• Title/Summary/Keyword: Transient stability

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A Study on Optimal Sequential Reclosing to Improve Transient Stability in Transmission System (송전계통 과도 안정도 향상을 위한 최적 순차 재폐로에 관한 연구)

  • Gwon, Gi-Hyeon;Oh, Yun-Sik;Park, Ji-Kyung;Jo, Kyu-Jung;Sohn, Seung-Hyun;Kim, Chul-Hwan
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.62 no.10
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    • pp.1354-1360
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    • 2013
  • In transmission system, reclosing scheme is very useful method to improve continuity of power supply and reliability of system. Especially, high speed reclosing which is used generally in transmission systems has a benefit improving transient stability. However, the reclosing can jeopardize the stability under the condition having high difference of voltage phase angle between both ends. Thus, this paper proposes optimal sequential reclosing scheme to improve transient stability due to reclosing operation. The optimal sequential reclosing is that each phase is closed sequentially considering transient energy. In this paper, 345kV and 154kV transmission system is modeled using EMTP (ElectroMagnetic Transient Program) to verify the performance and effectiveness of optimal sequential reclosing on transient stability. Also, Integral Square Error(ISE) method is used to assess the transient stability.

A Novel SIME Configuration Scheme Correlating Generator Tripping for Transient Stability Assessment

  • Oh, Seung-Chan;Lee, Hwan-Ik;Lee, Yun-Hwan;Lee, Byong-Jun
    • Journal of Electrical Engineering and Technology
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    • v.13 no.5
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    • pp.1798-1806
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    • 2018
  • When a contingency occurs in a large transmission route in a power system, it can generate various instabilities that may lead to a power system blackout. In particular, transient instability in a power system needs to be immediately addressed, and preventive measures should be in place prior to fault occurrence. Measures to achieve transient stability include system reinforcement, power generation restriction, and generator tripping. Because the interpretation of transient stability is a time domain simulation, it is difficult to determine the efficacy of proposed countermeasures using only simple simulation results. Therefore, several methods to quantify transient stability have been introduced. Among them, the single machine equivalent (SIME) method based on the equal area criterion (EAC) can quantify the degree of instability by calculating the residual acceleration energy of a generator. However, method for generator tripping effect evaluation does not have been established. In this study, we propose a method to evaluate the effect of generator tripping on transient stability that is based on the SIME method. For this purpose, the measures that reflect generator tripping in the SIME calculation are reviewed. Simulation results obtained by applying the proposed method to the IEEE 39-bus system and KEPCO system are then presented.

Identification of Correlative Transmission Lines for Stability Prediction

  • Cho, Yoon-Sung;Gilsoo Jang;Kwon, Sae-Hyuk;Yanchun Wang
    • KIEE International Transactions on Power Engineering
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    • v.11A no.4
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    • pp.15-20
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    • 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.

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Identification of Correlative Transmission Lines for Stability Diagnosis of Power System (전력계통의 안정도 진단이 가능한 선로 선정에 관한 연구)

  • 조윤성;장길수;권세혁
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.52 no.5
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    • pp.271-278
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    • 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

Designing an Emotional Intelligent Controller for IPFC to Improve the Transient Stability Based on Energy Function

  • Jafari, Ehsan;Marjanian, Ali;Solaymani, Soodabeh;Shahgholian, Ghazanfar
    • Journal of Electrical Engineering and Technology
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    • v.8 no.3
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    • pp.478-489
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    • 2013
  • The controllability and stability of power systems can be increased by Flexible AC Transmission Devices (FACTs). One of the FACTs devices is Interline Power-Flow Controller (IPFC) by which the voltage stability, dynamic stability and transient stability of power systems can be improved. In the present paper, the convenient operation and control of IPFC for transient stability improvement are considered. Considering that the system's Lyapunov energy function is a relevant tool to study the stability affair. IPFC energy function optimization has been used in order to access the maximum of transient stability margin. In order to control IPFC, a Brain Emotional Learning Based Intelligent Controller (BELBIC) and PI controller have been used. The utilization of the new controller is based on the emotion-processing mechanism in the brain and is essentially an action selection, which is based on sensory inputs and emotional cues. This intelligent control is based on the limbic system of the mammalian brain. Simulation confirms the ability of BELBIC controller compared with conventional PI controller. The designing results have been studied by the simulation of a single-machine system with infinite bus (SMIB) and another standard 9-buses system (Anderson and Fouad, 1977).

Application of Lyapunov Theory and Fuzzy Logic to Control Shunt FACTS Devices for Enhancing Transient Stability in Multimachine System

  • Kumkratug, P.
    • Journal of Electrical Engineering and Technology
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    • v.7 no.5
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    • pp.672-680
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    • 2012
  • This paper proposes the control strategy of the shunt Flexible AC Transmission System (FACTS) devices to improve transient stability in multimachine power system. The multimachine power system has high nonlinear response after severe disturbance. The concept of Lyapunov energy function is applied to derive nonlinear control strategy and it was found that the time derivative of line voltage is not only can apply to control the shunt FACTS devices in multimachine system but also is locally measurable signal. The fuzzy logic control is also applied to overcome the uncertainty of various disturbances in multimachine power system. This paper presents the method of investigating the effect of the shunt FACTS devices on transient stability improvement. The proposed control strategy and the method of simulation are tested on the new England power system. It was found that the shunt FACTS devices based on the proposed nonlinear control strategy can improve transient stability of multimachine power system.

A Method for Transient Stability Assessment using Maximum Generator Angle (발전기 최대 위상각을 이용한 전력계통 과도안정도 평가)

  • Lee, Duck-Jae;Jang, Gil-Soo;Kwon, Sae-Hyuk;Kim, Tae-Kyun;Choo, Jin-Boo
    • Proceedings of the KIEE Conference
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    • 2003.11a
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    • pp.239-241
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    • 2003
  • The time domain simulation method of transient stability presents accuracy and reliability, but it demands much computational time. Therefore it is necessary to filter out very stable and very unstable cases from a large set of contingencies. Following a disturbance, the shape and magnitude of representative generator angle which is most increased after fault clearing are the measure of transient stability. This paper propose a method that is not a calculation of the exact CCT of contingency, but a fast assessment of transient stability. Also it can help operators identify transient stability immediately without analyzing the graphical results. The proposed method is applied to the KEPCO system. The PSS/E is used as a time domain simulation engine by IPLAN.

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Transient Stability Analysis Based on OOP (객체지향기반 과도 안정도 해석)

  • Park, Ji-Ho
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.57 no.3
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    • pp.354-362
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    • 2008
  • This paper presents the new method of power system transient stability simulation, which combines the desirable features of both the time domain technique based on OOP(Object-oriented Programming) and the direct method of transient stability analysis using detailed generator model. OOP is an alternative to overcome the problems associated with the development, maintenance and update of large software by electrical utilities. Several papers have already evaluated this approach for power system applications in areas such as load flow, security assessment and graphical interface. This paper applied the object-oriented approach to the problem of power system dynamics simulation. The modeling method is that each block of dynamic system block diagram is implemented as an object and connected each other. In the transient energy method, the detailed synchronous generator model is so-called two-axis model. For the excitation model, IEEE type1 model is used. The developed mothed was successfully applied to New England Test System.

A Study on Adaptive Autoreclosure Scheme with Real-time Transient Stability

  • Jang Sung-Ik;Shin Myong-Chul;Yoon Chang-Dae;Campbell Ryan C.
    • Journal of Electrical Engineering and Technology
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    • v.1 no.1
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    • pp.8-15
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    • 2006
  • Since the power swing depends on the operating time of the relay, the swing's magnitude can be reduced by an autoreclosure relaying system with an optimal reclosing algorithm. This paper proposes a method for stability improvement using optimal reclosure relaying. An optimal reclosure algorithm is applied to identify both temporary and permanent faults, and to predict system stability by applying WAM and high speed communication technology. It provides optimal control by predicting and determining the degree of stability, considering the real time transient stability using EEEAC. For temporary faults, the algorithm determines the system's stability and either recloses optimally for stable systems, or inserts series capacitance before optimal reclosure for unstable systems. It also applies an optimal reclosure algorithm to minimize shock and damage to the power system when reclosure fails due to permanent faults.

An Evaluation of Reclosing Schemes in Korean Transmission Systems Considering Transient Stability (과도 안정도를 고려한 국내 송전선로 재폐로 방식 평가)

  • Oh, Yun-Sik;Gwon, Gi-Hyeon;Park, Ji-Kyung;Jo, Kyu-Jung;Sohn, Seung-Hyun;Kim, Chul-Hwan;Kim, Wan-Jong
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.62 no.6
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    • pp.731-736
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    • 2013
  • Most of faults occurring in transmission lines are transient faults. For such faults, automatic reclosing is economic and effective method to improve the reliability and transient stability of power system. Many countries apply various reclosing schemes considering issues of their own systems such as transient stability, rate of success. Currently, different reclosing schemes are applied in Korean transmission systems according to a rated voltage. In this paper, we conduct an evaluation of reclosing schemes in Korean transmission systems considering transient stability. Computer simulations are performed by using ElectroMagnetic Transient Program (EMTP) and transmission system is modeled based on actual data of Korea.