• Title, Summary, Keyword: voltage stability

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Jeju area's Voltage Stability Analysis which use the Real Time Voltage Stability Analysis Program (실시간 전압안정도 프로그램을 이용한 제주지역 전압안정도)

  • Lee, Sung-Woo;Ahn, Kyo-Sang;Seo, Dong-Wan;Jang, Moon-Jong
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.61 no.10
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    • pp.1387-1392
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    • 2012
  • These days people use a lot of electric power, because industry advancement and a standard of living is elevated. So voltage stability analysis and control problems are very important in these days. U.S.A has already developed voltage stability analysis program, and use it on power transmission scheme such as generator overhaul, transmission line off and so on. So voltage stability analysis is more and more interested in Korea, too. In this paper, we introduce a standard theory of voltage stability analysis and real time voltage stability analysis program that use sPMU(Satellite Phasor Measurement Unit). And we also introduce the calculation result about voltage stability in Jeju power transmission system.

A Study on the Voltage Stability Control Scheme using Real-time Monitoring Data (실시간 감시 정보를 이용한 전압안정도 제어 방안에 대한 연구)

  • Lee, Yun-Hwan
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.66 no.4
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    • pp.206-212
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    • 2017
  • In this paper, using the power system information obtained from real-time monitoring device, to analyze the voltage stability margin index and described the voltage stability control scheme for voltage stability enhancement. Based on the utilization of the voltage stability monitoring index based on local information provided by the PMU(Phasor Measurement Unit), the purpose of the plan is to control the system stably in real time. In order to apply the load control scheme, the voltage stability margin is calculated using the data acquired through the PMU installed in each load bus. If the voltage drops below a certain level, load control is performed for each. The effectiveness of the voltage stability control measures is applied to the actual KEPCO system to analyze the effectiveness.

Hybrid Voltage Stability Analysis (혼합형 전압안정도 해석)

  • Kim, Won-Gyeom;Kim, Geon-Jung;Ju, Un-Pyo;Lee, Sang-Jung
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.49 no.2
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    • pp.43-49
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    • 2000
  • It is a complex process to analyze power system voltage stability problems with all of the dynamics of a system, because a large power network system sophisticatedly consists of generators, lines, loads and so forth. So we considered the dynamics of loads so as to analyze voltage stability method- by carrying out an analysis of steady state voltage stability and dynamic voltage stability simultaneously. To perform a steady state voltage stability program in advance makes it possible to cut down on laborious calculations so that an analysis of dynamic voltage stability becomes concise. The validity and efficiency of the method presented in this paper were verified by applying the IEEE 14 bus system.

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A Voltage Stability Monitoring Algorithm using a Few PMUs in Metropolitan Area (한정된 위치의 PMU 정보를 이용한 수도권 전압안정도 감시 알고리즘)

  • Han, Sang-Wook;Lee, Byong-Jun
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.58 no.12
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    • pp.2328-2334
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    • 2009
  • Through the development of phasor measurement units (PMU), various aspects of power system dynamic behavior could be monitored and diagnosed. Monitoring dynamic voltage stability becomes one of achievements we can obtain from PMUs. It is very important to select the method appropriate to the KEPCO system since there are many voltage stability indices. In the paper, we propose an advanced WAVI (Wide Area Voltage Stability) for monitoring dynamic voltage stability. It reflects the PMU installation plan of KEPCO, thus it is suitable for KEPCO system specially. The salient features of the proposed index are; i) it uses only PMU measurements without coupling with EMS data. ii) it is computationally unburden so that it can be applied to real-time situation. The proposed index is applied to the KEPCO test system and the result shows that it successfully predicts voltage instability through the comparative studies.

Short-term Reactive Power Reserve Optimization Based on Trajectory Sensitivity

  • Sun, Quancai;Cheng, Haozhong;Zhang, Jian;Li, Baiqing;Song, Yue
    • Journal of Electrical Engineering and Technology
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    • v.12 no.2
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    • pp.541-548
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    • 2017
  • An increasing concern is paid to short-term voltage stability with the growth of penetration of induction motor loads. Reactive power reserve(RPR) of power system is critical to improve voltage stability. A definition of short-term voltage stability-related RPR(SVRPR) is proposed. Generators vary their contributions to voltage stability with their location and system condition, etc. Voltage support coefficient based on the second-order trace sensitivity method is proposed to evaluate SVRPR's contribution to short-term voltage stability. The evaluation method can account for the generator's reactive support in transient process and the contingency severity. Then an optimization model to improve short-term voltage stability is built. To deal with multiple contingencies, contingency weight taking into account both its probability and severity is proposed. The optimization problem is solved by primal dual interior point method. Testing on IEEE_39 bus system, it is indicated that the method proposed is effective. Short-term voltage stability is improved significantly by the way of SVRPR optimization. Hence, the approach can be used to prevent the happening of voltage collapse during system's contingency.

Analysis of Small Signal Stability Considering Voltage Stability (전압안정도를 고려한 미소신호안정도 해석)

  • Kim, D.J.;Moon, Y.H.;Yoon, J.Y.
    • Proceedings of the KIEE Conference
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    • pp.323-326
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    • 2001
  • This paper describes the algorithm which can not only take account of voltage suability but also consider small signal stability. As for voltage stability both CPF and PoC methods are utilized to pinpoint the exact voltage collapse point. Then, using the converged load flow results full system matrix is configured and its eigenvalues are computed. The suggested algorithm is applied to the Two-area system, and verified its usefulness. In addition this paper also deals with the results of analyzing the two-area system in terms of voltage stability and small signal stability.

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Assessment of Total Transfer Capability Using IPLAN: An Application of UPFC for Total Transfer Capability Enhancement

  • Lee Byung Ha;Kim Jung-Hoon;Kwak No-Hong;Lee Woon-Hee
    • KIEE International Transactions on Power Engineering
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    • v.5A no.3
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    • pp.244-251
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    • 2005
  • Power transfer capability has been recently highlighted as a key issue in many utilities. It is determined by the thermal stability, dynamic stability and voltage stability limits of generation and transmission systems. In particular, voltage stability affects power transfer capability to a great extent in many power systems. This paper presents a tool for determining total transfer capability from a static voltage stability viewpoint using IPLAN, which is a high level language used with the PSS/E program. The tool was developed so as to analyze static voltage stability and to determine the total transfer capability between different areas from a static voltage stability viewpoint by tracing stationary behaviors of power systems. A unified power flow controller (UPFC) is applied for enhancing total transfer capability between different areas from the viewpoint of static voltage stability. Evaluation of the total transfer capability of a practical KEPCO power system is performed from the point of view of static voltage stability, and the effect of enhancing the total transfer capability by UPFC is analyzed.

Extreme Learning Machine Approach for Real Time Voltage Stability Monitoring in a Smart Grid System using Synchronized Phasor Measurements

  • Duraipandy, P.;Devaraj, D.
    • Journal of Electrical Engineering and Technology
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    • v.11 no.6
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    • pp.1527-1534
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    • 2016
  • Online voltage stability monitoring using real-time measurements is one of the most important tasks in a smart grid system to maintain the grid stability. Loading margin is a good indicator for assessing the voltage stability level. This paper presents an Extreme Learning Machine (ELM) approach for estimation of voltage stability level under credible contingencies using real-time measurements from Phasor Measurement Units (PMUs). PMUs enable a much higher data sampling rate and provide synchronized measurements of real-time phasors of voltages and currents. Depth First (DF) algorithm is used for optimally placing the PMUs. To make the ELM approach applicable for a large scale power system problem, Mutual information (MI)-based feature selection is proposed to achieve the dimensionality reduction. MI-based feature selection reduces the number of network input features which reduces the network training time and improves the generalization capability. Voltage magnitudes and phase angles received from PMUs are fed as inputs to the ELM model. IEEE 30-bus test system is considered for demonstrating the effectiveness of the proposed methodology for estimating the voltage stability level under various loading conditions considering single line contingencies. Simulation results validate the suitability of the technique for fast and accurate online voltage stability assessment using PMU data.

A Study on Decentralized under Voltage Load Shedding Scheme for Preventing Wide-area Black Out (광역정전 예방을 위한 분산형 부하 제어 방안에 대한 연구)

  • Lee, Yun-Hwan
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.63 no.1
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    • pp.1-6
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    • 2014
  • An electric power system sometimes fails because of disturbances that occur unexpectedly, such as the uncontrolled loss of load that developed from cascading blackout. Which make stability through a little of under voltage load shedding should work. The development of phasor measurement unit(PMU) makes network supervision possible. The information obtained from PMU is synchronized by global positioning system(GPS). There are many real-time algorithms which are monitoring the voltage stability. This paper presents the study on the VILS(Voltage Instability Load Shedding) using PMU data. This algorithm computes Voltage Stability Margin Index(VSMI) continuously to track the voltage stability margin at local bus level. The VSMI is expressed as active and reactive power. The VSMI is used as an criterion for load shedding. In order to examine the algorithm is effective, applied to KEPCO system.

A Study on the Dynamic Voltage Stability Considering the Power System Security Control (계통(系統)의 안전성(安全性) 제어(制御)를 고려(考慮)한 동적(動的) 전압안정도(電壓安定度)에 관(關)한 연구(硏究))

  • Lee, Geun-Joon;Hwang, Jong-Young;Lee, Gil-Soon;Jeong, Tay-Ho;Kim, Keon-Jung;Kim, Yong-Bae
    • Proceedings of the KIEE Conference
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    • pp.54-60
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    • 1994
  • The cause of black out of Tokyo Power in 1987 has been identified as the voltage stability problem. After this event many researchers has been interested in voltage stability or voltage collapse phenomena. The voltage instability is different Com the transient stability in the sense of reactive power mismatch and the long duration time. In this study, we developed efficient tool for analyze and control the dynamic voltage instability. To analize specific condition of dynamic voltage stability, quasi-dynamic simulation method is developed. To provide proper mathmatical model for dynamic voltage stability, generator, SVC, OLTC, induction motor models are introducted. To provide specified dynamic voltage stability, the authors considered to use reactive loss function(${\partial}Q/{\partial}p_L$) as reactive power facility control index. This program was tested and identified its usefulness in real KEPCO system.

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