• Journal of Power Electronics
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• v.19 no.4
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• pp.858-868
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• 2019

With the widespread use of modern clean energy, lithium-ion batteries have become essential as a more reliable energy storage component in the energy Internet. However, due to the difference in monomers, some of the battery over-charge or over-discharge in battery packs restrict their use. Therefore, a novel multiphase interleaved converter for reducing the inconsistencies of the individual cells in a battery pack is proposed in this paper. Based on the multiphase converter branches connected to each lithium battery, this circuit realizes energy transferred from any cell(s) to any other cell(s) complementarily. This flexible interlaced converter is composed of an improved bi-directional Buck-Boost circuit that is presented with its own available control method. A simulation model based on the PNGV model of fundamental equalization is built with four cells in PSIM. Simulation and experimental results demonstrate that converter and its control achieve simple and fast equalization. Furthermore, a comparison of traditional methods and the HNFABC equalization is provided to show the performance of the converter and the control of lithium-based battery stacks.

• Journal of Korean Society on Water Environment
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• v.36 no.6
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• pp.535-545
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• 2020

This study aims to conserve and monitor energy use in public sewage treatment plants by utilizing data from the SCADA system and by controlling the aeration rate required for maintaining effluent water quality. Power consumption in the sewage treatment process was predicted using the equipment's uptime, efficiency, and inherent power consumption. The predicted energy consumption was calibrated by measured data. Additionally, energy efficiency indicators were proposed based on statistical data for energy use, capacity, and effluent quality. In one case study, a sewage treatment plant operated via the SBR process used ~30% of energy consumed in maintaining the bioreactors and treated water tanks (included decanting pump and cleaning systems). Energy consumption analysis with the K-ECO Tool-kit was conducted for unit processing. The results showed that about 58.7% of total energy consumed was used in the preliminary and biological treatment rotating equipment such as the blower and pump. In addition, the energy consumption rate was higher to the order of 19.2% in the phosphorus removal process, 16.0% during sludge treatment, and 6.1% during disinfection and discharge. In terms of equipment energy usage, feeding and decanting pumps accounted for 40% of total energy consumed following 27% for blowers. By controlling the aeration rate based on the proposed feedback control system, the DO concentration was reduced by 56% compared pre-controls and the aeration amount decreased by 28%. The overall power consumption of the plant was reduced by 6% via aeration control.

• Nuclear Engineering and Technology
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• v.52 no.7
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• pp.1367-1379
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• 2020

The small modular sodium-cooled fast reactor (SMSFR) is an important component of Generation-IV reactors. The objective of this work is to improve the reactivity control in SMSFR by using innovative systems, including burnable poisons and optimized control rods. SMSFR with MOX fuel usually exhibits high burnup reactivity loss that leads to high excess reactivity and potential fuel melting in control rod withdrawal (CRW) accidents, which becomes an important constraint on the safety and economic efficiency of SMSFR. This work applies two types of burnable poisons in a SMSFR to reduce the excess reactivity. The first one homogenously loads minor actinides in the fuel. The second one combines absorber and moderators in specific assemblies. The influence of burnable poisons on the core characteristics is discussed and integrated into the analysis of CRW accidents. The results show that burnable poisons improve the safety performance of the core in a significant way. Burnable poisons also lessen the demand for the number, absorption ability, and insertion depth of control rods. Two optimized control rod designs with rare earth oxides (Eu₂O₃ and Gd₂O₃) and moderators are compared to the conventional design with natural boron carbide (B₄C). The optimized designs show improved neutronic and safety performance.

• Journal of Electrical Engineering and Technology
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• v.3 no.4
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• pp.528-537
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• 2008

Primary frequency control(PFC) has the ability to regulate short period random variations of frequency during normal operation conditions and also to respond rapidly to emergencies. However, during the past decade, numerous significant sized blackouts occurred worldwide that resulted in serious economic losses. Therefore, the conclusion has been reached that the ability of the current PFC to meet an emergency is poor, and security of power systems should be improved. An alternative to enhance the PFC and thus security is to store excessive amounts of energy during off-peak load periods in efficient energy storage systems for substituting the primary control reserve. In this sense, superconducting magnetic energy storage(SMES) in combination with a static synchronous compensator(STATCOM) is capable of supplying power systems with both active and reactive powers simultaneously and very rapidly, and thus is able to enhance the security dramatically. In this paper, a new concept of PFC based on incorporating a STATCOM-SMES is presented. A complete detailed model is proposed and a new control scheme is designed, comprising an enhanced frequency control scheme, and a fully decoupled current control strategy in d-q coordinates with a novel controller to prevent dc bus capacitors voltage drift/imbalance. The performance of the proposed control schemes is validated through digital simulation carried out using MATLAB/Simulink.

• Journal of Hydrogen and New Energy
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• v.22 no.6
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• pp.835-841
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• 2011

The humidification is essential for performance enhancement of the electrolysis of PEMFC because proton conductivity depends on hydration of the proton exchange membrane. In this study, the humidification experiment did about On/Off control the humidification and dew condensation for PEMFC by using of the membrane humidifiers. As the results, it was possible to approximation control of the humidity by using of the solenoid valve On/Off control on the membrane humidifier. Also the problem on the dew condensation was resolved by approximation humidity control through solenoid valve On/Off control and the removal of the dew condensation in the flow channel was verified through visualization experiment.

• Journal of Electrical Engineering and Technology
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• v.12 no.3
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• pp.1007-1015
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• 2017

This paper proposes a new control technique of energy storage system (ESS) for smoothing the active power of renewable energy sources (RES) such as photovoltaic and wind turbine generation. As the penetration of RES into grid increases, it is difficult to maintain the permissible level of power quality, that is, voltage and frequency fluctuation in power systems. To solve this problem, ESS control methods using low pass filter (LPF) have been proposed for mitigating the fluctuation of RES output. However, those have a lot of drawbacks which need to be supplemented. Hence, this paper presents the improved active power control with additional reactive power control for maintaining power quality properly. The proposed method minimizes the capacity of ESS to be required for smoothing RES output fluctuation through mitigation of phase delay problem in LPF. In addition, the voltage regulation improves by using additional reactive power control. The proposed method was verified through simulation analysis using PSCAD/EMTDC.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2765-2770
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• 2003

This paper introduces a novel control algorithm, energy bounding algorithm, for stable haptic interaction. The energy bounding algorithm restricts energy generated by zero-order hold within consumable energy by physical damping that is energy consumption element in the haptic interface. The passivity condition can always be guaranteed by the energy bounding algorithm. The virtual coupling algorithm restricts the actuator force with respect to the penetration depth and restricts generated energy. In contrast, energy bounding algorithm restricts the change of actuator force with respect to time and restricts generated energy by zero-order hold. Therefore, much stiffer contact simulation can be implemented by the energy bounding algorithm. Moreover, the energy bounding algorithm doesn’t is not computationally intensive and the implementation of it is very simple.

• Journal of Navigation and Port Research
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• v.34 no.9
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• pp.705-709
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• 2010

Buildings nowadays are increasingly expected to need higher and more economic performance requirements. Energy consumption in buildings accounts for over 30% of total energy use. The Building Energy Management System (BEMS) and renewable energy (RE) technologies are considered as a potential measure to improve energy efficiency and reduce use of grid-power. It is, however, a challenge to utilise the intermittent energy supply of RE in building energy systems. This paper presents an experimental study on a RE-embedded BEMS. A control algorithm for the RE-embedded BEMS was designed to maximise the utilisation of RE and eventually to reduce electrical utility bill. The proposed system is tested at a laboratorial chamber with an air conditioner, fan and heater. The contribution of RE in building energy system is discussed to this end.

• ETRI Journal
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• v.37 no.4
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• pp.804-812
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• 2015

Energy harvesting (EH) technology in the field of wireless sensor networks (WSNs) is gaining increasing popularity through removing the burden of having to replace/recharge depleted energy sources by energy harvester devices. EH provides an alternative source of energy from the surrounding environment; therefore, by exploiting the EH process, WSNs can achieve a perpetual lifetime. In view of this, emphasis is being placed on the design of new medium access control (MAC) protocols that aim to maximize the lifetime of WSNs by using the maximum possible amount of harvested energy instead of saving any residual energy, given that the rate of energy harvested is greater than that which is consumed. Various MAC protocols with the objective of exploiting ambient energy have been proposed for energy-harvesting WSNs (EH-WSNs). In this paper, first, the fundamental properties of EH-WSN architecture are outlined. Then, several MAC protocols proposed for EH-WSNs are presented, describing their operating principles and underlying features. To give an insight into future research directions, open research issues (key ideas) with respect to design trade-offs are discussed at the end of this paper.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.371-372
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• 2008

In this paper, we consider wireless sensor networks with hard energy constraint, where each node is powered by a small battery. Under this hard constraint, reducing energy consumption is the most important design consideration for wireless sensor networks. Energy saving and control is an important issue, involved in the design of most sensor nodes. In this context, we focus on physical layer design where energy constraint problem can be modeled as an optimization of transmission modulation scheme[1]. Specifically, our analyses are based on energy control schemes that are relative to physical layer design on upper bound SEP MPSK in AWGN channels.