• Journal of Electrical Engineering and Technology
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• v.9 no.2
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• pp.379-389
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• 2014

Low frequency oscillations (LFOs) are load angle oscillations that have a frequency between 0.1-2.0 Hz. Power system stabilizers (PSSs) are very effective controllers in improvement of the damping of LFOs. PSSs are designed by linearized models of the power system. This paper presents a new model of the power system that has the advantages of the Single Machine Infinite Bus (SMIB) system and the multi machine power system. This model is named a single machine normal-bus (SMNB). The equations that describe the proposed model have been linearized and a lead PSS has been designed. Then, particle swarm optimization technique (PSO) is employed to search for optimum PSS parameters. To analysis performance of PSS that has been designed based on the proposed model, a few tests have been implemented. The results show that designed PSS has an excellent capability in enhancing extremely the dynamic stability of power systems and also maintain coordination between PSSs.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.39 no.1
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• pp.1-9
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• 1990

The structure of A matrix of one machine connected to the infinite bus is described for a full model. The A matrix can be partitioned to submatrices which depend on the initial operating point and do not depend on it. When the dynamic properties for several different operating points are desired, those submatrices can be obtained through simple column operation. Furthermore, the elements of A matrix can be directly calculated from the manufacturer's data. RMS quantities of the state variables for the initial operating point are used. This approach can save the labor for calculating the elements of A matrix for the dynamic stability analysis.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.32 no.9
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• pp.315-324
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• 1983

Dynamic stability problems have been experienced with a generator connected to an infinite bus through a long transmission line. Nuclear turbine-generator units #1 and #2 at the Winsconsin Electric Power Point Baech Station were found to be dynamically unstable when one unit is isolated on one of the lines to Milwaukee or when two units are isolaed on the lines to milwaukee. Power System Stabilizers(PSS) were applied to the excitation system to provide stable operation under these conditions. Suitable settings for the PSS were predetetermined analytically by computer method and root licus analysis of an equivalent single machine-infinite bus configuration. This procedure allows graphical approach to the design of power stabilizers and serves as assynthesis procedure when the design constraints are relaxed so the the speed stabilizer is required ro provide animprovement in system damping. A simplified model of the complete exciter generator system is shown to be adequate for this type of analysis.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.12-13
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• 2006

In this paper, RCF(Resistive Companion Form) analysis method which is used to analyze small signal stability problems of non-continuous systems including switching device. The RCF analysis method are applied to the power systems with the thyristor controled FACTS equipments such as TCSC. As a result of simulation, the RCF method is very powerful to calculate the oscillation modes exactly after the switching operations, and useful to analyze the small signal stability of power systems with switching devices such as FACTS equipments. As an applicable example of the RCF method in power system, the one machine infinite bus system including TCSC at generator terminal bus is investigated and the results proved that variations of oscillation modes after periodic switching operations of TCSC can be calculated exactly.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.249-250
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• 2015

Technological advance of power elcetronic devices using semiconductor switches in last several decades, invoke the increase of switching devices' penetration in the system like STATCOM or HVDC and also, increase the difficulty to adjust switching characteristics in the virtual simulating configuration, which are not capable of reflect the detailed phenomena. To investigate harmful effect of switching devices into the grid, detailed modeling of power electronic devices are necessary, and the first step for entire grid modelling is simulate power system in time domain model. In this paper, simple two bus system with synchronous generator and infinite bus on the other side has been compromised in two simulation environment, using PSS/E and Matlab/Simulink. Comparing the result of two simulation result will give answers to the fundamental difference between two type of simulation environment.

• KIEE International Transactions on Power Engineering
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• v.4A no.3
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• pp.134-140
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• 2004

This paper presents an improved group of energy functions reflecting generator damping effects for multi-machine power systems by using Center of Inertia (COI) formulation as an extension of the previous work. Since rotor angles at the Stable Equilibrium Point (SEP) of post-fault systems are generally calculated in COI, system transient energy can be found without assumption of infinite or slack bus, which is a crucial drawback of the absolute rotor angle frame approach. The developed energy functions have a structure preserving property with which it is very flexible to incorporate various models of power system components, especially various load and generator models. The proposed damping-reflected energy functions are applied to the Potential Energy Boundary Surface (PEBS) method, one of the direct methods. Numerical simulation of WSCC 9-bus shows that conservativeness of the PEBS method can be considerably reduced.

• Journal of Sensor Science and Technology
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• v.18 no.2
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• pp.139-146
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• 2009

A Multilayered microelectrode design is presented for large area travelling wave dielectrophoresis (TwDEP) separators. Most of typical TwDEP chip has been arrayed with 1000 electrodes in $20{\times}20\;mm^2$. However, there is a limitation of the device area that is critical in throughput, because when the area of TwDEP becomes larger, the resistance of microelectrodes for bus bar is also increased. In this paper, we successfully developed a novel TwDEP chip with extremely large area ($31{\times}25\;mm^2$) by a unique multilayered bus bar design. According to the resistance simulation of our microelectrodes, it is possible to realize a TwDEP chip with an infinite longitudinal length. We demonstrated the feasibility of our suggestion with latex microbeads and showed the potential of extremely high throughput separation with TwDEP technique.

• Proceedings of the KIEE Conference
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• 2007.11b
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• pp.165-167
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• 2007

This paper presents a analysis method for power system stability using a Modified Genetic-based Power System Stabilized(MGPSS). The proposed MGPSS parameters are optimized using Modified Genetic Algorithm(MGA) in order to maintain optimal operation of generator under the various operating conditions. To improve the convergence characteristics, real variable string is adopted. The results tested on a single machine infinite bus system verify that the proposed controller has better dynamic performance than conventional controller.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.12
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• pp.641-648
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• 2003

This paper proposes a novel UPFE based on H-bridge modules, isolated through single-phase multi-winding transformers. The dynamic performance of proposed system was analyzed by simulation with EMTDC, assuming that the UPFC is connected with the 138-kV transmission line of one-machine-infinite-bus power system. The proposed system can be directly connected to the transmission line without series injection transformers. It has flexibility in expanding the operation voltage by increasing the number of H-bridge modules.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.49 no.10
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• pp.479-485
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• 2000

This paper presents a analysis method for dynamic characteristics of power system using a Genetic-based Power System Stabilizer(PSS). The proposed PSS parameters are optimized using Genetic Algorithm(GA) in order to maintain optimal operation of generator under the various operating conditions. To decrease the computational time, real variable string is adopted. The results tested on a single machined infinite bus system verify that the proposed controller has better dynamic performance than conventional controller.