Energy distribution with DC microgrids in commercial buildings with power electronics

Abstract

This paper describes the application of a distributed DC microgrid in a commercial environment as well as the current state of the art and standardization efforts. The introduced grid features various sources and loads being interconnected with a 380 VDC bus. Here, focus lies on the implementation of a DC fast charge station for electro mobility into a DC grid as well as to elaborate the advantages compared to charging from the AC grid. Additionally, the application of DC nanogrids in workplace environments and their combination with a superordinate DC microgrid is presented. The benefits offered by nanogrids compared to conventional AC power supply in an office are discussed as well. Finally, the hardware to realize a DC microgrid within one electrical cabinet is introduced. Its versatility to fulfill a wide range of functions in the grid is shown as well

On Bidirectional DC Nano-Grids: Design Considerations and an Architecture Proposal

“…This has the same efficiency as the unipolar 380 V buses but is slightly safer and requires a third wire. The second solution is based on two or more DC buses with different voltage levels [4,7,15]. The high voltage DC bus (HV bus) is used for high power loads, RES and ESS, which are rarely disconnected from the grid.…”

“…It is not easy to set a single safe voltage for the LV bus. The most common proposals are 48 V [4,16], 24 V [7,15,16], and 12 V [16]. Another option is having a smart BP that is able to detect the load and to adapt its output voltage accordingly.…”

“…Some authors also propose substituting the traditional AC distribution with DC in these sub-grids, reducing the amount of energy transformations and improving the overall efficiency. Although this is especially relevant in data centers, where it is quite common to use DC nano-grids [7][8][9], it is also interesting for a household. As most of the loads in a house, RSS and ESS are DC native so it makes sense to adopt this DC nano-grid approach.…”

BLOND, a building-level office environment dataset of typical electrical appliances

“…Information and Communication Technology (ICT) devices, including computers, monitors, networking equipment, and battery chargers, mostly use direct current (DC) and require a power supply module. Recently, field research and trials have been conducted with buildings offering DC power sockets, removing the need for SMPSs 27 , 28 . Recent studies found that SMPSs can have a significant effect on EEM accuracy and can cause deviations of up to 582% when comparing smart meters to conventional meters 29 .…”

Analytical approach for industrial microgrid infeed peak power dimensioning

“…The switch from conventional AC to DC power supply infrastructure has become an increasingly discussed topic due to several promising benefits increasing overall energy efficiency potential reduction of the amount of raw materials necessary for energy transmission such as copper and insulation materials and minimizing the power conversion stages on the overall system level as discussed by [1], [2], [3], [4]. DC supply grids also enable more energy efficient adaption of renewable energy sources, such as photovoltaic panels, and energy storage elements being batteries since generation of DC voltage is inherent behavior of such technologies [5]. An application of a DC grid based robot work cell has been discussed as example for analytical power profile research within current paper.…”