• Proceedings of the KIEE Conference
• /
• 2008.07a
• /
• pp.29-30
• /
• 2008

This paper defines a concept of "protectability" for the performance evaluation of distance relay considering its sensitivity and selectivity. The paper starts from the probabilistic modeling of the errors, and based on this model, a detailed explanation of protectability calculation for each zone of the distance relay is presented. An effect of the Weighting Rate and the Measurement Deviation on the protectability evaluation is also given. By considering this effect, the optimization of relay setting can be realized. The proposed method is applied to a typical model system to show its effectiveness.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.11a
• /
• pp.468-471
• /
• 2002

A strong need to improve the quality of electric power is increased because of increasing use of the sensitive and small-sized electronic devices. The surges on the low-voltage ac power lines are induced by nearby lightning return strokes, and the facilities for HA, OA, FA, ME as well as computer are easily damaged by high-voltage transients. The behaviors of lightning surge characteristics transferred from the primary winding to the secondary winding in distribution transformers using a Marx generator were experimentally investigated. The transfer characteristics of lightning surge associated with a custom service ground of secondary side were also examined.

• Proceedings of the KIEE Conference
• /
• 2003.07a
• /
• pp.178-180
• /
• 2003

This paper proposes a real-time simulator that can simulate dynamic changes of a substation for intelligent SCADA system. The simulator consists of RTDS, voltage and current amplifier, IED, and RTU. The simulator is verified by system implementation and event simulation of a substation.

• Proceedings of the KIEE Conference
• /
• 2003.07a
• /
• pp.187-189
• /
• 2003

This paper presents new service restoration algorithm to deal with multiple faults such as main transformer fault, whole substation fault and simultaneous faults. The most important consideration of restoration planning for multiple outage areas is efficient use of redundant backup feeders. The proposed algorithm tries to restore all outage loads using outage area ordering method and tie switch exchange method that are newly proposed in this paper.

• Proceedings of the KIEE Conference
• /
• 2003.07b
• /
• pp.970-972
• /
• 2003

This paper presents a new speed sensorless control method of a permanent magnet synchronous motor based on instantaneous reactive power. The proposed algorithm is constructed by instantaneous reactive power in a synchronously rotating reference frame and is not affected by mechanical motor parameters, because mechanical equation is not used. The effectiveness of the proposed system is confirmed by the experimental results.

• Proceedings of the KIEE Conference
• /
• 2003.11a
• /
• pp.88-90
• /
• 2003

In this paper, an algorithm to compensate the distorted signals due to CT(Current Transformer) saturation is suggested. Firstly, WT(Wavelet Transform) is used to detect a start point and an end point of saturation. Filter banks which can be easily realized in real-time applications are employed in detecting CT saturation. Secondly, least-square curve fitting method is used to restore the distorted section of the secondary current. Fault simulations are performed on a power system model using EMTP(Electromagnetic Transient Program). A series of test results indicate that WT has superior detection accuracy and the proposed algorithm which shows very stable features under various levels of remanent flux is also satisfactory.

• Proceedings of the KIEE Conference
• /
• 2007.07a
• /
• pp.73-74
• /
• 2007

For a safe operation of HVDC systems, the fault location and clearance of faults in the HVDC lines are important. Past methods for fault location on HVDC cable depend on existence of assistance cables and fault resistance, broken cable and environment of fault location. For complement these problems, in this paper, fault location method using traveling wave and cross correlation function is proposed for HVDC cables. Voltage controlled source and current controlled source HVDC were modeled by EMTDC/PSCAD. The proposed algorithm were verified varying with fault distance, fault resistance.

• Proceedings of the KIEE Conference
• /
• 2004.11b
• /
• pp.24-27
• /
• 2004

This paper proposes a new algorithm of underground cable fault location based on the analysis of distributed parameter circuit. The proposed method firstly makes voltage and current equations for each of cores and sheathes respectively, and then establishes an equation of the fault distance according to the analysis of the fault conditions. Finally the solution of this equation is calculated by Newton-Raphson iteration method. The effectiveness of this proposed algorithm has been proven through PSCAD/EMTDC simulations.

• Proceedings of the KIEE Conference
• /
• 2007.07a
• /
• pp.31-32
• /
• 2007

In this paper, a fault section detection method is proposed for ungrounded system in the case of a single line-to-ground fault. A conventional method is used for faulted feeder selection according to the angular relationship between zero-sequence currents of the feeders and zero-sequence voltage of the system. Fault section detection is based on the comparison of phase angle of zero-sequence current. Proposed method has been testified in a demo system by Matlab/Simulink simulations. Based on Distribution Automation System(DAS), Feeder Remote Terminal Unit(FRTU) is used to collect those necessary data, at present a demo system is under developing using Manufacturing Message Specification (MMS) in IEC61850 standard.

• Proceedings of the KIEE Conference
• /
• summer
• /
• pp.378-380
• /
• 2004

Along with the increase of the importance of power quality, many various systems are dedicated in the analysis of power quality nowadays. But there still exists the same problems for realizing such kind of analysis systems well. One is the customization of the power quality measure devices; The other is an economic problem. This paper presents the usefulness and the advantage of the ICD (Intelligent Electronic Device) as the measure device of power quality And this paper detailedly describes the development procedure of web-based power quality monitoring system through ActiveX controls. Now this power quality monitoring system is already applied to the substation automation system.