• Title/Summary/Keyword: Novel energy storage system

Search Result 54, Processing Time 0.023 seconds

Optimization of SMES Windings Utilizing the First-Order Reliability Method (일차근사신뢰도법을 이용한 초전도 자기에너지 저장장치 권선 최적설계)

  • Kim, Dong-Wook;Jung, Sang-Sik;Sung, Young-Hwa;Kim, Dong-Hun
    • The Transactions of The Korean Institute of Electrical Engineers
    • /
    • v.60 no.7
    • /
    • pp.1354-1359
    • /
    • 2011
  • This paper presents a novel methodology for improving the reliability of electromagnetic devices and machines based on the reliability-based design optimization method. To achieve this, the method includes reliability analysis and optimization process taking into account uncertainties of design variables. One of the first-order reliability analysis techniques, called reliability index approach, is adopted to evaluate the reliability of performance functions with respect to probabilistic design variables. The proposed method has been successfully applied to designing a superconducting magnetic energy storage system. For verifying the efficiency and accuracy of the method, the results are compared with those of conventional optimization methods.

Improved Conditional Integrator Anti-Windup Method for Seamless Transfer of Bidirectional DC-DC Converter in Grid-Connected Battery Energy Storage System (계통연계형 배터리 에너지저장장치용 양방향 DC-DC 컨버터의 무순단 절체를 위한 조건부 적분 안티-와인드업 연구)

  • Eom, Jun-Yong;Choi, Sung-Jin;Lee, Hong-Hee
    • The Transactions of the Korean Institute of Power Electronics
    • /
    • v.25 no.5
    • /
    • pp.333-342
    • /
    • 2020
  • Power exchanges between the grid and the battery through a bidirectional DC-DC converter are essential for DC microgrid systems. In general, the battery is charged when the grid is connected, and the system is powered by the battery when the grid is disconnected. In this mode transition, the saturation of the voltage controller slows down output response and produces large transient errors in DC link voltage. To solve this problem, a novel anti-windup design is proposed to improve anti-windup performance further. The proposed method stabilizes DC bus voltage through a wider range of battery voltage with faster transition compared with that of conventional methods. The proposed method is verified through an experimental setup composed of a 125 W laboratory-scale DC microgrid system.

Bidirectional DC-DC Converter Based on Quasi-Sepic for Battery Charging System

  • Zhang, Hailong;Chen, Yafei;Kim, Dong-Hee;Park, Sung-Jun;Park, Seong-Mi
    • Journal of the Korean Society of Industry Convergence
    • /
    • v.23 no.2_1
    • /
    • pp.139-147
    • /
    • 2020
  • In order to satisfy the voltage levels of the low voltage battery side and high voltage DC bus, a high voltage gain with bidirectional operation is required. In this system, the cost effectiveness of the design is a critical factor; therefore, the system should be designed using a small number of components. This paper propose a novel bidirectional converter composed with a quasi-sepic and switched-indictor network. The proposed converter consists a small number of components with a high voltage gain ratio. Detailed analysis are made with respect to the operating mode, number of components, voltage and current ripple and efficiency. To verify performance of the proposed converter, simulation was performed is this paper. The simulation results are shown to verify the feasibility and performance of the proposed bidirectional converter.

Instantaneous Voltage Sag Corrector Controller Design of Power Line System (전력선 계통의 순시 전압 강하 제어기 설계)

  • Lee, Sang-Hoon;Hong, Hyun-Mun
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
    • /
    • v.20 no.3
    • /
    • pp.6-11
    • /
    • 2006
  • This paper describes the novel control techniques design of VSC(Voltage Sag Corrector) for the purpose of power line quality enhancement. A fast detecting technique of voltage sag is implemented through the detection of instantaneous value on synchronous rotating dq-reference frame. The first order digital filter is added in the detection algorithm to protect the insensitive characteristics against the noise. The relationship between the total detection time and cut-off frequency of the filter is described. The size of the capacitor bank used as the energy storage element is designed from the point of view of input/output energy with circuit analysis. Finally, the validity of the proposed scheme is proven through the simulated results.

Energy Conservation of RAID by Exploiting SSD Cache (SSD 캐시를 이용한 RAID의 에너지 절감 기법)

  • Lee, Hyo-J.;Kim, Eun-Sam;Noh, Sam-H.
    • Journal of KIISE:Computing Practices and Letters
    • /
    • v.16 no.2
    • /
    • pp.237-241
    • /
    • 2010
  • Energy conservation of server systems has become important. Though storage subsystem is one of the biggest power consumers, development of energy conservation techniques is challenging problem due to striping techniques like RAID and physical characteristics of hard disks. According to our observation, the size of footprint for a day or for hours is much smaller compared to the size of whole data set. In this paper, we describe a design of a novel architecture for RAID that uses an SSD as a large cache to conserve energy by holding such a footprint. We incorporate these approaches into a real implementation of a RAID 5 system that consists of four hard disks and an SSD in a Linux environment. Our preliminary results in actual performance measurements using the cello99 and SPC traces show that energy consumption is reduced by a maximum of 14%.

Recent Progress in Air-Conditioning and Refrigeration Research: A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2014 (설비공학 분야의 최근 연구 동향: 2014년 학회지 논문에 대한 종합적 고찰)

  • Lee, Dae-Young;Kim, Sa Ryang;Kim, Hyun-Jung;Kim, Dong-Seon;Park, Jun-Seok;Ihm, Pyeong Chan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
    • /
    • v.27 no.7
    • /
    • pp.380-394
    • /
    • 2015
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2014. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of heat and mass transfer, cooling and heating, and air-conditioning, the flow inside building rooms, and smoke control on fire. Research issues dealing with duct and pipe were reduced, but flows inside building rooms, and smoke controls were newly added in thermal and fluid engineering research area. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results for thermal contact resistance measurement of metal interface, a fan coil with an oval-type heat exchanger, fouling characteristics of plate heat exchangers, effect of rib pitch in a two wall divergent channel, semi-empirical analysis in vertical mesoscale tubes, an integrated drying machine, microscale surface wrinkles, brazed plate heat exchangers, numerical analysis in printed circuit heat exchanger. In the area of pool boiling and condensing, non-uniform air flow, PCM applied thermal storage wall system, a new wavy cylindrical shape capsule, and HFC32/HFC152a mixtures on enhanced tubes, were actively studied. In the area of industrial heat exchangers, researches on solar water storage tank, effective design on the inserting part of refrigerator door gasket, impact of different boundary conditions in generating g-function, various construction of SCW type ground heat exchanger and a heat pump for closed cooling water heat recovery were performed. (3) In the field of refrigeration, various studies were carried out in the categories of refrigeration cycle, alternative refrigeration and modelling and controls including energy recoveries from industrial boilers and vehicles, improvement of dehumidification systems, novel defrost systems, fault diagnosis and optimum controls for heat pump systems. It is particularly notable that a substantial number of studies were dedicated for the development of air-conditioning and power recovery systems for electric vehicles in this year. (4) In building mechanical system research fields, seventeen studies were reported for achieving effective design of the mechanical systems, and also for maximizing the energy efficiency of buildings. The topics of the studies included energy performance, HVAC system, ventilation, and renewable energies, piping in the buildings. Proposed designs, performance performance tests using numerical methods and experiments provide useful information and key data which can improve the energy efficiency of the buildings. (5) The field of architectural environment was mostly focused on indoor environment and building energy. The main researches of indoor environment were related to the evaluation of work noise in tunnel construction and the simulation and development of a light-shelf system. The subjects of building energy were worked on the energy saving of office building applied with window blind and phase change material(PCM), a method of existing building energy simulation using energy audit data, the estimation of thermal consumption unit of apartment building and its case studies, dynamic window performance, a writing method of energy consumption report and energy estimation of apartment building using district heating system. The remained studies were related to the improvement of architectural engineering education system for plant engineering industry, estimating cooling and heating degree days for variable base temperature, a prediction method of underground temperature, the comfort control algorithm of car air conditioner, the smoke control performance evaluation of high-rise building, evaluation of thermal energy systems of bio safety laboratory and a development of measuring device of solar heat gain coefficient of fenestration system.

New Soft-Switching Method of 3-phase Interleaved Bidirectional DC-DC Converter for Battery Charging and Discharging (배터리 충·방전용 3상 인터리브드 양방향 DC-DC 컨버터의 새로운 소프트 스위칭 방법)

  • Jung, Jae-Hun;Seo, Bo-Gil;Kwon, Chang-Keun;Nho, Eui-Cheol;Kim, In-Dong;Kim, Heung-Geun;Chun, Tae-Won
    • The Transactions of the Korean Institute of Power Electronics
    • /
    • v.19 no.4
    • /
    • pp.383-390
    • /
    • 2014
  • This paper deals with novel soft-switching method for a bidirectional DC-DC converter in battery charging and discharging system. The proposed soft-switching method provides ZVS and ZCS at turn-on, and ZVS at turn-off of the switch in both charging and discharging operation modes. The soft switching condition can be obtained in wide load range, and provide low switching loss as well as low voltage spike at turn-off of the switch. Proposed method is analyzed in charging and discharging mode. Simulation and experimental results validate the usefulness of the proposed soft-switching method.

Power Decoupling Control of the Bidirectional Converter to Eliminate the Double Line Frequency Ripple (더블라인 주파수 제거를 위한 양방향 컨버터의 전력 디커플링 제어)

  • Amin, Saghir;Choi, Woojin
    • Proceedings of the KIPE Conference
    • /
    • 2018.11a
    • /
    • pp.62-64
    • /
    • 2018
  • In two-stage single-phase inverters, inherent double line frequency component is present at both input and output of the front-end converter. Generally large electrolytic capacitors are required to eliminate the ripple. It is well known that the low frequency ripple shortens the lifespan of the capacitor hence the system reliability. However, the ripple can hardly be eliminated without the hardware combined with an energy storage device or a certain control algorithm. In this paper, a novel power-decoupling control method is proposed to eliminate the double line frequency ripple at the front-end converter of the DC/AC power conversion system. The proposed control algorithm is composed of two loop, ripple rejection loop and average voltage control loop and no extra hardware is required. In addition, it does not require any information from the phase-locked-loop (PLL) of the inverter and hence it is independent of the inverter control. In order to prove the validity and feasibility of the proposed algorithm a 5kW Dual Active Bridge DC/DC converter and a single-phase inverter are implemented, and experimental results are presented.

  • PDF

Optimal Characteristics of a Long-pulse $CO_2$Laser by Controlling SCR Firing Angle in AC Power Line

  • Noh, Ki-Kyung;Kim, Geun-Yong;Chung, Hyun-Ju;Min, Byoung-Dae;Song, Keun-Ju;Kim, Hee-Je
    • KIEE International Transactions on Electrophysics and Applications
    • /
    • v.2C no.6
    • /
    • pp.304-308
    • /
    • 2002
  • We demonstrate a simple pulsed $CO_2$ laser with millisecond long pulse duration in a tube at a low pressure of less than 30 Torr. The novel power supply for our laser system switches the voltage of the AC power line (60Hz) directly. The power supply doesn't need elements such as a rectifier bridge, energy-storage capacitors, or a current-limiting resistor in the discharge circuit. To control the laser output power, the pulse repetition rate is adjusted up to 60Hz and the firing angle of SCR(Silicon Controlled Rectifier) gate is varied from 30。 to 150。. A ZCS (Zero Crossing Switch) circuit and a PIC one-chip microprocessor are used to control precisely the gate signal of the SCR. The maximum laser output of 35 W is obtained at a total pressure of 18 Torr, a pulse repetition rate of 60 Hz, and a SCR gate firing angle of 90。 . In addition, the resulting laser pulse width is approximately 3㎳(FWHM). This is a relatively long pulse width, compared with other repetitively pulsed $CO_2$ lasers.

Effect of Al and Nb Doping on the Electrochemical Characteristics of Garnet-type Li7La3Zr2O12 Solid Electrolytes

  • Ahmed Tarif;Chan-Jin Park
    • Corrosion Science and Technology
    • /
    • v.22 no.6
    • /
    • pp.408-418
    • /
    • 2023
  • In this study, we synthesized and characterized garnet-type Li7-xAlxLa3Zr2-(5/4)yNbyO12 (LALZN) solid electrolytes for all-solid-state battery applications. Our novel approach focused on enhancing ionic conductivity, which is crucial for battery efficiency. A systematic examination found that co-doping with Al and Nb significantly improved this conductivity. Al3+ and Nb5+ ions were incorporated at Li+ and Zr4+ sites, respectively. This doping resulted in LALZN electrolytes with optimized properties, most notably enhanced ionic conductivity. An optimized mixture with 0.25 mol each of Al and Nb dopants achieved a peak conductivity of 1.32 × 10-4 S cm-1. We fabricated symmetric cells using these electrolytes and observed excellent charge-discharge profiles and remarkable cycling longevity, demonstrating the potential for long-term application in battery systems. The garnet-type LALZN solid electrolytes, with their high ionic conductivity and stability, show great potential for enhancing the performance of all-solid-state batteries. This study not only advances the understanding of effective doping strategies but also underscores the practical applicability of the LALZN system in modern energy storage solutions.