채수용 교수

This paper describes a detection algorithm for series dc arc faults to improve safety issues in dc microgrids. Series arc faults typically occur when gaps form in a current-flowing wire or contactor. Arc faults can create serious fire hazards if not detected and removed in a short time. To identify series arc faults accurately and quickly in dc microgrids, a series dc arc fault detection algorithm using relative magnitude comparison is proposed. The proposed algorithm detects the time of occurre

This paper describes a new digital current sharing method for parallel interleaved dc-dc converters. The difference between sensed inductor current values can cause unequal current distribution in the parallel dc-dc converters even though they are controlled by the same average current mode controller with a common current reference. To overcome this problem, a simple digital current sharing algorithm using input voltage ripple difference is proposed. The digital current sharing algorithm calcul

Arc fault detection is important technology to guarantee the safety of power systems and is therefore essential for producing practical power systems for real-world applications. However, fuses and arc fault detection devices (AFDD) struggle to detect series arc faults in DC systems, because the series arc fault induces small current variation between the normal and abnormal conditions. In addition, switching noise from the grid-connected inverter makes detecting arc fault conditions even more d

This paper proposes a single-stage light-emitting diode (LED) driver based on an inverted buck topology, using current path control switches. The proposed circuit consists of a control circuit, a bridge diode, and an inverted buck converter with multiple switches connected to the LED segments in parallel. Whereas the typical buck LED driver operates with a fixed LED forward voltage, the proposed driver operates with a variable LED forward voltage, according to the input voltage level. Because of

Arc fault detection is an important process for ensuring the safety of PV and grid-connected inverters and is essential for producing PV systems in real applications. However, it is difficult to detect series dc arc faults using conventional fuses because these faults produce only small current variations. In addition, the arc fault detection devices have limited performance, because they focused on arc fault detection between PV arrays and inverter. Moreover, they require the additional current

This paper proposes a distributed control strategy that considers several source characteristics to achieve reliable and efficient operation of a hybrid ac/dc microgrid. The proposed control strategy has a two-level structure. The primary control layer is based on an adaptive droop method, which allows local controllers to operate autonomously and flexibly during disturbances such as fault, load variation, and environmental changes. For efficient distribution of power, a higher control layer adj

This paper describes a new digital control method to enhance the dynamic performance of a dc-dc converter used in plasma display panel (PDP). A simple digital PID compensator with duty ratio feed-forward control is proposed to minimize the output voltage variation while the load current is continuously changing. The duty ratio feed-forward is calculated using noise-free load current information which is predicted by the available video data of the PDP. No separate current sensing circuit is requ

The energy research community is continuously pursuing improvements in power system resiliency and reliability. Microgrids offer a unique opportunity for enhanced reliability and resiliency by utilizing localized generation and energy storage when grid power is unavailable or too expensive. Energy management is a critical aspect of these systems to ensure proper balancing of sources and ensuring power supply to critical loads with minimum cost, especially in an islanded microgrid. This paper pre

The arc-fault phenomenon in photovoltaic (PV) systems has emerged as a major problem in recent years. Existing studies on arc-fault detection in conventional PV systems primarily focus on detecting typical stable arc-faults. Low-energy arc-faults are more challenging to detect than stable arc-faults because of their low current distortions, short durations, and nonlinear properties. These low-energy arc-faults, which are precursors to stable arc-faults, could even inflict serious damage on the s

AIMS: PEGylation - covalent modification of therapeutic peptides with polyethylene glycol (PEG) - is viewed as an effective way of prolonging the short lifetime of glucagon-like peptide-1 (GLP-1). In this study, we investigated the hypoglycaemic efficacies of PEGylated GLP-1s administered intranasally in type 2 diabetic db/db mice. METHODS: Three types of site-specific (Lys(34)) PEGylated GLP-1 analogues (PEG molecular weight: 1, 2 or 5 kDa) were synthesized. Their metabolic stabilities were eva

In an islanded hybrid ac/dc microgrid (IHMG), ac and dc subgrids are connected via interlinking converters (ICs). For reliable operation of an IHMG, achieving distributed generators’ power sharing (DGPS) throughout the entire IHMG and ICs’ power sharing (IPS) is the main objective in an IHMG. To improve efficiency of an IHMG, minimizing operating costs of DGs is required and thus cost-minimized DGPS needs to be achieved. Similarly, when multiple ICs operate in an IHMG, efficiency-maximized IPS c

A dc arc faultdetection has been studied to improve the reliability of renewable energies and energy storage systems. In this Letter, the control algorithm of dc optimizer is proposed to detect the dc series arc fault condition between the PV panel and dc optimizer. The operational principle of the detection algorithm considers the characteristics of both the PV panel and arc fault, which can detect and extinguish the dc series arc fault condition. The validity of the proposed algorithm is verif

Neural network models are data-driven and are effective for predicting and interpreting nonlinear or unexplainable physical phenomena. This study collected building information and heating energy consumption data from 16,158 old houses, selected key input variables that affect the heating energy consumption based on the collected datasets, and developed a deep neural network (DNN) model that showed the highest accuracy for the prediction of heating energy consumption in an old house. As a result

This paper describes a new digital feed-forward control method to enhance the dynamic performance of a dc-dc converter. The feed-forward duty ratio is calculated based on the charge balance of the output capacitor using the load current, and it is combined with the output of the digital PED feedback compensator. The feed-forward duty ratio propagates to the consecutive switching cycles during the load transient interval to immediately supply the required energy. The propagation length is decided