• Title, Summary, Keyword: Transfer stability

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Assessment of Total Transfer Capability Considering Transient Stability (과도 안정도를 고려한 총 송전용량 평가)

  • Park, Jin-Wook;Bae, In-Su;Kim, Jin-O;Kim, Kyu-Ho
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.19 no.7
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    • pp.94-99
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    • 2005
  • This paper presents a method to assess total transfer capability(TTC) considering transient stability. TTC is limited not only by the violation of system voltage and thermal limits, but also restricted by transient stability limit, TTC calculation is divided into two processes. The frist step is to calculate TTC without considering the transient stability constraint by using repeated power flow(RPF) method. The second step is to perform transient stability analysis based on TTC calculation in the frist step.

A study on the ATC(Available Transfer Capabilily) calculation using an Energy Function Method (에너지함수법을 이용한 가용송전용량(ATC) 계산에 관한 연구)

  • Kim, Jae-Hyeon;Jeong, Sung-Won;Kim, Yong-Il
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.22 no.2
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    • pp.94-100
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    • 2008
  • Available transfer capability(ATC) quantifies the viable increase in real power transfer from one point to another in a power system. ATC calculation has predominantly focussed on steady-state viability. But ATC assessment with transient stability constraints has a dominant part in overall ATC calculation. ATC assessment requires a reputation of (n-1) security assessment with constraints of thermal limits, voltage stability and dynamic stability. An estimation of determinant contingency screening method is used for computing eigenvalue of Jacobian matrix. This paper proposed a methods to ATC calculation using energy function. Constraints is used thermal limits, voltage stability and transient stability.

Effect of Shielding gas Composition on Arc Stability and Transfer mode of High deposition GMA Welding (고용착 GMA 용접의 Arc 안정성 및 용적이행 현상에 미치는 보호gas의 영향)

  • 경규담;천홍정;이정헌;강봉용;김희진
    • Journal of Welding and Joining
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    • v.15 no.1
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    • pp.109-115
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    • 1997
  • The arc stability and the metal transfer mode of high deposition GMA welding were investigated using various compositions of shielding gas with two types of filler, ie solid wire and metal cored wire. As for a solid wire, the transfer mode changed from axial spray to rotational spray with increasing wire feed rate (welding current) and the transition current was different with the gas composition. The gas composition also affected the apparent stability of rotating arc. As for a metal cored wire, on the other hand, no transition occurred and thus spray transfer mode could be applied with the welding current over 500A (deposition rate over 300g/min). Looking for the development of high deposition GMA welding process, above results were discussed in two different ways, one is to elevate the transition current, the other is to stabilize the rotational transfer mode.

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The Development of Equivalent System Technique for Deriving an Energy Function Reflecting Transfer Conductances (선로저항을 반영하는 에너지함수 유도를 위한 등가시스템 기법의 개발)

  • Moon, Young-Hyun;Cho, Byoung-Hoon;Roh, Tae-Hoon;Choi, Byoung-Kon
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.48 no.10
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    • pp.1175-1182
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    • 1999
  • This paper shows that a well-defined energy function can be developed to reflect the transfer conductances for multi-machine power systems under an assumption that all transmission lines have uniform R/X rations. The energy function is derived by introducing a pure reactive equivalent system for the given system. In this study, a static energy function reflecting transfer conductances is also derived as well as the transient energy function. The proposed static energy function is applied to voltage stability analysis and tested for various sample systems. The test results show that the accuracy of voltage stability analysis can be considerable improved by reflecting transfer conductances into the energy function.

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Effects of HTS cable Applied to the Voltage Stability Limited Power System (전압안정도 제약계통에 대한 고온초전도 케이블 적용효과)

  • Lee, Geun-Joon;Hwang, Si-Dol;Lee, So-Young;Byun, Chan-Geun
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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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.

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Influence of load transfer on anchored slope stability (앵커보강사면에서 안정해석시 하중전이의 영향)

  • Kim, Sung-Kyu;Park, Jong-Sik;Kim, Nak-Kyung;Joo, Yong-Sun;Kim, Tae-Hoon
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.1351-1358
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    • 2008
  • This paper presents how the load transfer mechanism of the ground anchor affects on the stability analysis of anchored slope. The finite element analysis and the conventional limit equilibrium analysis on the anchored slope were performed and compared. The limit equilibrium analysis of the anchored slope is quite open used in design practice due to the easiness of the analysis. However, the load transfer mechanism is not considered properly for the analysis. When the failure surface passes through the bonded length of an anchor, the anchor load is disregarded and the factor of safety for the anchored slope is smaller than it should be. In this study, the load transfer distribution was incorporated into the limit equilibrium stability analysis of the anchored slope and the results were compared with the results of finite element analysis.

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A Study on Development of Power Transfer Capability Calculation Algorithm Considering Voltage Stability Margin (전압안정도 여유를 고려한 수송능력산정 알고리즘의 개발에 관한 연구)

  • Kim, Yong-Ha;Lee, Bum;Moon, Hyuk-Ki;Jung, Hyun-Sung;Cho, Sung-Rin
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.17 no.3
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    • pp.18-24
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    • 2003
  • This paper presents a power transfer capability calculation algorithm considering voltage stability margin. In this method, voltage stability margin constraints are incorporated into a power transfer capability formulation to guarantee adequate voltage security levels in an interconnected power system The proposed method is applied to IEEE-24 reliability test systems and the results show the effectiveness of the method.

Establishing a stability switch criterion for effective implementation of real-time hybrid simulation

  • Maghareh, Amin;Dyke, Shirley J.;Prakash, Arun;Rhoads, Jeffrey F.
    • Smart Structures and Systems
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    • v.14 no.6
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    • pp.1221-1245
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    • 2014
  • Real-time hybrid simulation (RTHS) is a promising cyber-physical technique used in the experimental evaluation of civil infrastructure systems subject to dynamic loading. In RTHS, the response of a structural system is simulated by partitioning it into physical and numerical substructures, and coupling at the interface is achieved by enforcing equilibrium and compatibility in real-time. The choice of partitioning parameters will influence the overall success of the experiment. In addition, due to the dynamics of the transfer system, communication and computation delays, the feedback force signals are dependent on the system state subject to delay. Thus, the transfer system dynamics must be accommodated by appropriate actuator controllers. In light of this, guidelines should be established to facilitate successful RTHS and clearly specify: (i) the minimum requirements of the transfer system control, (ii) the minimum required sampling frequency, and (iii) the most effective ways to stabilize an unstable simulation due to the limitations of the available transfer system. The objective of this paper is to establish a stability switch criterion due to systematic experimental errors. The RTHS stability switch criterion will provide a basis for the partitioning and design of successful RTHS.

Effect of S on Spatter Generation and Droplet Transfer Phenomena of MAG Welding (MAG용접의 스패터 발생 및 용적이행현상에 미치는 S의 영향)

  • 안영호;이종봉;최원규
    • Journal of Welding and Joining
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    • v.19 no.5
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    • pp.486-491
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    • 2001
  • The effect of S content in welding wires on spattering characteristics and droplet transfer phenomena was studied. In MAG welding using 80%Ar-$20%CO_2$ shielding gas, spattering characteristics and droplet transfer phenomena were varied with S content of wire. Sulfur addition in wire reduced surface tension of droplet and weld pool, and made arc more stable in MAG welding. With increasing S content, the spattering ratio and the ratio of large size spatter ($d{\geq}1.0mm$) were reduced in short circuit transfer mode. In spray transfer mode, spattering ratio, however was increased when sulfur was added more than 0.020wt.% because surface tension of droplets and weld pool was reduced too much even though arc stability was improved.

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Development of Patient Transfer Techniques based on Postural-stability Principles for the Care Helpers in Nursing Homes and Evaluation of Effectiveness (자세안정성 원리에 기반한 환자이동기술 개발 및 효과검정)

  • Ma, Ryewon;Jung, Dukyoo
    • Journal of Korean Academy of Nursing
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    • v.46 no.1
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    • pp.39-49
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    • 2016
  • Purpose: This study was done to develop a postural-stability patient transfer technique for care helpers in nursing homes and to evaluate its effectiveness. Methods: Four types of patient transfer techniques (Lifting towards the head board of the bed, turning to the lateral position, sitting upright on the bed, transferring from wheel chair to bed) were practiced in accordance with the following three methods; Care helpers habitually used transfer methods (Method 1), patient transfer methods according to care helper standard textbooks (Method 2), and a method developed by the author ensuring postural-stability (Method 3). The care helpers' muscle activity and four joint angles were measured. The collected data were analyzed using the program SPSS Statistic 21.0. To differentiate the muscle activity and joint angle, the Friedman test was executed and the post-hoc analysis was conducted using the Wilcoxon Signed Rank test. Results: Muscle activity was significantly lower during Method 3 compared to Methods 1 and 2. In addition, the joint angle was significantly lower for the knee and shoulder joint angle while performing Method 3 compared to Methods 1 and 2. Discussion: Findings indicate that using postural-stability patient transfer techniques can contribute to the prevention of musculoskeletal disease which care helpers suffer from due to physically demanding patient care in nursing homes.