Low voltage DC distribution - are we ready yet?
01 Dec 2016-pp 1-6
TL;DR: A suitable voltage level of 48 V, and a suitable distribution scheme are presented along with some field experiences of installation of such systems as discussed by the authors, along with a suitable power distribution scheme.
Abstract: With the increasing use of power electronics in all types of appliances, and with the increasing penetration of solar PV, distribution of power in the DC form is becoming attractive This paper brings together various concerns that have been expressed in DC distribution at low voltages for consumption in domestic and other building needs The paper presents various arguments and attempts to arrive at a solution from various points of view A suitable voltage level of 48 V, and a suitable distribution scheme are presented along with some field experiences of installation of such systems
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TL;DR: In this article , the feasibility of low voltage direct current distribution system and its impact on social development is evaluated using the two largest scientific databases (SCOPUS and WOS) where the query (low voltage direct-current microgrid) resulted in 198 articles.
Abstract: The popularity of renewable energy systems has contributed significantly in the last years to the utility of low voltage direct current microgrids. However, these systems come with new challenges. This survey focuses on introducing a state-of-the-art low voltage direct current distribution system and sheds light on the challenges that must be faced in order to complete energy transition. This literature review was systematically carried out using the two largest scientific databases (SCOPUS and WOS) where the query (low voltage direct current microgrid) resulted in 198 articles. The purpose of this paper is not to reiterate the comparison of direct current with alternating current systems, which has already been discussed extensively. Instead, the objective of this survey is to assess the feasibility of the low voltage direct current distribution system and its impact on social development. To this end, this work provides valuable information for renewable energy planners, giving some insights or solutions to bridge the gap between the current energy network and the future DC energy microgrids. In particular, this article focuses on parameters such as grid topologies, distribution and voltage standardization efforts. The three major findings are: (i) the off-grid solutions enhance the efficiency rate in energy facilities (from 15% to 30%), and the vast majority of them are supported with energy storage systems to increase their reliability. However, in economic terms the most suitable systems still are the grid-connected solutions. Another finding is that (ii) the bus configurations are most used as well as the best in terms of their effectiveness to distribute low voltage and direct current energy within the microgrid. Lastly, (iii) the voltage value standardization around 48 V and 380 V, and even though there seems to be a clear convergence between them, the lack of agreement is delaying the massive implementation of these solutions worldwide. Finally, a novel assessment of social impacts and reflections on low voltage direct current microgrids is also included.
15 citations
01 Dec 2019
TL;DR: Time-domain simulations of each of these structures are discussed to confirm the need for the DDC to make a shift from conventional single-input-single-output (SISO) based two-port DDC configuration to the multi- input-multi- output (MIMO) based multiport designs.
Abstract: DC-DC power conversion, ranging from volt-fraction to ten of kVs, and mWs-MWs, is found in various applications, the latter making a human’s life comfortable. DC motor drives [1], telecommunications [2], satellite [3], fuel cell electric vehicles [4], are among many other such applications. The literature reports a large number of topology, and design variants of a DC-DC converter (DDC) as in [5]– [17] and references within, to achieve an improvement in the efficiency [18] of the DC-DC power conversion. The advent of novel configurations enables the DDC to make a shift from conventional single-input-single-output (SISO) based two-port DDC configuration to the multi-input-multi-output (MIMO) based multiport designs. This article highlights the need of this structure shift by detailing the SISO, multi-input-single-output (MISO), single-input-multi-output (SIMO), and the MIMO DDC structures. Afterward, this brief discusses time-domain simulations of each of these structures to confirm the aforesaid structure shift.
4 citations
01 Dec 2018
TL;DR: This paper shows that implementing hierarchical control for the residential distributed generation paves way for the power-sharing across different community grids thereby upgrading the existing AC smart grid operation.
Abstract: The recent advancements in renewable energy technologies is empowering residential consumers to meet their energy requirements from locally installed renewable energy devices and energy storage devices. In this context, the adjacent microgrids can interact and share these resources using a stable strategy through which economic, environmental and operational advantage can be gained. In this paper a three-level hierarchical control is introduced into residential houses to effectively share the power between houses coming under the community microgrid in such a way that users will get power at an optimized price. The hierarchical control algorithm is developed for primary control (Local control center), secondary control (Microgrid control center) and tertiary control (Upstream control). This paper shows that implementing hierarchical control for the residential distributed generation paves way for the power-sharing across different community grids thereby upgrading the existing AC smart grid operation.
2 citations
TL;DR: In this paper, a hybrid arrangement of combining the power harnessed from both the wind and the sun and stored in a battery can be a much more reliable and reliable and realistic power source.
Abstract: One of the major challenge in the power generation is heavily depends of thermal power plant based on coal, at the same time for construction of coal based thermal plant there is restriction from environment aspects, so it is necessary to promote renewable energy like solar and wind energy generation. In case of installing the hybrid energy system, the main causes behind requirement of this installation is the intermittency of various energy resources and unbalanced quantity of sources of energies. The performances of solar PV and wind turbine connected hybrid generating systems are much better in conditions where the sunbeam and wind shifts their rate of availability based on the seasonal changes. A hybrid arrangement of combining the power harnessed from both the wind and the sun and stored in a battery can be a much more reliable and reliable and realistic power source. But, still the load can be powered through the energy stored in the batteries even when there is absence of solar or wind. Hybrid system is usually built for design of system with lowest possible cost and also with maximum reliability. The high cost of solar PV cell makes it less competent for larger capacity designs.
References
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TL;DR: In this article, the use of DC power system to supply sensitive electronic loads is treated, and general design issues regarding DC power systems are discussed, and then the measurement results from a scaled laboratory setup are presented.
Abstract: In this paper, the use of DC power system to supply sensitive electronic loads is treated. First, general design issues regarding DC power systems are discussed, and then the measurement results from a scaled laboratory setup are presented. The results show that it is possible to supply sensitive electronic loads through an AC/DC interface, and to keep them online during grid transients. The use of a DC power system to supply sensitive electronic loads will have lower losses compared with a conventional AC uninterruptible power-supply solution due to fewer power conversion steps.
546 citations
"Low voltage DC distribution - are w..." refers background in this paper
...There has been much debate on a suitable voltage level for distribution [1,2]....
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23 Dec 2010
TL;DR: In this paper, suitable power electronic interfaces for sources/loads/storage elements are discussed along with their performance requirements, and the efficiency, cost and safety issues of the dc system with various voltage levels are compared.
Abstract: Depleting fossil fuels, increasing energy demand and concern over climate change due to CO 2 emission motivate the use of renewable sources. However, supplying electronics, variable speed drives and LED loads from renewable sources requires multiple ac-dc and dc-ac conversions. This causes substantial energy wastage before end use. To address this limitation, dc system is suggested, which offers high efficiency and reliability with low system cost. In this paper, suitable power electronic interfaces for sources/loads/storage elements are discussed along with their performance requirements. Further, efficiency, cost and safety issues of the dc system with various voltage levels are compared. With suitable case studies, optimal dc voltage level is determined for residential and commercial application. The proposed dc system with this optimum voltage level offers 10–22% improvement in energy efficiency over the conventional ac system.
207 citations
"Low voltage DC distribution - are w..." refers background in this paper
...There has been much debate on a suitable voltage level for distribution [1,2]....
[...]
...Based on a study of all the above factors including power conversion considerations [2], it is proposed that 48V be adopted as the voltage for DC distribution systems for...
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TL;DR: A recent study conducted by the Council for Energy, Environment, and Water (CEEW) across six states (Bihar, Jharkhand, Madhya Pradesh, Uttar Pradesh, West Bengal, and Odisha) found that about 50% of the households had no electricity despite having a grid connection as discussed by the authors.
Abstract: It is well established that access to energy is closely linked with socioeconomic development. India houses the largest share of the world's population deprived of electricity with about 237 million people lacking access (International Energy Agency). At the same time, in India, many households that do have access to electricity lack an uninterrupted and quality power supply. A recent study conducted by the Council for Energy, Environment, and Water (CEEW) across six states (Bihar, Jharkhand, Madhya Pradesh, Uttar Pradesh, West Bengal, and Odisha), found that about 50% of the households had no electricity despite having a grid connection. This indicates that there is an immediate need to address the quality, affordability, and reliability of the power supply in addition to extending the grid footprint.
84 citations
"Low voltage DC distribution - are w..." refers background in this paper
...Recent trials in providing uninterrupted power to Indian homes also make use of 48 V DC distribution [4-6]....
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07 Jun 2015
TL;DR: In this article, an efficient and affordable solar DC solution for powering off-grid homes is presented. But, the proposed solution is not suitable for the use of the generated PV power efficiently.
Abstract: India is a power deficit country and one third of its homes are off grid or near off grid. This paper presents an efficient and affordable Solar DC solution for powering such homes. Though several solutions have emerged in the past for powering these homes, those have been expensive and energy inefficient. These solutions rely on several DC to AC and AC to DC conversions, to feed the widely used AC home loads, thus, wasting a large chunk of the expensive power. The proposed Solar DC solution for off-grid homes (OGH) is developed to use the generated PV power efficiently. With this solution, the panel and battery size is reduced by 2 to 2.5 times and the cost to power a house is reduced to nearly half the cost of the existing solutions. The paper also presents a techno-economic comparison between the proposed OGH solution with some existing solar systems.
43 citations
"Low voltage DC distribution - are w..." refers background in this paper
...Recent trials in providing uninterrupted power to Indian homes also make use of 48 V DC distribution [4-6]....
[...]
07 Jun 2015
TL;DR: In this paper, a load management innovation to provide a limited but uninterrupted DC power supply to homes in India is presented, which enables addition of solar power directly to the DC power line and use of battery, without any converter.
Abstract: This paper presents a load-management innovation to provide a limited but uninterrupted DC power supply to homes in India. In a typically power deficient situation, load shedding becomes unavoidable. The duration and areas where load is shed are typically cycled. In worst situation, power outages last for a greater part of the day. To enable every home to get at least a limited amount of power 24×7, an innovative approach that combines use of DC power and load management has been proposed and implemented in several hundred homes in various locations. In order to make best use of limited power, a DC power line and energy efficient DC appliances are introduced and installed at homes. The approach also enables addition of solar power directly to the DC power line and use of battery, without any converter; the power-limit on DC line can thus be overcome. The paper describes the rationale, implementation and user feedback of the approach. Further improvements and plan for future are indicated.
10 citations
"Low voltage DC distribution - are w..." refers background in this paper
...Recent trials in providing uninterrupted power to Indian homes also make use of 48 V DC distribution [4-6]....
[...]