• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.323-324
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• 2012

최근 전력의 공급신뢰도의 하락으로 인하여 기존 송배전 설비의 신규건설 및 유지보수를 위한 투자의 필요성이 더욱 증대되고 있다. 이에 적절한 대안으로서 배터리를 이용한 에너지 저장 시스템(BESS, Battery Energy Storage System)이 대두되고 있다. 본 논문에서는 송배전 설비 투자 지연을 위한 BESS의 필요성에 대해 살펴보고 그 핵심 구성 요소인 PCS의 기능과 최신 동향에 대해 기술한다.

• Asian-Australasian Journal of Animal Sciences
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• v.20 no.11
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• pp.1636-1650
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• 2007

As an initial step toward a better understanding of the genome structure of Korean cattle (Hanwoo breed) and initiation of the framework for genomic research in this bovine, the bacterial artificial chromosome (BAC) end sequencing of 21,024 clones was recently completed. Among these clones, BAC End Sequences (BESs) of 20,158 clones with high quality sequences (Phred score ${\geq}20$, average BES equaled 620 bp and totaled 23,585,814 bp), after editing sequencing results by eliminating vector sequences, were used initially to compare sequence homology with the known bovine chromosomal DNA sequence by using BLASTN analysis. Blast analysis of the BESs against the NCBI Genome database for Bos taurus (Build 2.1) indicated that the BESs from 13,201 clones matched bovine contig sequences with significant blast hits (E<$e^{-40}$), including 7,075 single-end hits and 6,126 paired-end hits. Finally, a total of 5,105 clones of the Korean cattle BAC clones with paired-end hits, including 4,053 clones from the primary analysis and 1,052 clones from the secondary analysis, were mapped to the bovine chromosome with very high accuracy.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.10
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• pp.1390-1396
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• 2013

The paper estimated the reasonable market price of lead-acid battery energy storage system (BESS) intended for demand management of electricity customers. As time-of-use (TOU) tariffs have extended to a larger number of customers and gaps in the peak and off-peak rates have gradually risen, deployment of BESS has been highly needed. However, immature engineering techniques, lack of field experiences and high initial investment cost have been barriers to opening up ESS markets. This paper assessed electricity cost that BESS operation could save for customers and, based on the possible cost savings, estimated reasonable prices at which BESSs could become a more prospective option for demand management of customers. Battery scheduling was optimized to maximize the electricity cost savings that BESS would possibly achieve under TOU tariffs conditions. Basic economic factors such as payback period and return on investment were calculated to determine reasonable market prices. Actual load data of 12 industrial customers were used for case studies.

• The Transactions of the Korean Institute of Power Electronics
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• v.23 no.2
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• pp.86-93
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• 2018

In this work, control methods and operating modes are proposed to manage standalone microgrid. A standalone microgrid generally consists of two sources, namely, battery energy storage system (BESS) and diesel generator (DG). BESS is the main source that supplies active and reactive power regardless of load conditions, whereas DG functions as an auxiliary power source. BESS operates in a constant voltage constant frequency (CVCF) control, which includes proportional-integral + resonant controller in a parallel structure. In CVCF control, the concept of fundamental positive and negative transformation is utilized to generate a three-phase sinusoidal voltage under imbalanced load condition. Operation modes of a standalone microgrid are divided into three modes, namely, normal, charge, and manual modes. To verify the standalone microgrid along with the proposed control methods, a demonstration site is constructed, which contains 115 kWh lead-acid battery bank, 50 kVA three-phase DC - AC inverter, and 50 kVA DG and controllable loads. In the CVCF control, the total harmonic distortion of output voltage is improved to 1.1% under imbalanced load. This work verifies that the standalone microgrid provides high-quality voltage, and three operation modes are performed from the experimental results.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.64 no.2
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• pp.57-61
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• 2015

Current research and development efforts and other projects for energy storage systems (ESS) have recently been gaining attention. This is due to the many applications where ESS, particularly batteries, can be used. Among these are peak shaving, frequency regulation, and stabilization of renewable energy output. KEPCO has completed the construction and demonstration of a 4-MW battery energy storage system (BESS) located in Jeju City to verify its practicability in the power grid. KEPCO Research Institute has also been developing technology for the commercialization of BESS, and has been conducting a trial run of a 52-MW ESS (28MW + 24MW of Seo-Anseong and Shin-Yongin substations) constructed in 2014 for frequency regulation. This paper discusses the development of operation methods, as well as an operation user interface, for the safe operation and monitoring of BESS used for frequency regulation in a power system. Included are operation and simulation methods for various normal and transient frequency situations that can be experienced by a power system. Also discussed are the results obtained after applying these methods to the 4-MW BESS and the 52-MW ESS, both used for frequency regulation. The technology in this paper will be applied to 500MW ESS for frequency regulation of KEPCO by 2017. It is expected that this technology helps a safe and reliable operation and control of ESS for frequency regulation through its continuous upgrade.

• Journal of Power Electronics
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• v.17 no.6
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• pp.1625-1636
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• 2017

A power electronic transformer (PET) based on the cascaded H-bridge (CHB) and the isolated bidirectional DC/DC converter (IBDC) is capable of accommodating a large scale battery energy storage system (BESS) in the medium-voltage grid, and is referred to as a power electronic transformer based battery energy storage system (PET-BESS). This paper investigates the PET-BESS and proposes a coordinative control strategy for it. In the proposed method, the CHB controls the power flow and the battery state-of-charge (SOC) balancing, while the IBDC maintains the dc-link voltages with feedforward implementation of the power reference and the switch status of the CHB. State-feedback and linear quadratic Riccati (LQR) methods have been adopted in the CHB to control the grid current, active power and reactive power. A hybrid PWM modulating method is utilized to achieve SOC balancing, where battery SOC sorting is involved. The feedforward path of the power reference and the CHB switch status substantially reduces the dc-link voltage fluctuations under dynamic power variations. The effectiveness of the proposed control has been verified both by simulation and experimental results. The performance of the PET-BESS under bidirectional power flow has been improved, and the battery SOC values have been adjusted to converge.

• KEPCO Journal on Electric Power and Energy
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• v.5 no.3
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• pp.157-163
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• 2019

K-BEMS System was introduced to reduce peak load and to save total energy of the 120 buildings that KEPCO headquarter and branch offices use. K-BEMS system is composed of PV, battery, and hybrid PCS. In this system, ESS, PV, lighting is used to save building energy based on demand prediction. Currently, neural network technique for short past data is applied to demand prediction, and fixed scheduling method by operator for ESS charging/discharging is used. To enhance this system, KEPCO research institute has carried out this K-BEMS research project for 3 years since January 2016. As the result of this project, we developed new real-time highly reliable building demand prediction technique with error free and optimized automatic ESS charging/discharging technique. Through several field test, we can certify the developed algorithm performance successfully. So we will describe the details in this paper.

• Journal of IKEEE
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• v.28 no.1
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• pp.14-19
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• 2024

To determine the performance of recycled cells for application to residential BESS, cells used over the past 5 years were selected. The basic specifications of the cell used in the test are nominal voltage of 3.7[V], nominal capacity of 2,200[mAh], charging voltage of 4.05[V], continuous discharge current of 1[C](2,200[mA]), continuous charging current of 0.5[C](1,100[mA]). For new cells, the internal resistance was 21.3±1[mΩ], but for recycled cells, the average internal resistance was 25.38[mΩ], an increase of about 19.1[%]. The charge·discharge capacity was approximately 18.9~19.3[%] lower than that of a new cell. Because internal resistance and charge·discharge capacity are closely related to cell aging, cells to be applied to BESS need to use products with an initial internal resistance of 1.5 times or less and a charge·discharge capacity performance of 70[%] or more.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.2B no.3
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• pp.133-139
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• 2002

In this paper, a prototype of an active auxiliary quasi-resonant DC link (QRDCL) snubber assisted voltage source bidirectional power converter (AC to DC and DC to AC) operating at zero voltage soft-switching (BVS) PWM nlode is presented for a Battery Energy Storage System (BESS). The operating principle of this QRDCL circuit and multifunctional control-based converter system, including PWM inverter mode in which energy flows from the battery bank to the three-phase utility-grid in addition to an active PWM converter mode in which energy flows from the utility-grid to the battery banks are described respectively by the control implementation on the basis of d-q coordinate plane transformation. The multifunctional operation characteristics of this three-phase ZVS PWM bi-directional converter with QRDCL is demonstrated fer a BESS under the power conditioning and processing schemes of energy supply mode and energy storage mode, and compared with a conventional three-phase hard switching PWM bi-directional converter for a BESS. The effectiveness of the three-phase ZVS PWM hi-directional converter with QRDCL is proven via the simulation analysis.

• Journal of the Korean Solar Energy Society
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• v.31 no.5
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• pp.119-125
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• 2011

In this paper, we have studied about minimizing the Energy Storage System (ESS) capacity for mitigating the fluctuation of Wind Turbine Generation System (WTGS) by using Electric Double Layer Capacitor (EDLC) and Battery Energy Storage System (BESS). In this case, they have some different characteristics: The EDLC has the ability of generating the output power at high frequency. Thus, it is able to reduce the fluctuation of WTGS in spite of high cost. The BESS, by using Li-Ion battery, takes the advantage of high energy density, however it is limited to use at low frequency response. To verify the effectiveness of the proposed method, simulations are carried out with the actual data of 2MW WTGS in case of worst fluctuation of WTGS is happened. By comparing simulation results, this method shows the excellent performance. Therefore, it is very useful for understanding and minimizing the ESS capacity for mitigating the fluctuation of WTGS.