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The increasing importance of energy efficiency has led to several studies related to the construction of a reliable low voltage DC (LVDC) distribution system. Specifically, studies on a protection scheme that considers the fault characteristics of an LVDC distribution system are essential to improve system reliability. When compared to a conventional distribution system, the most distinct feature of an LVDC distribution system is the existence of a capacitive discharge current from converters under a fault condition that results in the prompt operation of protection devices. Therefore, this study involves proposing a precise and rapid technique to identify the fault section in an LVDC distribution system. The technique involves two stages, namely: an analysis stage to analyze the capacitive discharge current and a decision stage to identify the fault section based on the fault type. A detailed discussion of each step is presented and its feasibility is verified based on the results of simulations with an ElectroMagnetic Transients Program and MATLAB®.

Shear stress applied on the apical side of polarizing intestinal cells induces vacuole formation via the autophagy machinery. This response is relayed through apical microvilli that act as mechanosensors linking the physical environment to the intracellular trafficking pathways.

AbstractIn general, most vehicles are parked during the peak load time so that if we could control these Electric Vehicles suitably and provide the stored electricity from vehicle (battery) to grid, electrical peak load would be reduced. Above function is called as a Vehicle to Grid (V2G). In this paper, we propose the peak load shaving scheme to reduce the peak demand and analyze the effect of V2G system for the peak load shaving in the actual distribution system considering various penetration level of EVs. With the proposed method, peak demand power is reduced considerably.

AbstractAs an area of interest in energy efficiency in power systems, low voltage DC (LVDC) distribution system has elicited attention as a potential solution. This system is closely associated with the increase of distributed generations, as well as digital loads. Until now, however, the related standards and research remain insufficient to commercialize the LVDC distribution system. In particular, the establishment of the protection schemes for LVDC distribution systems is the primary task because it can affect the overall aspects, including reliability of the system. For the establishment of reliable protection schemes, the fault characteristics of LVDC distribution system must be identified precisely in a practical system. Thus, this paper shows that Prony’s method can be used to analyze the fault characteristics of LVDC distribution system. For this purpose, the fault characteristics are theoretically analyzed first. The analysis results are then verified by using ElectroMagnetic Transients Program (EMTP) and MATLAB®.

AbstractThis study presents a method for high-impedance fault (HIF) detection in a low-voltage DC (LVDC) distribution system via mathematical morphology (MM), which is composed of two elementary transformations, namely, dilation and erosion. Various MM-based filters are used to detect abnormal signals of current waveform. The LVDC distribution system, including power conversion devices, such as AC/DC and DC/DC converters, is modelled with electromagnetic transient program (EMTP) software to verify the proposed method. The HIF arc model in the DC system is also implemented with EMTP/MODELS, which is a symbolic language interpreter for EMTP. Simulation results show that the proposed method can be applied to detect HIF effectively in the LVDC distribution system.

Abstract– 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.