Assessment of the feasibility of interconnected smart DC homes in a DC microgrid to reduce utility costs of low income households
01 Jun 2017-pp 467-473
TL;DR: In this article, a community DC microgrid in an urban environment is analyzed, where up to 9 renovated dwellings are equipped with a smart DC power panel for loads such as LED lights, fans and air conditioning while a portion of loads will remain AC with an AC/DC converter interface between the loads.
Abstract: DC Microgrids (DC MG) present themselves as an obvious choice enabling integration of multiple renewable energy sources and distributed energy storage. This concept of DC electrification of homes in small communities is being explored in many parts of the world. Furthermore, typical household loads are increasingly becoming natively DC. In this paper, a community DC MG in an urban environment is analyzed. In combination with a community revitalization effort, up to 9 renovated dwellings (a mixture of apartments in a commercial property and houses) will be equipped with a smart DC power panel for loads such as LED lights, fans and air conditioning while a portion of loads will remain AC with an AC/DC converter interface between the loads. The smart DC power panel interfaces to the community DC MG. The effectiveness of driving down utility costs in a low-income household using this concept is compared to a home with conventional AC loads and AC loads with smart technologies. The efficacy of the DC MG to optimal installation and usage of solar energy and battery energy storage is determined and a notional smart energy management approach is presented.
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TL;DR: This study aims to provide a comprehensive review of the protection challenges in AC and DC microgrids and available solutions to deal with them.
Abstract: Microgrid, which is one of the main foundations of the future grid, inherits many properties of the smart grid such as, self-healing capability, real-time monitoring, advanced two-way communication systems, low voltage ride through capability of distributed generator (DG) units, and high penetration of DGs. These substantial changes in properties and capabilities of the future grid result in significant protection challenges such as bidirectional fault current, various levels of fault current under different operating conditions, necessity of standards for automation system, cyber security issues, as well as, designing an appropriate grounding system, fast fault detection/location method, the need for an efficient circuit breaker for DC microgrids. Due to these new challenges in microgrid protection, the conventional protection strategies have to be either modified or substituted with new ones. This study aims to provide a comprehensive review of the protection challenges in AC and DC microgrids and available solutions to deal with them. Future trends in microgrid protection are also briefly discussed
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119 citations
01 Nov 2017
TL;DR: This paper addresses discrimination of sudden short circuit faults using an ultra-fast normally-on Silicon Carbide (SiC) Junction Field Effect Transistor (JFET)-SiC based solid state circuit breaker (SSCB).
Abstract: A residential DC microgrid is being built in an underserved community in Milwaukee, Wisconsin. The short circuit protection for this DC system and discrimination of faults along the interconnecting cables is a significant challenge. This paper addresses discrimination of sudden short circuit faults using an ultra-fast normally-on Silicon Carbide (SiC) Junction Field Effect Transistor (JFET)-SiC based solid state circuit breaker (SSCB). JFET gating for turn-off is self-powered from the drain to source voltage that occurs during a high current fault. Fault characterization of the system is performed using PLECS — a high resolution power electronics systems simulation platform. Fault discrimination of series connected SiC JFETs, with settings adjusted by a simple resistor change, is a validated both using an LTSPice model and a laboratory test fixture.
16 citations
Journal Article•
TL;DR: It was found that when multiple conditioners are connected to the dc bus in a renewable energy system for household, it is possible to realize autonomous charging with good balance even without the current balance control.
Abstract: The control of CO2 emission is a global urgent issue, and the decarbonizing is being promoted in various fields. Also at residences, the electricity consumption is increasing instead of fossil fuels because of the electrification of heat source, shifting from gasoline car to EV and so on, therefore the reduction of the increasing burden of commercial power generation caused by the increase of electricity consumption at residence is extremely important task. Distributed power systems for households that can supply necessary electricity by renewable energy to each house is considered to be an effective solution. In order that the distributed power system which is desirable to be able to use various renewable energy become widely used for households, independent and autonomous operation of each power source is an important factor. This paper presents the behaviour of the power control in parallel operation of dc-dc converters directly connected to the dc bus with battery and the power behaviour of whole system. As a result, it was found that when multiple conditioners are connected to the dc bus in a renewable energy system for household, it is possible to realize autonomous charging with good balance even without the current balance control. It is important to expand use of the combination of dc bus and autonomous converters to utilize various renewable energy sources in the EV society coming in the near future.
10 citations
TL;DR: This article identifies and validates the use of ultrafast silicon carbide (SiC) junction field effect transistor (JFET)-based self-powered solid-state circuit breakers (SSCBs) as the enabling protective device for a 340 Vdc residential dc community microgrid.
Abstract: This article identifies and validates the use of ultrafast silicon carbide (SiC) junction field effect transistor (JFET)-based self-powered solid-state circuit breakers (SSCBs) as the enabling protective device for a 340 Vdc residential dc community microgrid. These SSCBs will be incorporated into a radial distribution system in order to enhance fault discrimination through autonomous operation. Because of the nature and characteristics of short-circuit fault inception in dc microgrids, the time–current trip characteristics of protective devices must be several orders of magnitude faster than conventional circuit breakers. The proposed SSCBs detect short-circuit faults by sensing the sudden voltage rise between its two power terminals and draw power from the fault condition itself to turn off SiC JFETs and then, coordinate with no-load contacts that can isolate the fault. Depending upon the location of the SSCBs in the microgrid, either unidirectional or bidirectional implementations are incorporated. Cascaded SSCBs are tuned using a simple resistor change to enable fault discrimination between upstream high-current feeds and downstream lower current branches. Operation of one of the SSCBs and three in cascaded arrangements are validated both in simulation and with a hardware test platform. Thermal impact on the SSCB is discussed as well. The target application is a residential dc microgrid that will be installed as part of a revitalization effort of an inner city Milwaukee neighborhood.
8 citations
Cites background from "Assessment of the feasibility of in..."
...Long lengths of wires between JFETs in a more realistic scenario would tend to reduce the compressed time response demands on the SSCB implementation and provide a wider range of adjustment for fault discrimination [12]....
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...3 and it was demonstrated that the current characteristics of a fault internal to the house are distinguishable from upstream feeds only by small amplitude differences that occur within a window of several microseconds [11], [12]....
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20 May 2019
TL;DR: In this article, a DC microgrid constructed on an island is introduced and discusses a centralized operation method for the DC system that optimizes the operation of a DC mini-grid.
Abstract: This paper introduces and discusses a DC microgrid constructed on an island. KEPCO constructed a DC microgrid system on an island called Seogeochado (West Geocha Island) through the ‘DC Island’ project. With regard to the DC Island project, which operates a DC system from generation source to customer, this paper examines the development of LVDC equipment and the implementation of an LVDC microgrid system based on calculations of the optimal renewable energy capacity performed by HOMER, an economic feasibility analysis tool. Also, this paper suggests a centralized operation method for the DC system that optimizes the operation of a DC microgrid on an island and discusses its demonstration.
8 citations
Cites background from "Assessment of the feasibility of in..."
...If DC microgrid systems are implemented for renewable energy sources such as PV and ESS and DC customers, easy interfacing with distributed renewable energy sources can be achieved while also increasing energy efficiency [1,2]....
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References
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TL;DR: The simulation results verify that the proposed hierarchical coordination strategy is an effective and efficient way for coordinating microgrid flows in an islanded community microgrid, while maintaining the rated frequency and voltage with each microgrid.
Abstract: In this paper, a community microgrid with multiple ac and dc microgrids is introduced and analyzed. Individual microgrids with different frequency and voltage requirements would operate as self-controlled entities, which could also cooperate with neighboring microgrids for providing back-up operations in the community microgrid. A hierarchical coordination strategy with primary, secondary, and tertiary coordination is proposed for the economic operation of an islanded community microgrid. The hierarchical strategy is also applied to a grid-connected community microgrid and the results are discussed. The simulation results verify that the proposed hierarchical coordination strategy is an effective and efficient way for coordinating microgrid flows in an islanded community microgrid, while maintaining the rated frequency and voltage with each microgrid. The simulation results also demonstrate the economic operation of a grid-connected community microgrid in which individual microgrids operate as autonomous agents, while satisfying the community objectives.
304 citations
TL;DR: A microgrid eases the integration of renewable energy sources (RESs) and energy-storage systems (ESSs) at the consumption level, aiming to increase power quality, reliability, and efficiency.
Abstract: The evidence that climate change is real and most likely caused by human-related activities has made the international community consider a new energy model. Europe has led the initiative, moving away from fossil fuels toward renewable energies, while powerful countries such as the United States and China are lagging behind and still rely heavily on coal, gas, and oil as energy sources. Europe has set ambitious goals for 2020 regarding the increase of renewable energy production, energy efficiency, and greenhouse gas emission reduction. The concept of a microgrid is perfectly aligned with the new energy strategy. A microgrid eases the integration of renewable energy sources (RESs) and energy-storage systems (ESSs) at the consumption level, aiming to increase power quality, reliability, and efficiency. The increasing importance of dc-based loads has reopened the discussion of dc versus ac distribution systems. As a consequence, much research has been done on dc distribution systems and their potential for residential applications. Furthermore, the growing presence and use of smart devices in homes reveal a promising future for intelligent homes integrated in the Internet of Things (IoT), where residential electrical power systems work in cooperation with smart devices to achieve smarter, more sustainable, and cleaner energy systems.
177 citations
"Assessment of the feasibility of in..." refers background in this paper
...The Appliance and Power Conversion Factors are derived from various studies online and published studies of smart AC and DC loads [26]-[31]....
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...The homes in the DC CMG can achieve more benefits if smart DC loads are incorporated into the home [26]....
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25 Jul 2010
TL;DR: In this paper, an overview of the recent advancement and also envisioned research and development on DC grids, with the objective of identification and discussion of the corresponding issues is presented and discussed.
Abstract: The ever increasing penetration depth of Distribution Energy Resources (DER) and the development of power electronics devices have a significant impact on the development of DC power transmission and distribution systems. This paper provides an overview of the recent advancement and also envisioned research and development on DC grids, with the objective of identification and discussion of the corresponding issues. Brief descriptions of DC grids at various voltage levels and their benefits are presented and discussed. Different layouts for the DC grids are presented and the associated technical issues are highlighted.
155 citations
"Assessment of the feasibility of in..." refers background in this paper
...AC supplies would necessarily include their own AC to DC converters, which waste between 7-12% of the energy used [14], [15]....
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07 Jun 2015
TL;DR: The European ENIAC R&D project consortium DC Components and Grid (DCC+G) is developing suitable, highly efficient components and sub systems for 380 VDC grid to show the benefits of DC grid concept on test site in an office environment as mentioned in this paper.
Abstract: The European ENIAC R&D project consortium DC Components and Grid (DCC+G) is developing suitable, highly efficient components and sub systems for 380 VDC grid to show the benefits of DC grid concept on test site in an office environment. The newly developed DC grid components and their integration into a generic system are presented in this paper. The targeted overall efficiency saving compared to AC grid is 5% and the energy conversion from PV (photo voltaic) is calculated to be 7% more cost effective compared to traditional PV installations. This paper also shows the realized DC grid prototypesupplying an office building of the Fraunhofer Institute in Erlangen, Germany, and describes general benefits of a DC grid system. The DC grid prototypeconsists of a DC lighting system, a DC low power supply for IT infrastructure, DC electric vehicle charger, a DC μCHP unit, DC photovoltaic MPPT units, a central rectifier and grid controller unit as well as a mixed AC/DC power monitoring unit. It is shown that less conversion losses and higher distribution efficiency can be achieved with a 380 VDC grid compared to conventional AC grids.
95 citations
"Assessment of the feasibility of in..." refers background in this paper
...In [2], low voltage DC grid prototype with some DC loads are explored....
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18 May 2012
TL;DR: In this article, the characteristics of current and potential future DC products and power systems are described and compared. But, the authors focus on DC power systems, and do not address DC power control systems.
Abstract: This document catalogs the characteristics of current and potential future DC products and power systems
90 citations