• Journal of Electrical Engineering and Technology
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• 제13권5호
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• pp.1831-1840
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• 2018

During a power swing, distance relays may mistakenly spread fault throughout the power grid, causing a great deal of damage. In some cases, such mistakes can cause global outages. For this reason, it is critical to make a distinction between power swings and faults in distance relays. In this paper, a new method is proposed based on RMS measurement to differentiate between faults and power swings. The proposed method was tested on two standard grids, demonstrating its capability in detecting a power swing and simultaneous fault with power swing. This method required no specific configurations, and was independent of grid type and zoning type of distance relays. This feature in practice allows the relay to be installed on any grid with any kind of coordination. In protective relays, the calculations applied to the microprocessor is of great importance. Distance relays are constantly calculating the current RMS values for protection purposes. This mitigates the computations in the microprocessor to detect power swings. The proposed method was able to differentiate between a fault and a power swing. Furthermore, it managed to detect faults occurring simultaneously with power swings.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 추계학술대회 논문집 학회본부 A
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• pp.13-16
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• 2000

Continuation power flow has been developed to remove the ill-condition problem caused by singularity of power flow Jacobian at and near steady-state voltage instability point in conventional power flow. When solving large-scale power transmission systems, continuation power flow require large computational costs. Therefore, technique to improve the speed of continuation power flow system was required. In this paper Decoupled Power Flow Method (DPFM), Enhanced Decoupled Power Flow Method (EDPFM), Robust Fast Decoupled Power Flow Method (RFDPFM) are applied to continuation power flow algorithm to improve the speed of continuation power flow system.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.580-584
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• 2011

Sound power is one of the most significant factors to predict and assess noise from sound source. However, many researchers developed indirect methods to calculate the sound power with noise level because it is impossible to measure sound power directly while a train is running. In this paper, we proposes a method to estimate separately each sound power for rolling noise and propulsive noise with the noise emitted from rolling stocks and verifies the validity of the estimation method using other sound power estimation formula.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 학술대회 논문집 정보 및 제어부문
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• pp.735-737
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• 2004

This paper proposes a method of fault diagnostics on switching mode power supply. When the error of switching mode power supply cannot be found when the conventional diagnostics is performed, this proposed method first performs diagnosis on the switching mode power supply strictly to judge the operating condition. This method analyzes the PWM wave which depends on the load change, to make sure the feedback control of the power supply to diagnosis the operation of the power supply system.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2000년도 전력전자학술대회 논문집
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• pp.752-755
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• 2000

This paper describes a new algorithm for active power filters which can be control source current symmetrically under unbalanced condition in power system. Positive sequency voltage is detected by symmetrical coordinate method and compensating reference current of active power filters is calculated using by accurate phase angle information of positive sequency voltage. The basic principle of the proposed method is described in detail and the conventional and proposed phase detecting methods are compared and discussed through the simulation results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 추계학술대회 논문집 학회본부 A
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• pp.85-88
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• 2000

This paper proposes a methodology to compute the servicing price of reactive power management and voltage control in competitive electrical power market. Compound method is proposed and its result is proved by a sample test. The method can be useful in providing additional insight into power system operation and can be used to determine tariffs of reactive power management service.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제54권1호
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• pp.41-44
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• 2005

A new method to reduce the computation time in power/ground-plane analysis is proposed. The existing method using the two dimensional infinite series summation take a lot of computation time. The proposed method is based on the approximation of impedance in the frequency domain through the Mobius transform. This method shows the good accuracy and the high speed in computing. In the case of impedance calculation for 9'x4' board, the proposed method takes 0.16 second of computing time whereas the existing method takes 2.2 second. This method can be applied to the analysis and design of power/ground-plane that need a lot of computation steps.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.489-493
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• 2007

Mmulti-domain noise analysis method using Power Flow Boundary Element Method(PFBEM) has been developed successfully. Some applications are introduced. several examples. PFBEM is a numerical analysis method formulated by applying Boundary Element Method(BEM) to Power Flow Analysis(PFA). PFBEM is very powerful in predicting noise level in medium-to-high frequency ranges. However there are restrictions in analyzing the coupled structures and multi-media. In this paper, an analysis method for multi-domain acoustic problems in the diverse acoustic fields is suggested. And the developed method is applied to the car interior and exterior multi-domain noise analysis.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 전력전자학술대회 논문집
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• pp.287-290
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• 1998

This paper presents PWM method which modulates two third period only during one cycle of power converter. This method is compared with the conventionl sinusoidal modulation method applying to the power converter with large capacity necessitating low switching frequency. The presented modulation method enables to reduce power semiconductor rating, minimize switching loss, and improve the current wave form.

• 대한전기학회논문지
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• 제33권9호
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• pp.364-371
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• 1984

This paper describes a method for the state estimation in electric power system. The state values are estimated through the weighted least square method considering the bad data. Then, the bad data are identified by using sensitivity coefficients of power system after being detected the bad data through the distribution of T. This method was applied to the model power system, and, the results of test for proposed method are given.