Decentralized current limiting in meshed DC distribution grids

Abstract

Meshed dc distribution grids have advantages over radial connected ones. Challenges arise when this is done on the same voltage level and the full potential power might not be usable in certain configurations. This paper shows how the power flow in meshed dc grids can be increased by limiting the currents at congested lines. This can be done in a decentralized way with only local current measurements. Several realization possibilities for current limiting devices are introduced and discussed. Dynamic simulations are performed.978-1-4799-9880-7/15/$31.00 ©2015 IEEE

Toward the Universal DC Distribution System

“…With the increased utilization of the grid infrastructure due to electrical vehicles, heat pumps and solar panels, it would be preferable to take advantage of available meshed connections [18]. In DC distribution grids, DC/DC or AC/DC converters take the role of traditional AC transformers.…”

“…Large galvanically connected low voltage grids could emerge which have to be taken into account for power flow control and protection. Ensuring line limits can be done in a decentralized way without communication [18].…”

Towards a DC distribution system - opportunities and challenges

“…Current limiting can be used to increase the maximum power transfer between different nodes when there are many paths from one node to another node having differences in impedance [11]. By varying the voltage drop over the current limiting element in the line, maximum power transfer can be obtained.…”

Partially Rated Power Flow Control Converter Modeling for Low-Voltage DC Grids

“…In any dc system, a challenge is to achieve efficient load sharing [10]. This challenge is enhanced when multiterminal (meshed) or ring topologies are used and is referred to as current limiting or power flow control [24], [25]. Power flows in meshed grids are coupled since the number of interconnection between nodes is higher than the number of nodes.…”

“…Different approaches were already introduced for the power flow control, both for high voltage dc and lvdc grids. The first method is based on changing the line resistance with a variable resistor and was described for both the hvdc [26], [27], and lvdc [25]. Naturally, such an approach is inherently inefficient.…”