• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 하계학술대회 논문집
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• pp.406-410
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• 1991

This paper presents an improved algorithm of optimal measurement system design with a reliability evaluation method for large power system. The proposed algorithm is developed to consider the dummy bus and to achieve highest accuracy of the state estimator as well with the limited Investment cost. The dummy bus in the power system is impossible to install measurement meter, while real and reactive power measurement values are exactly zero. Thus, the effect on these dummy bus measurements is considered in the proposed algorithm. On the other hand, P/C model is developed by taking advantage of the matrix sparsity. The improved program is successfully tested for KEPCO system with PSS/E lineflow calculated data package.

• Journal of information and communication convergence engineering
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• 제14권3호
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• pp.184-190
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• 2016

We present experimental demonstrations of electromagnetic bandgap (EBG) structures for the wideband suppression of radiated emissions from a power bus in high-speed printed circuit boards (PCBs). In most of the PCB designs, a parallel plate waveguide (PPW) structure is employed for a power bus. This structure significantly produces the wideband-radiated emissions resulting from parallel plate modes. To suppress the parallel plate modes in the wideband frequency range, the power buses based on the electromagnetic bandgap structure with a defected ground structure (DGS) are presented. DGSs are applied to a metal plane that is connected to a rectangular EBG patch by using a via structure. The use of the DGS increases the characteristic impedance value of a unit cell, thereby substantially improving the suppression bandwidth of the radiated emissions. It is experimentally demonstrated that the DGS-EBG structure significantly mitigates the radiated emissions over the frequency range of 0.5 GHz to 2 GHz as compared to the PPW.

• 대한전기학회논문지
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• 제41권2호
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• pp.107-117
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• 1992

This paper presents an improved algorithm of optimal measurement design with a reliability evaluation method for a large power system. The proposed algorithm is developed to consider the dummy bus and to achieve highest accuracy of the state estimator as well with the limited investment cost. The dummy bus in the power system is impossible to install measurement meter, while real and reactive power measurements is considered in the proposed algorithm. On the other hand, P/C model is developed by taking advantage of the matrix sparsity. The improved program is successfully tested for KEPCO system with PSS/E lineflow calculated data package.

• 전자공학회논문지B
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• 제32B권6호
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• pp.932-942
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• 1995

A spacecraft power system can be divided into two types : DET system(Direct Energy Transfer system) and PPT system(Peak Power Tracking system). In a DET system employing the regulated bus voltage control method, the battery charger and discharger are widely used for the bus voltage regulation. The battery charger has two different modes of operation. One is the bus voltage regulation mode and the other is the charge current regulation mode. The battery discharger is employed to provide the power when the spacecraft is in the earth's shadow or the sun is eclipsed. The operating mode, charging or discharging, is selected by a power control circuit. In this paper, small-signal dynamic characteristics of battery charging and discharging system are analyzed to facilitate design of control loop for optimum performance. Control loop designs in various operating modes are discussed. Anaylses are verified through experiments.

• 전기의세계
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• 제23권1호
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• pp.61-68
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• 1974

This paper attempts to develop the algorithms and computer program for load flow solution and faults analysis of large power system by small digital computer. The Conventional methods for load flow solution and fault analysis of large power system require too much amount of computer memory space and computing time. Therefore, this paper describes the methad for reducing the computer memory space and computing time as follows. (1) Load Flow Solution; This method is to store each primitive impedance of lines along with a list of bus numbers corresponding to the both terminals of lines, and to store only nonzero element of bus admittance matrix. (2) Faults Analysis: This method is to partition a large power system into several groups of subsystems, form individual bus impedance matrix, store them in the storage, and assemble the only required portion of them to original total system by algorithm.

• 전기학회논문지
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• 제61권6호
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• pp.859-864
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• 2012

The computer network plays an important role in modern digital controllers within a safety system of a nuclear power plant. For the reliable and realtime data communication between controllers, this paper proposes a modified high-reliable MVB(multi-function vehicle bus) as a main control network for a safety system of a nuclear power plant. The proposed network supports the state-based communication in order to ensure the deterministic communication latency, and very fast network recovery when the bus master fails compare to the standard MVB. This paper also shows the implementation results using a FPGA-based testbed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.298-299
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• 2008

In this paper, supposed that can measure power quality of bus and can calculate this cost in case electric charges about customer are imposed by each bus. When reflected this in system planning, expected cost proposed following method through sample system. We calculated the nodal cost by OPF(optimal power flow) in system and the drop numbers that happen during year of loads utilizing VSCC. Also calculated BPQC using the disruption numbers. As a result, calculated bus total cost including power quality cost through case study.

• Journal of Electrical Engineering and information Science
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• 제2권5호
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• pp.51-59
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• 1997

This paper presets a methodology of improving a conventional model in power systems using Genetic Algorithms(GAs) and suggests a GAs-based model which can directly solve the real-valued optimum in an optimization procedure. In applying GAs to the power flow, a new fitness mapping method is proposed using the proposed using the probability distribution function for all the payoffs in the population pool. In this approach, both the notions on a way of the genetic representation, and a realization of the genetic operators are fully discussed to evaluate he GAs' effectiveness. The proposed method is applied to IEEE 5-bus, 14-bus and 25-bus systems and, the results of computational experiments suggest a direct applicability of GAs to more complicated power system problems even if they contain nonlinear algebraic equations.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2017년도 전력전자학술대회
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• pp.198-199
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• 2017

This paper proposed a new control method for supercapacitor (SC) to compensate the pulse load transient and enhance the power quality of dc microgrid. By coordinating the operation frequency, the supercapacitor is controlled to handle the surge current component while the low-frequency current component is dealt with by remaining sources in the system. Based on the state of charge and dc bus voltage level, the SC unit operation mode is automatically decided. Meanwhile, the dc bus voltage level indicates the power demand of the whole system; by regulating the dc bus voltage, the mismatch of power demand is covered by SC unit. The effectiveness of proposed method is verified by experiment prototype formed by two distributed generation and one supercapacitor unit.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2015년도 전력전자학술대회 논문집
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• pp.367-368
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• 2015

This paper introduces a shunt active power filter with a small DC bus capacitor by adding additional low-pass filter (LPF). The DC link voltage fluctuation is impressively suppressed with a small value in spite of the low value of DC-link capacitor under the steady-state condition. Consequently, the cost and volume of power converter are significantly reduced thanks to the reduced value of DC-bus capacitor. On the other hand, an indirect control strategy is used to maintain grid-side current when non-linear loads are connected to the system. By using proportional-integral (PI) and modified repetitive controller (RC) in dq0 frame, the calculation time is greatly decreased by 6 times compared with the conventional RC, and the number of measurement devices is also minimized. As a result, the acquired total harmonic distortion (THD) is lower than 2% regardless of the load conditions. Simulation results are carried out in order to verify the effectiveness of the proposed control strategy.