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High-speed auto-reclosing is used in power system protection schemes to ensure the stability and reliability of the transmission system; leader-follower auto-reclosing is one scheme type that is widely used. However, when a leader-follower reclosing scheme responds to a permanent fault that affects a transmission line in the proximity of a generation plant, the reclosing directly impacts the turbine-generator shaft; furthermore, the nature of this impact is dependent upon the selection of the leader reclosing terminal. We therefore analyzed the transient torque of the turbine-generator shaft according to the selection of the leader-follower reclosing end between both ends of the transmission line. We used this analysis to propose an adaptive leader-end reclosing algorithm that removes the stress potential of the transient torque to prevent it from damaging the turbine-generator shaft. We conducted a simulation in actual Korean power systems based on the ElectroMagnetic Transients Program (EMTP) and the Dynamic Link Library (DLL) function in EMTP-RV (Restructured Version) to realize the proposed algorithm.

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When secondary arc is caused by single phase tripping, arc should be extinguished prior to high speed reclosing which can make the system restore. In this paper, we analyzes secondary arc extinction by applying two methods that are shunt reactor and High Speed Grounding Switches (HSGS). To verify the effects of these methods in arc extinction aspects, two factors are discussed. One is secondary arc extinction time, and another is recovery voltage. Especially, secondary arc waveform and amplitude value are analyzed to identify the effects of arc extinction methods. Simulation is conducted by using ElectroMagnetic Transient Program (EMTP) based on actual Korea 765kV transmission system.

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