• KEPCO Journal on Electric Power and Energy
• /
• v.2 no.2
• /
• pp.227-232
• /
• 2016

To test the effectiveness of using an energy storage system for frequency regulation, the Energy New Business Laboratory at KEPCO Research Institute installed a 4 MW energy storage system (ESS) demonstration facility at the Jocheon Substation on Jeju Island. And after the successful completion of demonstration operations, a total of 52 MW ESS for frequency regulation was installed in Seo-Anseong (28 MW, governor-free control) and in Shin-Yongin (24 MW, automatic generation control). The control system used in these two sites was based on the control system developed for the 4 MW ESS demonstration facility. KEPCO recently finished the construction of 184 MW ESS for frequency regulation in 8 locations, (e.g. Shin-Gimjae substation, Shin-Gaeryong substation, etc.) and they are currently being tested for automatic operation. KEPCO plans to construct additional ESS facilities (up to a total of about 500 MW for frequency regulation by 2017), thus, various operational tests would first have to be conducted. The high-speed characteristic of ESS can negatively impact the power system in case the 500 MW ESS is not properly operated. At this stage we need to verify how effectively the 500 MW ESS can regulate frequency. In this paper, the effect of using ESS for frequency regulation on the power system of Korea was studied. Simulations were conducted to determine the effect of using a 524 MW ESS for frequency regulation. Models of the power grid and the ESS were developed to verify the performance of the operation system and its control system. When a high capacity power plant is tripped, a 24 MW ESS supplies power automatically and 4 units of 125MW ESS supply power manually. This study only focuses on transient state analysis. It was verified that 500 MW ESS can regulate system frequency faster and more effectively than conventional power plants. Also, it was verified that time-delayed high speed operations of multiple ESS facilities do not negatively impact power system operations. It is recommended that further testing be conducted for a fleet of multiple ESSs with different capacities distributed over multiple substations (e.g. 16, 24, 28, and 48 MW ESS distributed across 20 substations) because each ESS measures frequency individually. The operation of one ESS facility will differ from the other ESSs within the fleet, and may negatively impact the performance of the others. The following are also recommended: (a) studies wherein all ESSs should be operated in automatic mode; (b) studies on the improvement of individual ESS control; and (c) studies on the reapportionment of all ESS energies within the fleet.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.34 no.11
• /
• pp.1757-1763
• /
• 2010

Flywheel energy storage system (FESS) is defined as a high speed rotating flywheel system that can save surplus electric power. The FESS is proposed as an efficient energy storage system because it can accumulate a large amount of energy when it is operated at a high rotating speed and no mechanical problems are encountered. The FESS consists of a shaft, flywheel, motor/generator, bearings, and case. It is difficult to simulate rotor dynamics using common structure simulation programs because these programs are based on the 3D model and complex input rotating conditions. Therefore, in this paper, a program for the FESS based on the 2D FEM was developed. The 2D FEM can model easier than 3D, and it can present the multi-layer rotor with different material each other. Stiffness changing of the shaft caused by shrink fitting of the hub can be inputted to get clear solving results. The results obtained using the program were compared with those obtained using the common programs to determine any errors.

• Journal of the Korean Data and Information Science Society
• /
• v.8 no.2
• /
• pp.111-118
• /
• 1997

Adding a noise tolerance factor to the Relaxation learning algorithm in Hop-field network improves noise tolerance without effecting storage capacity. The new algorithm is called the Pseudo-Relaxation algorithm, and the convergence of the algorithm has been proved. It is also shown that the noise tolerance factor does not effect learning speed.

• Journal of information and communication convergence engineering
• /
• v.9 no.3
• /
• pp.282-286
• /
• 2011

Recently, a name retrieval function is widely used on navigation systems. In this paper, we propose the new dynamic hashing algorithm for a name retrieval function on it. The proposed dynamic hashing algorithm by constructing an index using the variance information of character is the better than existing methods in terms of storage capacity and retrieval speed. The algorithm proposed in this paper can be useful on systems that have limited resources as well as navigation systems.

• The Transactions of the Korea Information Processing Society
• /
• v.5 no.1
• /
• pp.249-257
• /
• 1998

다층 인쇄회로기판에서 고속 신호를 정확하고 신속하게 배선 설계하려면, 물리적 설계 규칙과 신호 잡음을 고려한 전기적 설계 규칙을 정립하고, 적용할 신호 검증 도구를 사용하여 신호의 충실성을 검증하여야 한다. 본 논문은 현재 개발 제작되어 동작 중에 있는 HIPSS(High Performance Storage System)보드에 대한 전기적 설계 규칙과 고속 신호의 배선에 따른 일부 고속 신호의 신호 검증 방법을 설명한다. 또한 전기적 설계 규칙을 적용하여 인쇄회로기판을 설계하는 경우, 발생하는 신호 지연, 반사 그리고 누화 등의 신호 잡음을 검증 도구를 이용하여 시뮬레이션 하고, 분석한 결과를 보이며, 수정된 고속 신호의 배선 설계를 확인한다.

• Proceedings of the Korean Fiber Society Conference
• /
• 1998.10a
• /
• pp.280-282
• /
• 1998

Communications, data storage or computation by manipulating the optical signals have the strong advantages over the traditional electronic circuits in regard to the data handling speed and capacity. Effective manipulation of the optical signals, however, requires materials of large nonlinear coefficients and of fast response time. Polymeric materials are one of the promising materials to meet the requirements for nonlinear optical (NLO) materials. (omitted)

• Proceedings of the KSME Conference
• /
• 2008.11a
• /
• pp.1391-1393
• /
• 2008

In this paper, the long-term reliability for 1.25G transceiver in use of high speed optical access network is investigated. High temperature storage tests and accelerated life tests are used to long-term reliability. Accelerated aging test have been during 3,000 hour of the three accelerated aging conditions by caused high temperature stress. Mean life is assumed to follow the Arrhenius relationship and analysis from the failure data obtained in the accelerated aging conditions.

• Journal of the Korean Society for Railway
• /
• v.2 no.4
• /
• pp.32-39
• /
• 1999

A flywheel system which can compensate electric power is presented. The designed system has a capability of providing real and imaginary power instantaneously as well as storing energy. In this paper, a control algorithm is designed. The designed algorithm is to control the secondary side current of the wound rotor induction motor using voltage-based PWM inverter. The flywheel system has advantages in converter size and power quality improvement comparing to the conventional system.

• Proceedings of the IEEK Conference
• /
• 2002.07c
• /
• pp.1436-1439
• /
• 2002

In this paper, based on the data link model characterized by the spaceborne small SAR system, the high rate multi-channel data link module is designed including link storage, link processor, transmitter, and wide-angle antenna. The design results are presented with the performance analysis on the data link budget as well as the multi-mode data rate in association with the SAR imaging mode of operation from high resolution to the wide swath.

• Journal of the Korea Safety Management & Science
• /
• v.4 no.3
• /
• pp.35-43
• /
• 2002

For the unconfined vapor cloud explosion accident by the continuous release of gas-liquid flow of various saturated liquids in a vessel at ground level, overpressures were estimated and analyzed with various release conditions and materials by TNT equivalency model with vapor dispersion. We found that at same release conditions, overpressure showed n-heptane > xylene > n-hexane > toluene > n-heptane > benzene, respectively and that overpressure was increased with increasing the hole diameter and the storage pressure, but it was increased with decreasing the wind speed, the interested distance, and the vessel thickness.