• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.484_485
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• 2009

Power output of a wind farm fluctuates throughout a day. This affect a distance relay for wind farm intertie protection because a voltage of a relaying point varies due to fluctuating output of a wind farm. This paper describes the analysis of the response of a distance relay for intertie protection when the power output of a wind farm increases. A series of single phase to ground faults were also simulated and analyzed with PSCAD/EMTDC generated data.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.212-214
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• 2000

The distance relay technique used for transmission line protection operates overreach and underreach to the self protection region because the power system becomes complex and fault conditions are different. To solve these problems, this paper describes new technique to set the reliable self protection lesion. The trip region of the quadrilateral distance relay is set by training of multi layer recurrent elman network. The proposed network is able to reach the trip zone for the fault impedance, fault initial angle and source impedance variance correctly.

• Proceedings of the KIEE Conference
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• 2003.07a
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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.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.4
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• pp.28-34
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• 2012

Installing surge protection devices for a low-voltage system is important to ensure the survival of electric or electronic devices and systems. If surge protection devices (SPD) are installed without consideration of the concept of lightning protection zones, the equipment to be protected might be damaged despite the correct energy coordination of SPDs. This damage is induced by the reflection phenomena on the cable connecting an external SPD and the load protected. These reflection phenomena depend on the characteristics of the output of the external SPD, the input of the loads, and the cables between the load and the external SPD. Therefore, the SPD has an effective protection distance under the condition of the specific load and the specific voltage protection level of SPD. In this paper, PSCAD/EMTDC software is used to simulate the residual voltage characteristics of SPD Entering the low-voltage device. And by applying a certain voltage level, the effective protection distances of SPD were analyzed according to the each load and length of connecting cable, and the effectiveness of SPD were verified.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.6
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• pp.1053-1058
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• 2010

A large modern wind farm should satisfy the requirements for a grid and accomplish the optimization of the wind farm system. The wind farm intertie protection system should consider a Fault Ride-Through (FRT) requirement for more reliable protection. The wind farm should keep connected to the grid in the case of a grid fault whilst it should be isolated for an intertie fault. This paper proposes a distance relaying algorithm suitable for wind farm intertie protection considering the FRT requirement. The proposed algorithm estimates the impedance based on a differential equation method because the frequency of the voltage and current deviates the nominal frequency. The algorithm extends the reach of Zone 1 up to 100 % of the length of the intertie to implement the FRT requirement. To discriminate an intertie fault from a grid fault, the algorithm uses a voltage blocking scheme because the magnitude of the voltage at the relaying point for an intertie fault becomes less than that for a grid fault. The performance of the algorithm is verified using a PSCAD/EMTDC simulator under various fault conditions. The algorithm can discriminate successfully the intertie fault from grid fault and thus helps to implement the FRT requirement of a wind farm.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.3
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• pp.161-167
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• 2004

Zone 3 of the distance relay is used to provide the remote back-up protection in case of the failure of the primary protection. However, the risk lot mal-operations under stressed conditions such as heavy loading, voltage and transient instability is usually high. Zone 3 is used in combination with the derivatives of the voltage, and current, etc to prevent mal-operations. Sometimes, the impedance characteristics that restrict the tripping area of relay are used to avoid the mal-operations due to load encroachment. This paper presents a novel Zone 3 scheme based on combining the steady-state components (i.e. 60Hz) and the transient components (TCs) using a state diagram that visualizes the sequence of studies that emanate from the sequence of events. The simulation results show that the novel zone 3 distance relay elements using the proposed method operates correctly for the various events.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.11
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• pp.1885-1891
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• 2007

This paper presents a distance relaying algorithm for phase-to-ground faults in transmission lines under Multi-Agent protection environment. In normal condition, a distance relay agent stores the latest states, e.g., voltage of source side, voltage of the opposite side and the loading conditions, etc., through communication between the agents. Once a fault occurs, the relay calculates the fault location using the knowledge about the states just before the fault happens. This stand-alone operation is to improve reliability under the fault condition at which the accuracy or time required for communication may not be guaranteed. The mathematical expression of fault location is derived through loop analysis, before hand, in the manner that both fault current from the opposite end and fault resistance are included implicitly so that their effects are minimized. The suggested algorithm is applied to a typical transmission system with two power sources on both ends to show its effectiveness.

• Proceedings of the KIEE Conference
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• 1994.11a
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• pp.42-44
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• 1994

This paper presents the method of estimating integral coefficients of new distance relaying algorithm for transmission line protection. The proposed method is based on the differential equation calculates impedance value by approximation of integral term of integro-differential equation which relate voltage with current. As a result, we can determine the integral coefficients in least square error sense in frequency domain and we take into consideration the analog filter characteristics and frequency domain characteristics of the system to be protected. The simulation results showed that these coefficients can be successfully used to obtain impedance value in distance relay.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.8
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• pp.438-445
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• 2004

This paper presents a new numerical spectral domain algorithm devoted to blocking unsuccessful automatic reclosing onto permanent faults and fault distance calculation. Arc voltage amplitude and fault distance are calculated from the fundamental and third harmonics of the terminal voltages and currents phasors. From the calculated arc voltage amplitude it can be concluded if the fault is transient arcing fault or permanent arcless fault. If the fault is permanent automatic reclosure should be blocked. The algorithm can be applied for adaptive autoreclosure, distance protection, and fault location. The results of algorithm testing through computer simulation and real field record are given.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.442_443
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• 2009

A large wind farm should satisfy the requirements for a grid and accomplish the optimization of the wind farm system. In that point of view, the wind farm intertie protection system, which must consider the Fault Ride-Through (FRT) requirement for more reliable protection, should be improved. This paper proposes a modified distance relay suitable for protection of a wind farm intertie considering a FRT requirement. The frequency change is used to discriminate the intertie fault from a outside zone fault. The performance of the proposed algorithm is verified using a PSCAD/EMTDC simulator.