A Low-Voltage DC Backbone with Aggregated RES and BESS: Benefits Compared to a Traditional Low-Voltage AC System

Abstract

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.

Impact Assessment of Electric Vehicle Charging in an AC and DC Microgrid: A Comparative Study

“…The latter connects the LVDC backbone through a central DC/AC inverter to the point of common coupling (PCC) of the AC microgrid, further referred to as the single point of connection (SPoC). Another finding of the referred study [9] is that conversion losses in the proposed architecture can decrease significantly-up to 12 percentage points-compared to a traditional AC microgrid. This is mainly driven by the favourable system voltages which led to a lower voltage ratio and hence lower conduction and switching losses of the converter.…”

“…In that context, previous research has demonstrated that an LVDC backbone architecture benefits from multiple advantages for energy communities centred on a single feeder [9]. LVDC backbones consist of aggregated PV systems and a central BESS.…”

Optimization over decision trees: a case study for the design of stable direct-current electricity networks

“…charging stations for e-mobility or computer systems, operate on a DC basis. The interconnection of these components in DC microgrids, which are typically operated as subsystems of AC grids, avoids unnecessary dc-ac and AC-DC conversion and enables a cost-efficient subgrid design as well as an increased self-consumption of renewable energies, see Azaioud et al (2021). An essential element for the reliable design and operation of LVDC microgrids is the preservation of network stability.…”

An approach to the impedance modelling of low-voltage cables in digital twins

“…Primitive impedance matrices or series impedances form the foundation for modelling distribution networks. Unbalance analysis or harmonic inspection, as well as simulations of the impact RES generates on distribution networks [19,[24][25][26][27] necessitate accurate modelling of the lines in order to produce accurate results. While calculating the primitive impedance matrix, geometrical parameters are important.…”