• KIEE International Transactions on Power Engineering
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• 제5A권4호
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• pp.344-349
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• 2005

In conventional small signal stability analysis, the system is assumed to be invariant and the state space equations are used to calculate the eigenvalues of the state matrix. However, when a system contains switching elements such as FACTS equipments, it becomes a non-continuous system. In this case, a mathematically rigorous approach to system small signal stability analysis is performed by means of eigenvalue analysis of the system's periodic transition matrix based on the discrete system analysis method. In this paper, the RCF (Resistive Companion Form) method is used to analyze the small signal stability of a non-continuous system including switching elements. Applying the RCF method to the differential and integral equations of the power system, generator, controllers and FACTS equipments including switching devices should be modeled in the form of state transition equations. From this state transition matrix, eigenvalues that are mapped into unit circles can be computed precisely.

• Journal of Electrical Engineering and Technology
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• 제2권4호
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• pp.428-433
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• 2007

This paper describes the new eigenvalue algorithm exploiting the Implicit Restarted Arnoldi Method (IRAM) and its application to power systems. IRAM is a technique for combining the implicitly shifted mechanism with a k-step Arnoldi factorization to obtain a truncated form of the implicitly shifted QR iteration. The numerical difficulties and storage problems normally associated with the Arnoldi process are avoided. Two power systems, one of which has 36 state variables and the other 150 state variables, have been tested using the ARPACK program, which uses IRAM, and the eigenvalue results are compared with the results obtained from the conventional QR method.

• 대한전자공학회논문지SP
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• 제37권2호
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• pp.60-67
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• 2000

기존의 적응 어레이 시스템은 입력 신호에 고유치의 최대 값과 최소 값의 차이가 큰 다중 간섭 신호가 입사될 경우에 모든 간섭 신호를 제거하지 못하는 결정적인 문제점을 가지고 있다 본 논문에서는 기존의 Applebaum 어레이의 출력부에 자동이득조절장치를 부착한 어레이 시스템을 제안한다 고유치가 확산된 신호가 입사될 경우, 신호 전력이 큰 간섭 신호는 수 회 반복 수렴 후에 쉽게 제거되고 어레이 출력에는 고유치 확산의 원인이 되는 상대적으로 낮은 전력의 간섭 신호만 존재하게 된다 이 때 자동이득조절장치가 출력에 잔존해 있는 낮은 전력의 간섭 선호를 순간적으로 증폭시켜 입력의 저전력의 간섭 신호와 출력 신호 사이의 상관값을 높여서 가중치 벡터가 적응하도록 한다 컴퓨터 모의 실험 결과 제안한 모델에서는 이러한 고유치 확산 문제를 해결하여 다중 간섭 신호 환경에서 어레이 출력의 높은 신호 대 잡음비와 빠른 수렴 속도를 얻을 수 있었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.644-645
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• 2007

In this paper, the eigenvalue sensitivity analysis algorithm in discrete systems by the RCF method are presented and applied to the power system including TCSC. The RCF analysis method enabled to precisely calculate eigenvalue sensitivity coefficients of dominant oscillation modes after periodic switching operations. These simulation results are very different from those of the conventional continuous system analysis method such as the state space equation method

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 A
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• pp.54-56
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• 1993

A systematic procedure for determining the elements of system state matrix is suggested. The interrelation of submatrices of the system matrix is investigated. Each element or each block can be represented in algebraic form. These results can be applied in the eigenvalue sensitivity analysis with respect to the changes in controller parameters.

• KIEE International Transactions on Power Engineering
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• 제4A권2호
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• pp.79-83
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• 2004

A new small signal stability analysis method for eigenvalue analysis is presented. This method utilizes the Resistive Companion Form (RCF) for the computation of the transition matrix over a specified time interval, which corresponds to a single cycle operation of the system. This method is applicable to any system, with or without switching element. An illustrative example of the method is presented and the eigenvalues are compared with those of the conventional state space method (analog) in order to demonstrate the accuracy of the proposed eigenvalue analysis method. Also, the variations of oscillation modes that are caused by the switching operation can be precisely analyzed using this method.

• 대한전기학회논문지:전력기술부문A
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• 제53권3호
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• pp.140-151
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• 2004

This paper presents the HVDC system modelling for analysis of subsynchronous oscillation and the design of the subsynchronous oscillation damping controller in HVDC system with the aid of novel eigenvalue analysis program. The HVDC system models include both the steady-state model for power flow calculation and the dynamic model for constructing the state matrix. The design procedures of the subsynchronous oscillation damping controller (SODC), which is integrated with PI controller at rectifier, consist of three steps:1) to identify the dominant torsional oscillation mode in the AC/DC system;2) to determine the parameters of the SODC for compensating the phase lagging due to the rectifier controller;3) to validate the control parameters and to determine the appropriate gain using a time-domain simulation program. The proposed design method has been tested against two AC/DC systems for validation.

• 대한전기학회논문지
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• 제43권3호
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• pp.372-380
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• 1994

A systematic procedure for the elements of system state matrix in multimachine systems with loads and eigenvalue technique which utilize stage matrix have widespread application in the analysis of small signal stability. Synchronous machines are represented by either a two-axis model or classical model. The interrelationship of submatrices of system matrix is investigated. Once elements of one submatrix are determined, they can be used to calculate the elements of the other submatrix. The approach is useful in the eigenvalue sensitivity analysis for various initial conditions and for the adjustment of generator controller parameters. It is illustrated for a three-machine and nine-bus multimachine system(WSCC system) with constant impedance loads.

• KIEE International Transactions on Power Engineering
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• 제4A권4호
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• pp.178-191
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• 2004

This paper presents a new approach to HVDC system control for damping subsynchronous oscillation (SSO) involving HVDC converters and turbine generator shaft systems. This requires a novel eigenvalue analysis (NEA) program, derivation of HVDC system modeling considering steady-state conditions and dynamic conditions in the combined AC/DC system, and an appropriate control scheme. The method suggested makes possible the design of a subsynchronous oscillation damping controller (SODC) to provide positive damping torque for the range of torsional modes in combined AC/DC systems. There are three steps involved in the design of a SODC； first the worst torsional mode is determined using the NEA program, next the SODC parameters are designed for the range of that torsional mode, and then finally an off-line simultaneous time domain program such as PSCAD/EMTDC is used to verify the parameters of the SODC. The suggested SODC design method is applied to two AC/DC systems, and its practicality is verified using the PSCAD/EMTDC simulation program.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1997년도 춘계학술발표회논문집(1)
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• pp.27-32
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• 1997

In this paper, a new multigrid method is developed to solve the reactor eigenvalue problems. The new algorithm can be used in any matrix equation concerned with the eigenvalue problem. The finite difference neutron diffusion problem is considered demonstration of the performance of the new multigrid algorithm. The numerical results show that the new multigrid algorithm works well and requires much shorter (7~10 times) computing time compaired to the production code VENTURE.