A Study on Operation Zone of Distance Relay on Transmission Line Connected UPFC of KEPCO Systems

Seung-Hyuk Lee, Chang-Ho Jung, Il-Ryong Lee, Jin-O Kim


This paper presents an apparent impedance calculation procedure for distance relaying oftransmission line involving UPFC (Unified Power Flow Controller) devices between Kangjin andJangheung of KEPCO (Korea Electric Power Cooperation) systems. The presence of UPFCsignificantly affects the trip boundaries that are also adversely affected by fault resistance combineswith remote end infeed. Depending on the UPFC location, the trip boundary is influenced by thefault location, pre-fault condition, the arc fault resistance and the parameters of the UPFC itself(series voltage magnitude and phase angle). With the changes of these parameters, the measurementand protective range (trip boundaries) of the adaptive distance relay can also be changed. So, toanalyze the operating characteristic of relaying in the power system is the most important part in thefield of system protection.

This paper presents the apparent impedance calculations and the distance relay settingcharacteristics for faults involving the UPFC in the KEPCO systems.

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