• Progress in Superconductivity
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• 제3권2호
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• pp.235-240
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• 2002

In this paper, we investigated the current limiting characteristic in the magnetic shielding type fault current limiter(MSFCL). The circuit analysis was executed by using finite differential method(FDM). This paper suggests that the current limiting performance can be achieved in two ways (resistive and inductive one), according to design parameter. By comparing current limiting characteristics in two ways and surveying the important parameters which determine the operational way after fault occurs in the design of MSFCL, it is shown that the magnetic shielding type fault current limiter can be operated in either resistive or inductive way.

• 대한전자공학회논문지SD
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• 제38권11호
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• pp.836-845
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• 2001

고정도 전류-모드 신호 처리를 위한 새로운 완전-차동형 바이폴라 전류 감산기(FCS)와 이를 이용한 전류-제어 전류 증폭기(CCCA)를 설계했다. 완전-차동 전류 출력을 얻기 위해, FCS는 낮은 전류-입력 임피던스를 갖는 두 개의 전류 폴로워가 좌우 대칭적으로 구성되어 있다. CCCA는 출력전류를 바이어스 전류로 제어하기 위해 완전 차동형 전류 감산기(FCS)와 단일 전류 출력단을 갖는 전류 이득 증폭기(CGA)로 구성되었다. 시뮬레이션 결과 FCS는 5 Ω의 전류-입력 임피던스와 우수한 선형성을 갖는다는 것을 확인하였다. 또한, CCCA는 바어이스 전류를 100μA에서 20 mA까지 가변했을 경우 20 MHz의 3-dB 차단 주파수를 갖는다는 것을 확인하였다. FCS와 CCCA의 전력 소비는 각각 1.8 mW와 3 mW이다.

• 전력전자학회논문지
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• 제6권1호
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• pp.13-20
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• 2001

본 논문에서는 큰 출력 저항파 기준 전류와의 정합 특성이 우수한 새로운 전류 미러를 제안한다. CMOS 증폭기 회로에서 전원 전압이 작아지는 경우 출럭 전압의 스윙 폭이 전원 전압에 의해 제한되는 단점이 있으므로 제안된 회로는 이런 단점을 해결하기 위해 출력단의 스윙을 키우고, 안정된 동작올 할 수 있도록 한다. 출력단 부하가 큰 경우에 구동 능력을 증대시키고, 작은 전원 전압을 가질 때에도 큰 출력 스윙을 갖는 전류 미러를 시뮬레이션을 통해 가존의 캐스코드 전류 미러와 Regulated 전류 미러의 특성을 비교 및 고찰한다.

• 대한전자공학회논문지TE
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• 제37권5호
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• pp.17-27
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• 2000

SCH 양자우물 레이저에서 수치적 모델을 이용하여 캐리어의 양자우물 subband 점유에 따른 광 이득, 광 미분 이득과 재결합 전류를 계산하고, 이를 해석적 캐리어 포획 및 탈출 모델과 연계하여 양자우물 주입 전류와 SCH bulk 캐리어의 관계를 도출하였다. 이를 토대로 SCH 영역과 양자우물의 캐리어 비율과 전류 비율을 얻고, 이에 따른 광 이득과 광 미분 이득의 변화를 고찰하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 A
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• pp.485-487
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• 2001

Current differential protective relaying with harmonic restraint module is, in general, used to protect transformer. But It is hard to distinguish inrush and internal winding fault with differential current protective relaying. This paper presents the new protective algorithm for transformers using 3-phase differential current's d1 coefficient values in wavelet transform. Various states of transformer was simulated using EMTP. Internal winding fault and inrush are classified within shorter time using the proposed algorithm.

• 대한전기학회논문지:전력기술부문A
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• 제51권3호
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• pp.134-142
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• 2002

This paper presents a new method for the protective relaying scheme in power transformer using wavelet based neural networks. This approach is as fellows. After approximation and detail information is extracted by daub wavelet transform from differential current of power transformer, the former is used for obtaining the rate of differential currents and restrain currents, the latter used as the input of artificial neural networks to avoid the Hiss-operation in over-exciting state and magnetizing inrush state of power transformer. The simulation of EMTP with respect to different faults, inrush conditions and over-exciting conditions in power transformer have been conducted, and the results preyed that the proposed method is able to discriminate magnetizing inrush states, over-exciting stales and internal faults.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 A
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• pp.329-331
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• 2003

PROSET2000 that is integrated protective management system had developed and used in order to automate the setting process of protective relays in transmission system protection. PROSET2000 have database for relay setting and automated for relay setting program within. This paper proposed PCM current differential relay setting program point of Object Oriented Programming paradigm using Unified Modeling Language about additional relay in PROSET2000. Nevertheless each relay uses same current differential but setting method is different. This paper discribed different thing about setting method of each relay and evaluated more effective and corrective relay setting program using UML.

• 대한전기학회논문지
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• 제43권5호
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• pp.711-720
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• 1994

A distance relaying algorithm for detecting faults at power transmission line is presented in this paper. The algorithm is based on differential equation from relaton between voltage and current, which is composed of lumped resistance and inductance. During the fault transient state,the voltage and current signals are severely distorted due to the exponentially decaying DC offset and high frequency components, In spite of using small data, the presented integral method to evaluate R and L from voltage and current has high performance against these harmonics including DC offset. Therefore, the presented algorithm can be implemented with only a low order anti-aliasing analog filter and dosen't need any digital filter to remove specific components.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 추계학술대회 논문집 전력기술부문
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• pp.217-219
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• 2004

The second harmonic component could be decreased by magnetizing inrush when there have been changes to the material of the iron core or its design methodology. The higher the capacitance of the high voltage status and underground distribution, the more the differential current includes the second harmonic during the occurrence of an internal fault. Therefore, the conventional second harmonic-restrained RDR needs modification. This paper describes an advanced numerical algorithm that utilizes terminal voltage, differential current harmonics, harmonic ratio, and flux-differential current slope. Based on the results of testing with WatATP99 simulation data, the proposed algorithm was proven to be faster and more reliable.

• Journal of Electrical Engineering and Technology
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• 제13권6호
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• pp.2301-2309
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• 2018

In a field-oriented vector-controlled permanent magnet synchronous motor (PMSM) control system, the d-axis current control loop can offer a free degree of freedom which can be used to improve control performances. However, in the industry the desired d-axis current command is usually set as zero without using the free degree of freedom. This paper proposes a method to use the degree of freedom for control performance improvement. It is assumed that both the inner loop proportional-integral (PI) current controller and the q-axis outer loop PI speed controller are tuned by the well-known tuning rules. This paper gives an optimal d-axis reference current command generator such that some useful performance indexes are minimized and/or a tradeoff between conflicting performance criteria is made. This paper uses a differential evolution algorithm to autotune the parameter values of the optimal d-axis reference current command generator. This paper implements the proposed control system in real time on a Texas Instruments TMS320F28335 floating-point DSP. This paper also gives experimental results showing the practicality and feasibility of the proposed control system, along with simulation results.