Integration of Electric Springs and Multi-Port Transformers—A New Solution for AC Microgrids with Renewable Energy Sources

Abstract

Abstract:The new concept of integrating electric springs (ESs) and multi-port transformers (MTPs) as an active solution for energy management in alternating current (AC) microgrids is proposed. With an ES located at the port where storage devices previously were, the so-called critical flux is regulated to a constant value within the core of the transformer. The voltage on each winding is then clamped so that critical load (CL) voltage is regulated to a predefined value. The integration of ESs and MPTs can ensure a safer environment for ES utilization. Thus, the power generated by renewable energy sources can be safely used at residential locations with no need to worry about voltage fluctuations across CLs. Moreover, users can sell electricity to the power companies considered as CLs when the electricity generation of the AC microgrids or the home-installed renewable energy resources exceeds the personal consumption. In the paper, isolated topologies for ESs with three-and four-port transformers are examined, and a theoretical analysis of the ES operation is carried out. Then, equivalent circuits of the isolated ES topologies have been derived. Analysis of the ES operation and effectiveness of the isolated ES topologies are validated by both simulations and experiments.

Hardware structures, control strategies, and applications of electric springs: a state‐of‐the‐art review

“…For instance, an adjustment in the base topology of ES‐2 includes a multiport transformer with two or three secondary windings. The transformer's primary is connected to the V ES, and the secondary is connected in series with the non‐critical load [35, 36]. This topology provides isolation between the ES and the electric grid, as well as the capability to step‐up the voltage applied to the non‐critical load.…”

Review of the current challenges and methods to mitigate power quality issues in single‐phase microgrids

“…On the other hand, batteries have several known limitations such as a large footprint, short service life and high cost [82] which could limit the application of ESs in single‐phase microgrids. The third generation of electrical springs (ES‐3) replaces the batteries with a back‐to‐back single‐phase inverter [78, 85, 87] as shown in Fig. 9 c .…”

The State of the Art of Topologies for Electric Springs

“…Compared to non-isolated ES-2, Isolated ES-2 can provide the users with a safer environment because of the isolation among the network participants: microgrid, SLs and CLs. What's more, it extends the applications of the ESs due to many features, like the possibility for the users to sell high-quality electricity to the power companies and the voltage stabilization of more CLs when the power generation exceeds the local needs [21].…”

“…For single-phase ESs, the versions are sequenced in this paper as ES-1 [12], ES-2 [18] and ES-3 [19]. The others are modified versions of ES-2 [20][21][22].…”