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    Item type:Publication,
    Design and application of daylight-based lighting controller on LED luminaire
    (2020-05-01)
    Bunjongjit, Sulee
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    ; ; ;
    Patcharoen, Theerasak
    This paper proposes a control circuit for Light Emitting Diode (LED) luminaire based on the amount of daylight. This system uses both natural daylight and artificial light from a luminaire to reach the desired illuminance on a working plane. The control circuit operates by receiving an illuminance value from a light sensor and comparing it with a set value in the microcontroller before limiting the light intensity of LED by sending a control Pulse Width Modulation (PWM) signal to the LED driver. In the experimental setup, the controller and a physical model of a working space were built in order to field test the LED daylight control circuit. Electrical characteristics such as voltage, current, and power were measured with a power meter. Illumination characteristics in terms of illuminance on a working plane were determined using a lux meter. The results from actual field tests revealed that this LED control circuit was able to reduce the power consumption of the lighting system while keeping the illuminance on the working plane at the standard value. Both simulation results and the actual experiment of the control circuit proved that it could be used to improve the energy efficiency of both newly installed and retrofitted lighting systems.
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    Item type:Publication,
    Transient Analysis to Distinguish Mechanically Switched Capacitors Using Discrete Wavelet Transform and Artificial Intelligence
    (2026-01-01)
    Thongsuk, Surakit
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    Bunjongjit, Sulee
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    ; ;
    Capacitor banks are widely used in modern power systems for reactive power compensation and voltage regulation. However, switching operations of mechanically switched capacitors (MSCs) can generate transient phenomena, such as inrush currents, which may resemble fault currents and lead to misoperation of protection systems. Therefore, accurate detection and classification of transient events are essential for reliable system operation. This study proposes a hybrid approach for transient signal analysis and classification by integrating the discrete wavelet transform (DWT) with artificial intelligence (AI) techniques, including probabilistic neural networks and fuzzy inference systems (FIS). The DWT performs time–frequency analysis to extract multi-scale wavelet features from three-phase current signals. The proposed method enables both discrimination between inrush and fault currents and multi-class classification of transient events among six capacitor switching conditions, namely base case, pre-insertion resistor, pre-insertion inductor, current limiting reactor, 6% reactor, and synchronous closing. The methodology is validated using PSCAD/EMTDC simulations under isolated and back-to-back capacitor switching scenarios. The results demonstrate that the proposed DWT–AI approach achieves high classification accuracy exceeding 95%, outperforming conventional methods based on DWT alone and DWT combined with FIS. Furthermore, the proposed method improves protection system performance by reducing false tripping caused by transient inrush currents, while maintaining reliable fault detection capability. The findings confirm that integrating time–frequency signal processing with AI-based classification provides an effective and practical solution for transient event discrimination in MSC capacitor bank systems.
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    Item type:Publication,
    An Approach for Voltage Drop Improvement in Distribution Line Using High-Voltage Capacitor Bank
    (2025-01-01)
    Songsukthawan, Panapong
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    Thongsuk, Surakit
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    Phannil, Natthanon
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    Bunjongjit, Sulee
    Distribution line voltage drops cause power losses and a general decline in the efficiency of the electrical power system. In this study, PSCAD software is used to evaluate the elements that impact the voltage drop in the distribution line, including distribution line length, electric load power factor, and electric load capacity, both with and without capacitor bank installation. The 22-kV overhead distribution line in Thailand served as the basis for the simulation model’s creation. It has been suggested to install capacitor bank-based techniques to increase voltage on distribution lines. The findings show that the voltage drop is significantly influenced by the distribution line distance, electric load power factor, and electric load capacity. The voltage drop can be minimized to the greatest extent by properly arranging capacitor banks.
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    Item type:Publication,
    Impact of Electromagnetic Interference Filter Performance in a System without and with Grounding for Supporting the Nanogrid Road Lighting System
    (2021-04-27) ;
    Bunjongjit, Sulee
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    This study focuses on the comparison of conducted electromagnetic interference (EMI) mitigation for a nanogrid road lighting system, using a passive EMI filter between ungrounded and grounded systems. An inverter was used as the equipment under test in the experiment. The inverter is a power conversion device that receives power from the source and supplies power to the AC electrical load of an LED luminaire. There are two points where the self-generated noises propagate to other nearby devices/equipment. For this reason, this study shows the EMI spectrum from both the DC input and AC output of the inverter. The results of both sides were additionally compared between the two case studies: ungrounded and grounded systems. The real EMI testing results were also compared with the EMI/electromagnetic compatibility standard. The results confirm the effectiveness and benefits of system grounding, integrated with the proposed passive EMI filter.
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    Energy Harvesting from Railway-Induced Vibrations Using Piezoelectric Nanogrid Systems
    (2025-01-01) ;
    Songsukthawan, Panapong
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    Bunjongjit, Sulee
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    This paper investigates the feasibility of piezoelectric nanogrid systems designed to harvest mechanical energy from vibrations induced by passing trains. Two membrane-based piezoelectric module mounting configurations - sleeper-mounted at a 5 cm offset from the rail, and recessed side-mounted - were rigorously analyzed using Finite Element Method (FEM) simulations for structural durability and energy-harvesting performance. Realistic excitation waveforms, synthesized from FEM modal characteristics combined with actual field measurement data, were employed in detailed MATLAB/Simulink electrical simulations. Results demonstrated a superior electrical current output from the side-mounted configuration (2.2839 A) compared to the sleeper-mounted arrangement (1.30195 A). A practical assessment revealed that only 9 side-mounted or 16 sleeper-mounted modules are necessary to effectively charge a standard 12V 20Ah LiFePO4 battery. Moreover, daily accumulated energy of approximately 68-70 Wh could reliably power essential low-power devices at railway stations, confirming the proposed piezoelectric nanogrid system's viability as a robust, efficient, and scalable energy-harvesting solution.
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    Item type:Publication,
    Downtime Reduction with Fast Restart Function in a Beverage Production System
    (2023-01-01) ;
    Phannil, Natthanon
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    Thongsuk, Surakit
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    Bunjongjit, Sulee
    Bottled-beverage production systems require considerable machinery and sophisticated control systems. A malfunction in the production system can result in machine stoppages, thereby decreasing productivity and resulting in the production output not meeting the required target. Therefore, the problem of frequent stoppages of the production system must be resolved. The ‘Fast Restart Function’ is a proposed feature that can help reduce machine downtime by decreasing the time required for the product to drain from the conveyor. In this study, using this strategy, the investigated manufacturing system’s efficiency increased from 86.81% to 90.29%, enabling an increase in the average production capacity by 27,187 bottles per day, i.e., a 3.48 percent increment of the daily capacity. When employed in inefficient production systems or systems facing frequent shutdowns, this system is of considerable value for mitigating production stoppages.
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    Item type:Publication,
    Comparative Study between On- and Off-Grid Photovoltaic to Reduce Peak Demand in Residential Houses
    (2026-01-01) ;
    Sottiyaphai, Chayanut
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    Bunjongjit, Sulee
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    Songsukthawan, Panapong
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    Phannil, Natthanon
    This study proposes a programmable logic controller (PLC)-based energy management system integrated with an off-grid photovoltaic (PV) system and battery storage to reduce residential peak demand. The proposed system dynamically manages power supply between the distribution grid, PV generation, and battery storage based on real-time power demand measurements. When the measured power exceeds a predefined threshold, stored renewable energy is utilized to support high-load conditions and mitigate peak demand. Experimental results obtained from a residential-scale test system demonstrate that the proposed off-grid PV system with PLC control can reduce peak demand by up to 29.68% and 15.57% under office-working and work-from-home scenarios, respectively, compared with conventional grid supply and on-grid PV systems without storage. In addition, the system achieves electricity cost reductions of up to 13.63% under Time-of-Use tariffs and up to 11.42% under normal electricity rates, depending on load behavior. These results indicate that integrating PLC-based control with off-grid PV and battery storage can effectively mitigate residential peak demand and reduce electricity expenses under realistic operating conditions.
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    Item type:Publication,
    Study on coordination of protective relays in distribution system with distributed generation
    (2020-01-01) ;
    Songsukthawan, Panapong
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    In the recent decade, many countries around the globe have been increased the proportion of electrical power generation from renewable energy sources, which results in rising in the penetration level of distributed generation (DG). However, the installation of DG into the distribution system may raise many issues that can impact the distribution system in both the technical and economic aspects. When DG is connected to a distribution system, it can affect the performance of the system and the protective device already installed owing to the change of voltage level, short-circuit level and direction of power flow in the system. For this reason, a protective device may cause the malfunction because the bus impedance of the system is changed; this will result in a change of the current in each bus. This paper aims to study the coordination between the protective relay and the DG installed into the distribution system. The distribution system under investigation is a part of the Provincial Electricity Authority (PEA). Under this research, DG data that are connected to the PEA distribution is used. The simulations are performed using digital simulation and electrical network calculation program (DIgSILENT).