T&D facilities is so difficult because of the civil complaints and the additional cost according to the concerning field conditions. Therefore, various researches and methods have been considered to get solutions in the demand side and energy storage systems have been in the spotlight because of the various functions such as peak shaving, load shifting, and power system stabilizing, and so on. Residential small size batteries are considered in this paper and the economic analysis is carried out to evaluate the reasonable subsidy levels for the deployment of energy storage systems. Various economic parties are considered to find reasonable subsidy level comparing each other, which parties consist of utilities, participants and non-participants in general. The evaluation is based on California Standard Practice Test and the results are able to be used as subsidy guidelines.

OPERATION ALGORITHMS FOR A FUEL CELL HYBRID ELECTRIC VEHICLE

  • PARK C.;KOOK K.;OH K.;KIM D.;KIM H.
    • International Journal of Automotive Technology
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    • v.6 no.4
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    • pp.429-436
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    • 2005
  • In this paper, operation algorithms are evaluated for a fuel cell hybrid electric vehicle (FCHEV). Power assist, load leveling and equivalent fuel algorithm are proposed and implemented in the FCHEV performance simulator. It is found from the simulation results that the load leveling algorithm shows poor fuel economy due to the system charge and discharge efficiency. In the power assist and equivalent fuel algorithm, the fuel cell stack is operated in a relatively better efficiency region owing to the battery power assist, which provides the improved fuel economy.

A Study on the Cost Effective DSM Method for Lighting Power Control through Pilot Test Based on Pre-Verified Methodologies (다양한 형태의 조명(형광등) 전력제어 실증시험을 통한 비용효과적인 전력수요관리방법 도출)

  • Yang, Seung-Kwon;Kim, Dae-Young
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.27 no.2
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    • pp.7-13
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    • 2013
  • The portion of lighting power consumption for our country is up to 20~30% of the total amount. Currently, most of the DSM(Demand side management) of lighting power is delivered in supply of high efficient lighting to customers. On the contrary, applications of lighting power to power load leveling are still rare. In this paper, the simulations for various control types of lighting power for load leveling are tried, and we obtained the cost effective and optimal control method through that. This simulation was executed in test office with fluorescent light by us based on applying 8 control types(on, off & dimming), considering customers' satisfaction, for instance, minimum intensity of illumination allowed. According to the result of this test, we found that mixed type(chessboard(on-off) plus dimming control(10%)) is most effective.

The Method of Battery Lifetime Optimization for V2G System considering Load Leveling (부하평준화를 고려한 V2G 시스템의 배터리 수명 최적화 기법)

  • Shin, Chang-Hyun;Kim, Do-Yun;Won, Il-Kuen;Kim, Young-Real;Won, Chung-Yuen
    • Proceedings of the KIPE Conference
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    • 2014.07a
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    • pp.538-539
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    • 2014
  • The development of smart grid technologies will enable enhanced utilization of electric vehicles(EV) as portable energy storage devices which can provide power system-wide. Because significant increase of EV in the near future, V2G(Vehicle-to-Grid) system will soon become a reality. This paper presents the optimal method of a battery lifetime depending on depth of discharge(DOD) considering load leveling.

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Feasibility Study on Leveling Method of Electric Power Load by Applying Thermal Storage Air Conditioning System (축열식 열원시스템 적용에 의한 전력부하 평준화의 경제성 검토)

  • Lee, Chulgoo
    • Journal of the Korean Society for Geothermal and Hydrothermal Energy
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    • v.15 no.1
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    • pp.9-17
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    • 2019
  • Reducing global warming potential has become important, and as one of those methods for reducing it, economic evaluation by applying ice thermal storage air conditioning system was performed. The floor area and height of the subject building was assumed $5,000m^2$ and 20 m. Absorption chillerheater system and air source heat pump system was used for comparing to the subject system, and payback period method was used to perform economic evaluation. Although the running cost of ice thermal storage system is reduced compared to two systems, the ratio is not significant compared to the increase of initial construction expenses, and payback period was calculated to be about 7.7 and 79.3 years. However, the heat storage system should be approached from the viewpoint of long term rather than the economic standard in the present standard.

System Design and Performance Analysis of $MnO_2$ Pseudo-capacitor for Digital Communication Applications (디지털 통신 응용을 위한 $MnO_2$, Pseudo-capacitor의 시스템 설계 및 성능평가)

  • Seong W. K.;Hong M. S.;Kim S. W.
    • Journal of the Korean Electrochemical Society
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    • v.3 no.4
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    • pp.241-245
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    • 2000
  • The objective of this work Is to design, fabricate, and characterize pseudo-capacitor using amorphous $MnO_2\;nH_2O$ electrode material. The cyclic voltammogram under 100mV/s scan rate of the material shows the electrochemically stable potential window of 1V and the specific capacitance of 250F/g. The TDMA pulse test result indicates that the TDMA system (2 parallel-pseudo-capacitor systems) has the ohmic voltage drop of 0.22V and the capacitor voltage drop of 0.38V. The total voltage drop of the TDMA system is 0.60V and less than 1V of which value is the maximum voltage drop requirement or the TDMA satellite phone. Also, the TDMA system had the ESR of $55m{\Omega}$ and the capacitance of 105mF. Therefore, it is confirmed that the TDMA system has the application feasibility as load-leveling capacitor for the satellite phone.