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

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 threeand 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.