http://doi.org/10.5207/JIEIE.2024.38.3.161

Jeong-Ju Park ; In-Tae Kim ; An-Seop Choi ; Yu-Sin Kim

In modern society, energy conservation is an emerging essential task. Since modern people spend most of their daytime hours indoors, they are greatly influenced by artificial lighting, thus there is a need for the development of human-centered lighting is reguired that helps regulate Circadian rhythm. In this study, an energy-saving control system was developed for public institutions, to conserve lighting energy. Energysaving control system was developed by integrating a daylight-responsive dimming algorithm, which adjusts indoor lighting brightness by sensing the amount of daylight entering the building, and an indoor shading automatic control algorithm, which adjusts the shading based on solar radiation and changes in the sun’s altitude. In addition, an empirical study analyzed the energy-saving effect achieved by a color temperature control algorithm, which helps regulate Circadian rhythm when applying the energy-saving control system. The empirical study targeted the Administrative Welfare Center, a public institution building, and lasted for a total 18 months from September 26, 2022 to February 29, 2024. The energy saving was analysed from 09:00 to 18:00. Additionally, a satisfaction survey was carried out among workers to assess their experiences with dimming control, shading control, and correlated color temperature variation. Base on the analysis, the lighting energy saving effect was found to be 21.5% on average. Additionally the satisfaction survey revealed that the most respondents were content with dimming control, shading control, and color temperature variation scoring an average of 3 or more.

http://doi.org/10.5207/JIEIE.2024.38.3.168

Soo-Gil Kim

A system using a triangular interferometer to generate complex holograms with bias and twin-image removal is proposed. In this system, the complex amplitude of a point light source is separated into ordinary and extraordinary waves by a PBS. These two waves pass through the fast and slow axes of a half-wave plate at different speeds, creating a phase difference. By using a quarter-wave plate and a linear polarizer, cosine and sine functions are obtained and electronically combined to generate the complex hologram, as demonstrated through mathematical derivation. The analysis of the reconstructed image using the complex hologram shows that the angle between the incident wave and the optic axis does not significantly affect the resolution, while the thickness of the wave plate plays a decisive role in the resolution.

http://doi.org/10.5207/JIEIE.2024.38.3.173

Hyun-Jae Cho ; Rae-Young Kim

In the case of ground design, the earth voltage, touch voltage and step voltage are higher on the outside than on the mesh internal, especially on the outermost, making it difficult to suppress the potential gradient increasing. In this paper, we will find out the reduction effect of potential gradient when ground conductor is add to mesh grounding system outermost, where potential gradient occurs rapidly, and utilize it for design application.

http://doi.org/10.5207/JIEIE.2024.38.3.181

Hee-Jun Lee ; Young-Hyok Ji ; Sang-Hun Park ; Myung-Ki Baek ; Sung-Ju Kim

This paper proposes a new buck-boost converter with multi-mode for photovoltaic MLPE(Module Level Power Electronics). The proposed converter consists of two SiC MOSFET switches, two Si diodes, an inductor, and an input/output capacitor. Control of the proposed converter has buck control, boost control, bypass control, and RSD control modes depending on the PV module status. the control of proposed converter operates using a multi-carrier PWM control method. The proposed control method has the advantage of being able to control modes without complex algorithms. Also, The design of the heatsink and component selection are crucial for reducing the size and weight of the MLPE system. In this paper, proposed converter is verified through an simulation about operation and thermal analysis.

http://doi.org/10.5207/JIEIE.2024.38.3.192

Seong-Jun Kim ; Geun-Hong Lee

This paper presents the implementation of a microgrid system within the test-bed, focusing on the seamless integration of diverse distributed energy resources via an ICT-based control infrastructure. It outlines the attainment of key quantitative benchmarks, including energy consumption substitution rates and solar power generation forecasting precision. Moreover, the study showcases a noteworthy 15% reduction in electricity expenditure facilitated by solar power generation and demand response strategies. Additionally, it details the design and deployment of the microgrid integrated control system, alongside the establishment of heterogeneous renewable energy assets, culminating in the realization and validation of community-scale microgrid frameworks.

http://doi.org/10.5207/JIEIE.2024.38.3.201

An-Yeol Ko ; Do-Yun Kim ; Seong-Yun Kang ; Junsin Yi ; Chung-Yuen Won

In this paper, a method and control algorithm for detecting resonance failures in resonant auxiliary power supply for railway vehicles is proposed. To achieve lightweighting of auxiliary power supply, it is imperative to reduce the input voltage to enable high-speed switching, thereby reducing the weight and volume of winding materials. Therefore, this paper proposes a control algorithm for lightweighting resonant auxiliary power supply for railway vehicles by applying LLC resonant converters, simultaneously proposing a method for detecting resonant destruction failures caused by abnormalities in converter components. The proposed algorithm uses the input stage buck converter to reduce the LLC resonant converter input voltage for high-speed switching and then controls the inverter input voltage through the LLC resonant converter. The proposed topology utilizes input buck converters to reduce the input voltage for high-speed switching and subsequently controls the input voltage of the inverter through LLC resonant converters. In addition, this paper proposes an inverter control algorithm to reduce harmonic distortions (THD) in the output voltage. The proposed algorithm analyzes and formulates a method for detecting resonance current peaks based on load capacity for resonance failure detection while the harmonic reduction algorithm utilizes d-q transformation to extract and nullify 5th and 7th order harmonics in the voltage.

http://doi.org/10.5207/JIEIE.2024.38.3.212

Jaeho Seo ; Yong Wook Lee

In this paper, we investigate the continuous wavelength tuning of the flat-top comb spectrum by harnessing continuous quarter-wave polarization conversion in an optical fiber filter based on a polarization-diversity loop configuration (PDLC). The fiber filter consists of two polarization-maintaining fiber segments of equal length to create comb spectra, four quarter-wave retarders (QWRs) to tune the spectrum wavelength, a polarization beam splitter to form the PDLC, and a half-wave retarder to maximize the spectrum visibility. Using the Jones calculus, we theoretically found specific orientation angles of the four QWRs for the continuous wavelength tuning of the flat-top comb spectrum. From the spectral calculation at these specific orientation angles of the four QWRs, it was confirmed that the continuous wavelength tuning of the flat-top comb spectrum could be implemented by appropriately adjusting the orientation angles of the four QWRs. The theoretical prediction was then experimentally demonstrated.

http://doi.org/10.5207/JIEIE.2024.38.3.218

Kyung-Min Lee ; Chul-Won Park

A first class generator IED require high reliability and speed. Since loss of excitation and power swing of a generator commonly use impedance trajectory-based protection techniques, accurate identification is required to prevent malfunction or non-operation. In this paper, as part of the pioneering application of intelligent IEDs, we aim to analyze and identify loss of excitation and power swing simulations. First, we introduce a first class generator IED and then summarize loss of excitation and power swing. Based on the correction report and PSS/E data for the generator system of the Chilbo hydroelectric power plant, the generator control system and protection IED are designed using PSCAD. Based on the correction report and PSS/E data for the generator system of a Chilbo hydro power plant, the generator control system and loss of excitation IED are designed using PSCAD. After verifying the adequacy of the model through steady-state simulation, we intend to identify loss of excitation and power swing phenomenon based on the impedance through 13 simulations performed while varying various conditions of loss of excitation and power swing.

http://doi.org/10.5207/JIEIE.2024.38.3.227

Young-Min Kwon ; Min-Wook Hwang ; Sungwoo Bae

As the method of flow control has changed from passive control by shape design to active control by plasma actuators, it has become possible to apply it to various fields and to control flow more efficiently. Plasma actuators are categorized into Dielectric Barrier Discharge (DBD) and Sliding Discharge (SD) depending on their configuration, with SD plasma actuators having the advantage of higher induced flow velocities and the ability to create a wide range of induced flows. However, SD plasma has a larger number of electrodes and types of input power than DBD plasma actuators, so optimization requires analysis under various conditions of power and actuator. In this paper, we designed AC power and DC power with variable voltage and frequency for optimization analysis of SD plasma actuator under various conditions, and conducted experiments for analysis. Additionally, the operating characteristics of the SD plasma actuator were confirmed through a smoke experiment. The variable AC power supply for various experiments was designed to vary the voltage up to 10kV and frequency from 4kHz to 40kHz, and the DC power supply was designed to vary the voltage up to 6kV.

http://doi.org/10.5207/JIEIE.2024.38.3.233

Yeon-Ho Choi ; Chung-Kyo In ; Jae-Jung Yun

When estimating the state of health(SOH) of a battery using a data-driven methods, the quality of the degradation parameter reflecting capacity fade has a significant impact on the estimation performance. In general, lithium-ion batteries operate under various conditions, and the quality of the degradation parameters varies accordingly. Therefore, the quality of degradation parameters must be verified under various conditions. In this paper, incremental calculation-based degradation parameters were extracted and analyzed under the slow and fast charging conditions of the battery. Incremental capacity analysis (ICA) and differential thermal voltammetry (DTV) were used as methods to extract degradation parameters. As a result of analyzing the extracted degradation parameters, it was confirmed that various high-quality degradation parameters can be extracted under slow charging conditions, but it is difficult to extract high-quality degradation parameters under fast charging conditions.

http://doi.org/10.5207/JIEIE.2024.38.3.242

Yang-Woo Yoo

This paper proposed a method to improve the reliability of the method for detecting arc faults, which is one of the caused of fires occurring in solar power generation systems, and confirmed the results through experimental results. In order to improve the detection reliability of arc faults, a method of applying three major factors was proposed. First, as a method of selecting the frequency band related to arc faults, the frequency band was selected from 10kHz to 70kHz by excluding power noise and EMI/EMC noise components. Second, the average value of the power spectrum density was calculated for each section in the 10kHz range rather than calculating the average value with the entire data in the corresponding section. Third, the size of the noise component was attenuated using a moving average. The arc fault detection results were compared with the existing method using an arc fault detection algorithm applying three factors. At this time, it was confirmed that the method presented in this paper had the highest arc fault detection rate of 96.5%. And it was confirmed that the th acr fault detection rate was improved by about 20% compared to the previous method.

http://doi.org/10.5207/JIEIE.2024.38.3.247

Byeong-Hyeon An ; Jeong-Sik Oh ; Tae-Hun Kim ; Jae-Deok Park ; Soon-Youl So ; Tae-Sik Park

Global energy paradigms are shifting as the power sector aims to reduce carbon emissions by decreasing reliance on coal power and transitioning to renewable energy sources. However, renewable energy sources are inherently intermittent, making them less suitable as baseload power sources and resulting in an imbalance between generation and load due to geographical constraints of distributed energy resources. To address these challenges, research is being conducted on large-scale power transmission technologies such as HVAC and HVDC. Recently, interest has emerged in the LFAC method, which transmits power at one-third of the standard frequency. This approach offers advantages in reducing the charging capacity of subsea cables, making it a focus of studies in offshore wind power integration. However, economic analyses of large-scale power transmission using LFAC systems in onshore networks remain scarce. This paper aims to determine the economic cross-point distance of LFAC systems for large-scale renewable energy interconnections. To achieve this, we estimated the investment costs of each transmission technology, calculated transmission costs including losses and overhead transmission line installation costs according to distance, and conducted an economic analysis of different transmission methods based on distance. The results indicate that LFAC systems have an economic cross-point distance between those of HVAC and HVDC.