• 전기학회논문지
• /
• 제57권7호
• /
• pp.1123-1128
• /
• 2008

The necessity of online dynamic security assessment is getting apparent under Electricity Market environments, as operation of power system is exposed to more various operating conditions. For on-line dynamic security assessment, fast transient stability analysis tool is required for contingency selection. The TEF(Transient Energy Function) method is a good candidate for this purpose. The clustering of critical generators is crucial for the precise and fast calculation of energy margin. In this paper, we propose a new method for fast decision of mode of instability by using stability indices and energy margin. The method is a new version of our previous paper.[1] Case studies are showing very promising results.

• 전기학회논문지
• /
• 제67권8호
• /
• pp.994-1001
• /
• 2018

In this paper, to studied about future power system construction using PSS / E-Python API. Python-based future system automatical construction methods and modeling of renewable sources. it confirmed the stability of the powert system for each renewable area by calculating the weighted short circuit ratio (WSCR) index. it calculated the short circuit ratio (SCR) and selected the transmission line linkage scenario to improve the stability of vulnerable areas. it confirmed the WSCR index improvement through the selected transmission line linkage of scenario, and analyzed the stability of the renewable power system applying the scenario. It describes Facts and Shunt devices adjustment for the load flow convergence. It describes the stable methed of the bus voltage through the transformer Ratio Tap adjustment. By performing PSS/E ASCC using the Python it was performed three-phase short circuit fault capacity analysis, it is confirmed whether excess of the fault current circuit breaker capacity. In order to contingency accident analysis, it have described the generation of one or two line list of each areas using the Python. The list is used to contingency analysis and describe the soluted of the transmission line overload through comparison before and after adding the scenario line.

• 대한전기학회논문지:전력기술부문A
• /
• 제54권6호
• /
• pp.306-314
• /
• 2005

In this paper, a new approach that is based on EEAC & only with network solutions for CS&S in the transient stability assessment is developed. The proposed CS&S algorithm in conjunction with EEAC to include the capability of performing on-line TSA without TDS is used to calculate the critical clearing time for stability index. In this algorithm, all generators are represented by classical models and all loads are represented by constant impedance load models. The accelerating & synchronizing power coefficient as an index is determined at its disturbance through solving network equation directly. As mentioned above, a new index for generator is generally used to determine the critical generators group. The generator rotor angle is fixed for non-critical generators group, but has equal angle increments for critical generators group. Finally, the critical clearing time is calculated from the power-angle relationship of equivalent OMIB system. The proposed CS&S algorithm currently being implemented is applied to the KEPCO system. The CS&S result was remarkably similar to TSAT program and SIME. Therefore, it was found to be suitable for a fast & highly efficient CS&S algorithm in TSA. The time of CS&S for the 139 contingencies using proposed CS&S algorithm takes less than 3 seconds on Pentium 4, 3GHz Desktop.

• Geomechanics and Engineering
• /
• 제28권5호
• /
• pp.463-475
• /
• 2022

In the mine exploitation stage; one of the critical issues is the stability assessment of post-pillars. The instability of post-pillars leads to serious safety hazards in mining operations. The focus of this study is to assess the stability of post-pillars in the 130# stope in the central ore body at Trepça hard rock mine by employing both conventional (i.e., critical span curve) and numerical methods (i.e., FLAC3D). Moreover, a new numerical based index (i.e., Pillar Yield Ratio-PYR) was proposed. The aim of PYR index is to determine a border line between stable, potentially unstable, and failure state of post-pillars at a specific mine site. The critical value of pillar width to height ratio is 2.5 for deep production stopes (e.g., > 800 m). Results showed that pillar size, mining height and mining depth significantly have affected the post-pillar stability. The reliability of numerical based index (i.e., PYR) is verified based on empirical underground pillar stability graph developed by Lunder, 1994. The proposed pillar yield ratio index and pillar stability graph can be used as a design tool in new mining areas at Trepça hard rock mine and for other situations with similar geotechnical conditions.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2004년도 하계학술대회 논문집 A
• /
• pp.91-93
• /
• 2004

This paper is to develope the fast screening algorithm for on line transient security assessment. All generators are represented in a classical model and stability index is defined as a ratio between acceleration power and deceleration power Critical machines and remaining machines are identified based on stability index and aggregated into two equivalent machines. And finally equivalent machines are reduced into OMIB system then CCT is computed. The Proposed algorithm is applied to the KEPCO system and obtained the reasonable results compared with TSA Tool.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1990년도 한국자동제어학술회의논문집(국제학술편); KOEX, Seoul; 26-27 Oct. 1990
• /
• pp.902-906
• /
• 1990

On-line robust control based on a stability index for time-delay systems has been developed. The purpose of the proposed design algorithm is to on-line tune a filter in the control loop. The problem of robust control with an incorrect given bound on the modeling error is investigated. Illustrative examples are presented to show the promise of the proposed method.

• KIEE International Transactions on Power Engineering
• /
• 제11A권4호
• /
• pp.15-20
• /
• 2001

Power system stability is correlated with system structure, disturbances and operating conditions, and power flows on transmission lines are closely related with those conditions. This paper proposes a methodology to identify correlative power flows for power system transient and small-signal stability prediction. In transient stability sense, the Critical Clearing Time is used to select some dominant contingencies, and Transient Stability Prediction index is proposed for the quantitative comparison. For small-signal stability discusses a methodology to identify crucial transmission lines for stability prediction by introducing a sensitivity factor based on eigenvalue sensitivity technique. On-line monitoring of the selected lines enables to predict system stability in real-time. Also, a procedure to make a priority list of monitored transmission lines is proposed. The procedure is applied to a test system, and it shows capabilities of the proposed method.

• 대한전기학회논문지:전력기술부문A
• /
• 제52권5호
• /
• pp.271-278
• /
• 2003

Power system stability is correlated with system structure, disturbances and operating conditions, and power flows on transmission lines are closely related with those conditions. This paper proposes a methodology to identify correlative power flows for power system transient and small-signal stability prediction. In transient stability sense, the Critical Clearing Time is used to select some dominant contingencies, and Transient Stability Prediction index is proposed for the quantitative comparison. For small-signal stability, this paper discusses a methodology to identify crucial transmission lines for stability Prediction by introducing a sensitivity factor based on eigenvalue sensitivity technique. On-line monitoring of the selected lines enables to predict system stability in real-time. Also, a Procedure to make a priority list of monitored transmission lines is proposed. The procedure is applied to a test system and the KEPCO systems in the year of 2003 and it shows capabilities of the proposed method

• 유기물자원화
• /
• 제14권2호
• /
• pp.63-70
• /
• 2006

본 연구에서는 폐기물매립지의 안정화 정도를 용이하게 평가하기 위하여 매립폐기물의 분해정도를 수치화 할 수 있는 매립지의 안정화 지수 개발을 목적으로 하였다. 안정화 지수를 개발하기 위하여 50개소의 사용종료 매립지를 대상으로 침출수 수질, 매립가스 조성, 매립폐기물의 물리화학적 특성 자료를 수집하여 이들의 매립연령별 환경특성을 고찰하였다. 그리고 이들 환경지표중 폐기물매립지의 안정화와 상관도가 높은세부 환경지표로서 침출수의 BOD/CODcr, 발생가스중의 $CH_4$농도, 매립폐기물의 C/N가 안정화 지표로 선정하였다. 각 지표에 대한 매립연령별 추세선을 이용하여 지수화한 결과 매립지 안정화 지수로 다음과 같은 식을 얻을 수 있었다. $$I_{LS}=S_L+S_G+S_W$$ $$S_L=-\{4.892+16.587{\cdot}ln[BOD/COD_{Cr]\}$$ $$S_G=53.872-12.782{\cdot}ln[CH_4]$$ $$S_W=79.382-20.013{\cdot}ln[C/N]$$ (단, $S_L$, $S_G$, and $S_W$는 각각 33.3점이 최대값이다.) 여기서, $I_{LS}$ : 매립지 안정화 지수 $S_L$ : 침출수의 안정화 점수 $S_G$ : 매립가스의 안정화 점수 $S_W$ : 폐기물의 안정화 점수.

• 한국동물학회지
• /
• 제30권1호
• /
• pp.44-52
• /
• 1987

The spontaneous bilateral asymmetry was analyzed in the hermaphroditic fish Rivulus marmoratus to obtain base line data on the developmental stability of this fish. The results obtained were as follows; 1. Eight kinds of countable anatomical characters except numbers of otolith and radii branchiostegi showed bilateral asymmetry at the frequency ranging from 9.8% to 64.7%. 2. Asymmetry index was not significantly different from that of gonochoristic fish species previously reported. Genetical implication of the results was discussed in relation to developmental stability and homozygosity of this species.