DC microgrid in residential buildings (original) (raw)

The Low Voltage Direct Current (LVDC) system concept has been growing in the recent times due to its characteristics and advantages like renewable energy source compatibility, more straightforward integration with storage utilities through power electronic converters, and distributed loads. This paper presents the energy efficiency performances of a proposed LVDC supply concept and other classical PV chains architectures. A PV source was considered in the studied nanogrids. The notion of relative saved energy (RSE) was introduced to compare the studied PV systems energy performances. The obtained results revealed that the use of the proposed LVDC chain supply concept increases the nanogrid efficiency. The installed PV power source in the building should be well sized regarding the consumed power in order to register a high system RSE. The efficiency of the new LVDC architecture is 10% higher than the conventional LVDC one.

Direct current (DC) microgrids (MG) constitute a research field that has gained great attention over the past few years, challenging the well-established dominance of their alternating current (AC) counterparts in Low Voltage (LV) (up to 1.5 kV) as well as Medium Voltage (MV) applications (up to 50 kV). The main reasons behind this change are: (i) the ascending amalgamation of Renewable Energy Sources (RES) and Battery Energy Storage Systems (BESS), which predominantly supply DC power to the energy mix that meets electrical power demand and (ii) the ascending use of electronic loads and other DC-powered devices by the end-users. In this sense, DC distribution provides a more efficient interface between the majority of Distributed Energy Resources (DER) and part of the total load of a MG. The early adopters of DC MGs include mostly buildings with high RES production, ships, data centers, electric vehicle (EV) charging stations and traction systems. However, the lack of expertise and ...

Low voltage direct current (LVDC) distribution systems have recently been considered as an alternative approach to provide flexible infrastructure with enhanced controllability to facilitate the integration of low-carbon technologies (LCTs). To date, there is no business-as-usual example of LVDC for utility applications and only few trials have been developed so far. The deployment of LVDC in general will present revolutionary changes in LV distribution networks. This will require are thinking of network design principles and the enablement of integrated solutions. This discussion paper reviews the current practice in utility-scale LVDC distribution networks worldwide. The paper also presents a new multi-zone architecture approach which can be used to better understand future of LVDC systems, and exploit their inherent flexibility to allow synergistic integration of multiple energy technologies.

The increasing penetration of PV into the distribution grid leads to congestion, causing detrimental power quality issues. Moreover, the multiple small photovoltaic (PV) systems and battery energy storage systems (BESSs) result in increasing conversion losses. A low-voltage DC (LVDC) backbone to interconnect these assets would decrease the conversion losses and is a promising solution for a more optimal integration of PV systems. The multiple small PV systems can be replaced by shared assets with large common PV installations and a large BESS. Sharing renewable energy and aggregation are activities that are stimulated by the European Commission and lead to a substantial benefit in terms of self-consumption index (SCI) and self-sufficiency index (SSI). In this study, the benefit of an LVDC backbone is investigated compared to using a low-voltage AC (LVAC) system. It is found that the cable losses increase by 0.9 percent points and the conversion losses decrease by 12 percent points compared to the traditional low-voltage AC (LVAC) system. The SCI increases by 2 percent points and the SSI increases by 6 percent points compared to using an LVAC system with shared meter. It is shown that an LVDC backbone is only beneficial with a PV penetration level of 65% and that the BESS can be reduced by 22% for the same SSI.

In the present scenario, electronic load is continuously increasing in the buildings which needs Direct Current (DC) input. These loads require conversion from AC to DC power. On the other hand the Renewable Energy Sources (RES) such as Solar Photovoltaic (PV) produce DC power which has to be converted into AC to tie into electric power systems and again converted into DC for DC compatible loads. These AC-DC and DC-AC-DC conversion stages introduce the energy losses. The DCDS eliminates the conversion stages. It can also decrease the power losses to an acceptable extent. In this paper two case studies have been described 1) the building is based on the AC Distribution System (ACDS) and supplied by public utility including PV and battery bank, 2) The building is based on DC Distribution System (DCDS) equipped by PV and battery bank including public utility. Results have been simulated in the LABVIEW environment. Outcomes show that the DC distribution system with DC internal technology appliances provide the largest energy saving and reduce the building load.

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The main problem of energy supply in the developing counties is that a very large portion of their rural population still does not have access to a secure supply of electricity. DC microgrids seems an attractive solution due to lower capital, operation, engineering and maintenance costs. Many developing countries have shown interest in the development of such systems in order to improve the quality of their inhabitants’ life, together with the development of the local economies (creation of new jobs) through the creation of local energy communities. This paper reviews the conditions under which DC microgrids provide an attractive option for local energy communities in the developing world. It also reviews the best practices of DC local energy communities in developing countries and highlights relevant issues, e.g. regulatory framework, standardization, protection, secure supply etc. that have to be faced, in order to establish DC microgrids in rural areas