• 한국기계가공학회지
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• 제19권4호
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• pp.16-23
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• 2020

An electric vehicle operates at high currents and requires real-time monitoring of the entire system for ensuring efficiency and safety of the vehicle. Current sensors are applied to drive the motors, inverters, and battery control systems, and are the key components to ensure constant monitoring of the magnitude and waveforms of the operating current. In this study, a heat treatment process condition to influence the performance of Permalloy current sensors was developed; the correlation between the output capacity, low-temperature characteristics, and high-temperature characteristics of the current sensor was studied; and the process was optimized to meet the required output accuracy and temperature characteristics.

• 전자공학회논문지S
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• 제35S권3호
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• pp.185-192
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• 1998

This paper presentsa new currnet control method ofthe six-pulse cycloconverter which is used as a variable speed drive system of a large capacity ac mortor. For a high performance control as a vector control, it is necessary that the output current control ofthe power converter has a good characteristic in transient state. A new proposed current control method is that the output current of a cycloconverter is followed after the current reference directly as fast as possible under any condition. Simultion results for the proposed new current control method are shown and its validity of the proposed method is confired.

• 전기학회논문지P
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• 제63권1호
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• pp.24-28
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• 2014

An induction motor is most widely used to obtain driving force in the industrial field. The induction motor is generated a high current at starting. A starting current is often more than five times of rated current. A high starting current can cause problems such as voltage drop in the power system. In order to solve these problems, a reactor starting method has been widely applied in a large motor capacity. There are differences in the operating characteristics of induction motor corresponding the switching time of reactor tap. In this study, I analyzed that current, torque, power of induction motor are different from changing time and tap setting values of reactor tap.

• 전기학회논문지
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• 제57권5호
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• pp.755-760
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• 2008

The increase of fault current due to larger power demand has caused the capacity of power machines in grid to increase. To protect the power system effectively from the larger fault current, several countermeasures have been proposed. Among them, the superconducting fault current limiter (SFCL) has been expected as one of the most effective solutions. Therefore, to introduce SFCL into power distribution system, the analysis on protection in power distribution system with SFCL is essential. In this paper, the problems of the protective coordination in power distribution system with SFCL were described.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.63-64
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• 2008

The increase of fault current due to large demand has caused the capacity of power machines in power grid to increase. To protect the power system effectively from the large fault current, several superconducting fault current limiters have been proposed. however, in order to apply superconducting fault current limiters into power system, there are many problems such as cost, recovery, AC loss, and cryogenic. In order to solve these problems, hybrid superconducting fault current limiter(HSFCL) was proposed. However, HSFCL also has a problem that is protective coordination in distribution system with HFSCL. In this paper, HSFCL limiting after half cycle modeled and analyzed about protective coordination.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2003년도 학술대회 논문집
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• pp.58-61
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• 2003

A typical HTS power transmission cable has multi-layer conductor structure to increase the current capacity. The current distribution among the conductor tapes is controlled mainly by pitches and winding directions of the layers, because the inductance of the layer is determined by the pitch and the winding direction. However, usually the current is not evenly distributed among the layers. This paper describes a method to make the current distribution more uniform and hence reduce the AC loss. If we choose a good combination we can find the optimal pitches and make an even current distribution. We studied the effect of the winding direction on a 2-layer cable by a statistical way. Calculation results and discussions will be presented.

• 한국초전도ㆍ저온공학회논문지
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• 제7권2호
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• pp.35-38
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• 2005

One of the most serious problems in KEPCO system operation is higher fault current than the SCC(Short Circuit Capacity) of circuit breaker. There are many alternatives to reduce the increased fault current such as isolations of bus ties, enhancement of SCC of circuit breaker, applications of HVDC-BTB(Back to Back) and FCL(fault current limiter). But, these alternatives have some drawbacks in viewpoints of system stability and cost. As the superconductivity technology has been developed, the resistance type HTS-FCL(High Temperature Superconductor Fault Current Limiter) can be one of the most attractive alternatives to solve the fault current problem. To evaluate the accurate transient performance of resistance type HTS-FCL, it is needed that the dynamic simulation model considering transient characteristics during quenching and recovery state. Under this background, this paper presents the EMTDC model for resistance type HTS-FCL considering the nonlinear characteristic of final resistance value when quenching and recovery phenomena by fault current injection and clearing occurs.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2003년도 학술대회 논문집
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• pp.36-39
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• 2003

HTS (High Temperature Superconducting) cable termination current lead has been designed based on simplified boundary conditions such as fixed temperature at both end and sdiabatic/convection in the side wall. However, in the real situation the current lead is enclosed with insulators and exposed to insulation oil and L$N_2$. Therefore it is necessary to consider them for the proper current lead design. In this paper, several important design parameters were chosen and their effect on the temperature distribution and heat loads on the current lead has been investigated. It was found that current lead has to be 2 stage to reach the minimum temperature requirement of insulation oil and insulator is required to reduce the cooling capacity of cryogenic system.

• 대한전기학회논문지:전력기술부문A
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• 제53권4호
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• pp.199-207
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• 2004

The 765(㎸) transformer is operated using two parallel tanks because of its high capacity. The protective relay (61) for the current phase balance of a 765(㎸) transformer would misoperate by excessively, circulation current of each tanks caused by a mismatch of ULTC Tap. In this paper, the phenomenon was analyzed, and the setting rules of relay for bank protection are studied. The result of analysis is verified by the simulation of 765(㎸) transformer with the Power Systems Computer Aided Design(PSCAD). Thereby an appropriate setting rule of the current phase balance relay is recommended.

• 조명전기설비학회논문지
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• 제28권12호
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• pp.6-12
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• 2014

The safety and reliability of the power system short-circuit current, the short-circuit current depends on the failure to obtain the objective is to quickly eliminate the breaking capacity of the circuit-breaker selection of the cable, the insulation of electrical equipment and protective relay an important factor in determining the level correction and protective relay selection scheme to be meaningful. Standards used in the domestic circuit breaker is applied to the production of IEC standard, but the American National Standards (ANSI / IEEE) by NEMA specification of the fault current calculations and the application of the asymmetric coefficient Korea. Therefore, in this paper, the IEC 60909 standard IEC breaker fault current calculation method and the method for selection of system configurations reviewed and protection system for reviewing the configuration of various protective relays appropriate correction and the correction value is main protection, back-up protection the equipment so that the period of protection relay coordination to minimize accidents and accident protection to minimize interruptions proposed for cooperation.