• Journal of the Korean Institute of Intelligent Systems
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• v.8 no.5
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• pp.72-82
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• 1998

Power transformer protective relay should block the tripping during magnetizing imrush and rapidly operate the tripping during internal faults. But traditional approaches maloperate in the case of magnetizing inrush with low second harmonic component and internal faults with high second harmounic component. To enhance the fault detection sensitivities of conventional technuques, flux-differential current derivative curve by fuzzy theory approaches is used. This paper deals with fuzzy logic based protective relaying for power transformer. The proposed fuzzy based relaying algorithm consisits of flux-differential current derivative curve, harmonics restraint, and precentage differential characteristic curv. The proposed relaying was tested with relaying signals obtained from Salford EMTP simulation package and showed a fast and accurate trip operation.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.365-367
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• 2005

This paper proposes a hardware of IED for power transformer protection that is well constructed using DSP chip and MPU chip. The performance of the adaptive relaying algorithm, by real-time testing in a prototype of it, has been verified. And test results indicate the proposed relaying of the IED was proven to be faster and more reliable.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.4
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• pp.295-300
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• 2014

The frequency is an important operating parameter of a power system. There is an increasing importance of constant monitoring of frequency to achieve stable power supply by WAMS(wide area monitoring system) and FNET(Frequency Monitoring Network). This paper is part of development of a network-based frequency monitoring and failure prediction system for wide-area intelligent protection relaying. In this paper, analysis of propagation speed of power frequency by generation drop using the PSS/E was carried out. For dynamic analysis, the 11 metropolitan areas offices of KEPCO divided into five groups of Seoul, Gangwon, Chungcheong, Honam, and Yeongnam group, study was performed.

• Journal of the Korean Institute of Intelligent Systems
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• v.9 no.5
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• pp.538-544
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• 1999

In this paper, we propose a new fault detection algorithm for transmission line protection using ANFIS(Adaptive Network Fuzzy Inference System). The developed system consists of two subsystems: fault type classification, and fault location estimation. We use rms value, zero sequence component and positive sequence of current, and then using learning method of neural network, premise and consequent parameters are tuned properly. To prove the performance of the proposcd system, generated data by EMTP(Electr0- Magnetic Transient Program) sin~ulationi s used. It is shown that the proposed relaying classifies fault types accurately and advances fault location estimation.

• Proceedings of the KIEE Conference
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• 2005.10a
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• pp.122-127
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• 2005

This paper proposes a prototype IED hardware design and it's real-time experimental results. To evaluate performance of the IED, the study is well constructed power system model including power transformer utilizing the EMTP software and the testing is made through simulation of various cases. The relaying that is well constructed using DSP chip and RISC CPU etc. has been developed and the prototype IED has been verified through on-line testing by LabVIEW simulator. The results show that an advanced relaying based prototype IED never mis-operated.

• Proceedings of the KIEE Conference
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• 2003.07a
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• pp.268-270
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• 2003

This paper proposes a software design and hardware implementation of Intelligent Electronic Device(IED) for power transformer. The relaying algorithm is based on DFT. The protection functions implemented include RDR with a second harmonic restraint for magnetizing inrush, OCR, OCGR, OVR, and UVR etc. The main board of IED is based on the TMS32C32 Processor. The IED was tested with relaying signals obtained for EMTP simulation package.

• Proceedings of the KIEE Conference
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• 1998.07g
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• pp.2281-2283
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• 1998

In this paper, we propose a digital differential protection of power transformer using intelligent schemes. Intelligent schemes is based on fuzzy logic and neural networks. To enhance the distinction between fault and inrush of conventional approaches, relaying technique by fuzzy logic and neural networks are used. We used transformer inrush currents, external and internal fault signals, which are obtained from EMTP simulation.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.517-519
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• 2005

In this paper, we consider a digital protection IED(Intelligent Electric Device) for a distributed power system. The IED can measure various elements for protection and communicate with another devices through network. The protection IED is composed of specific function modules: signal process module which converts analog signal from PT and CT handle algorithm to digital one; communication module for connection with another IEDs; input/output module for user-interfaces. A general purpose DSP board with TMS320C2812 is used in the IED. In order to verify the proposed IED, experimental researches with the power system simulator DOBLE has been carried out for a phase earth fault. The results show an under-voltage relaying algorithm has been realized sucessfully in the hardware system.

• Proceedings of the KIEE Conference
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• 1998.07c
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• pp.1094-1096
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• 1998

An intelligent power transformer protective relaying algorithm based on fuzzy decision-making is proposed. To distinguish external faults with CT saturation, overexcitation and inrush conditions from internal faults, a newly designed fuzzy-rule base is used. The Dempster-Shafer's rule of combition is used for fuzzy inference. A series of the S/W and H/W tests show the proposed protection algorithm has practically sufficient sensitivity and selectivity.

• Proceedings of the KIEE Conference
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• 1997.07c
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• pp.891-893
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• 1997

In this paper an intelligent power transformer protective relaying algorithm based on Fuzzy Decision-Making is presented. The introduced protection algorithm contains several internal fuzzy rule-bases including bpa(Basic Probability Assignment: m) which are subject to off-line pre-installation by the analysis of the transformer transient characteristics for detecting the internal fault. Dempster-Shafer's rule of combination is used for the inference method with rules to decide the situation of a transformer, The proposed algorithm immunes to the saturation of transformer, inrush conditions, over excitation, and external fault. The included results of testing show practically sufficient sensitivity and selectivity of the proposed algorithm.