• Transactions on Electrical and Electronic Materials
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• v.16 no.6
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• pp.293-302
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• 2015

Degraded data stability, weaker write ability, and increased leakage power consumption are the primary concerns in scaled static random-access memory (SRAM) circuits. Two new SRAM cells are proposed in this paper for achieving enhanced read data stability and lower leakage power consumption in memory circuits. The bitline access transistors are asymmetrically gate-underlapped in the proposed SRAM cells. The strengths of the asymmetric bitline access transistors are weakened during read operations and enhanced during write operations, as the direction of current flow is reversed. With the proposed hybrid asymmetric SRAM cells, the read data stability is enhanced by up to 71.6% and leakage power consumption is suppressed up to 15.5%, while displaying similar write voltage margin and maintaining identical silicon area as compared to the conventional memory cells in a 15 nm FinFET technology.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2004.05a
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• pp.447-450
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• 2004

This paper presents the basic application idea of superconductor cable for voltage stability limited power system. In bulk power system, the transfer capability of transmission line is often limited by the voltage stability, and superconductor cable could be on of the countermeasure to enhance heat transfer limit as well as voltage stability limit. Steady state voltage stability approach by P-V curve is used to calculate the maximum transfer capability of initial system and superconductor applied system IEEE-14 bus system is used to demonstrate its applicability.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.4
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• pp.457-466
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• 1996

The Voltage stability problem has recently been dealt with in the literature from various points of view. The diverse theories have been established in voltage stability analysis because of the complicates of power systems and diverse phenomena of voltage collapse. Through rigorous mathematical operations, this paper shows that all the major methods used in static voltage stability, i.e - Jacobian method, voltage sensitivity method, real and reactive power loss sensitivity method and energy function method - have an identical background in theory. The results from the test in sample systems have shown the validity of this verification. (author). refs., figs., tabs.

• KIEE International Transactions on Power Engineering
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• v.11A no.4
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• pp.33-38
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• 2001

The KEPS(KEPCO＇s Enhanced Power system Simulator) Real Time Digital Simulator(RTDS) is the largest real time power system simulator ever built. A power system which includes 320 (3-phase) buses and 90 generators has been modeled and run in real time. Since such large-scale systems were involved, it was not practical to validate them using non-real time electro-magnetic transient programs such as EMTDC™ or EMTP. Instead, the results of the real time electromagnetic transient simulation were validated by comparing to transient stability simulations run using PTI's PSS/E™ program. The comparison of results from the two programs is very good in almost all cases. However, as expected, some differences did exist and were investigated. The differences in the results were primarily traced to the fact that the electromagnetic transient solution algorithm provides more detail solutions and therefore greater accuracy than the transient stability algorithm. After finding very good comparison of results between RTDS Simulator and PSS/E, and after investigating the discrepancies found, KEPCO gained the necessary confidence to use the large-scale real time simulator to analyze and develop their power system.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.1623-1624
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• 2013

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.8
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• pp.1366-1373
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• 2010

Purpose of the electric power system planning and operation is to supply the electric energy to customers continuously and economically. With the mutual exclusive laws of nature between reliability and economic, finding the meeting point is very important but not easy. Commonly the probabilistic reliability indices of the electric power systems are represented with negatively. And the effectiveness of FACTS on the probabilistic reliability could not be reflected with common methods. In this paper, a method to evaluate the probabilistic arrival power at each load point is presented. With this new proposed method, probabilistic reserve margin at load points can be calculated and which can be used with positive reliability index also. Using the P-V analysis, the voltage stability is considered in reliability evaluation. It is expected that the proposed method will be useful expecially in reliability evaluation of electric power system which has voltage restriction.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.228-229
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• 2006

The RCF analysis method is used to analyze small signal stability of power systems including GTO controlled FACTS equipment such as STATCOM. To apply the RCF analysis method in power system small signal stability problems, the state transition equations of power system equipments and power systems with STATCOM are presented. In eigenvalue analysis of power systems by the RCF analysis method, the STATCOM is modelled into the equivalents voltage source model and the PWM switching circuit model. As a result of simulation, the RCF analysis method is very powerful to calculate the oscillation modes exactly after the switching operations, and useful to analyze the small signal stability of power systems with periodically operated switching device such as the STATCOM.

• Advances in Energy Research
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• v.2 no.1
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• pp.47-59
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• 2014

Back-to-back STATCOM configuration is an extension of STATCOM in which the reactive power at two-sides and the real power flow through the DC link can be controlled concurrently and independently. This flexible operation brings many advantages to the micro-grids, distributed generation based systems, and deregulated power systems. In this paper, the dynamic control characteristics of the back-to-back STATCOM is investigated by simulating the detailed converter-level model of the converters in PSCAD. Various case studies in a single-machine test system are studied to present that the real power control feature of the BtB-STATCOM, even with a simple controller design, can enhance the transient stability of the machine under different fault scenarios.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.106-108
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• 2005

High accuracy and stability digital controlled power supply for magnet is developed at PLS. This power supply has three sections. The first section is digital controller including DSP&FPGA and precision ADC, the second section consists of IGBT driver and four quad IGBT switch, and the third section is LC output filter section. AC input voltage of power supply is 3-phase 21V, output current is 0 ${\sim}$ 150 A dc. Switching frequency of four quad IGBT switch is 25 kHz. The output current of power supply has very high accuracy of 100 A step resolution at full range and the stability of +/- 1.5 ppm for short term and +/- 5 ppm for long term. This paper describes characteristics of filter and output current performance improvement after LC output filter at four quad digital power supplies.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.9 no.3
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• pp.238-243
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• 2009

This paper present same thodology for the classification of power system voltage stability, the trajectory of which to instability is monotonic, using an interior point method based support vector machine(IPMSVM). The SVM based voltage stability classifier canp rovide real-time stability identification only using the local measurement data, without the topological information conventionally used.