Energy Management System of DC Microgrid in Grid-Connected and Stand-Alone Modes: Control, Operation and Experimental Validation

Lee, Hoon; Kang, Jiwoo; Choi, Bong-Yeon; Kang, Kyung-Min; Kim, Mina; An, Chang-Gyun; Yi, Junsin; Won, Chung-Yuen

doi:10.3390/en14030581

Cited by 11 publications

(6 citation statements)

References 27 publications

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“…To simplify the analysis of the magnetic circuit, Figure 2a,b were replaced with a simple magnetic circuit and an equivalent circuit, respectively, as shown in Figure 2c. In the magnetic circuit shown in Figure 2c, l c is the effective length of the iron core, l g is the effective length of the air gap is l g , and the magnetomotive force is given by Equation (2).…”

Section: Force Characteristics Of Electromagnetic Contactorsmentioning

confidence: 99%

“…Recently, the importance of direct current (DC)-type electromagnetic contactors (MCs) has increased owing to the activation of renewable power sources, microgrids, electric vehicles, and the like [1][2][3]. In the future, when the full DC power demand is achieved, many MCs are expected to be driven by DC power owing to the lack of sufficient alternating current (AC) power [4,5].…”

Section: Introductionmentioning

confidence: 99%

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Two-Level Excitation Current Driver to Reduce the Driving Power of an Electromagnetic Contactor

Park,

Kim,

Lim

2024

Electronics

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As the capacity of the electrical system increases, so does the capacity of the electromagnetic contactor (MC). This increases the burden on the MC drive, which consumes unnecessary power in the system. MC is characterized by different initial starting-operating currents and holding currents to maintain contact. However, the operating voltage is constant regardless of the operating state. The initial starting current is considerably larger than that required to maintain contact. However, once the electromagnetic contactor is in the closed state, the current to maintain the contact is relatively small compared to the initial starting operating currents. Therefore, this study proposes two types of two-level excitation-current type MC drives that can reduce the drive power by employing features that have different conditions depending on the operating state of the MC. The overall drive power is reduced by applying different excitation currents based on the operating state. The controller and system proposed in this study were simulated using Powersim 9.1 (PSIM), and the feasibility was verified by manufacturing an analog-type driver using LM2576 and a digital-type driver using an MCU. The simulation and experimental results provide significant data for verifying the high performance and reliability of the proposed controller and system.

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Section: Force Characteristics Of Electromagnetic Contactorsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Two-Level Excitation Current Driver to Reduce the Driving Power of an Electromagnetic Contactor

Park,

Kim,

Lim

2024

Electronics

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“…A general configuration of a hybrid MG with distributed generation (DG) and loads connected to both the AC and DC buses is shown in Figure 1 [18]. A converter between both systems, called an ILC, controls the voltage and current.…”

Section: Configuration Of the Hybrid Microgridmentioning

confidence: 99%

A Study on Energy Management and Cooperative Control Considering LVRT in a Hybrid Microgrid

Lee

Kim

et al. 2023

Energies

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Recently, the establishment of technical standards for grid connection has gained interest in academia and industry. These standards have focused on the reactive power control function of the grid-connected inverter and maintenance of grid operation, and include detailed information about the grid support function. However, remote control communication and control devices for grid support functions, and other distributed sources, such as wind power and energy storage systems, other than inverters have not been addressed. In this paper, the control of the interlinking converter (ILC) in a hybrid microgrid considering low voltage ride-through (LVRT) among grid support functions is investigated. The proposed method consists of an energy management system considering LVRT and a cooperative control scheme. In the energy management system, an algorithm capable of mode selection was constructed by applying the LVRT curve. Then, considering the LVRT situation, the allowable reactive power range of the ILC was mathematically analyzed through the cooperative control of the energy storage device and the ILC. The proposed method enables us to perform active and reactive power control of the ILC in a hybrid distribution network, considering the power factor under various conditions. This functionality, such as supplying reactive power, significantly contributes to the enhanced grid resilience with distributed power sources, including renewable energy. The proposed strategies were verified through experiments after configuring an experimental set of distributed power sources.

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“…An alternative approach with increasing research focus is the application of direct current (DC) microgrids [16] that can improve distribution efficiency by reducing power conversion stages. Research on distributed energy resources using renewable energy on DC microgrids is gaining momentum [17]. As battery costs decline and electricity prices fluctuate more, the battery would gradually replace cooling storage.…”

Section: Introductionmentioning

confidence: 99%

The Interaction between Short- and Long-Term Energy Storage in an nZEB Office Building

Stamatellos,

Stamatellou

2024

Energies

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The establishment of near-autonomous micro-grids in commercial or public building complexes is gaining increasing popularity. Short-term storage capacity is provided by means of large battery installations, or, more often, by the employees’ increasing use of electric vehicle batteries, which are allowed to operate in bi-directional charging mode. In addition to the above short-term storage means, a long-term storage medium is considered essential to the optimal operation of the building’s micro-grid. The most promising long-term energy storage carrier is hydrogen, which is produced by standard electrolyzer units by exploiting the surplus electricity produced by photovoltaic installation, due to the seasonal or weekly variation in a building’s electricity consumption. To this end, a novel concept is studied in this paper. The details of the proposed concept are described in the context of a nearly Zero Energy Building (nZEB) and the associated micro-grid. The hydrogen produced is stored in a high-pressure tank to be used occasionally as fuel in an advanced technology hydrogen spark ignition engine, which moves a synchronous generator. A size optimization study is carried out to determine the genset’s rating, the electrolyzer units’ capacity and the tilt angle of the rooftop’s photovoltaic panels, which minimize the building’s interaction with the external grid. The hydrogen-fueled genset engine is optimally sized to 40 kW (0.18 kW/kWp PV). The optimal tilt angle of the rooftop PV panels is 39°. The maximum capacity of the electrolyzer units is optimized to 72 kW (0.33 kWmax/kWp PV). The resulting system is tacitly assumed to integrate to an external hydrogen network to make up for the expected mismatches between hydrogen production and consumption. The significance of technology in addressing the current challenges in the field of energy storage and micro-grid optimization is discussed, with an emphasis on its potential benefits. Moreover, areas for further research are highlighted, aiming to further advance sustainable energy solutions.

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Energy Management System of DC Microgrid in Grid-Connected and Stand-Alone Modes: Control, Operation and Experimental Validation

Cited by 11 publications

References 27 publications

Two-Level Excitation Current Driver to Reduce the Driving Power of an Electromagnetic Contactor

Two-Level Excitation Current Driver to Reduce the Driving Power of an Electromagnetic Contactor

A Study on Energy Management and Cooperative Control Considering LVRT in a Hybrid Microgrid

The Interaction between Short- and Long-Term Energy Storage in an nZEB Office Building

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