• Title/Summary/Keyword: Transient stability enhancement

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Transient Stability Enhancement by DSSC with Fuzzy Supplementary Controller

  • Khalilian, Mansour;Mokhtari, Maghsoud;Nazarpour, Daryoosh;Tousi, Behrouz
    • Journal of Electrical Engineering and Technology
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    • v.5 no.3
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    • pp.415-422
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    • 2010
  • The distributed flexible alternative current transmission system (D-FACTS) is a recently developed FACTS technology. Distributed Static Series Compensator (DSSC) is one example of DFACTS devices. DSSC functions in the same way as a Static Synchronous Series Compensator (SSSC), but is smaller in size, lower in price, and possesses more capabilities. Likewise, DSSC lies in transmission lines in a distributed manner. In this work, we designed a fuzzy logic controller to use the DSSC for enhancing transient stability in a two-machine, two-area power system. The parameters of the fuzzy logic controller are varied widely by a suitable choice of membership function and parameters in the rule base. Simulation results demonstrate the effectiveness of the fuzzy controller for transient stability enhancement by DSSC.

Generation Rescheduling Based on Energy Margin Sensitivity for Transient Stability Enhancement

  • Kim, Kyu-Ho;Rhee, Sang-Bong;Hwang, Kab-Ju;Song, Kyung-Bin;Lee, Kwang Y.
    • Journal of Electrical Engineering and Technology
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    • v.11 no.1
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    • pp.20-28
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    • 2016
  • This paper presents a generation rescheduling method for the enhancement of transient stability in power systems. The priority and the candidate generators for rescheduling are calculated by using the energy margin sensitivity. The generation rescheduling formulates the Lagrangian function with the fuel cost and emission such as NOx and SOx from power plants. The generation rescheduling searches for the solution that minimizes the Lagrangian function by using the Newton’s approach. While the Pareto optimum in the fuel cost and emission minimization has a drawback of finding a number of non-dominated solutions, the proposed approach can explore the non-inferior solutions of the multiobjective optimization problem more efficiently. The method proposed is applied to a 4-machine 6-bus system to demonstrate its effectiveness.

Transient Stability Enhancement of Power System by Using Energy Storage System (풍력터빈 발전기가 연계된 전력계통에서 에너지저장시스템이 과도안정도에 미치는 영향)

  • Seo, Gyu-Seok
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.6
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    • pp.592-597
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    • 2019
  • A conventional method to improve transient stability in power system is the use of reactive power compensation devices such as STATCOM and SVC. However, this traditional method cannot prevent a rapid voltage collapse brought on by motors stalling due to system fault. On the other hand, ESS(Energy Storage System) provides fast-acting, flexible reactive and active power control. The fast active power compensation with energy storage system plays a significant role in transient stability enhancement after a major fault of power system. In this paper, transient stability enhancement method by using energy storage system is proposed for the power system including a dynamic load such as large motor. The effectiveness of energy storage system compared to conventional devices in enhancing transient stability of power system is presented. The results of simulations show that the simultaneous injection of active and reactive power can enhance more effectively transient stability.

Preventive and Emergency Control of Power System for Transient Stability Enhancement

  • Siddiqui, Shahbaz A.;Verma, Kusum;Niazi, K.R.;Fozdar, Manoj
    • Journal of Electrical Engineering and Technology
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    • v.10 no.1
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    • pp.83-91
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    • 2015
  • This paper presents preventive and emergency control measures for on line transient stability (security) enhancement. For insecure operating state, generation rescheduling based on a real power generation shift factor (RPGSF) is proposed as a preventive control measure to bring the system back to secure operating state. For emergency operating state, two emergency control strategies namely generator shedding and load shedding have been developed. The proposed emergency control strategies are based on voltage magnitudes and rotor trajectories data available through Phasor Measurement Units (PMUs) installed in the systems. The effectiveness of the proposed approach has been investigated on IEEE-39 bus test system under different contingency and fault conditions and application results are presented.

Transient Stability Enhancement of Power System Connected to a Wind Farm Using STATCOM (STATCOM을 이용한 풍력단지가 연계된 전력계통의 과도안정도 향상)

  • Seo, Gyu-Seok;Park, Ji-Ho
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.16 no.6
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    • pp.4115-4120
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    • 2015
  • To ensure the transient stability of power system connected to a wind farm, wind power plant must be able to supply reactive power at the point of the common coupling(PCC). The reactive power capability of each individual wind turbine may not sufficient to maintain stability. Also, there are large reactive power losses in connection cables between wind farm and PCC. The static synchronous compensator(STATCOM) is considered for transient stability enhancement, because it provides many advantages such as the fast response time and superior reactive power support capability. In this paper, the effectiveness of a STATCOM in enhancing transient stability of power system connected to a wind farm is presented. The results of dynamic simulations show that STATCOM installed at the PCC can enhance transient stability.

Simulation of Reactive Power Compensation in Grid-Connected Wind Power Generation System (계통연계 풍력발전시스템의 무효전력 보상에 대한 시뮬레이션)

  • Ro, Kyoung-Soo;Jang, Bo-Kyoung
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.25 no.6
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    • pp.82-89
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    • 2011
  • Reactive power support is considered to be necessary for dealing with a voltage stability issue with wind turbine system employing squirrel-cage induction generator(SCIG). This paper analyses steady-state characteristics of the SCIG wind turbine system by simulating torque-slip characteristics of SCIG with respect to variations of interconnecting network strength and generator terminal voltage. It also presents dynamics analysis of SCIG wind turbine system on Simulink to investigate the impact of static var compensator(SVC) and static synchronous compensator(STATCOM) on transient stability enhancement. It analysed transient stability with varying fault duration times and compared the transient stability characteristics with varying rated capacities of SVC and STATCOM. It is shown that the STATCOM has a better performance and reactive power support compared to SVC.

Enhancement of Power System Transient Stability and Power Quality Using a Novel Solid-state Fault Current Limiter

  • Fereidouni, A.R.;Vahidi, B.;Mehr, T. Hoseini;Doiran, M. Garmroodi
    • Journal of Electrical Engineering and Technology
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    • v.6 no.4
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    • pp.474-483
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    • 2011
  • Solid-state fault current limiters (SSFCL) in power systems are alternative devices to limit prospective short circuit currents from reaching lower levels. Fault current limiters (FCL) can be classified into two categories: R-type (resistive) FCLs and L-type (inductive) FCLs. L-type FCL uses an inductor to limit fault level and is more efficient in suppressing voltage drop during a fault. In contrast, R-type FCL is constructed with a resistance and is more effective in consuming the acceleration energy of generators during a fault. Both functions enhance the transient stability of the power system. In the present paper, a novel SSFCL is proposed to enhance power system transient stability and power quality. The proposed SSFCL uses both functions of an L-type and R-type FCL. SSFCL consists of four diodes, one self-turn-off IGCT, a current-limiting by-pass inductor (L), and a variable resistance parallel with an inductor for improvement of power system stability and prevention of over-voltage across SSFCL. The main advantages of the proposed SSFCL are the simplicity of its structure and control, low steady-state impedance, fast response, and the existence of R-type and Ltype impedances during the fault, all of which improve power system stability and power quality. Simulations are accomplished in PSCAD/EMTDC.

Transient Stability Enhancement of Power System by Using Energy Storage System (에너지저장시스템을 이용한 전력계통의 과도안정도 향상)

  • Seo, Gyu-Seok
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.12
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    • pp.26-31
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    • 2017
  • The conventional method of improving the transient stability in a power system is the use of reactive power compensation devices, such as the STATCOM and SVC. However, this traditional method cannot prevent the rapid voltage collapse brought about by the stalling of the motor due to a system fault. On the other hand, the ESS (Energy Storage System) provides fast-acting, flexible reactive and active power control. The fast-acting power compensation provided by an energy storage system plays a significant role in enhancing the transient stability after a major fault in the power system. In this paper, a method of enhancing the transient stability using an energy storage system is proposed for power systems including a dynamic load, such as a large motor. The effectiveness of the energy storage system compared to conventional devices in enhancing the transient stability of the power system is presented. The results of the simulations show that the simultaneous injection of active and reactive power can enhance the transient stability more effectively.

An Improvement of Transient Stability of Multi-machine Power System (다기계통의 과도 안정도 향상)

  • Kim, Soo-Nam;You, Seok-Ku
    • Proceedings of the KIEE Conference
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    • 1997.07c
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    • pp.911-913
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    • 1997
  • This paper presents a method for optima] placement of series capacitors in order to improve the power system transient stability, using genetic algorithms. For the formulation, this paper considers the objective function which is the energy margin as the difference between transient energy and critical energy. The most important factor in determining an accurate critical energy is the controlling unstable equilibrium point (UEP). This paper proposes the controlling UEP methods, concurrently with the DFP(Davidon-Fletcher-Powell) method, which enables the enhancement of multi-machine analysis. The proposed method is applied to 6-bus, 7-line, 4-machine model system to show its effectiveness in determining the locations to install series capacitors and the it's size to be installed in system, simultaneously.

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Improving Stability of a Large Capacity Generation Station of KEPCO System (대규모 계통에서의 지역계통의 안정화 방안)

  • Kim, H.M.;Chun, Y.H.;Oh, T.K.;Kim, J.I.;Kim, Y.S.;Kim, I.S.;Chu, J.B.
    • Proceedings of the KIEE Conference
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    • 2000.07a
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    • pp.94-98
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    • 2000
  • This paper presents topics on transient stability enhancement at a large capacity generation station in Korea. The reinforcement of the transmission lines, generation tripping and reactive compensation are considered as alternative to improve transient stability. Comparative study results show characteristics of each alternative.

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