Integration of Flexible Loads and Electric Spring Using a Three-Phase Inverter

In this article, a new structure of the electric spring (ES) system using a three-phase inverter is proposed. Noncritical or flexible loads associated with ES can be turned into a smart load. The smart load consumes power adaptively to achieve quick demand response in the future smart grid. Compared to previous ES topologies, the new structure of ES eliminates the battery storage and isolation transformer. The benefit of size and weight reduction results in further improvement on power density of the system. The control strategy is developed and the optimal operating condition for the new ES system is explicitly studied. Power inverter prototype has been built and tested to demonstrate not only the functionality but also the practicality of the new proposal. At the end of the article, the power capability of the new ES system is investigated and compared with previous ES to highlight its features.