전기철도용 과전류 계전기 최적화 연구

Abstract

According to electrification of railroad in domestic and gradually increasing dependency for using electric power in operating the system, the demands that are suppling stable power in the electric railway and power quality improvement increase rapidly. Also importance of protective relay which is main part for maintain the stability in the grid increases steadily. Protective relay can clearly detect the type of the fault like electric tramway fault or transformer fault, amplitude of the fault voltage and current, the impedance. It can control the shut down system in the grid for prevent the expansion of the fault state and also find the faulting spot. The causes of the fault in the AC electric railroad system are short circuit in the substation or the feeding circuit and line to ground fault. The fault occurs the high voltage and the large current, it should be remove in a moment. Therefore by replacing the protective relay in perfect location can detect the fault and organize circuit with protection in electric tramway system. Recently there are no big difference between the fault current and load current because of the high speed technology and using regenerative electric tram. Thus protective system is essential to avoid malfunction by protective relay. Domestic electric tram has distinctive electric uniqueness. Various of relay which developed in internal and external are widely used for construct the reliable gird. When there is a fault or the overload in the grid, it causes the large current than steady state current. The over current relay detects the current which high rated and sends the block signal. It removes the fault and overloaded states by relatively simple mechanism so it is prevalent in electric tramway system. In this paper, decide the suitability of over current relay in protective device coordination to suggest the proper value by running the real simulation of 3 substation in Ho-nam. Also calculate the value of over current relay in the changed power feeding system by applying high speed tram. Finally verify the reliability by applying in the real grid.