Investigation of smart grid topologies using pilot installations experimental results

Abstract

In order to make smart grid feasible, the respective (a) topology and (b) control infrastructure should be determined first for the low level of the grid, i.e. microgrids or even smaller grids like a residential in-house grid, and be expandable in a larger scale. Additionally, the experimental investigation of properly designed interconnected microgrids could simulate the behavior of the whole distribution grid and thus facilitate in the transition from the traditional to the smart electric grid. Two smart grid topologies are presented in this paper. The respective infrastructure for two small-scale microgrids, one for each topology, is presented. A first comparison between the two topologies is outlined and verified by the experimental investigation of the respective microgrids.

Improved Energy Storage Management and Strategies for PV Connected Smart Microgrids

“…SCUs are also necessary for the ac loads (or group of loads) and ac generators as shown in Fig. 1 [17], [18]. The SCUs are categorized in load SCUs (L-SCUs), generators SCUs (G-SCUs), storage SCUs (S-SCUs), and interconnection SCUs (I-SCUs), for connecting the small grid of the ac-bus to the remaining grid (SD).…”

“…Then, a brief description of the proposed iterative control algorithm is presented, whereas in the next section, the details are supplied on the energy storage management and the PV plants active power control strategies. Finally, the simulation results reveal that the new microgrid control strategies improve power supply reliability in grid connected and islanded situations [17] and [18].…”

Advanced energy storage and demand-side management in smart grids using buildings energy efficiency technologies

“…The last module is integrated into software that runs on a microgrid-dedicated PC. This topology is implemented at the facilities of the Technological Educational Institute of Western Macedonia [1], [9], [10].…”

“…This parameter is taken into account, since tests showed that switching on-off large loads could lead to great discharging currents, which in their turn are misleading indications for the correct estimation of the SoC by the linear method. The wrong SoC estimation can lead to unnecessary load rejection and thus decreased power supply reliability [9], [10]. Thus, the term "pseudo State of Charge" (pseudo-SoC) is defined as the SoC that is assigned to the batteries on purpose, when great discharging currents appear in a 2-minutes period and the (V mean-2 , I mean-2 ) point skips one of the above SoC areas, i.e.…”

“…During islanded operation of microgrids, accurate estimation and proper management of State of Charge (SoC) of energy storage systems are very important [7], [8]. In [9], [10] it is shown that improper control infrastructure and algorithms of a microgrid can affect grid operation negatively, leading to wrong SoC estimation and degradation of power supply reliability of customers. More specifically, undesirable control actions at islanding mode operation is reported, such as constant load switching, quick batteries charging and discharging, and insufficient exploitation of renewable energy sources, even in cases that matching of available supply, demand and storage has achieved.…”