• 대한전기학회논문지:전력기술부문A
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• 제50권9호
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• pp.411-416
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• 2001

Distance relay is the most widely used in transmission line protection because it is applicable not only as main protection but also as back-up protection. However, the protection range of the distance relay is always fixed in the unchangeable operating range while the power system varies, and therefore the distance relay is the device that is the highly influenced by the power system changes. In this regard, this paper describes an approach to minimize the mal-operation of the distance relay due to the power system changes through changing protection range of the distance relay into optimal condition in response to the load variation and power system condition. Also mal-function of the distance repay in case of high resistance ground faults could be minimized through modeling the protection range into quadratic function.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 A
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• pp.305-307
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• 2003

This paper presents an apparent impedance calculation procedure for distance relaying of transmission line involving FACTS (Flexible AC Transmission System) devices, particularly the UPFC (Unified Power Flow Controller), between Kangjin and Jangheung in Korea. With the changes of UPFC's parameters, the measurement and protective range (trip boundaries) of the adaptive distance relay can also be changed. So, it is the most important part in the field of system protection to analyze the operating characteristic of relaying system. The presence of UPFC significantly affects the trip boundaries which are also adversely affected by fault resistance combined with remote end infeed. This paper presents the apparent impedance calculations and the distance relay setting characteristics for faults involving the UPFC in the KEPCO system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 C
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• pp.893-895
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• 1998

This paper presents the adaptive setting method of distance relay under the single line ground fault. The apparent impedance measured at the relaying point and actual impedance is different because of fault resistance and various prefault loading condition. For a resistance earth fault detection, relay setting zone is adaptively changed with measured load current and bus voltage at the relaying point to avoid maloperation.

• 조명전기설비학회논문지
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• 제18권6호
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• pp.37-44
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• 2004

전력계통분야의 복합 대형화에 유연한 대처와 전력조류의 최적화 도모를 위해 사용되는 FACTS(Flexible AC Transmission System)기기 중 가장 유용한 UPFC(Unified Power Flow Controller)는 선로의 전압을 임의의 크기와 위상을 갖도록 제어하여 선로로 전송되는 유ㆍ무효전력을 총체적으로 보상하는 기능을 갖는다. 이런 UPEC가 계통에 연계되어 운영된다면 송전선로 매개변수가 변하기 때문에 계통의 영향을 많이 받는 거리계전기는 불필요한 오동작이 발생하게 된다. 즉 거리계전기에서 바라본 임피던스 영역(Impedance Zone)이 송전선로에 UPFC 연계시 각각의 보상 값에 의해 상당한 변화를 보임으로, 기존의 방식으로 정정된 Relay Setting Zone과 Adaptive Setting Zone은 현저한 오차가 발생하게 된다. 그러므로 계통에 연계된 UPFC의 운전 조건을 고려한 거리계전기 보호구간의 재설정이 필요하게 된다. 따라서 본 논문의 목적은 학습이 가능한 신경회로망(ANN)을 이용하여 거리계전기 동작의 신속성(Speed)을 기본으로 전력계통의 다양한 환경에 대해 거리계전기 응동 특성을 향상시키는데 있다. 학습 방법으로는 정적 및 동적인 비선형 시스템의 인식과 다변수 시스템에 적용 가능한 역전파 알고리즘(Back-propagation Algorithm)을 사용했다.

• 대한전기학회논문지:전력기술부문A
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• 제53권4호
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• pp.221-226
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• 2004

Power system has recently used Double-circuit Line and Multi-circuit Line in the industrial development. This has an advantage of system stability and reliability, but the complexity of the system has a disadvantage that makes it difficult to protect the power line. Double-circuit Line has two operation conditions in the Single-circuit operation and Double-circuit operation, so it has mutual impedance. To make it possible for the remaining single-line to operate independently while there is a fault with first line or when maintenance is needed, a trip region for the single-circuit operation should be set in order to set the relay trip region. An optimal trip region for each operation, a different operational conditions for the relay setting should be calculated. In this paper, trip regions of each operation condition have been compared by considering mutual impedance and fault resistance that led to the calculation of fault impedance. Also, as we know that one of the advantages in the distance relay is the back-up protection, we calculated the trip region(Zone-2) in consideration of the mutual impedance.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제53권4호
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• pp.221-221
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• 2004

Power system has recently used Double-circuit Line and Multi-circuit Line in the industrial development. This has an advantage of system stability and reliability, but the complexity of the system has a disadvantage that makes it difficult to protect the power line. Double-circuit Line has two operation conditions in the Single-circuit operation and Double-circuit operation, so it has mutual impedance. To make it possible for the remaining single-line to operate independently while there is a fault with first line or when maintenance is needed, a trip region for the single-circuit operation should be set in order to set the relay trip region. An optimal trip region for each operation, a different operational conditions for the relay setting should be calculated. In this paper, trip regions of each operation condition have been compared by considering mutual impedance and fault resistance that led to the calculation of fault impedance. Also, as we know that one of the advantages in the distance relay is the back-up protection, we calculated the trip region(Zone-2) in consideration of the mutual impedance.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 A
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• pp.196-198
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• 2002

This paper represents a new approach for the protective relay of power transmission lines using a Artificial Neural Network(ANN). A different fault on transmission lines need to be detected, classified and located accurately and cleared as fast as possible. However, The protection range of the distance relay is always designed on the basis of fixed settings, and unfortunately these approach do not have the ability to adapt dynamically to the system operating condition. ANN is suitable for the adaptive relaying and the detection of complex faults. The backpropagation algorithm based multi-layer perceptron is utilized for the learning process. It allows to make control to various protection functions. As expected, the simulation result demonstrate that this approach is useful and satisfactory.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 B
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• pp.1370-1372
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• 2004

At present. distance relay and ${\Delta}I$ current increment relay are used as primary and secondary protection in the AC feeder system. However. electric railway vehicles according to power electronic's development had developed resistance control, thyristor phase control and PWM control system. and operation of train is increasing in a feeder section. Therefore this paper analyzes the load characteristics and situation of relay's maloperation caused by load current increase, harmonics, regenerative braking current and operation of the different vehicles in same feeder section. Based on this analysis. this paper proposes consideration items for relay correction and advanced adaptive relay that can change operation area according to load current.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 A
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• pp.317-319
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• 2003

This paper describes an adaptive distance relay for double-circuit line protection with mutual impedance and fault resistance. Double-circuit lines have two operating condition; both lines of a double-circuit line are in operation and one line is switched-off and both ends of the line are grounded. For optimal distance protection, the trip region is calculated, which have respect to mutual impedance and fault resistance.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권12호
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• pp.5800-5818
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• 2018

Interference may occur when several co-located wireless body area networks (WBANs) share the same channel simultaneously, which is compressed by resource scheduling generally. In this paper, a QoS-aware Adaptive Coloring (QAC) scheduling algorithm is proposed, which contains two components: interference sets determination and time slots assignment. The highlight of QAC is to determine the interference graph based on the relay scheme and adapted to the network QoS by multi-coloring approach. However, the frequent resource assignment brings in extra energy consumption and packet loss. Thus we come up with a launch condition for the QAC scheduling algorithm, that is if the interference duration is longer than a threshold predetermined, time slots rescheduling is activated. Furthermore, based on the relative distance and moving speed between WBANs, a prediction model for interference duration is proposed. The simulation results show that compared with the state-of-the-art approaches, the QAC scheduling algorithm has better performance in terms of network capacity, average delay and resource utility.